EU backs broader use of Comirnaty as COVID booster than US

The EMA has given the go-ahead to the use of Pfizer and BioNTech's COVID-19 vaccine Comirnaty as a booster for all people aged 18 or more, but says EU member states must decide for themselves whether to make a third dose available to their citizens.

The regulator's human medicines committee (CHMP) said that a third dose of Comirnaty can be given six months after the completion of the primary course of two injections with the jab.

The scope is much broader than the green light given by the FDA last month to booster shots of Comirnaty in the US, which covered people aged 65 years and older, adults at high risk of severe COVID-19, and those exposed to the virus because of their work or living conditions.

Ultimately however the decision on exactly who will be in line to receive a booster dose of the vaccine will be up to member state governments.

"At national level, public health bodies may issue official recommendations on the use of booster doses, taking into account emerging effectiveness data and the limited safety data," said the EMA in a statement.

"The risk of inflammatory heart conditions or other very rare side effects after a booster is not known and is being carefully monitored," it added.

The CHMP also concluded that Comirnaty and Moderna's SpikeVax shot can be offered to people with severely weakened immune systems, at least 28 days after their second dose, to shore up their immunity against SARS-CoV-2.

The CHMP is currently evaluating wider use of SpikeVax as a booster, while an FDA advisory committee is due to meet on 14-15 October to discuss booster jabs from both Moderna and Johnson & Johnson.

More evidence of waning immunity?

The CHMP announcement came as a new US study has suggested that there is a "substantial" waning of antibody responses and T cell immunity to SARS-CoV-2 and its variants, six months after the second dose of Comirnaty.

The study – published on the Biorxiv.org preprint server – only included 56 healthy volunteers and has not been peer-reviewed. Nevertheless, the authors suggest that the findings lend weight to other reports of waning efficacy of vaccines and the emergence of variants of concern that are resistant to antibody neutralisation.

The results " suggest a third booster immunisation might be warranted to enhance the antibody titres and T cell responses," they conclude.

The study follows comments made by BioNTech chief executive Ugur Sahin to the Financial Times, in which he suggested that new formulations of vaccines will be needed to deal with new variants of SARS-CoV-2.