COVID-19 vaccine trials (Moderna) The pressure to have a COVID-19 vaccine out quickly is intense, but for front-runner AstraZeneca, trials have come to a stand-still. The reason? A single, unexplained illness in one vaccine volunteer. However, experts say situations like this aren’t uncommon. “This certainly happens in any large-scale trial where you have tens of thousands of people invested in taking part and some of them may get ill,” said Dr. Francis Collins, director for National Institutes of Health. “People leave those vaccine trials and they go back out into the world. And in the world, you get exposed to a lot of different bacteria and viruses,” explained Dr. Glen Nowak, director of the Center for Health and Risk Communication at the University of Georgia. Nowak says it could delay getting the vaccine out, but it’s worth it to make sure the vaccine is safe. “The fact that they’re doing it as a result of just one individual should give us some confidence that they’re being really vigilant in wanting to make sure that these vaccines are as safe as they can actually be,” he said. Even if AstraZeneca’s vaccine is to blame, and its doses are thrown away, doctors at the National Institutes of Health says it’s part of the process and plans to get a vaccine out could stay on schedule. “The reason that we’re investing not in one but six different vaccines is because of the expectation that they won’t all work,” Collins said. Nowak says none of the other coronavirus vaccine trials have announced any pauses or adverse reactions.