Pfizer Says Early Data Signals COVID-19 Vaccine Is Effective

Pfizer's experimental COVID-19 vaccine appears to be working. The vaccine was found to be more than 90% effective, according to clinical results released by the company Monday.

That news comes from an interim analysis of a study involving 43,538 volunteers, 42% of whom had "diverse backgrounds."

Each participant got two injections spaced 21 days apart. The analysis compared the number of cases of COVID-19 among the volunteers getting the vaccine, with an approximately equal sized group of volunteers who got an injection of a liquid that didn't contain the vaccine.

Drugmaker Pfizer said Monday an early look at data from its coronavirus vaccine shows it is more than 90% effective -- a much better than expected efficacy if the trend continues.

The so-called interim analysis looked at the first 94 confirmed cases of Covid-19 among the more than 43,000 volunteers who got either two doses of the vaccine or a placebo. It found that fewer than 10% of infections were in participants who had been given the vaccine. More than 90% of the cases were in people who had been...