The second dose of the BNT162b2 mRNA vaccine does not boost SARS-CoV-2 neutralizing antibody response in previously infected subjects

Excerpt

While SARS-CoV-2 vaccination of uninfected hosts is proceeding worldwide, whether and how to vaccinate those recovered from natural infection remains debatable. A single-dose mRNA vaccine administration has been reported to boost SARS-CoV-2 neutralizing antibodies (NtAb) in subjects with past infection [1, 2] while the effect of a second dose in such subjects has not been documented. Within a health care worker (HCW) surveillance and vaccination program running at a SARS-CoV-2 referral hospital, we assessed the dynamics of SARS-CoV-2 NtAb in 22 uninfected and 34 previously infected individuals who completed the 2-dose schedule of the BNT162b2 mRNA vaccine. All the subjects received the second dose vaccine 3 weeks after the first dose. The subjects included in the uninfected group had no SARS-COV-2 RNA detection in the tests performed according to the hospital surveillance program and at the time of NtAb testing. In addition, all the subjects had been tested for the presence of a neutralizing antibody titer at baseline, i.e., at the time of the first vaccine administration, and confirmed as negative. …