Doses of the Pfizer-BioNTech coronavirus disease (COVID-19) vaccine are seen at a COVID-19 vaccination centre in Seoul, South Korea, March 10, 2021. REUTERS/Kim Hong-Ji
Regulators were aiming to complete the process by Friday, but were still working through "a substantial amount of paperwork and negotiation with the company," the Times said, citing people familiar with the planning who were not authorized to speak publicly about it.
The agency declined to comment.
It had set an unofficial deadline for approval of around Labor Day on Sept. 6, the report said.
The approval could boost the vaccination campaign by convincing more unvaccinated Americans that Pfizer's shot is safe and effective and also make local officials more comfortable in implementing vaccine mandates.
The U.S. military is expected to require that service members get vaccinated soon after Pfizer's shot is authorized and other major U.S. employers could follow suit.
Vaccine hesitancy has been a major hurdle to the White House's goal of getting all eligible Americans vaccinated against the coronavirus.
Only around 60% of adults aged 18 and over have been fully vaccinated even as the new Delta variant of COVID-19 has contributed to a surge in cases.
Full approval of Pfizer's shot would also make it easier for physicians to prescribe a third booster shot to people who could benefit from an additional dose.
The FDA has authorized Pfizer's shot as a booster for people with weakened immune systems, but the White House plans to offer them much more widely in the coming months.
The White House earlier this week said it plans to give out 100 million booster shots, many supplied by Pfizer, to at-risk Americans, including anyone whose initial inoculation is more than 8 months old, starting in September.
Some experts, including at the World Health Organization say there is not yet enough data be certain boosters are needed.
Pfizer's vaccine was authorized for emergency use in December and more than 203 million people in the United States have so far received it. None of the three authorized COVID-19 vaccines have received full FDA approval.
Reporting by Katanga Johnson, Michael Erman and Manojna Maddipatla; Editing by Arun Koyyur, Daniel Wallis and Chris Reese