In comparison, taking a Pfizer-BioNTech booster jab after Pfizer-BioNTech vaccination further reduces the risk of infection by 62 per cent. Mr Ong and MOH's director of medical services Kenneth Mak took the Moderna booster jab after being inoculated with Pfizer-BioNTech's vaccine. The results for other combinations, such as a Moderna booster jab with Moderna vaccination, "may not be as meaningful" as the sample sizes are "not very large", said Mr Ong at a COVID-19 multi-ministry task force press conference.