The Trump administration's communications on a COVID-19 vaccine haven't exactly been seamless.

CDC Director Robert Redfield testified Wednesday that a vaccine won't be "fully available to the American public" until probably "late second quarter, third quarter 2021." That's consistent with estimates from National Institute of Allergy and Infectious Diseases chief Dr. Anthony Fauci, National Institutes of Health Director Francis Collins, and Moncef Slaoui, the chief scientist at Operation Warp Speed, the federal vaccine initiative.

President Trump said Redfield "made a mistake" with his timeframe and shared "incorrect information." He predicted there will be a vaccine before Election Day and up to 100 million doses delivered by the end of the year — more than double the CDC's most optimistic projection. White House Chief of Staff Mark Meadows said Thursday the goal is for 300 million doses by Jan. 1 and "we believe that we can get the vast majority of those at risk with a distribution model that would be available at the end of October."

Moderna, testing one of the most promising vaccine candidates in Phase 3 trials, said Thursday it may not even know if its vaccine works until next year. Stéphane Bancel, Moderna's CEO, said he anticipates massive vaccine shortages "in the first half of next year, at least maybe until Labor Day next year."

Assuming at least one of the half-dozen late-stage vaccines pans out and wins approval from an outside panel of experts, states will then have to overcome "a host of logistical and supply chain challenges" to get it distributed to the public, starting with health care and other essential workers, Politico reports. "State officials overseeing the largest and most complex vaccination campaign in history say the effort will require a level of careful coordination with the federal government that's been lacking during the pandemic."

"Many things could still go wrong," and "all the claims and counterclaims about when a vaccine will be ready and how safe it will be — some coming from Trump himself — have created a great deal of public hesitancy, beyond the regular anti-vaccination sentiments," Politico health editor Joanne Kenen writes. But "we've seen amazing science over the last eight or nine months," and "with each passing day, a vaccine is getting closer." Even if the first efforts "aren't as powerful as we'd like," she adds, it will help contain the virus. Peter Weber