Outside advisers to the US Food and Drug Administration on Friday unanimously recommended the agency authorize a second shot of Johnson & Johnson's Covid-19 vaccine for all recipients of the one-dose inoculation.
The agency is also considering lowering the recommended age for booster shots of the Pfizer/BioNTech vaccine to people as young as 40, FDA official Dr. Peter Marks told the advisory panel.
The FDA's Vaccines and Related Biological Products Advisory Committee backed the shots for all J&J recipients aged 18 and older at least two months after their first dose.
The FDA is not bound to follow the recommendation, but typically does.
After hearing presentations from J&J and FDA scientists, many members of the advisory panel asked if J&J's single-dose vaccine should actually be considered a two-dose shot for everyone.
They pointed to the lower levels of virus neutralizing antibodies it provokes compared to vaccines using messenger RNA (mRNA) technology from Moderna Inc and Pfizer/BioNTech.