Antibody responses to Sinopharm/BBIBP-CorV in pregnant mothers in Sri Lanka

Background There are limited data regarding the safety and immunogenicity of the Sinopharm/BBIBP-CorV vaccine in pregnancy. Therefore, we sought to investigate the antibody responses and maternal and fetal adverse events following this vaccine in pregnant mothers in Sri Lanka. Methods and findings SARS-CoV-2 receptor binding domain (RBD) specific total antibodies and ACE2 blocking antibodies were measured by ELISA in pregnant mothers (n = 94) who received the vaccine in the first (n = 2), second (n = 57) and third (n = 33) trimester of pregnancy. Data regarding adverse events and fetal and maternal outcomes were obtained from the women once they delivered. No adverse maternal or fetal complications reported such as miscarriage, thrombotic events, hypertensive disorders, fetal death, preterm delivery, or congenital anomalies were reported. 58/94 (61.7%) had RBD binding antibodies and were found to be seropositive at the time of recruitment. All women seroconverted after the second dose and 31/36 previously uninfected women and 57/58 previously infected women gave a positive response to ACE2 blocking antibodies. The RBD binding antibody levels (p = 0.0002) and ACE2 blocking antibodies (p<0.0001) were significantly higher in previously infected individuals post-second dose compared to uninfected individuals. Conclusions The Sinopharm/ BBIBP-CorV vaccine appeared safe and induced high seroconversion rates and ACE2 blocking antibodies in pregnant mothers in the second and third trimester in pregnancy. However, the RBD binding antibodies and ACE2 blocking antibodies post-second dose were significantly higher in previously infected pregnant mothers post-second dose, suggesting that two doses of the vaccine are likely to be less immunogenic in previously unexposed individuals.

Antibody responses to Sinopharm/BBIBP-CorV in pregnant mothers in Sri Lanka.

BACKGROUND: There are limited data regarding the safety and immunogenicity of the Sinopharm/BBIBP-CorV vaccine in pregnancy. Therefore, we sought to investigate the antibody responses and maternal and fetal adverse events following this vaccine in pregnant mothers in Sri Lanka. METHODS AND FINDINGS: SARS-CoV-2 receptor binding domain (RBD) specific total antibodies and ACE2 blocking antibodies were measured by ELISA in pregnant mothers (n = 94) who received the vaccine in the first (n = 2), second (n = 57) and third (n = 33) trimester of pregnancy. Data regarding adverse events and fetal and maternal outcomes were obtained from the women once they delivered. No adverse maternal or fetal complications reported such as miscarriage, thrombotic events, hypertensive disorders, fetal death, preterm delivery, or congenital anomalies were reported. 58/94 (61.7%) had RBD binding antibodies and were found to be seropositive at the time of recruitment. All women seroconverted after the second dose and 31/36 previously uninfected women and 57/58 previously infected women gave a positive response to ACE2 blocking antibodies. The RBD binding antibody levels (p = 0.0002) and ACE2 blocking antibodies (p<0.0001) were significantly higher in previously infected individuals post-second dose compared to uninfected individuals. CONCLUSIONS: The Sinopharm/ BBIBP-CorV vaccine appeared safe and induced high seroconversion rates and ACE2 blocking antibodies in pregnant mothers in the second and third trimester in pregnancy. However, the RBD binding antibodies and ACE2 blocking antibodies post-second dose were significantly higher in previously infected pregnant mothers post-second dose, suggesting that two doses of the vaccine are likely to be less immunogenic in previously unexposed individuals.

Immune responses following the first dose of the Sputnik V (Gam-COVID-Vac).

As the first dose of Gam-COVID-Vac, is currently used as a single dose vaccine in some countries, we investigated the immunogenicity of this at 4 weeks (327 naïve individuals). 88.7% seroconverted, with significantly lower seroconversion rates in those over 60 years (p = 0.004) and significantly lower than previously seen with AZD1222 (p = 0.018). 82.6% developed ACE2 receptor blocking antibodies, although levels were significantly lower than following natural infection (p = 0.0009) and a single dose of AZD1222 (p < 0.0001). Similar titres of antibodies were observed to the receptor binding domain of WT, B.1.1.7 and B.1.617.2 compared to AZD1222, while the levels for B.1.351 were significantly higher (p = 0.006) for Gam-COVID-Vac. 30% developed ex vivo IFNγ ELISpot responses (significantly lower than AZD1222), and high frequency of CD107a expressing T cells along with memory B cell responses. Although single dose of Gam-COVID-Vac was highly immunogenic, administration of a second dose is likely to be beneficial.

Comparison of two assays to detect IgG antibodies to the receptor binding domain of SARS­CoV­2 as a surrogate marker for assessing neutralizing antibodies in COVID-19 patients.

BACKGROUND: Neutralizing antibodies (NAbs) are important for protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection. In this study, two assays that are correlated with NAbs were compared: the haemagglutination test (HAT) and the surrogate virus neutralization test (sVNT). METHODS: The specificity of the HAT was compared with the sVNT, and the sensitivity and persistence of antibodies in patients with varying severity of illness was assessed in a cohort of 71 patients at 4-6 weeks and 13-16 weeks. The kinetics were assessed in the first, second, and third weeks in patients with varying severity of acute illness. RESULTS: The specificity of the HAT was >99%, and sensitivity was similar to the sVNT. The levels of HAT were significantly and positively correlated with those of the sVNT (Spearman's r = 0.78, P < 0.0001). Patients with moderate and severe illness had higher HAT titres when compared to those with mild illness. Six of seven patients with severe illness had a titre of >1:640 during the second week of illness, whereas only five of 31 patients with a mild illness had a titre of >1:160 in the second week of illness. CONCLUSIONS: Since the HAT is a simple and very cheap assay to perform, it would be ideal to use as an indicator of NAbs in resource-poor settings.