The chief scientific adviser for the administration’s effort to accelerate production of a coronavirus vaccine said he would quit if there was political interference in the process.

The remarks by Moncef Slaoui, who co-leads President Trump’s “Operation Warp Speed,” come amid reports that the Centers for Disease Control and Prevention told officials in all 50 states and the U.S. territories to prepare for vaccine distribution for high-priority groups as early as Nov. 1. That deadline — two days before the presidential election — has fueled concerns of political pressure to fast track vaccine approval ahead of Election Day.

In a separate interview, Slaoui said it was “possible but very unlikely” that a coronavirus vaccine will be ready to distribute by the end of October or early November.

Here are some significant developments: