Earliest US filing for COVID vaccine would be late November: Pfizer

That timeline makes it unlikely, however, that a vaccine will be available before the US election, as President Donald Trump has promised. Pfizer, which is developing the vaccine with German partner BioNTech, said that it may confirm if the vaccine is effective as soon as this month but that it also needs safety data from a 44,000-person clinical trial that will not be available until next month.

The Pfizer news, published in a letter from its chief executive on its website, lifted the US stock market and the company's shares. Shares fell slightly of rival vaccine maker Moderna Inc, which is close to Pfizer in its vaccine development. "So let me be clear, assuming positive data, Pfizer will apply for Emergency Authorization Use in the US soon after the safety milestone is achieved in the third week of November," Pfizer Chief Executive Albert Bourla said, noting that he published the letter to provide greater clarity on the timeline for the vaccine.

People around the world are counting on a vaccine to control the spread of the coronavirus, which has killed more than a million people and ravaged the global economy. Fears of delays were raised after trials for two rival vaccines were put on hold in the United States in recent weeks.

Trump has said repeatedly that there would be a vaccine available before the Nov. 3 election. When asked about the Pfizer news, White House spokesman Judd Deere said, "The president continues to be optimistic that we will have one or more vaccines very soon, before the end of the year."

The US government's Operation Warp Speed program has spent billions of dollars on development of vaccines and treatments. It has signed a deal to buy Pfizer vaccine shots if they work. But the rush to develop a vaccine has raised concerns that the US Food and Drug Administration, acting in haste, might not conduct an adequate review.

US health officials have sought to assuage those concerns. Earlier this month, the FDA formalized a requirement that the vaccine-makers collect two months of safety data on one-half of trial participants.

Pfizer has been trying to demonstrate that its decision-making is being driven by science rather than politics, Mizuho analyst Vamil Divan said. "Just getting it to the market is only a small part of it," Divan said. "People should actually be willing to take it."

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