The United States’ Food and Drug Administration on Wednesday authorised the use of booster shots of Covid-19 vaccines developed by Moderna and Johnson & Johnson. The agency also allowed mixing and matching of booster doses.

The Centres for Disease Control and Prevention will consult an expert panel later this week before finalising these recommendations, reported AP.

The FDA said that beneficiaries of Moderna Covid-19 vaccine who are aged 65 years and older or are adults at high risk of severe infection because of their health conditions or jobs can get the booster shot. They can get the booster jab six months after completing their initial vaccination.

The health agency authorised the booster jab after studying the immune response of 149 adults participants from clinical trials who received a booster dose at least six months after their second dose and compared to that of 1,055 participants who just received the primary two jabs.

The study showed that the participants who got the booster shot had a better antibody response 29 days after receiving the extra jab.

A safety study on 171 adults participants who got the booster shot showed that the most common side effects were pain at the injection site, tiredness, headache, muscle and joint pain, chills, swollen lymph nodes in same arm as the injection, nausea and vomiting and fever.

The health agency said that Moderna booster dose should be administered in half the quantity of dose that is given during the primary vaccination.

The FDA said that the Johnson & Johnson booster shot can be administered to all adults at least two months after they have received the primary shot. Johnson & Johnson vaccine is based on a single-shot regimen.

The authorisation for using Johnson & Johnson’s booster dose was based on the evaluation of immune response data of 39 participants from a clinical trial including 24 participants aged between 18 and 55 and 15 participants who were 65 years of age and older. The study participants received a booster dose about two months after their first dose and the results demonstrated a booster response.

“Overall, approximately 9,000 clinical trial participants have received two doses of Janssen [Johnson & Johnson] Covid-19 vaccine administered at least two months apart and of these, approximately 2,700 have had at least two months of safety follow-up after the booster dose,” the agency said. “Janssen’s safety analyses from these studies have not identified new safety concerns.”

The FDA had in September given authorisation for the use of booster shots of the Pfizer-BioNTech Covid-19 vaccine for high-risk adults and those aged 65 and above.

On Wednesday, acting FDA Commissioner Janet Woodcock said that the vaccination continued to be the most effect way to prevent Covid-19, including the serious consequences of the disease such as death and hospitalisation.

“The available data suggest waning immunity in some populations who are fully vaccinated,” she said. “The availability of these authorized boosters is important for continued protection against Covid-19 disease.”