Short-term immune response after inactivated SARS-CoV-2 (CoronaVac®, Sinovac) and ChAdOx1 nCoV-19 (Vaxzevria®, Oxford-AstraZeneca) vaccinations in health care workers
Watsamon Jantarabenjakul,1,2,3 Napaporn Chantasrisawad,1,2,3 Thanyawee Puthanakit,2,3 Supaporn acharapluesadee,4 Nattiya Hirankarn,5 Vichaya Ruenjaiman,5 Leilani Paitoonpong,1,6 Gompol Suwanpimolkul,1,6 Pattama Torvorapanit,1 Rakchanok Pradit,1 Jiratchaya Sophonphan,7 Opass Putcharoen1,6
1 Thai Red Cross Emerging Infectious Diseases Clinical Center, King Chulalongkorn Memorial Hospital, Bangkok, Thailand
2 Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
3 Center of Excellence in Pediatric Infectious Diseases and Vaccines, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
4 King Chulalongkorn Memorial Hospital, Bangkok, Thailand
5 Center of Excellence in Immunology and Immune-Mediated Diseases, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
6 Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
7 The HIV Netherlands Australia Thailand Research Collaboration (HIV-NAT), Thai Red Cross AIDS Research Centre, Bangkok, Thailand
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).
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 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 two doses of the AZ for 4 weeks had seroconversion, comparable to the COVID-19 pneumonia patients (92.5%), with a reduction to 39.2% (95%CI: 28.4-50.9%) at 12 weeks. When using the anti-SARS-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 at 4 weeks.
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 SARS-CoV-2 variants of concern.
Key words: SARS-CoV-2 vaccine, COVID-19 vaccine, Surrogate viral neutralizing antibody titer, Anti-SARS-CoV-2 total antibody, Health care workers, Inactivated SARS-CoV-2 vaccine,