Purpose To monitor the effectiveness of the single dose Ad26.COV2.S COVID-19 vaccine among health care workers (HCW) as compared to the general unvaccinated population in South Africa~Study design Open-label, single-arm phase 3B vaccine implementation study~Rationale South Africa is severely affected by the global COVID-19 epidemic, but currently no vaccine has been rolled out. The recent promising results of the 'ENSEMBLE' trial conducted by Janssen in South Africa, and the availability of a limited amount of vaccine doses, provide the rationale for a cohort study of vaccinated HCWs to inform the larger vaccine rollout.~Study participants Health Care workers age 18 and above working in the South African public and private health care sector (N=500 000) Study sites Department of Health Vaccine administration sites across South Africa supported by the Sisonke (Together) (VAC31518COV3012) trial Research Site Investigators and Study Staff~Study duration Participants will receive a single dose of vaccine at enrolment; to monitor outcomes the DATCOV surveillance system and NICD line list will be reviewed for up to 2 years post-vaccination.~A sub-cohort (approx. 850-1000 people) consisting of special sub-populations will be followed up at approx. 1, 3, 6 weeks and 6 months post vaccination. This group will also have outcomes monitored for up to a further 18 months, bringing their total follow-up duration to 2 years post-vaccination~Study products Ad26.COV2.S by Janssen administered as a single injection~Primary objectives • To assess the effectiveness of Ad26.COV2.S vaccine on severe COVID, hospitalizations and deaths in HCWs as compared with the general unvaccinated population in South Africa.~Secondary objectives • To estimate the incidence of symptomatic SARS CoV-2 infections in HCW~To estimate vaccine uptake among HCWs in South Africa~To monitor the genetic diversity of breakthrough SARS CoV-2 infections To monitor immunological responses (neutralising, non-neutralising antibodies and T cell responses) in HCWs with breakthrough infections~To measure baseline SARS CoV-2 antibody testing to evaluate pre-existing immunity in up to 100 000 HCWs.~In a subgroup of participants (approx. 850-1000 people) including representative sub-populations of interest, e.g. elderly, immune compromised:~To compare serum neutralization and immune responses before and after vaccination at 0, 6 weeks and up to 6 months.~To explore clotting parameters post vaccination at weeks 0, 1, 3.~To monitor for asymptomatic infection~Exploratory objectives To set up a comprehensive safety desk and establish a link between the national pharmacovigilance system to assist with monitoring safety and any unexpected adverse effects
To monitor the effectiveness of the single-dose Ad26.COV2.S COVID-19 vaccine among health care workers (HCW) in South Africa