CONCERNS about the effectiveness of multiple MMR vaccine booster doses in individuals who remain seronegative after the standard two-dose schedule have been highlighted in a new study. Researchers found that while some nonresponders showed temporary increases in antibody levels, long-term immunity remained weak, raising questions about current booster strategies.
The study examined 24 individuals who had no detectable measles antibodies years after completing the two-dose MMR vaccination series. Of these, 11 seroconverted after receiving a single booster dose, while 13 required an additional booster. However, neutralizing antibody levels remained low in both groups, and immunity waned significantly within 3 years.
To better understand the underlying immune response, the researchers assessed cellular immunity in 10 nonresponders. After exposure to inactivated measles virus, these individuals showed no significant activation of T, B, or NK cells, suggesting a lack of immunological memory to measles. In contrast, their immune response to rubella remained intact, indicating that their nonresponsiveness was specific to the measles component of the vaccine.
These findings suggest that current MMR booster strategies may not be sufficient for individuals with waning immunity or primary vaccine failure. Instead, the study authors emphasize the need for improved vaccine formulations that can generate stronger and more durable immune responses.
With measles cases on the rise worldwide due to declining vaccination rates and waning immunity, identifying effective strategies to maintain long-term protection is critical. This research underscores the importance of re-evaluating booster policies and exploring alternative approaches to measles immunity.
Reference: Anichini G et al. Seronegative Vaccinees May Not Benefit From Multiple Booster Doses of MMR Vaccine in Restoring Immunity. J Med Virol. 2024;96(12):e70135.
Anaya Malik | AMJ
