Surge in good news: Vaccines mostly block asymptomatic disease spread

Last week, new data from Israel, where nearly 60 percent of the country’s 9 million residents have received at least one dose of a vaccine, suggested that the Pfizer-BioNTech vaccine is 94 percent effective at preventing asymptomatic infections.

A separate study conducted by researchers at Cambridge University, in the United Kingdom, found that a single dose of the Pfizer vaccine can reduce asymptomatic infections by 75 percent. The results, which have yet to be peer-reviewed, came from an analysis of around 4,400 tests conducted on vaccinated health care workers in Cambridge over a two-week period in January.

In Johnson & Johnson’s trials, the company’s vaccine was found to be 74 percent effective against asymptomatic infections. And according to a report released in December by the Food and Drug Administration, early data suggested that Moderna’s vaccine may also protect against asymptomatic infections, but the company has said more research is needed.

Source: ‘Very promising’ data shows vaccines may stop Covid transmission, but big questions remain