Induction of SARS-CoV-2 neutralizing antibodies by CoronaVac and BNT162b2 vaccines in naïve and previously infected individuals

Predicting the efficacy of new coronavirus vaccines – Are neutralising antibodies enough?

“…Despite the inclusion of the whole virion in CoronaVac the nucleocapsid component appears to be a poor B-cell antigen though it may contribute to T cell responses along with other non-spike structural proteins. 8 T cell responses, which likely play a role in protection especially against severe disease, 9 were found to be greater after CoronaVac than BNT162b2 in a head-to-head study, 8 and may, as postulated by Muena et al , 2 help explain the lower predicted efficacy of CoronaVac based on Nab responses than observed in the Chilean population.…”

“…Muena et al 2 found robust Nab responses after two CoronaVac doses in previously infected individuals, reaching similar levels to those seen in convalescent sera. It would have been interesting to measure the Nab responseto SARS-CoV-2 variants in CoronaVac recipients with previous infection to assess whether, as reported for third doses of CoronaVac, Nabs to Alpha, Beta and Delta variants as well as the ancestral Wuhan strain are generated.…”

“…While Muena et al 2 found strong responses to the SARS-CoV-2 nucleocapsid antigen in naturally infected individuals there was little response after two doses of CoronaVac even in those previously infected. Despite the inclusion of the whole virion in CoronaVac the nucleocapsid component appears to be a poor B-cell antigen though it may contribute to T cell responses along with other non-spike structural proteins.…”

“…In this edition of eBioMedicine , a “real world” test of the validity of the equation derived by Khoury et al 1 is reported by Muena et al. 2 The authors measured the ratio between Nab titres in those receiving an inactivated whole virion vaccine (CoronaVac) or the mRNA spike-based vaccine BNT162b2 during the vaccination campaign in Chile and titres in naturally infected individuals; the efficacies predicted from these ratios using the Khoury et al equation 1 were then compared with effectiveness data for both vaccines generated during the campaign. 3 The ratio was 0.2 for CoronaVac and 5.2 for BNT162b2 giving predicted effectiveness of around 50% and 97% respectively, compared with the observed effectiveness in the Chilean population of 65.9% for CoronaVac and 92.6% for BNT162b2.…”

“… 3 The ratio was 0.2 for CoronaVac and 5.2 for BNT162b2 giving predicted effectiveness of around 50% and 97% respectively, compared with the observed effectiveness in the Chilean population of 65.9% for CoronaVac and 92.6% for BNT162b2. 3 The data from -Muena et al., 2 together with published results of Phase 3 trials in Indonesia 4 and Turkey 5 suggest that the Khoury et al. equation underestimates the efficacy of CoronaVac.…”