Figure 3.
Neutralisation of SARS-CoV-2 lineages B and P.1 by plasma from previously infected or vaccinated individuals, according to PRNT50
Plasma samples were tested by PRNT in Vero cells after incubation with 100 plaque-forming units of different isolates of SARS-CoV-2 (B and two isolates of P.1 lineages). PRNT50 represents the sample dilution that showed a 50% reduction in plaque formation compared with a control well inoculated with SARS-CoV-2 alone (without plasma), after linear regression analysis. Each data point represents the mean of all plasma samples for each group at each dilution level (shown as log2 serum dilution) and error bars represent SD. (A) Plasma from blood donors previously infected with SARS-CoV-2 (n=21). (B) Plasma from individuals vaccinated with a single dose of CoronaVac vaccine during the Brazilian vaccination programme (n=18), collected at a median 21 days (IQR 21–21; range 20–23) after receipt of the first dose. (C) Plasma from individuals vaccinated with two doses of CoronaVac vaccine during the Brazilian vaccination programme (n=38), collected at a median 21 days (IQR 20–23; range 17–38) after receipt of the second dose. (D) Plasma from individuals vaccinated with two doses of CoronaVac vaccine in the Sinovac phase 3 trial (n=15), collected at a median 158 days (IQR 156–170; range 134–260) after receipt of the second dose. All PRNT curves for each sample used in the study are shown in appendix 2 (pp 4–7). PRNT=plaque reduction neutralisation test.