Medical Disclaimer: Written by a layperson with a need to understand and present valid data. This article presents data-driven analysis of publicly available epidemiological and clinical research regarding MMR vaccination. The author is not a medical professional, and this content is intended for informational and educational purposes only. It should not be considered medical advice, diagnosis, or treatment recommendations. Individual medical decisions should always be made in consultation with qualified healthcare providers who can evaluate your specific health circumstances, medical history, and risk factors. If you have questions or concerns about vaccination for yourself or your family members, please consult your physician, pediatrician, or other licensed healthcare professional. In medical emergencies, call 911 or seek immediate medical attention.
Bottom Line Up Front: Measles cases so far for the year were at 1,544 as of September 30, 2025. The highest since elimination in 2000. Some are questioning whether we still need the mumps and rubella components of the MMR vaccine, let alone the measles vaccine. The answer is unequivocal: yes. Mumps causes testicular inflammation in 40% of post-pubertal males, with 30-87% of bilateral cases resulting in infertility. Estimates of infertility after bilateral orchitis vary considerably across studies; small clinical series report rates up to 30–87% but larger surveillance data are less consistent. See clinical reviews. Rubella infection during early pregnancy carries a 90% risk of causing congenital rubella syndrome. Devastating birth defects including deafness, blindness, heart defects, and intellectual disability. The low case numbers we see today exist precisely because of vaccination. Meanwhile, serious vaccine side effects occur in roughly 1 in 40,000 doses and are typically temporary and treatable. The benefits overwhelmingly outweigh the risks, which is why stopping vaccination would be catastrophic.
In the Upstate region of South Carolina, eight cases of measles have officials on high alert. The October 2025 outbreak, the first significant cluster in the state in years, has reignited conversations about vaccine-preventable diseases. But amid justified concern about measles, a more dangerous question has emerged in some circles: if mumps and rubella cases are so rare, do we really still need those vaccines?
It’s a seductive argument. Measles dominates headlines with 1,544 cases in 2025 (as of September 30, 2025). Mumps? Just 226 cases (as of September 11, 2025). Rubella? Fewer than 10 annually. The numbers seem to suggest that mumps and rubella have been conquered, making those vaccine components unnecessary baggage in the MMR shot.
This reasoning is not just wrong—it’s dangerously backward. Those low numbers aren’t evidence that we don’t need the vaccines. They’re evidence that the vaccines work.
The South Carolina Wake-Up Call
South Carolina’s measles outbreak offers a preview of what happens when vaccination rates slip. On October 2, 2025, the South Carolina Department of Public Health confirmed what officials had feared: the state had a full-blown measles outbreak. Eight cases in the Upstate region, five of them epidemiologically linked in just the past month. All patients unvaccinated. Two cases with no known source of exposure, indicating unrecognized community spread.
“Measles is highly contagious, and there is risk for continued, rapid spread of the disease in the Upstate among communities with low immunization rates,” said Dr. Linda Bell, the state epidemiologist. Her warning applies equally to mumps and rubella – diseases that remain endemic globally and require only declining vaccination rates to resurge domestically.
The outbreak is part of a larger national crisis. As of September 30, 2025, the United States has recorded 1,544 confirmed measles cases, the highest number since measles was declared eliminated in 2000. Three people have died this year, the first measles deaths in the U.S. in a decade. Nationally, MMR vaccination coverage among kindergarteners has fallen below the 95% threshold needed for herd immunity, with some communities seeing much lower rates.
Among unvaccinated people with measles, about 1 in 5 are hospitalized, 1 in 20 children may develop pneumonia, and about 1–3 per 1,000 may die. Figures drawn from CDC clinical data.
This is what vaccine hesitancy looks like in practice. And measles is just the canary in the coal mine.
See: 🏛️ South Carolina Department of Public Health: DPH Confirms Measles Outbreak in Upstate Region, 🏛️ CDC Measles Cases and Outbreaks, 📊 CDC MMWR: Measles Update United States January-April 2025, 🏛️ CDC Measles Clinical Data
The Mumps Case: More Than Just Swollen Cheeks
The argument that mumps vaccination is no longer necessary rests on a fundamental misunderstanding of what mumps actually does. Yes, cases are relatively rare with 226 reported as of September 2025. But mumps isn’t just puffy cheeks and a tender jaw. For post-pubertal males, it’s a legitimate threat to fertility.
The Orchitis Reality
Orchitis, inflammation of the testicles, is the most feared complication of mumps, and it occurs with concerning frequency. According to the CDC Pink Book, orchitis occurs in approximately 30% of unvaccinated and 6% of vaccinated post-pubertal males, demonstrating that vaccination substantially reduces this risk. Some clinical reviews and outbreak cohorts report rates approaching 40% in certain adult male populations, though estimates vary across studies and settings. That’s not a rare complication. It’s a substantial risk that vaccination significantly mitigates.
The condition typically appears 4-8 days after parotid gland swelling, though it can occur up to 6 weeks later. In 10-30% of orchitis cases, both testicles are affected. The pain is severe. The swelling is dramatic. And the long-term consequences can be devastating.
Between 30-50% of affected testicles show testicular atrophy, permanent shrinkage. This isn’t cosmetic. It’s functional damage. Impaired fertility occurs in approximately 13% of patients who develop mumps orchitis. But when both testicles are involved – bilateral orchitis – the infertility rate jumps to between 30% and 87%, depending on the study. Estimates of infertility after bilateral orchitis vary considerably across studies; small clinical series from outbreak settings report rates up to 30–87%, while larger surveillance studies show more variable results. Readers should consult clinical reviews for study-level detail on these estimates.
Think about those numbers. A disease that we can prevent with a vaccine carries a 40% risk of testicular inflammation in adult males. Of those cases, up to 87% with bilateral involvement may become infertile. This isn’t theoretical. This is young men losing their ability to have biological children because of a preventable viral infection.
The Deafness Risk
Mumps can also cause permanent hearing loss, though it’s relatively rare. Permanent deafness occurs in approximately 1 in 20,000 mumps cases. About 1 in 25 people with mumps experience temporary hearing loss, but permanent loss of hearing is uncommon. When it does occur, it primarily affects unilateral hearing (only 20% bilateral).
The onset is sudden. Tinnitus, ataxia, and vomiting precede permanent hearing loss. There’s no treatment. Once the auditory nerve is damaged, it’s permanent. A preventable vaccine could have stopped it.
Why Low Numbers Don’t Mean Low Risk
The 226 mumps cases in 2025 represent successful vaccination, not disease irrelevance. The mumps vaccination program, which began in 1967, has resulted in a more than 99% decrease in cases. In 1968, there were 152,209 mumps cases. By 2003, that number had fallen to just 231.
But mumps hasn’t disappeared. It remains endemic globally, and outbreaks still occur in the United States, particularly in settings with close contact like college campuses and close-knit communities. During the 2004-2005 outbreak in England and Wales, 6.1% of estimated mumps patients were hospitalized, 4.4% developed orchitis, 0.35% developed meningitis, and 0.33% developed pancreatitis.
If we stop vaccinating, those numbers don’t stay at 226. They return to pre-vaccine levels. And with them comes the 40% orchitis rate, the permanent deafness, the meningitis, the encephalitis. The low case numbers aren’t proof we don’t need the vaccine. They’re proof the vaccine works.
See: 🏛️ CDC Mumps Cases and Outbreaks, 🏛️ CDC Pink Book,📊 PMC: Mumps Orchitis Clinical Aspects and Mechanisms, 📊 PMC: Mumps Complications England Wales 2002-2006, 🎯 NHS: Mumps Complications, 🎯 Mayo Clinic: Mumps
The Rubella Case: Why We Vaccinate for Nine Months of Pregnancy
If the mumps argument rests on misunderstanding disease severity, the rubella argument collapses under the weight of what congenital rubella syndrome actually does to babies. This is where the “low case numbers” logic becomes not just wrong but morally indefensible.
Rubella was eliminated from the United States in 2004. Since then, fewer than 10 cases are reported annually, and most are imported from international travel. So why keep vaccinating?
Because pregnant women still exist. And when they contract rubella, the consequences are catastrophic.
Congenital Rubella Syndrome: A 90% Nightmare
When a pregnant woman contracts rubella during early pregnancy, she has up to a 90% chance of passing the virus to her developing fetus. If infection occurs during the first 11 weeks after conception, the infant has a 90% risk of being affected by congenital rubella syndrome. If infection occurs between weeks 12-20, the risk drops to 20%. After the fourth month, maternal rubella infection is less likely to harm the fetus. Rubella infection during early pregnancy carries up to a ~90% risk of congenital rubella syndrome and devastating birth defects.
But that first trimester window, when many women don’t yet know they’re pregnant, is devastating. Congenital rubella syndrome can cause:
- Hearing loss and deafness (one of the most common defects)
- Cataracts and glaucoma (congenital blindness)
- Congenital heart disease (patent ductus arteriosus, peripheral pulmonary artery stenosis, ventricular and atrial septal defects)
- Intellectual disability and developmental delays
- Microcephaly (abnormally small head)
- Neurodevelopmental disorders: Congenital rubella syndrome has been associated with markedly higher rates of neurodevelopmental disorders (including autistic-spectrum features) in historical CRS cohorts; modern reviews advise interpreting this within the larger literature on congenital infection and neurodevelopment
- Hepatosplenomegaly (enlarged liver and spleen)
- Thrombocytopenic purpura (bleeding disorders)
- Bone disease and growth retardation
Rubella infection during pregnancy can also result in miscarriage, stillbirth, or fetal death. The developing baby is at risk for severe birth defects with devastating, lifelong consequences. Many complications are apparent at birth, but some, like developmental delays, autism, diabetes, and thyroid disease, may not appear until weeks, months, or years later.
The Global Burden
While the United States has maintained rubella elimination status since 2004, congenital rubella syndrome remains a global public health concern with more than 100,000 cases reported annually worldwide. This matters because rubella is still common in many parts of the world, and international travel can bring the virus back to the United States.
The virus spreads through respiratory droplets when an infected person coughs or sneezes. Up to 50% of infections may be asymptomatic, meaning infected individuals don’t know they’re spreading the virus. Infants born with congenital rubella syndrome can continue to shed the virus in nasopharyngeal secretions and urine for a year or more, posing ongoing transmission risks.
Why “Just Don’t Get Pregnant” Isn’t an Answer
Some might argue that if only pregnant women are at risk, we could simply ensure pregnant women are vaccinated rather than vaccinating everyone. This reasoning fails on multiple fronts.
First, the MMR vaccine is a live attenuated vaccine and cannot be given during pregnancy due to theoretical teratogenic risk. Women must be vaccinated at least 28 days before conception. But nearly half of pregnancies in the United States are unplanned. Meaning many women become pregnant before they can ensure vaccination.
Second, herd immunity protects pregnant women who cannot be vaccinated or whose immunity has waned. When vaccination rates fall below 95%, rubella can circulate in communities, putting every pregnant woman at risk regardless of her vaccination status.
Third, we don’t live in isolated bubbles. An unvaccinated person who contracts rubella abroad and brings it home can trigger chains of transmission. If that chain reaches a pregnant woman, even a vaccinated one, since no vaccine is 100% effective, the result could be a child born with devastating, preventable birth defects.
The 1962-1965 rubella pandemic in the United States resulted in an estimated 12.5 million rubella cases and 20,000 cases of congenital rubella syndrome. Babies were born deaf, blind, with heart defects, with intellectual disabilities. This is what happens when rubella circulates freely. This is what vaccination prevents.
See: 🏛️ CDC Impact of U.S. MMR Vaccination Program – Rubella, 🏛️ CDC Clinical Overview of Rubella, 🏛️ CDC CRS, 📊 StatPearls: Congenital Rubella, 🎯 Cleveland Clinic: Congenital Rubella Syndrome, 🎯 Mayo Clinic: Rubella, 📊 CDC MMWR: CRS Incidence, 🌍 ECDC: Congenital Rubella Syndrome
The Vaccine Risk Reality: What the Data Actually Shows
Every medical intervention carries risks. The MMR vaccine is no exception. But the risks are far smaller. And far less severe than the diseases it prevents. Let’s examine what adverse events actually look like.
Common, Mild Side Effects
The most common side effects of MMR vaccination are mild and temporary:
- Sore arm from the injection or redness where the shot is given
- Fever (usually low-grade)
- Mild rash
- Swelling of glands in the cheeks or neck
- Temporary pain and stiffness in joints (mostly in teenage or adult women who did not already have immunity to the rubella component)
These occur in a small percentage of vaccinated individuals and resolve on their own within days. They’re uncomfortable, not dangerous.
Rare Serious Reactions
More serious reactions happen rarely:
Febrile seizures: These can occur after MMR vaccination, though they are rare and have not been associated with any long-term effects or permanent damage. Because the risk of febrile seizures increases as infants get older, it’s recommended that they get vaccinated as soon as recommended to minimize risk.
Immune thrombocytopenic purpura (ITP): This is a disorder that decreases the body’s ability to stop bleeding. The risk of ITP has been shown to be increased in the six weeks following MMR vaccination, with one study estimating 1 case per 40,000 vaccinated children. However, ITP is usually not life-threatening. Treatment may include blood transfusion and medications, and most cases resolve without long-term complications. The excess ITP risk after MMR is small. Roughly 1 case per 40,000 doses, and most cases are transient and treatable. (cases as of September 30, 2025).
Importantly, ITP can also happen after natural measles infection and at higher rates than after vaccination. The vaccine prevents more cases of ITP than it causes.
Severe allergic reactions: As with any medicine, there is a very remote chance of a vaccine causing a severe allergic reaction. Anyone who has ever had a life-threatening allergic reaction to the antibiotic neomycin or any other component of MMR vaccine should not get the vaccine.
Contraindications: People with serious immune system problems should not get MMR vaccine, as it may cause an infection that could be life-threatening in immunocompromised individuals. Pregnant women should not receive the vaccine due to theoretical risk to the fetus.
The Risk-Benefit Calculation
Let’s put these numbers in perspective:
Vaccine serious adverse event risk: Approximately 1 in 40,000 doses (temporary, usually treatable ITP)
Disease serious complication risks without vaccine:
- Measles: 1 in 5 hospitalized, 1 in 20 develop pneumonia, 1-3 in 1,000 die
- Mumps: 40% develop orchitis (males), 13-87% infertility with bilateral orchitis, 1 in 20,000 permanent deafness
- Rubella: 90% chance of CRS if infected in first trimester of pregnancy, causing deafness, blindness, heart defects, intellectual disability
The mathematics are unambiguous. The risk of serious harm from the diseases is orders of magnitude higher than the risk of serious harm from the vaccine. Two doses of MMR vaccine are 97% effective at preventing measles and rubella, and 86% effective at preventing mumps.
The Autism Myth
No discussion of MMR vaccine safety would be complete without addressing the autism claim. Multiple large-scale studies across multiple countries have found no link between the MMR vaccine and autism. The original study claiming such a link was fraudulent, has been retracted, and the physician who published it lost his medical license.
Scientists in the United States and other countries have carefully studied the MMR vaccine, and none has found a link between autism and the MMR vaccine. The overwhelming scientific consensus is clear: MMR vaccine does not cause autism.
See: 🏛️ CDC: MMR Vaccine Safety, 🏛️ CDC: Possible Side Effects from Vaccines, 🏛️ CDC: MMR Vaccine VIS, 🏛️ CDC: Measles Vaccination, 🎯 Cleveland Clinic: MMR Vaccine, 🏛️ NIH Library of Medicine, 🏛️NIH PMC, 🎯 WebMD: Adult MMR Vaccine Guidelines
Why Low Numbers Are Not Evidence of Safety to Stop
The circular logic trap is seductive: “Cases are low, therefore we don’t need the vaccine.” But this confuses effect with cause. Cases are low precisely because we have the vaccine. Remove the vaccine, and cases return to pre-vaccination levels.
The Historical Record
Before vaccines, these diseases were endemic:
- Measles: 3-4 million cases annually before 1963 vaccine introduction
- Mumps: 152,209 cases in 1968, first year after vaccination program began
- Rubella: 12.5 million cases during the 1962-1965 pandemic, resulting in 20,000 congenital rubella syndrome cases
Vaccination didn’t just reduce these numbers—it nearly eliminated them. But “eliminated” doesn’t mean “eradicated.” All three viruses still circulate globally. International travel, unvaccinated travelers, and declining vaccination rates can reintroduce and spread these diseases rapidly.
The UK’s Mumps Lesson
The United Kingdom provides a cautionary tale. Following the discredited and fraudulent Wakefield autism study in 1998, MMR vaccination rates in the UK plummeted. By 2003, national MMR coverage had fallen to 82%, with some areas below 75%.
The result? Sharp increases in mumps cases and mumps orchitis. Between March and September 2005, 11 patients with mumps orchitis were admitted to one UK unit alone. Another hospital reported 25 cases of mumps orchitis between September 2004 and April 2005. The affected age group? Young adults who had either never received the MMR vaccine or had received only a single dose.
These weren’t historical cases from the pre-vaccine era. These were young men in the 2000s losing fertility because vaccination rates had dropped. The outbreak demonstrated conclusively that declining vaccination leads directly to disease resurgence and that mumps orchitis remains a real threat when the virus circulates.
The Measles Warning
We’re watching this play out in real-time with measles. The United States declared measles eliminated in 2000. For years, cases remained low. Fewer than 100 annually in many years. Then vaccination rates began to slip.
2019 saw 1,274 measles cases, the highest since elimination. 2025 has already surpassed that with 1,544 cases as of September 30. Three deaths this year – the first in a decade. Multiple outbreaks across dozens of states. The U.S. risks losing its measles elimination status if transmission continues for 12 consecutive months.
Measles is resurging not because the virus changed, but because vaccination rates dropped below the 95% threshold needed for herd immunity. The same will happen with mumps and rubella if we stop vaccinating. The viruses haven’t gone anywhere. They’re waiting.
See: 📊 PMC: Mumps orchitis, 🏛️ CDC: History of Measles, 📊 Wikipedia: Measles resurgence, 📊 Johns Hopkins IVAC
The Global Reality: Endemic Everywhere Else
The United States exists in a globalized world. Even if we somehow achieved 100% vaccination domestically, these diseases would remain endemic in much of the world. International travel, both Americans going abroad and visitors coming here, constantly reintroduce these viruses.
Measles Global Status
Globally, measles remains a major killer. In 2023, an estimated 10.3 million people were infected with measles worldwide. Right now, measles outbreaks are happening in every region of the world. Between 2000 and 2023, measles vaccination prevented an estimated 60 million deaths globally.
Canada is experiencing its worst measles activity in years, with 5,006 cases in 2025. Alberta has recorded 1,914 measles cases since March 2025 alone, with two children dying – including a premature infant whose mother contracted measles during pregnancy.
Mumps and Rubella Worldwide
Mumps remains common in many countries despite widespread vaccination programs. Many nations have not yet achieved high coverage rates, meaning travelers can easily encounter the virus abroad. College students studying abroad, businesspeople traveling internationally, and tourists all risk exposure.
Rubella continues to circulate in regions where vaccination programs are not yet universal. As of 2023, 175 of 194 WHO member countries (90%) had introduced rubella-containing vaccine—which means 19 countries still have not. In these countries, an estimated 24,000 congenital rubella syndrome cases occurred in 2019, representing 75% of the estimated 32,000 cases worldwide.
The Travel Connection
Most rubella cases in the United States since 2012 have evidence of infection while living or traveling outside the country. The same pattern holds for measles and mumps. Unvaccinated individuals contract these diseases abroad and bring them home, where they can spread to other unvaccinated individuals and, occasionally, to vaccinated individuals (no vaccine is 100% effective).
In April 2025, Mexico issued a warning for people traveling to the United States and Canada due to high measles case rates. The CDC has stepped up its guidance for travelers, advising that anyone traveling internationally should be vaccinated with two doses of the MMR vaccine.
We cannot wall off the United States from global disease circulation. We can only protect ourselves through vaccination.
See: 🏛️ CDC: Global Measles Outbreaks, 🏛️ WHO: Measles United States of America, 📊 CDC MMWR: CRS Incidence, 🌍 PAHO: Rubella, 📊 CIDRAP
What Stopping Vaccination Would Actually Mean
Let’s be explicit about what would happen if we stopped mumps and rubella vaccination based on current low case numbers.
The Mumps Scenario
Current state: 226 cases in 2025. 40% of post-pubertal males who get mumps develop orchitis. That’s approximately 90 cases of orchitis this year among the cases we know about.
Without vaccination: We return toward pre-vaccination levels. In 1968, there were 152,209 mumps cases. If 40% of post-pubertal males in that population developed orchitis, we’d be looking at tens of thousands of orchitis cases annually. With 30-87% of bilateral cases resulting in infertility, we’d be looking at thousands of young men losing fertility every year.
We’d also see increased cases of mumps meningitis (which occurred in 0.35% of cases in the UK outbreak), pancreatitis (0.33% of cases), and permanent deafness (1 in 20,000 cases). Scale that to pre-vaccine case levels, and the human cost becomes staggering.
The Rubella Scenario
Current state: Fewer than 10 cases annually (2024 data), nearly all imported. Zero to a handful of congenital rubella syndrome cases per year. Rubella elimination maintained since 2004.
Without vaccination: Rubella would begin circulating domestically again. With approximately 3.7 million births annually in the United States, even a small percentage of pregnant women contracting rubella in the first trimester would result in hundreds or thousands of babies born with congenital rubella syndrome each year.
These babies would be born deaf, blind, with heart defects, with intellectual disabilities, with autism. They would require lifelong medical care, special education, assistive devices, and support services. The economic cost would be in the billions. The human cost would be immeasurable.
And unlike mumps orchitis, which affects only the individual who contracts mumps, congenital rubella syndrome creates a lifetime of disability for an infant who had no choice in the matter. Every case represents a preventable tragedy.
The Herd Immunity Collapse
Both scenarios assume all else remains equal, that only mumps and rubella vaccination stops while measles vaccination continues. But vaccination behavior isn’t isolated. If public health authorities signal that mumps and rubella vaccines are unnecessary, confidence in all vaccines erodes.
We’d likely see further declines in overall MMR coverage, accelerating the measles resurgence we’re already experiencing. We might see declining confidence in other childhood vaccines. The result would be resurgence not just of mumps and rubella, but of multiple vaccine-preventable diseases simultaneously.
The social cost would extend beyond disease burden. Outbreaks close schools. They strain healthcare systems. They create fear and disruption in communities. They hit vulnerable populations – infants too young to be vaccinated, immunocompromised individuals who cannot be vaccinated, and pregnant women – the hardest.
See: 🏛️ CDC: Routine MMR Vaccination Recommendations, 🏛️ HHS: Maintain elimination of measles, rubella, CRS, and polio
The Verdict: Benefits Overwhelmingly Outweigh Risks
The case for continued mumps and rubella vaccination isn’t close. It’s overwhelming.
For Mumps:
- Disease risk: 40% orchitis rate in adult males, up to 87% infertility with bilateral involvement, permanent deafness, meningitis, pancreatitis
- Vaccine risk: Approximately 1 in 40,000 chance of temporary, treatable ITP; mild side effects in small percentage
- Current low cases: Direct result of vaccination success, not evidence of disease irrelevance
- Without vaccination: Return to 150,000+ annual cases, thousands of orchitis cases, hundreds of permanent disabilities
For Rubella:
- Disease risk: 90% chance of CRS in first trimester pregnancy, causing deafness, blindness, heart defects, intellectual disability, autism
- Vaccine risk: Approximately 1 in 40,000 chance of temporary, treatable ITP; temporary joint pain in some adult women; mild side effects
- Current low cases: Direct result of elimination through vaccination, maintained only by continued high coverage
- Without vaccination: Hundreds to thousands of babies born annually with devastating, permanent birth defects
The Mathematics:
- Vaccine serious adverse event: ~1 in 40,000 (temporary, treatable)
- Mumps serious complication: 40% orchitis, 13-87% infertility, permanent deafness
- Rubella serious complication: 90% CRS in first trimester, lifetime disability
The benefits of MMR vaccination are measured in millions of prevented cases, thousands of prevented deaths, and countless avoided disabilities. The risks are measured in rare, usually temporary, treatable adverse events.
This isn’t a close call. This isn’t a matter of opinion. This is what the data shows, unequivocally.
Conclusion: Low Numbers Are Success, Not Permission to Stop
South Carolina’s measles outbreak is a warning. It shows what happens when vaccination rates slip and disease prevention gives way to disease crisis. Eight cases in the Upstate. All unvaccinated. Evidence of community spread.
The question isn’t whether we should stop vaccinating for mumps and rubella because case numbers are low. The question is whether we understand why case numbers are low in the first place.
Those low numbers represent one of public health’s greatest achievements. The near-elimination of diseases that once caused millions of cases, thousands of deaths, and countless disabilities. They represent generations of children who didn’t go deaf from mumps, young men who remained fertile, babies who weren’t born with devastating birth defects.
They represent vaccines working exactly as intended.
The moment we treat success as permission to stop is the moment we begin the slide back toward pre-vaccine disease levels. We’ve seen it with measles – 1,544 cases in 2025, the highest since elimination. We saw it in the UK with mumps when vaccination rates dropped. We see it globally in regions where vaccination programs haven’t reached universal coverage.
The viruses haven’t changed. They haven’t become less dangerous. They haven’t disappeared. They’re still endemic in most of the world, still capable of rapid spread, still capable of causing the same complications they always did.
What changed was vaccination. What protects us is vaccination. What would put us back at risk is stopping vaccination.
The data is clear. The risks of disease far exceed the risks of vaccination. The benefits of vaccination far exceed any theoretical benefit of avoiding a vaccine with a 1 in 40,000 serious adverse event rate.
We still need mumps and rubella vaccines. We need them as much today as we did before these diseases were eliminated. Because elimination isn’t eradication. It’s sustained success that requires sustained effort.
The alternative—returning to a world where young men routinely lose fertility to mumps orchitis, where babies are routinely born deaf and blind from congenital rubella syndrome—is unconscionable when we have safe, effective vaccines that prevent it.
Low case numbers aren’t evidence we can stop. They’re evidence we must continue.
Methodology
This analysis examines the scientific evidence for continued mumps and rubella vaccination despite low current case numbers. The analysis synthesizes data from multiple sources:
Epidemiological Data: Current case counts from CDC surveillance systems (2025 data through September 30), historical case data from pre-vaccine eras, outbreak data from U.S. and international sources, and elimination status documentation.
Disease Complication Rates: Peer-reviewed studies on mumps orchitis incidence and infertility outcomes, congenital rubella syndrome risk by trimester, permanent disability rates from natural infections, and hospitalization and mortality data.
Vaccine Safety Data: CDC and FDA vaccine adverse event monitoring systems, clinical trial safety data, post-market surveillance studies, and comparative risk analysis between vaccine adverse events and disease complications.
International Comparisons: WHO global disease burden estimates, comparative vaccination program outcomes, case studies of vaccination rate declines and disease resurgence (UK mumps, U.S. measles), and global elimination/eradication efforts.
Risk-Benefit Analysis: Quantitative comparison of vaccine adverse event rates versus disease complication rates, population-level impact projections, herd immunity threshold modeling, and cost-benefit analyses from public health literature.
All statistical claims are verified against primary sources. The analysis examines why low current case numbers represent vaccination success rather than evidence that vaccination is no longer necessary, and quantifies the risks of stopping vaccination programs.
Data Availability: Most recent complete epidemiological data is through September 30, 2025 for measles and mumps cases, 2024 for rubella cases. Vaccine safety data draws on decades of post-licensure surveillance. Disease complication rates are based on clinical studies spanning multiple decades and geographic regions.
Research Collaboration: This analysis represents comprehensive research across epidemiology, vaccinology, public health policy, and medical literature. Human strategic analysis identified the logical fallacy in the “low numbers mean we don’t need vaccines” argument and structured the rebuttal around quantitative risk-benefit analysis.
Sources
Source Legend
🏛️ = Government Data & Reports
📊 = Academic Research & Studies
💼 = Economic & Labor Analysis
🌍 = International Comparisons
🔵 = Left-leaning Sources
🔴 = Right-leaning Sources
🎯 = Centrist Sources
🏛️ Government Data & Reports
🏛️ South Carolina Department of Public Health: DPH Confirms Measles Outbreak in Upstate Region
October 2, 2025 outbreak confirmation, eight cases including five epidemiologically linked, unvaccinated patients, community spread evidence
https://dph.sc.gov/news/dph-confirms-measles-outbreak-upstate-region
🏛️ CDC: Measles Cases and Outbreaks
1,544 confirmed cases as of September 30, 2025; highest since elimination in 2000; outbreak definitions and tracking
https://www.cdc.gov/measles/data-research/index.html
🏛️ CDC: Mumps Cases and Outbreaks
226 cases as of September 11, 2025; vaccination program history; 99%+ decrease since 1967; outbreak patterns
https://www.cdc.gov/mumps/outbreaks/index.html
🏛️ CDC: Impact of U.S. MMR Vaccination Program – Rubella
Elimination status since 2004; fewer than 10 cases annually; 20th anniversary of elimination; pre-vaccine era comparison
https://www.cdc.gov/rubella/vaccine-impact/index.html
🏛️ CDC: Clinical Overview of Rubella
Clinical presentation, transmission patterns, 99%+ incidence decrease from pre-vaccine era, import-related cases
https://www.cdc.gov/rubella/hcp/clinical-overview/index.html
🏛️ CDC: Measles, Mumps, Rubella (MMR) Vaccine Safety
Common side effects, rare serious reactions, ITP incidence (1 per 40,000), febrile seizure data, contraindications
https://www.cdc.gov/vaccine-safety/vaccines/mmr.html
🏛️ CDC: Possible Side Effects from Vaccines
Comprehensive vaccine adverse event data, frequency of side effects, serious reaction rates across all vaccines
https://www.cdc.gov/vaccines/basics/possible-side-effects.html
🏛️ CDC: MMR Vaccine Information Statement (VIS)
Official vaccine information: what MMR prevents, who should get it, timing, risks and benefits, contraindications
https://www.cdc.gov/vaccines/hcp/current-vis/mmr.html
🏛️ CDC: Measles Vaccination
Two-dose schedule, effectiveness (97% measles/rubella, 86% mumps), lifetime protection, international travel recommendations
https://www.cdc.gov/measles/vaccines/index.html
🏛️ CDC: Routine MMR Vaccination Recommendations for Providers
Healthcare personnel requirements, outbreak response protocols, presumptive evidence of immunity, catch-up schedules
https://www.cdc.gov/vaccines/vpd/mmr/hcp/recommendations.html
🏛️ CDC: History of Measles
Pre-vaccine era: 3-4 million cases annually, 400-500 deaths per year; vaccine introduction 1963; elimination declared 2000
https://www.cdc.gov/measles/about/history.html
🏛️ CDC: Global Measles Outbreaks
10.3 million global cases in 2023; outbreaks in every world region; international travel risks; elimination status by country
https://www.cdc.gov/global-measles-vaccination/data-research/global-measles-outbreaks/index.html
🏛️ CDC: Mumps Symptoms and Complications
Orchitis, oophoritis, meningitis, encephalitis, pancreatitis, deafness; complication rates; recovery timelines
https://www.cdc.gov/mumps/signs-symptoms/index.html
🏛️ CDC: Fast Facts – Rubella and Congenital Rubella Syndrome
90% CRS risk in first trimester; global burden 100,000+ cases annually; vaccine-preventable birth defects
https://www.cdc.gov/global-rubella-vaccination/data-research/facts-stats/index.html
🏛️ HHS: Maintain Elimination of Measles, Rubella, CRS, and Polio
Healthy People 2030 objectives; elimination status maintenance; vaccination coverage targets; threat assessment
https://odphp.health.gov/healthypeople/objectives-and-data/browse-objectives/infectious-disease/maintain-elimination-measles-rubella-congenital-rubella-syndrome-and-polio-iid-01
🏛️ WHO: Disease Outbreak News – Measles United States of America
378 cases January-March 2025; two deaths (first in decade); international notification; outbreak characterization
https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON561
📊 Academic Research & Studies
📊 CDC MMWR: Measles Update – United States, January 1-April 17, 2025
800 cases through April 17; 82% associated with New Mexico/Oklahoma/Texas outbreak; 85 hospitalizations; three deaths
https://www.cdc.gov/mmwr/volumes/74/wr/mm7414a1.htm
📊 CDC MMWR: Estimated Current and Future Congenital Rubella Syndrome Incidence
24,000 CRS cases in 19 countries without vaccination; 75% of global cases; projected impact of universal vaccination
https://www.cdc.gov/mmwr/volumes/74/wr/mm7418a3.htm
📊 PMC: Mumps Orchitis – Clinical Aspects and Mechanisms
40% orchitis rate in young adult men; bilateral in 10-30%; 30-50% testicular atrophy; 13% impaired fertility; 30-87% infertility with bilateral involvement
https://pmc.ncbi.nlm.nih.gov/articles/PMC8013702/
📊 PMC: Mumps Complications and Effects of Mumps Vaccination, England and Wales, 2002-2006
2004-2005 outbreak: 6.1% hospitalized, 4.4% orchitis, 0.35% meningitis, 0.33% pancreatitis; vaccination reduced risks significantly
https://pmc.ncbi.nlm.nih.gov/articles/PMC3377415/
📊 PMC: Mumps orchitis (UK 2005 outbreak)
Sharp increase when vaccination rates dropped; 11 cases March-September 2005 in one unit; 25 cases in another hospital; affected unvaccinated young adults
https://pmc.ncbi.nlm.nih.gov/articles/PMC1633545/
📊 StatPearls: Congenital Rubella
Global burden 100,000+ cases annually; natural rubella infection one of few known causes of autism; first trimester 90% risk; pathogenesis mechanisms
https://www.ncbi.nlm.nih.gov/books/NBK507879/
📊 Wikipedia: Measles resurgence in the United States
Elimination 2000; 2019 outbreak 1,274 cases; 2025 outbreak timeline; state of emergency declarations; vaccination rate declines
https://en.wikipedia.org/wiki/Measles_resurgence_in_the_United_States
📊 Johns Hopkins IVAC: U.S. Measles Cases Hit Highest Level Since Declared Eliminated in 2000
1,281 cases as of July 7, 2025; exceeds 2019 record; unvaccinated/unknown status comprise nearly all cases; elimination status at risk
https://publichealth.jhu.edu/ivac/2025/us-measles-cases-hit-highest-level-since-declared-eliminated-in-2000
📊 CIDRAP: Another Canadian baby dies from measles as South Carolina reports outbreak
Canadian premature infant death; mother contracted measles during pregnancy; Alberta 1,914 cases since March; global context
https://www.cidrap.umn.edu/measles/another-canadian-baby-dies-measles-south-carolina-reports-outbreak
📊 ScienceDirect: Maternal exposure to rubella infection elevates risk of CRS
85% severe birth defects if first trimester infection; 100,000 global CRS cases annually; teratogenic mechanisms; timing criticality
https://www.sciencedirect.com/science/article/abs/pii/S0074774225000236
📊 Wikipedia: Congenital rubella syndrome
90% risk weeks 0-11 after conception; 20% risk weeks 12-20; clinical definition criteria; diagnostic methods; multidisciplinary management
https://en.wikipedia.org/wiki/Congenital_rubella_syndrome
📊 PubMed: Changing epidemiology of congenital rubella syndrome in the United States
122 CRS cases 1985-1996; 44% Hispanic infants; 81% missed postpartum vaccination opportunities; prevention importance
https://pubmed.ncbi.nlm.nih.gov/9728530/
📊 Medscape: Pediatric Rubella Overview
1962-1965 epidemic: 12.5 million U.S. cases, 20,000 CRS cases; vaccination coverage history; incidence decline; elimination progress
https://emedicine.medscape.com/article/968523-overview
📊 Medscape: Mumps Practice Essentials
One-third post-pubertal males develop orchitis; 35% testicular atrophy; 13% impaired fertility; permanent deafness 0.5-5 per 100,000; pancreatitis 5%
https://emedicine.medscape.com/article/966678-overview
📊 Wikipedia: Mumps
Case-fatality rate 1.6-3.8 per 10,000; orchitis 20-30% post-pubertal males; 30-50% testicular atrophy; vaccine strain comparison; global epidemiology
https://en.wikipedia.org/wiki/Mumps
📊 ScienceDirect: Characteristics of reported mumps cases in the United States 2018-2023
8,006 cases 2018-2023; 85.4% occurred pre-April 2020; COVID-19 pandemic effect on transmission; age distribution shifts; endemic status maintained
https://www.sciencedirect.com/science/article/abs/pii/S0264410X24008053
🎯 Centrist Sources
🎯 Cleveland Clinic: MMR Vaccine Overview
What vaccine prevents, who should get it, effectiveness rates, side effects, contraindications; patient education resource
https://my.clevelandclinic.org/health/procedures/mmr-vaccine
🎯 Cleveland Clinic: Congenital Rubella Syndrome
CRS complications by system; up to 85% risk in first 12 weeks; diagnosis and management; prevention through pre-pregnancy vaccination
https://my.clevelandclinic.org/health/diseases/congenital-rubella-syndrome
🎯 Cleveland Clinic: Mumps Overview
Symptoms, complications by age and sex; orchitis, oophoritis, meningitis, deafness; vaccine protection; mild vs serious disease
https://my.clevelandclinic.org/health/diseases/15007-mumps
🎯 Mayo Clinic: Mumps Symptoms and Causes
Complication rates post-puberty; orchitis fertility impact; encephalitis; hearing loss; pancreatitis; miscarriage risk; vaccine importance
https://www.mayoclinic.org/diseases-conditions/mumps/symptoms-causes/syc-20375361
🎯 Mayo Clinic: Rubella Symptoms and Causes
Pregnancy risks; CRS as leading cause of congenital deafness; first trimester danger; MMR protection; autism link debunked
https://www.mayoclinic.org/diseases-conditions/rubella/symptoms-causes/syc-20377310
🎯 WebMD: Adult MMR Vaccine Guidelines
Who needs vaccination, timing, contraindications, pregnancy precautions, benefits vs risks, side effect management
https://www.webmd.com/vaccines/adult-mmr-vaccine-guidelines
🎯 NHS (UK): Mumps Complications
1 in 3 males post-puberty develop orchitis; 1 in 25 temporary hearing loss; 1 in 20,000 permanent deafness; joint pain in adults
https://www.nhs.uk/conditions/mumps/complications/
🎯 Boston Children’s Hospital: Congenital Rubella
First trimester most dangerous; fourth month+ less likely to harm; no cure for CRS; heart defects often correctable; nervous system damage irreversible
https://www.childrenshospital.org/conditions/congenital-rubella
🎯 Mount Sinai: Congenital Rubella Information
Rash at birth, low birth weight, small head, heart abnormalities, visual problems; treatment symptom-based; outcome depends on severity
https://www.mountsinai.org/health-library/diseases-conditions/congenital-rubella
🌍 International Comparisons
🌍 ECDC: Congenital Rubella Syndrome
85 per 100 affected if infection in first three months pregnancy; infant virus shedding up to one year; EU vaccination schedules
https://www.ecdc.europa.eu/en/congenital-rubella-syndrome
🌍 PAHO: Rubella
Americas declared rubella-free 2015; MMR adoption timeline; surveillance strategies; regional framework for elimination maintenance
https://www.paho.org/en/topics/rubella
🌍 WHO: Immunization Data Portal – Mumps
Global mumps case reporting; vaccination program tracking; regional aggregate data; country-specific immunization coverage
https://immunizationdata.who.int/global/wiise-detail-page/mumps-reported-cases-and-incidence
