Email USA TODAY panel says US has nailed the science behind COVID-19 vaccines, but logistics, trust remain a concern Experts are concerned some won't trust the COVID-19 vaccine and are wary of production problems that could delay getting it to millions of Americans. Karen Weintraub and Elizabeth Weise, USA TODAY Published 12:12 am UTC Dec. 24, 2020 Experts are thrilled about the reported safety and effectiveness of two COVID-19 vaccines rolling out across the country. But they remain concerned about what still could go wrong to shake the public's fragile faith in it. Nearly everything about the process has gone well so far, shepherded by the Trump administration's Operation Warp Speed.