The World Health Organization's vaccine advisors on Monday advised that patients with weakened immune systems be given an extra dose of the approved Covid-19 vaccines.
People over-60 who have been taken two doses of the Chinese Sinovac and Sinopharm vaccines should be provided with a third dose of the same jab, said the UN's Strategic Advisory Group of Experts on Immunisation (SAGE), reports AFP.
The experts made it clear that they were not proposing an additional "booster dosage" for the general public.
Pfizer-BioNTech, Johnson & Johnson, Moderna, Sinopharm, Sinovac, and AstraZeneca have all received WHO clearance for emergency use during the pandemic.
SAGE held a four-day meeting last week to review the latest information and data on a range of vaccines for Covid-19 and other diseases.
"SAGE recommended that moderately and severely immunocompromised persons should be offered an additional dose of all WHO EUL (emergency use listing) Covid-19 vaccines as part of an extended primary series," the group said.
"These individuals are less likely to respond adequately to vaccination following a standard primary vaccine series and are at high risk of severe Covid-19 disease."
A different vaccine "may also be considered based on vaccine supply and access considerations".
SAGE added that when implementing this recommendation, countries should initially aim at maximising two-dose coverage in that population, and thereafter administer the third dose, starting in the oldest age groups.