Healthcare regulators at the United States Centers for Disease Control and Prevention recommended the COVID-19 vaccines produced by Moderna and Pfizer over those made by Johnson & Johnson on Thursday.

The expert panel, which is formally known as the Advisory Committee on Immunization Practices, reportedly based their recommendation on a tip from the United States Food and Drug Administration that linked the Johnson & Johnson COVID vaccine to the risk of rare but potentially life-threatening blood clots.

The health regulators said that the blood clotting issue linked to the single-dose vaccine has been linked to at least nine confirmed deaths in the United States and also appears to be less effective than its two-dose alternatives.

The panel recommendation, which was passed on from the Food and Drug Administration first, will now land on the desk of Dr Rochelle Walensky, the director of the Centers for Disease Control and Prevention. Walensky will decide if the decision should be accepted by the body or not.

Until now the U.S. has treated all three COVID-19 vaccines available to Americans as an equal choice, since large studies found they all offered strong protection and early supplies were limited.

So far, all healthcare regulators in the country have kept all three federally approved COVID vaccines at the same pedestal, presenting them as an equal choice for Americans. 

Johnson & Johnson’s vaccine initially was welcomed as a single-dose option that could be especially important for hard-to-reach groups like homeless people who might not get the needed second dose of the Pfizer or Moderna options, according to reports from Associated Press.

However, the advisors said Thursday that it was time to recognise a lot has changed since vaccines began rolling out a year ago. More than 200 million Americans are considered fully vaccinated, including about 16 million who got the Johnson & Johnson shot.

(With AP inputs)