Do health-care workers need a COVID-19 vaccine booster?

Following the results of the ENSEMBLE 2 study, which demonstrated improved vaccine efficacy of a two-dose regimen of Ad26.COV.2 vaccine given 2 months apart, we expanded the Sisonke study which had provided single dose Ad26.COV.2 vaccine to almost 500 000 health care workers (HCW) in South Africa to include a booster dose of the Ad26.COV.2. Sisonke 2 enrolled 227 310 HCW from the 8 November to the 17 December 2021. Enrolment commenced before the onset of the Omicron driven fourth wave in South Africa affording us an opportunity to evaluate early VE in preventing hospital admissions of a homologous boost of the Ad26.COV.2 vaccine given 6-9 months after the initial vaccination in HCW. We estimated vaccine effectiveness (VE) of the Ad26.COV2.S vaccine booster in 69 092 HCW as compared to unvaccinated individuals enrolled in the same managed care organization using a test negative design. We compared VE against COVID19 admission for omicron during the period 15 November to 20 December 2021. After adjusting for confounders, we observed that VE for hospitalisation increased over time since booster dose, from 63% (95%CI 31-81%); to 84% (95% CI 67-92%) and then 85% (95% CI: 54-95%), 0-13 days, 14-27 days, and 1-2 months post-boost. We provide the first evidence of the effectiveness of a homologous Ad26.COV.2 vaccine boost given 6-9 months after the initial single vaccination series during a period of omicron variant circulation. This data is important given the increased reliance on the Ad26.COV.2 vaccine in Africa.

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Immunogenicity of a BNT162b2 vaccine booster in health-care workers

The Lancet Microbe ◽

10.1016/s2666-5247(21)00272-x ◽

2021 ◽

Author(s):

Esther Saiag ◽

Hanoch Goldshmidt ◽

Eli Sprecher ◽

Ronen Ben-Ami ◽

David Bomze

Keyword(s):

Health Care ◽

Health Care Workers ◽

Care Workers ◽

Vaccine Booster

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

10.1101/2021.08.27.21262721 ◽

2021 ◽

Author(s):

Watsamon Jantarabenjakul ◽

Napaporn Chantasrisawad ◽

Thanyawee Puthanakit ◽

Supaporn Wacharapluesadee ◽

Nattiya Hirankarn ◽

...

Keyword(s):

Health Care ◽

Immune Response ◽

Health Care Workers ◽

Seroconversion Rate ◽

Rapid Decline ◽

Short Term ◽

Rapid Reduction ◽

Viral Neutralization ◽

Care Workers ◽

Vaccine Booster

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.

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