A research published in the International Journal of Infectious Diseases demonstrated that a single BNT162b2 mRNA vaccine dose in patients suffering from mild or asymptomatic previous infection can more effectively boost SARS-CoV-2 humoral immunity to levels greater in comparison with those procured by complete two-vaccination in uninfected individuals.

Ilaria Vicenti and investigators evaluated the SARS-CoV-2 neutralizing antibody (NtAb) titres in earlier infected (mild or asymptomatic infection; n=41) or uninfected (n=16) health care workers who received 1 or 2 doses of vaccine. The NtAbs were titrated as dose-inhibiting 50% of the virus replication (ID50). The assessment was performed at the first vaccination dose (T1_inf) and after 21 days (T2_inf). In uninfected individuals, assessments were done at 20 days following the first (T2_uninf) and 20 days following the second dose (T3_uninf).

A noteworthy link between days from diagnosis and NtAb levels at T2_inf was found. NtAb titres increased at different assessment times in infected and uninfected individuals, as shown in Table 1:

Nevertheless, the levels of NtAb at T2_inf were considerably greater as compared to at T2_uninf and T3_uninf. Thus, vaccination of individuals having mild or asymptomatic prior infection further enhances SARS-CoV-2 immunity.