The largest city in the US as well as several states in the past week have opened eligibility for additional Covid-19 vaccine doses to all adults, anticipating federal approval by US agencies.
New York City health officials on Monday said adults should be allowed to decide whether to receive a booster as long as they are six months out from their last dose, pointing to rising cases, cooler weather pushing activities indoors and the city's high population density.
This follows similar moves by Colorado, California, New Mexico and several other states that have widened eligibility over the past two weeks, as the country has reported increasing cases in the lead-up to the Thanksgiving holiday.
These steps bypass federal booster regulations, which only allow people to receive an additional dose if they are over 65, have an underlying medical condition or are at high risk for exposure.
Even with these policies in place, people who do not fall into these categories have been able to receive booster shots as many vaccine providers do not check qualifications.
The Centres for Disease Control and Prevention (CDC) says 15 per cent of fully vaccinated people in the US have received a booster shot. A total of 70.6 per cent of US adults have been fully vaccinated.
Pfizer last week formally applied for an emergency use authorisation that would make all adults over the age of 18 eligible for a third dose.
The Food and Drug Administration (FDA)'s top vaccine official, Dr Peter Marks, told CNN on Tuesday that evaluating Pfizer's request to approve additional doses for all adults is the agency's “highest priority".
The New York Times reported later on Tuesday that the FDA may approve Pfizer's booster for adults as soon as Thursday.
A national federal authorisation would still require the CDC's approval and the agency announced its independent vaccine panel will review the Pfizer application on Friday.
Many doctors have voiced support for the expansion of eligibility.
“The data is becoming increasingly clear,” Dr Ashish Jha of Brown University tweeted. “It is time for every adult six months out to get a booster.”
“Every adult in this country more than six months out from their second mRNA shot should get a booster,” Dr Jonathan Reiner of George Washington University tweeted.
The rising pro-booster sentiment among the doctors, health officials and leaders is due to increasing cases as the country heads into the winter months as well as waning vaccine efficacy.
Researchers found the efficacy of Pfizer's regime, for example, dips to 93 per cent after a month but can plummet as low as 53 per cent after four months. The company says a booster dose would return efficacy to 96 per cent.