Anti‐SARS‐CoV‐2 IgG antibody levels among Thai healthcare providers receiving homologous and heterologous COVID‐19 vaccination regimens

Abstract

Background We examined SARS‐CoV‐2 anti‐spike 1 IgG antibody levels following COVID‐19 vaccination (AstraZeneca [AZ], Sinovac [SV], Pfizer‐BioNTech [PZ]) among Thai healthcare providers. Methods Blood specimens were tested using enzyme‐linked immunosorbent assay. We analyzed seven vaccination regimens: (1) one dose of AZ or SV, (2) two doses of homologous (2AZ, 2SV) or heterologous (1AZ + 1PZ) vaccines, and (3) three doses of heterologous vaccines (2SV + 1AZ, 2SV + 1PZ). Differences in antibody levels were assessed using Kruskal–Wallis statistic, Mann–Whitney test, or Wilcoxon matched‐pairs signed‐rank test. Antibody kinetics were predicted using fractional polynomial regression. Results The 563 participants had median age of 39 years; 92% were female; 74% reported no underlying medical condition. Antibody levels peaked at 22–23 days in both 1AZ and 2SV vaccinees and dropped below assay's cutoff for positive (35.2 binding antibody units/ml [BAU/ml]) in 55 days among 1AZ vaccinees compared with 117 days among 2SV vaccinees. 1AZ + 1PZ vaccination regimen was highly immunogenic (median 2279 BAU/ml) 1–4 weeks post vaccination. 2SV + 1PZ vaccinees had significantly higher antibody levels than 2SV + 1AZ vaccinees 4 weeks post vaccination (3423 vs. 2105 BAU/ml; p ‐value < 0.01), and during weeks 5–8 (3656 vs. 1072 BAU/ml; p ‐value < 0.01). Antibodies peaked at 12–15 days in both 2SV + 1PZ and 2SV + 1AZ vaccinees, but those of 2SV + 1AZ declined more rapidly and dropped below assay's cutoff in 228 days while those of 2SV + 1PZ remained detectable. Conclusions 1AZ + 1PZ, 2SV + 1AZ, and 2SV + 1PZ vaccinees had substantial IgG levels, suggesting that these individuals likely mounted sufficient anti‐S1 IgG antibodies for possible protection against SARS‐CoV‐2 infection.

Heterologous Prime-boost of SARS-CoV-2 inactivated vaccine and mRNA BNT162b2 among Healthy Thai Adolescents

“…The heterologous prime-boost vaccination with CoronaVac and BNT162b2 as primary series has been used in adults in Thailand, which demonstrated comparable anti-receptor-binding-domain (anti-RBD) IgG and surrogate virus neutralization test (sVNT) against wild type and Delta variant at 4 weeks after 2 nd dose to homologous BNT162b2 regimen [3] . Also, the heterologous booster in 2-dose CoronaVac vaccinees using AZD1222 (ChAdOx1 nCoV-19, AstraZeneca) or BNT162b2 has been used in adult program in Thailand [4] , [5] . Heterologous prime boost vaccination strategy could benefit in terms of increased coverage during vaccine shortages and might lessen the concern of myocarditis after COVID-19 mRNA vaccinations in children.…”

Vaccine effectiveness of CanSino (Adv5-nCoV) COVID-19 vaccine among childcare workers – Mexico, March–December 2021

“…Such findings have compelled many technical advisory groups to explore the value of homologous or heterologous boosting to better maintain the level of protection initially offered by mRNA vaccines [26,27]. While effective, single-dose COVID-19 vaccination with products like CanSino tend to provide less protection than multi-dose schedules [28], and further analyses of this cohort of childcare workers might be useful in assessing the utility and optimal timing of homologous or heterologous boosting against SARS-CoV-2, as has been done with other single-dose COVID-19 vaccines [29][30][31].…”