ABSTRACT
The SARS-CoV-2 variant Omicron is now under investigation. We evaluated cross-neutralizing activity against Omicron in COVID-19 convalescent patients (n=23) who had received two doses of an mRNA vaccination (BNT162b2 or mRNA-1273). Surprisingly and interestingly, after the second vaccination, the subjects neutralizing antibody titers including that against Omicron all became seropositive, and significant fold-increases (21.1-52.0) were seen regardless of the subjects disease severity. Our findings thus demonstrate that at least two doses of mRNA vaccination to SARS-CoV-2 convalescent patients can induce cross-neutralizing activity against Omicron.
ABSTRACT
In March 2021, Japan is facing a 4th wave of SARS-CoV-2 infection. To prevent further spread of infection, sera cross-neutralizing activity of patients previously infected with conventional SARS-CoV-2 against novel variants is important but is not firmly established. We investigated the neutralizing potency of 81 COVID-19 patients sera from 4 waves of pandemic against SARS-CoV-2 variants using their authentic viruses. Most sera had neutralizing activity against all variants, showing similar activity against B.1.1.7 and D614G, but lower activity especially against B.1.351. In the 4th wave, sera-neutralizing activity against B.1.1.7 was significantly higher than that against any other variants, including D614G. The cross-neutralizing activity of convalescent sera was effective against all variants but was potentially weaker for B.1.351.
