US Centres for Disease Control and Prevention (CDC) Director Rochelle Walensky on Friday approved the use of Covid-19 booster vaccines for immunocompromised people as the country suffers a large surge of coronavirus cases due to the highly transmissible Delta variant.
The move follows a unanimous vote by an independent vaccine advisory panel which ruled that a third dose is recommended for those who are moderately or severely immunocompromised.
The recommendation applies to those aged 12 years or older who have been fully vaccinated with either the Pfizer-BioNTech or Moderna vaccines. The authorisation does not apply to the Johnson & Johnson vaccine at this time, the CDC said on Friday, due to a lack of data.
With Dr Walensky's approval, immunocompromised people can receive their additional dose as early as this weekend.
Patients will not need proof that they are immunocompromised to receive the booster, health officials said.
"It will be a patient's attestation and there will be no requirement for proof or prescription or a recommendation from an individual's healthcare provider," CDC official Dr Amanda Cohn said, speaking before the advisory panel on Friday.
The decision also follows a pivotal US Food and Drug Administration (FDA) authorisation for booster shots for immunocompromised people that was announced late on Thursday night.
The emergency use authorisation paves the way for people who have had an organ transplant or those with a similar level of weakened immune system to receive an extra dose.
The patients may consult with their doctor to see if they are eligible, FDA representative Abby Capobianco said.
“After a thorough review of the available data, the FDA determined that this small, vulnerable group may benefit from a third dose of the Pfizer-BioNTech or Moderna vaccines,” Janet Woodcock, the FDA's acting commissioner, said in a tweet on Thursday.
“Others who are fully vaccinated are adequately protected do not need an additional dose of Covid-19 vaccine at this time.”
Vulnerable groups make up less than 3 per cent of US adults, Dr Walensky said before the authorisation was announced.
Supporting the move to approve an additional shot, Paul Offit, director of the Vaccine Education Centre at the Children's Hospital of Philadelphia, said it would be important for the CDC to provide clear recommendations about who should receive it.
Countries like Israel and the UAE have moved forward to allow additional booster shots, while others such as France and Germany are exploring an approval in the near future.
The UAE has recommended that high-risk and fully vaccinated people receive a third dose of a vaccine three months after their second dose.
Israel has already started administering a third booster shot to people aged 60 and above after the country's health ministry reported a decrease in the effectiveness of the Pfizer vaccine in preventing infections and symptomatic illness.
Scientists are still divided over the broad use of boosters among those without underlying problems as benefits of the boosters remain undetermined.
Pfizer has said the efficacy of the vaccine it developed with partner BioNTech declines over time, citing a study that showed 84 per cent effectiveness from a peak of 96 per cent four months after a second dose.
Moderna has also said it sees the eventual need for booster doses, especially since the Delta variant has caused “breakthrough” infections in fully vaccinated people.
Reports of infections among vaccinated people and concerns about diminishing protection have galvanised wealthy nations to distribute booster shots, even as many countries struggle to access first vaccine doses.
The World Health Organisation has called for a moratorium on booster shots until a greater portion of the world's population has been vaccinated against Covid-19.
News agencies contributed to this report