The UK is banking on coronavirus vaccines to bring the Covid epidemic under control, but scientists warn that in the autumn and winter another virus, influenza, may bounce back and hit us hard.
Why might the next flu season be tough?
Flu seasons are bad when virulent strains of the virus meet people with little or no immunity. In the past few years, the UK has experienced relatively low numbers of flu cases, with hardly any in the season just gone because lockdowns and other Covid measures dramatically reduced the spread of influenza. According to the Royal College of General Practitioners, cases of flu in the community were about 95% lower than normal last season.
With so little virus in circulation, population immunity will have waned, leaving people more vulnerable to flu when the world reopens and transmission picks up again. There is also more uncertainty over the effectiveness of the flu vaccine this year, because the decision on which strains to include in the shot was taken on fewer samples than usual.
How bad could it be?
In a typical year, seasonal flu kills about 7,000 people in the UK, with the number of infections up to thousands of times higher. In the season ahead, reduced immunity could double the number of cases we would normally see, according to Prof Peter Openshaw, a member of the government’s new and emerging respiratory virus threats advisory group (Nervtag). The potential impact on hospital admissions and deaths is unclear, not least because Covid has already caused a lot of extra deaths among old and frail people. If the UK experiences a serious wave of coronavirus in the winter, there is a chance some Covid restrictions will be reintroduced, or people may switch back to social distancing and mask-wearing voluntarily, all of which will keep influenza rates down.
What does it mean for the NHS?
The health service always comes under strain in the winter and influenza can be a major factor in the number of people who need hospital care. If influenza bounces back as the country faces a resurgence in coronavirus, there is a risk the NHS will be overwhelmed.
The NHS may need to sort flu patients from Covid patients to give them different treatments. The antiviral flu drug oseltamivir is most effective when it is given as soon as patients are admitted. “The problem you’ll have with coronavirus and flu around at the same time is: who are the flu guys? You’ve got to give oseltamivir straight away, you don’t have time to wait for test results,” says Dr John McCauley, the director of the Worldwide Influenza Centre at the Francis Crick Institute in London.
One option might be to start people on oseltamivir if there is any suspicion they have flu, McCauley says, and then stop the treatment if a flu test comes back negative. Another concern is that some patients may have flu and Covid at once, which nearly doubles the risk of dying compared with Covid infection alone.
How should we prepare?
Surveillance of influenza cases around the world, in the southern hemisphere, the Middle East and tropical regions, should provide early warning of the flu season to come, but most important is to ensure that people who are vulnerable to influenza and Covid – and there is considerable overlap – are well-protected by vaccines. All adults should have the opportunity to receive two shots of Covid vaccine before the flu season starts and the NHS aims to repeat last year’s extended flu vaccination programme, making flu shots available to everyone aged 50 and over, in addition to children and the usual at-risk groups.
Flu vaccines are not as effective as Covid vaccines – 50% effectiveness is considered good – but they still make a huge difference. “With flu, you are on a knife-edge. It doesn’t take a lot to have a bad flu season,” says McCauley. “There is always uncertainty and vaccination is the insurance policy. You can’t afford not to be prepared for a flu epidemic. It doesn’t matter if it doesn’t happen: vaccines are cheap.”
Can Covid and flu jabs be given together?
Going into the winter, some people may need Covid booster jabs to top up their immunity, particularly those who had their first vaccine in December or January. This will be easier for the NHS to deliver if Covid boosters are given at the same time as flu shots. Studies are under way to look at the feasibility of giving both together and are expected to have answers later in the year.
“It’s a major challenge to get flu vaccines into people, but it is a challenge to which the NHS regularly rises,” says Openshaw. “But trying to administer separate vaccines for Covid and an intensified flu vaccination campaign is a huge challenge if they aren’t to be given simultaneously.”