Countries where COVID-19 vaccines have rolled out quickly, such as Israel and the UK, are starting to give an indication of how well they work. Their early results suggest the vaccines are highly effective at preventing people from being hospitalised or dying from the disease.
Israeli data shows that the Pfizer/BioNTech vaccine has reduced severe disease by 92% and hospitalisations by 87%. And a Public Health England preprint – a paper yet to be reviewed by other scientists – suggests that one dose of either the Pfizer or Oxford/AstraZeneca vaccine cuts the risk of hospitalisation by 80%.
However, it’s less clear how good the vaccines are at stopping people from spreading the virus. But given what we know about how they work, we shouldn’t be surprised if they are less effective at stopping people transmit the virus than preventing them becoming ill. This is because the type of immunity they generate is likely to be better at fighting off severe rather than mild infections.