According to findings from a UK trial, COV-BOOST, fourth doses of COVID-19 vaccines have shown an increase in protection against the virus, especially in those over the age of 70.
However, scientists have cautioned that any short-term protection against infection is unlikely to be sustained.
In April 2022, the UK made fourth doses available to the over-75s age group and to those most vulnerable.
Countries such as Germany and Israel have already begun to offer all adults a fourth dose.
Any further decisions on whether to offer boosters to a larger part of the population in the autumn
will take into consideration whether new sub-variants are spreading, and what the level of added pressure is from COVID-19 on hospitals and the care system.
The decisions will be based on recommendations from the Joint Committee on Vaccination and Immunisation (JCVI), which advises health ministers on the use of vaccines and their benefit.
The COV-BOOST study, involving 133 people, showed that two weeks after their fourth dose, the vaccines were ‘well-tolerated’ and ‘boosted immunity’.
Researchers reported that “peak responses after the fourth dose were similar to, and possibly better than, peak responses after the third dose”.
Despite this, the study – published in The Lancet Infectious Diseases – summarised that a big increase in anti-spike antibodies would probably wane rapidly, as was demonstrated after third doses.
Participants in the study included 70-year-olds and some under 70, and all received a dose of Pfizer or a half dose of Moderna around six months after having their third dose.
Professor Saul Faust, leader of the COV-BOOST study from the University of Southampton, said: “There was good boosting in all groups, particularly for the over-70s, and the half dose of Moderna was slightly higher.”
Faust also highlighted that the recent Omicron wave means much of the population will have been infected recently and will now have high antibody levels. This would mean that they are unlikely to gain much further protection from another dose.
Commenting on the study findings, UK Health and Social Care Secretary Sajid Javid said this “further evidence underlines the importance of people coming forward for their booster as soon as they are eligible”.