David Bridges
The alarming resurgence of measles cases in the U.S. and globally has raised critical questions for many individuals: How well protected am I against measles, and should I consider receiving a booster vaccination? Understanding your immunity status is essential, especially as the disease becomes more prevalent.
It is crucial to highlight that the measles, mumps, and rubella (MMR) vaccine is remarkably effective, offering approximately 97% protection against measles when the standard two-dose regimen is administered. The majority of Americans have been vaccinated with the MMR vaccine, primarily due to widespread childhood immunization programs initiated across the nation beginning in the 1980s, which have significantly reduced the incidence of these diseases.
These vaccination programs mandate that children receive various vaccines to enroll in public schools, although families may obtain medical or personal exemptions based on state regulations. As we enter the 2023-2024 school year, it’s estimated that around 93% of school-aged children in the U.S. have received their MMR vaccinations. However, this percentage has slightly declined in recent years, now falling below the community immunity threshold necessary to effectively curtail the spread of this highly contagious virus, contributing to the recent outbreaks.
The ongoing measles outbreaks in Texas, New Mexico, and Oklahoma, now exceeding 500 confirmed cases, are primarily occurring in communities with low vaccination rates. Those who are unvaccinated, particularly very young children, are significantly more susceptible to contracting measles. Therefore, it is essential to evaluate specific scenarios where individuals might need or want to receive catch-up vaccinations to bolster their immunity.
Walter Orenstein, a professor at the Emory University School of Medicine and former director of the U.S. immunization program at the CDC, explains that two types of measles vaccines were first introduced in the U.S. in 1963. One was a live, attenuated virus vaccine, which is still in use today albeit with modifications for safety, while the other was an inactivated, or killed, measles virus vaccine. Unfortunately, the inactivated vaccine was ineffective in providing lasting immunity and increased the risk of developing a severe form of measles, known as atypical measles, among those who later contracted the virus naturally. This vaccine was withdrawn from the market by 1967, but some individuals vaccinated during that time still remain today.
“If someone received the inactivated vaccine between 1963 and 1967, or if they are uncertain about the vaccine they received, it is advisable to receive an additional dose of the effective measles vaccine,” Orenstein stated in an interview with Gizmodo. Individuals who were vaccinated during this era or are unsure of their vaccination history are encouraged to obtain at least one dose of the current effective measles vaccine to ensure their protection.
Most people born before 1957 have likely contracted measles, which typically provides long-lasting immunity, so they are generally safe from the disease. The Centers for Disease Control and Prevention (CDC) advises that healthcare workers born before 1957 who lack documented evidence of measles infection (either through medical records or laboratory tests) should consider the standard two-dose vaccination series to ensure they are adequately protected.
It is also important to recognize that individuals born between 1968 and 1989 received only a single dose of the MMR vaccine. While even this one shot is highly effective—approximately 93% effective—most individuals in this group are likely well protected. However, the CDC recommends that adults who are at a higher risk of measles exposure should receive their second dose if they haven’t already done so. Those considered at higher risk include college students, healthcare workers, individuals traveling internationally, and others identified by public health officials as being at risk, such as those living in areas experiencing active outbreaks.
Although the nearly 100% protection afforded by complete MMR vaccination is impressive, it does leave a small margin of vulnerability. Occasionally, a fully vaccinated individual who is exposed to measles during an outbreak may still become ill. This could occur if the immune system did not generate a robust protective response during vaccination or if an individual’s immunity has diminished over time.
Fortunately, the issue of waning immunity is not a significant concern for most individuals. Studies suggest that the vaccine’s effectiveness declines by approximately 0.22% to 0.04% annually. This indicates that it would take 5 to 25 years for an average person to experience just a 1% decrease in their protection following their MMR vaccinations.
If you have concerns about your susceptibility to measles or are uncertain of your vaccination status, it’s wise to consult your primary care physician. Your doctor may perform a blood test to check for measles antibodies or may proactively recommend an MMR dose as a precaution. While the prospect of receiving a needle may be unappealing, rest assured that the MMR vaccine is very safe, and an additional shot is perfectly acceptable even if you believe you are already well protected.
“One benefit of already being immune is that if they receive the vaccine, their bodies will neutralize the vaccine virus before any reaction can occur,” Orenstein remarked.
Outside of a few specific situations, measles poses a more significant threat to the unvaccinated population, which includes individuals who are too young or medically unable to receive vaccinations, such as those with severely compromised immune systems. The most effective strategy for containing the virus, according to Orenstein, is ensuring that everyone who is eligible gets vaccinated.
“That’s why achieving high immunization rates within our communities is essential. The measles virus requires transmission from an infectious person to a susceptible individual to survive. If an infectious person only comes into contact with immune individuals, the transmission chain is disrupted, thereby indirectly protecting those who cannot be vaccinated due to legitimate medical reasons,” Orenstein emphasized.
Children should ideally receive their first MMR vaccination between 12 and 15 months of age, followed by a second dose between 4 and 6 years of age. However, children at increased risk of exposure during outbreaks or international travel may be given these vaccinations earlier or receive an additional dose to ensure their safety.
Measles is an extremely contagious disease that can pose serious health risks, particularly to children and those unable to get vaccinated. If you fall into a high-risk category or are uncertain about your vaccination status, it’s advisable to consult with your doctor as soon as possible to discuss the best course of action.
Brandon Fletcher
