A prospective study reported a persistent but declining anti-COVID humoral immunity at 6 months after complete vaccination with BNT162b2 mRNA in healthy people. However, it was more significant among older persons. Researchers aimed to determine neutralizing antibodies (Nabs) kinetics against coronavirus up to 6 months following 2^nd dose of BNT162b2 vaccine.

Estimation of Nabs levels was done on days 1 (prior to the 1^st vaccine shot), 8, 22 (prior to the 2^nd  shot), 36, 50, and three and six months following the 2^nd vaccination. The study incorporated 308 healthy participants without malignant disease. At 6 months, the percentage of people with Nabs values less than 30%, less than 50%, and more than 75% are shown in Table 1:

Elimination of Nabs was found to be biphasic. Initially, Nabs were eliminated at a relatively slower rate. However, after 3 months, Nabs elimination was 5.7 times higher. At all the evaluated time points, older age was inversely linked with Nabs levels. According to the estimation of a population modeling assessment, about half of the people will have Nabs titers less than 73.8% and 64.6% at nine and twelve months, respectively, after complete vaccination.

Thus, the findings of the study offered pivotal insights into the timing of robust booster vaccinations, that might be age-dependent.