A fourth-dose Covid jab might be on the cards for the general population after a UK trial found it increased protection against the virus.
The majority of people in the UK received their third vaccine in the winter when the government rolled out the booster programme in response to the huge surge in infections triggered by the Omicron variant.
A small category of the public have been able to access a fourth dose since April, but – based on new research – it looks like this could be rolled out to more people in the autumn.
Does a fourth dose increase protection?
Yes – the results of a new UK trial, published in Lancet Infectious Diseases, revealed that two weeks after their fourth jab, the vaccines were “well-tolerated” and “boosted immunity” among the 133 study participants.
Everyone in the study was vaccinated with either a dose of Pfizer or a half dose of Moderna approximately six months after their third jab.
The study leader, Professor Saul Faust from the University of Southampton, said: “We’ve demonstrated a fourth dose of Covid-19 vaccines can produce a substantial boost to both the antibody and cellular immunity when you give them more than six months after the third dose.”
He continued: “There was good boosting in all groups, particularly for the over-70s and the half dose of Moderna was slightly higher.”
There was a 1.6-fold increase in antibodies for those who received Pfizer and more than twofold increase for those who received the Moderna.
“Peak responses to the fourth dose were similar to, and possibly better than, peak responses after the third dose,” the experts also concluded.
T-cells, an essential part of the immune system, were also boosted after the vaccine – suggesting long-term protection was increased alongside symptomatic infection, both in those over and under 70 years of age.
Health secretary Sajid Javid said the study shows “further evidence underlining the importance of people coming forward for their booster as soon as they are eligible”.
Are there any downsides?
Just like after the third dose, it appears that Covid antibodies wane quite quickly after injection.
Prof. Faust also suggested that the surge of infections seen with the recent Omicron wave suggests most of the public will have been infected recently, and have high antibody levels – defeating the point of a fourth jab.
He said those who had little waning of their immune responses before their fourth dose only saw a small increase in antibodies.
He explained: “That indicates there may be a ceiling, a maximum antibody level with the T-cell response effects.”
Why can’t everyone get a fourth dose now?
Some nations – including Israel and Germany – have already rolled out a fourth dose.
However, in the UK, the government will only make a decision based on the advice from the JCVI – Joint Committee on Vaccination and Immunisation.
This independent panel identifies new variants of concern and potential pressure on hospitals. Downing Street has waited for the experts’ nod before making a key move related to the vaccines, such as offering it to children, throughout the pandemic.
So this particular study won’t trigger an immediate response from Downing Street – especially as it only had a small number of participants.
More research is needed to look at how the immune response fares over a longer time frame as well, before more people can access it.
Who is currently eligible for a fourth dose?
Adults aged 75 and over, along with residents in care homes for older adults and anyone aged 12 and over with weakened immune systems have been entitled to a fourth jab since April.
Appointments can be booked three months after your previous dose, but the NHS recommends having the spring dose approximately six months later to maximise its effects.
It has not yet been revealed who the government might extend the fourth jab to in the autumn.
Should we keep getting boosters?
Professor Danny Altmann, immunologist at Imperial College London, suggested that this new study shows how important it is to get another vaccine dose.
He told The Guardian: “Just because our first-generation vaccines wane rapidly and offer rather permeable protection nowadays, does not suggest we should give up and have no further boosters.
“On the contrary, many of us, even with high apparent antibody levels, actually show [little] protective neutralisation of Omicron, there is all the more urgency to use [fourth] doses – in all age groups – to boost levels back up into the protective range.”
However, professor of paediatrics at the University of Bristol and a member of the JCVI, Adam Finn, suggested last month that anyone who is not yet middle-aged probably does not need a fourth dose.
“I think it’s questionable whether young, healthy people will ever be offered another Covid vaccine beyond dose three – at least with the vaccines and variants we have now.”
He added: “You just don’t achieve anything very useful by [further] immunising healthy young people with these vaccines because they rarely get sick – which the vaccines prevent.”
Yet, he pointed out that this could all change in the future, if other more dangerous variants emerged.
Vaccines also reduce long Covid symptoms, regardless of your age.