Private Covid boosters are available for people who do not qualify to receive these vaccines on the NHS. But is it worth paying for a shot? With most people now having been exposed to Sars-CoV-2 through previous vaccination and/or infection, our immune systems are generally well equipped to recognise and kill the virus if we become infected. Even so, unless we’ve recently been infected or received a booster, the number of antibodies circulating in our blood is likely to be low. Antibodies help to prevent us from catching Covid by binding to the virus and stopping it entering our cells. Although memory cells will quickly start churning out new antibodies if they encounter Sars-CoV-2, there will be a slight time lag before they reach high enough levels to block infection, potentially providing a window for Covid to take hold. Such infections will still usually be shorter and milder than if you’d never experienced Covid, but they remain an unpleasant inconvenience. Covid boosters are a quick and safe means of topping up these antibodies. Yet, in the UK, eligibility for the free NHS spring 2024 booster Covid vaccine is restricted to people aged 75 years and older, residents in care homes for older people, and those aged six months and over with a weakened immune system. In the US, the Centers for Disease Control and Prevention (CDC) recommends that people aged 65 and above should receive an additional dose of the Covid-19 vaccine, while the Food and Drug Administration (FDA) has proposed that everyone is offered an annual, single-dose booster – similar to the annual flu shot – with a second dose for those at greater risk of severe disease, including children under two years and adults aged 50 or older. According to a modelling study published in Annals of Internal Medicine in March, this strategy could result in 123, 869 fewer hospitalisations, 5,524 fewer deaths and save $3.63bn (£2.9bn) in direct healthcare costs each year – assuming uptake was similar to that of the annual flu shot – compared with a scenario where just 20% of the population received an annual Covid booster. Prof Stephen Griffin, a virologist at the University of Leeds, is not surprised by these results and favours the FDA’s approach. “It is based on a very good assessment of clinical benefits, hence recognising the importance of protecting both young children as well as over 50s,” he said. “Kids under five are at heightened risk after Sars-CoV-2 infection compared to primary schoolchildren – especially under ones – and there is no reason why they should be exposed to infection when a very good, safe vaccine is available.” One issue is that the UK has tended to focus on hospitalisations and deaths in its cost-benefit analysis, rather than considering other outcomes such as long Covid, Griffin added. Even so, he and other UK experts have welcomed the expansion of access to Covid boosters – though they worry the cost is likely to limit their uptake. Prof Neil Mabbott, an immunopathologist at the University of Edinburgh, said: “When people are having to prioritise other needs during a cost of living crisis, they shouldn’t necessarily be worrying about should I pay for a vaccine or not.” Mabbott believes that anyone over the age of 50 would benefit from a further booster, “because their immunity from previous boosters will be waning”. “There’s also the issue of long Covid to consider,” he said. “There’s still a large amount of people who have it or may develop it, through even having what can be a relatively mild dose of Covid-19.” Prof Lawrence Young, a virologist at the University of Warwick, thinks having a booster makes sense for those aged 65 and older, those with clinical conditions such as diabetes, heart problems and autoimmune conditions, and those living with vulnerable individuals. “This will not only provide personal protection from severe Covid and limit infection of more vulnerable individuals, but will also restrict the spread of the virus, and hopefully any new variants, in the general population,” he said.