Tens of millions of people in the UK are being urged to have flu and Covid vaccines as soon as possible amid fears of a winter “twindemic” that poses a serious risk to public health.
UK Health Security Agency (UKHSA) officials are braced for a resurgence in flu infections capable of causing severe disease in the coming months, and are concerned it will coincide with the major wave of coronavirus that is already building.
While Covid restrictions kept influenza at extremely low levels in the past three years, the return to almost pre-pandemic levels of mixing in the UK means the virus is ripe to bounce back this season, when immunity in the population is low.
“There are strong indications we could be facing the threat of widely circulating flu, lower levels of natural immunity due to less exposure over the last three winters, and an increase in Covid-19 circulating with lots of variants that can evade the immune response,” said Dr Susan Hopkins, the chief medical adviser at UKHSA.
“This combination poses a serious risk to our health, particularly those in high-risk groups.”
The NHS comes under pressure every winter as the cold weather drives up hospital admissions, but if flu and Covid spread widely at the same time, the health service could face a particularly difficult season.
Health officials are especially worried about the H3N2 flu strain picked up by global surveillance and which fuelled the early return of influenza in Australia this year. H3N2 can cause more severe disease than other flu strains and was responsible for the UK’s last bad flu season in 2017-18, in which there were about 22,000 excess deaths and twice as many hospital admissions.
About 33 million people in the UK are eligible for a free flu vaccine this autumn, including children being offered the nasal spray vaccine. Health officials are keen to improve uptake in pregnant women, less than half of whom took up the offer of the vaccine last year, and in young children who are unlikely to have any natural immunity to the virus.
About 26 million of those who qualify for a free flu shot are also eligible for an autumn Covid booster. Under NHS plans, these will be updated shots from Pfizer and Moderna, which target the original and Omicron variants. Flu and Covid shots are available for all over-50s, people at clinical risk, those living with immunosuppressed people, and frontline health and social care workers. Where possible Covid and flu shots will be given at the same time.
“This winter could be the first time we see the effects of the so-called ‘twindemic’ with both Covid and flu in full circulation, so it is vital that those most susceptible to serious illness from these viruses come forward for vaccines in order to protect themselves and those around them,” said Steve Russell, the NHS director for vaccinations and screening. “If you have been offered a flu vaccination or Covid booster you should book in as soon as possible.”
There are no signs yet that the flu season has arrived in the UK, but Covid cases and hospitalisations have begun to rise as new Omicron variants that are better able to evade immunity from vaccines and past infection gain ground. Research in 2020 found that people diagnosed with flu and Covid at the same time were twice as likely to die as those who only tested positive for Covid.
Peter Openshaw, a professor of experimental medicine at Imperial College London, said low levels of flu over the past two winters mean hardly anyone has natural immunity to influenza any more. “This winter, I think we’re particularly concerned that infections may have a much bigger impact, and may be going to cause trouble in people who normally wouldn’t be included in the vaccination campaign.”
Another concern is that people may be reluctant to have both Covid and influenza vaccines. “I think some people are feeling, ‘I’ll have one vaccine, but I won’t have two’,” Openshaw said. “We know that giving both the flu vaccine and the Covid vaccine simultaneously is safe, and they do not interfere with one another. People really do need to get both, because they act quite differently against two different viruses.”
Dr Tom Peacock, a virologist at Imperial College London, said based on data from the southern hemisphere, the UK could experience its first proper flu season post-pandemic this year. “It could well be pretty bad, particularly when combined with a Covid wave,” he said.
But Dr Julian Tang, a virologist at the University of Leicester, cautioned that there was still huge uncertainty over what will happen in the UK. “Although the flu season in Australia is followed by the flu season in the UK, the virus doesn’t just pack up and leave Australia for the UK.
“You can’t really predict the details of what’s coming in the UK’s influenza season, but the important thing is to get vaccinated. If Covid precautions such as masking, social distancing and improved ventilation indoors are maintained, this will also reduce the number seasonal of flu infections.”
