Comparison of the immunogenicity of five COVID-19 vaccines in Sri Lanka

Abstract

To determine the antibody responses elicited by different vaccines against SARS-CoV-2, we compared antibody responses in individuals 3 months post-vaccination in those who had received different vaccines in Sri Lanka. Abs to the receptor binding domain (RBD) of the ancestral (wild type) virus (WT) as well as to variants of concern (VoCs), and ACE2 blocking Abs, were assessed in individuals vaccinated with Moderna (n = 225), Sputnik V (n = 128) or Sputnik light (n = 184) and the results were compared with previously reported data on Sinopharm and AZD1222 vaccinees. A total of 99.5% of Moderna, >94% of AZD1222 or Sputnik V and >70% of Sputnik light, >60% of Sinopharm vaccine recipients, had a positive response to ACE2 blocking antibodies. The ACE2 blocking antibody levels were highest to lowest was Moderna > Sputnik V/AZD1222 (had equal levels) > Sputnik light > Sinopharm. All Moderna recipients had antibodies to the RBD of WT, alpha and beta, while positivity rates for delta variant was 80%. The positivity rates for Sputnik V vaccinees for the WT and VoCs were higher than for AZD1222 vaccinees while those who received Sinopharm had the lowest positivity rates (<16.7%). The total antibodies to the RBD were highest for the Sputnik V and AZD1222 vaccinees. The Moderna vaccine elicited the highest ACE2 blocking antibody levels followed by Sputnik V/AZD1222, while those who received Sinopharm had the lowest levels. These findings highlight the need for further studies to understand the effects on clinical outcomes.

Keywords: COVID-19; antibodies; memory; vaccination.

FIGURE 1

SARS‐CoV‐2 specific total antibodies to the receptor binding domain (RBD) in those who received different vaccines at 3 months following full vaccination. Total antibodies to the RBD were measured by ELISA in all individuals who received two doses of Sinopharm (n = 203), AZD1222 (299), Sputnik 1 dose (Sputnik light, n = 184), Sputnik 2 doses (Sputnik V, n = 127) and Moderna 2 dose (n = 227) (a). Total antibodies to the RBD were also measured in 20‐ to 39‐year‐olds who received two doses of Sinopharm (n = 61), AZD1222 (129), Sputnik 1 dose (n = 45), Sputnik 2 doses (n = 50) and Moderna 2 doses (n = 50) (b). Total antibodies to the RBD were also measured in 40 to 59‐year‐olds who received two doses of Sinopharm (n = 120), AZD1222 (152), Sputnik 1 dose (n = 139), Sputnik 2 doses (n = 77) and Moderna 2 doses (n = 129) (c). In those >60 years of age, the analysis was carried out in those who received 2 doses of Sinopharm (n = 22), 2 doses of AZD1222 (n = 18) and 2 doses of Moderna (n = 48) (d). The differences in antibody titres (antibody index) between different vaccines were analysed using the Mann–Whitney test. All tests were two‐tailed. The lines indicate the median and the inter quartile range. Only P values which indicate a significant difference are shown in the figure.

FIGURE 2

SARS‐CoV‐2 ACE2 blocking antibodies in those who received different vaccines at 3 months following full vaccination. ACE2 blocking antibodies were measured by the sVNT assay in 20‐ to 39‐year‐olds who received two doses of Sinopharm (n = 110), AZD1222 (224), Sputnik 1 dose (Sputnik light, n = 50), Sputnik 2 doses (Sputnik V, n = 50) and Moderna 2 doses (n = 48) (a). ACE2 blocking antibodies were also measured in 20‐ to 39‐year olds who received two doses of Sinopharm (n = 41), AZD1222 (26), Sputnik 1 dose (n = 25), Sputnik 2 doses (n = 50) and Moderna 2 doses (n = 48) (b). ACE2 blocking antibodies were also measured in 40‐ to 59‐year‐olds who received two doses of Sinopharm (n = 48), AZD1222 (26), Sputnik 1 dose (n = 25), Sputnik 2 doses (n = 77) and Moderna 2 doses (n = 132) (c). In those >60 years of age, the analysis was carried out in those who received 2 doses of Sinopharm (n = 21), 2 doses of AZD1222 (n = 17) and 2 doses of Moderna (n = 44) (d). The differences in ACE2 blocking antibodies (% of inhibition) between different vaccines were analysed using the Mann–Whitney test. All tests were two‐tailed. The lines indicate the median and the inter quartile range. The positive cut‐off value if shown as a red dotted line. Only P values which indicate a significant difference are shown in the figure.

FIGURE 3

SARS‐CoV‐2 specific antibodies to the receptor binding domain (RBD) of the ancestral (WT) virus and variants of concerns in those who received Sputnik V and Moderna 3 months following the second dose. Antibodies to the RBD were measured by the haemagglutination test (HAT) in those who received two doses of Moderna in 20‐ to 39‐years‐old (n = 26) or two doses of Sputnik V (n = 25) and those who were aged 40 to 59 years who received two doses of Moderna (n = 25) or Sputnik V (n = 46). Antibodies were measured by HAT to the WT (a), B.1.1.7 (b), B.1.351.1 (c) and B.1.617.2 (d). The differences between HAT titres for between the two vaccines were analysed using the Mann–Whitney test. All tests were two‐tailed. The lines indicate the median and the inter quartile range. The positive cut‐off value if shown as a red dotted line. Only P values which indicate a significant difference are shown in the figure.