Recent vaccination and boosters reduce infectiousness, but infection risk remains high, a study in California prisons found.According to the researchers, vaccination and boosting, especially when recent, helped to limit the spread of COVID-19 in California prisons during the first Omicron wave, according to an analysis by researchers at University of California San Francisco, US, that examined transmission between people living in the same cell.The study demonstrates the benefits of vaccination and boosting, even in settings where many people are still getting infected, in reducing transmission, it said.The study also shows the cumulative effects from boosting and the additional protection that vaccination gives to those who were previously infected. The likelihood of transmission fell by 11 percent for each additional dose, it said.”A lot of the benefits of vaccines to reduce infectiousness were from people who had received boosters and people who had been recently vaccinated,” said Nathan Lo, senior author of the study.”Our findings are particularly relevant to improving health for the incarcerated population,” said Lo.