High correlation between binding IgG (anti-RBD/S) and neutralizing antibodies against SARS-CoV-2 six months after vaccination

Abstract

Vaccination is considered the most important measure to control the COVID-19 pandemic. Extensive follow-up studies with distinct vaccines and populations are able to promote robust and reliable data to better understand the effectiveness of this pharmacologic strategy. In this sense, we present data regarding binding and neutralizing antibodies throughout time, from vaccinated and previously infected (PI) health care workers (HCW) in Portugal. We analyzed serum samples of 132 HCW, vaccinated and with previous SARS-CoV-2 infection. Samples were collected before vaccination (baseline, M1), at second dose vaccine uptake (M2), and 25-70 days (M3) and 150-210 days (M4) after the second dose for vaccinated individuals. The IgG (anti-RBD/S) antibody geometric mean titer found on vaccinated HCW at M2 (814.7 AU/ml; 95% CI 649.8-1021.5) were significantly higher than those found on PI HCW at recruitment (M1) (252.6 AU/ml; 95% CI 108.7 - 587.1), and the neutralizing antibodies (nAb) were similar between these groups, 93.2 UI/ml (95% CI 73.2-118.5) vs. 84.1 UI/ml (95% CI 40.4-155.9), respectively. We detected about 10-fold higher IgG (anti-RBD/S) antibodies titers in M3 when compared with M2, with a slightly but significant decrease in titers from 36 days after the second dose vaccine uptake. The increase of nAb titers were correlated with IgG (anti-RBD/S) antibodies titers, however, contrasting to IgG (anti-RBD/S) antibodies titers, we did not detect a decrease in nAb titer from 36 days after a second vaccine dose uptake. At M4, was observed a decrease of 8-fold in binding IgG (anti-RBD/S) and nAb. No significant differences in antibody titers were observed by sex, age or chronic diseases. Our results suggest that IgG (anti-RBD/S) antibodies titers and nAb titers could be correlated, but ongoing follow up of the cohort, is required to better understand this correlation, and the duration of the immune response.

Antibody response to SARS-CoV2 among COVID-19 confirmed cases, and correlates with neutralizing assay in a subgroup of patients in Delhi National Capital Region, India

“…Although previous studies have shown good correlation between the Anti-RBD antibodies and virus neutralization (13,14), present study shows a different picture as almost all the participants had Anti-RBD antibodies, but only 69% had neutralizing titre. Anti-RBD antibody levels were significantly higher among participants that had neutralizing antibodies compared to participants who didn't.…”

“…Our finding is in agreement with the other previous studies. (14,15) Also neutralizing titre and anti-RBD antibody titre were significantly higher among the health care workers, which might be due to repeated exposure of SARS-CoV2 among them. Participants who had history of contact with COVID-19 positive participants had significantly higher anti-RBD antibodies.…”

15-month follow-up of anti-spike receptor binding domain (RBD) SARS-CoV-2 antibodies among healthcare workers in Boston, MA

“…However, others have shown that binding and neutralizing antibody titers are thought to be correlated with each other (10-14). Specifically, the anti-s RBD IgG assay used here has been highly correlated with neutralizing antibodies elicited by vaccination strengthening our use of this quantitative measure of immunity in our cohort (12).…”

Correlation Analysis of Anti-SARS-CoV-2 RBD IgG and Neutralizing Antibody against SARS-CoV-2 Omicron Variants after Vaccination

“…Previous studies demonstrated that high titers of anti-RBD antibodies and NAbs were induced in vaccinated individuals [ 7 , 8 , 9 ]. A high correlation between RBD binding antibodies and NAbs was revealed [ 25 ]. Therefore, some health care settings and private health services use anti-RBD IgG levels to predict vaccine effectiveness in vaccinated individuals.…”