Short-Term Immune Response After Inactivated SARS-CoV-2 (CoronaVac®, Sinovac) And ChAdOx1 nCoV-19 (Vaxzevria®, Oxford-AstraZeneca) Vaccinations in Thai Health Care Workers

Abstract

Background: Inactivated SARS-CoV-2 (CoronaVac,Sinovac, or SV) and ChAdOx1 nCoV-19 (Vaxzevria,Oxford-Astra Zeneca, or AZ) vaccines have been administered to the health care workers (HCWs) in Thailand. Objective: To determine the short-term immune response after the SV and AZ vaccinations in HCWs. Methods: In this prospective cohort study, HCWs who completed a 2-dose regimen of the SV or AZ were included. Immune response was evaluated by surrogate viral neutralization test (sVNT) and anti-SARS-CoV-2 total antibody. Blood samples were analyzed at 4 and 12 weeks after the complete SV vaccination and at 4 weeks after each dose of the AZ vaccination. The primary outcome was the seroconversion rate at 4-weeks after complete immunization. Results: Overall, 185 HCWs with a median (IQR) age of 40.5(30.3-55.8) years (94 HCWs in the SV group and 91 in the AZ group) were included. At 4 weeks after completing the SV vaccination, 60.6% (95%CI:50.0-70.6%) had seroconversion evaluated by sVNT(≥68%inhibition), comparable to the patients recovered from mild COVID-19 infection(69.0%), with a rapid reduction to 12.2%(95%CI:6.3-20.8) at 12 weeks. In contrast, 85.7%(95%CI:76.8-92.2%) HCWs who completed the second dose of the AZ for 4 weeks had seroconversion, comparable to the COVID-19 pneumonia patients(92.5%). When using the anti-SAR-CoV-2 total antibody level(≥132 U/ml) criteria, only 71.3% HCWs in the SV group had seroconversion, compared to 100% in the AZ group. Conclusion: A rapid decline of short-term immune response in the HCWs after the SV vaccination indicates the need for a vaccine booster, particularly during the ongoing spreading of the SAR-CoV-2 variants of concern.

Sinopharm Vaccine, SARS-CoV-2 breakthrough infections and Hemoglobinopathies

“… 2 The efficacy and safety of the inactivated COVID-19 vaccination have also been shown based on local data, 3 , 4 similar to the current report by Karimi et al According to statistics on the efficacy of inactivated COVID-19 Vaccine in our scenario, 60.6 percent of patients had seroconversion evaluated by sVNT 4 weeks after finishing the SV vaccination, which is comparable to patients recovered from moderate COVID-19 infection (69.0 percent). 3 The inactivated COVID-19 Vaccine’s side effects were typically well-tolerated and unremarkable. In one-fifth to one-third of vaccine recipients, pain at the injection site and headache are the two most common side effects.…”

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

“…Our data corroborate other studies that reported SV‐, AZ, and PZ‐elicited antibodies wane over time although the rate of decline is unclear, and the impact on protection against infection and on illness attenuation is undefined 12–16,35 . In this study, a significant reduction of antibody levels was observed among participants who completed the primary series of SV and those receiving 2SV + 1AZ, in a relatively short period (i.e., during the observed time).…”

“…COVID‐19 vaccines elicit detectable antibodies in early stages, but the antibody levels wane over time. 12 , 13 , 14 , 15 , 16 For example, a study among 3808 PZ vaccinees reported that humoral response decreased 6 months after completion of the primary series. 15 Further, infections with different SARS‐CoV‐2 variants among persons immunized with all COVID‐19 vaccine products have been reported, 17 , 18 , 19 , 20 prompting countries to adjust vaccination regimens based on resources and vaccine availability.…”

“…As of December 2021, one COVID‐19 vaccine (BNT162b2, Pfizer‐BioNTech [PZ]) has received full approval from the U.S. Food and Drug Administration for use in individuals aged ≥16 years, 11 whereas others (e.g., ChAdOx1 nCoV‐19, also known as AstraZeneca [AZ], CoronaVac, also known as Sinovac [SV]) are authorized for emergency use only by the WHO. COVID‐19 vaccines elicit detectable antibodies in early stages, but the antibody levels wane over time 12–16 . For example, a study among 3808 PZ vaccinees reported that humoral response decreased 6 months after completion of the primary series 15 .…”

A randomized clinical trial of a booster dose with low versus standard dose of AZD1222 in adult after 2 doses of inactivated vaccines

“…The inactivated SARS-CoV-2 vaccine (CoronaVac, Sinovac Life Sciences, Beijing, China) was shown to be effective in protecting against severe COVID-19 and COVID-19-related death, with two-dose efficacy of 65.9% against COVID-19 and 86.3% against COVID-19–related death [5]. However, the efficacy of this vaccine gradually decreased during the extended follow-up period, as shown by the increasing incidence of symptomatic SARS-CoV-2 infection in immunized individuals [6] and waning immunity [7]. Furthermore, CoronaVac was shown to induce lower neutralizing antibodies against variants of concern [8].…”