SARS-CoV-2 Omicron Symptomatic Infections in Previously Infected or Vaccinated South African Healthcare Workers

We investigated Omicron infections among healthcare workers (HCW) presenting with symptoms of SARS-CoV-2 infection and evaluated the protective effect of vaccination or prior infection. Between 24 November and 31 December 2021, HCW in Johannesburg, South Africa, were tested for SARS-CoV-2 infection...

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Bibliographic Details
Published in:Vaccines (Basel) Vol. 10; no. 3; p. 459
Main Authors: Nunes, Marta C., Mbotwe-Sibanda, Sthembile, Baillie, Vicky L., Kwatra, Gaurav, Aguas, Ricardo, Madhi, Shabir A.
Format: Journal Article
Language:English
Published: Switzerland MDPI AG 17.03.2022
MDPI
Subjects:
Antibodies
Communication
Confidence intervals
Coronaviruses
COVID-19
COVID-19 diagnostic tests
COVID-19 vaccines
Health care
Hypotheses
IgG antibody
Immunoglobulin G
Immunoglobulins
Infections
Medical personnel
Mutation
Nucleic acids
Omicron
Proteins
reinfection
SARS-CoV-2
Severe acute respiratory syndrome coronavirus 2
Spike protein
Vaccination
Vaccines
Viral diseases
South Africa
COVID-19
SARS-CoV-2
reinfection
Omicron
vaccination
ISSN:2076-393X, 2076-393X
Online Access:Get full text
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Summary:We investigated Omicron infections among healthcare workers (HCW) presenting with symptoms of SARS-CoV-2 infection and evaluated the protective effect of vaccination or prior infection. Between 24 November and 31 December 2021, HCW in Johannesburg, South Africa, were tested for SARS-CoV-2 infection by Nucleic Acid Amplification Test (NAAT). Blood samples collected either at the symptomatic visit or in the 3 months prior, were tested for spike protein immunoglobulin G (IgG). Overall, 433 symptomatic HCW were included in the analysis, with 190 (43.9%) having an Omicron infection; 69 (16.7%) were unvaccinated and 270 (62.4%) received a single dose of the Ad26.COV.2 vaccine. There was no difference in the odds of identifying Omicron between unvaccinated and Ad26.COV.2 vaccinated HCW (adjusted odds ratio (aOR) 0.81, 95% confidence interval (CI): 0.46, 1.43). One-hundred and fifty-four (35.3%) HCW had at least one SARS-CoV-2 NAAT-confirmed prior infection; these had lower odds of Omicron infection compared with those without past infection (aOR 0.55, 95%CI: 0.36, 0.84). Anti-spike IgG concentration of 1549 binding antibody unit/mL was suggestive of significant reduction in the risk of symptomatic Omicron infection. We found high reinfection and vaccine breakthrough infection rates with the Omicron variant among HCW. Prior infection and high anti-spike IgG concentration were protective against Omicron infection.
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Membership of the Wits VIDA HCW Study Group is provided in the Acknowledgments.
ISSN:2076-393X
2076-393X
DOI:10.3390/vaccines10030459