The Cases of Breakthrough Measles Infections, Why Do They Happen?

However, these breakthrough measles infections—measles infection in a vaccinated person—are rare but nevertheless laudable occurrences. The MMR vaccine is well-proven, but no vaccine gives 100% protection. With outbreaks of measles still emerging in countries around the world, particularly in those communities where vaccination rates are subsiding, it has been important to establish what the factor is for these breakthrough cases to occur, in order to facilitate public health awareness and landscape response [1].

1. Waning Immunity Over Time

The decline of immunity is one of the main reasons behind breakthrough infections. It is also highly effective, with two doses preventing around 97% of cases. But immunity can wane after a period of time, particularly for those that only had one dose or were vaccinated a long time ago. Antibody levels can drop, some studies have found, especially among those who never got natural exposure to the virus that serves as a natural booster.

2. Primary Vaccine Failure

Sometimes, though rarer, some people do not develop any immunity after vaccination—this is called failure of primary vaccination. It may occur due to:

Improper vaccine storage of the vaccine or questions about how the vaccine was stored and administered

Genetics influencing immune response

The immunological considerations upon first infection (i.e., maternal antibodies could potentially interfere the vaccine response if the first dose is given too early)

3. Secondary Vaccine Failure

Secondary vaccine failure, on the other hand, is when a person has an immune response to the vaccine or an infection, but it decreases over time. This occurs in the face of an adequate primary response, unlike in primary failure. Although the body can boost immunity against SARS-CoV-2 — the virus that causes COVID-19 — if someone does not receive booster doses against the virus or is debilitated (immunocompromised), secondary failures are more likely to be experienced.

4. Immunocompromised Conditions

People with compromised immune systems, including people with HIV/AIDS, cancer, and people who are taking immunosuppressive drugs, may not respond as robustly to the vaccine or lose any immune response more quickly. Although vaccinated, they are more vulnerable to breakthrough infection because of an impaired ability to elicit or maintain a protective immune response.

5. Genetic Changes in Strains of the Virus that Causes Measles

Well, measles has only one serotype (meaning that the vaccine protects against all known strains), and small genetic differences in circulating virus strains can potentially alter how effective vaccine-induced immune protection from infection is. These variants have not yet meaningfully undermined vaccine efficacy as of this writing, but it will be important to continue to monitor the situation.

6. High-vax Areas and a False Sense of Security

But in populations in which most people are vaccinated, there may be a strange bump in breakthrough cases, simply because most people are vaccinated. Among these communities, the few people infected with measles are sometimes individuals who've been vaccinated—not because the vaccine isn't working, but because only a minuscule number are not vaccinated. This could lead to an illusion regarding the efficacy of a vaccine.

7. Lack of Vaccination Deserves COMPREHENSIVE Representation

Here are not those breakthrough cases where first one gets the only single dose of two. The first provides only around 93% protection; the second brings that up to 97%. Falling behind on the second dose leaves a person much more at risk for a breakthrough infection.

Conclusion

Breakthrough measles infections in vaccinated individuals are rare but underscore the need for (1) continued high vaccination coverage, (2) completion of the two-dose schedule, and (3) surveillance of population immunity over time, especially among vulnerable groups. The MMR vaccine is still one of the best measures out there to protect against measles, but keeping a lid on this transmissible virus will require ongoing monitoring of immunity rates, the development of effective boosters and vaccination campaigns in poorer countries where outbreaks are still a risk.

For those uncertain about their vaccination status or if they need a booster, it is best to check with a health care provider. Not only is measles prevention a matter of personal health; it is a matter of public health.