(Bloomberg) -- Researchers have started recruiting South African health workers to take part in a vaccine trial that will compare the use of Johnson & Johnson and Pfizer Inc. Covid-19 shots as boosters. 

The health workers being targeted for the study were part of an initial trial known as Sisonke that saw almost half a million people given an initial dose of J&J’s vaccine. 

The trial, which will be carried out by Johannesburg’s Wits Reproductive Health and HIV Institute, will run for six months, according to an invitation to potential participants. Participants will be randomly allocated a full or half dose of a vaccine made by either J&J, or Pfizer and BioNTech SE. 

A booster trial using a second J&J dose has already been run on some Sisonke participants. The government has in recent weeks begun offering both J&J and Pfizer boosters, with the stipulation that those administered with the vaccine receive the same inoculation they got initially. 

The new study has been named Booster After Sisonke Study, or BaSiS. 


©2022 Bloomberg L.P.