Thousands of swab samples are processed and analysed by scientists at Public Health England (PHE) on a weekly basis to survey the prevalence of different respiratory diseases in the population.
But of the 685,243 samples that have been reviewed at PHE’s laboratories since the first week of January, not a single one has tested positive for influenza.
In the week up 31 December 2020, just one case of flu was confirmed by laboratory analysis.
Dr Vanessa Saliba, head of flu at PHE, told The Independent: “The decrease in flu cases this year is likely due to changes in our behaviour, such as social distancing, face coverings and handwashing, as well as the reduction in international travel.
“In England, more than 15 million people receive the flu jab every year, which helps protect them from flu and also stops them spreading it to others.
“This season’s immunisation programme is on track to be the most successful ever, with the highest levels of vaccine uptake recorded for those 65 years and over, 2 and 3-year-olds and healthcare workers.”
PHE runs nationwide surveillance of influenza all year round, and produces a weekly report on the virus and other respiratory illnesses between October and April to capture activity during peak flu season.
Separate data gathered by Royal College of GPs’ (RCGP) research and surveillance centre has shown that the rates of influenza-like symptoms stood at 0.5-1.3 per 100,000 persons for December – well below the five-year average for this time of year.
With widespread social distancing and mask-wearing measures in place throughout the UK, the usual routes of transmission for influenza have been blocked.
The virus has a natural R rate of 1.3-1.5, depending on the different strain. In comparison, the basic R value for Sars-CoV-2 – the virus that causes Covid-19 – is estimated to be around the 2.5-3.0.
This means influenza is far less infectious and easily spread than coronavirus, helping to further explain its fading prevalence in the UK population.
Such trends have raised the need to reconsider the country’s approach to dealing with influenza, according to Christina Pagel, a professor of operational research at University College London.
“There’s been no flu season anywhere in the world this year, including the UK,” she told The Independent. “Flu is one of the big reasons that the NHS struggles every winter. But what I think is really interesting is that people say we live with flu deaths every year and kind of assumed they were unavoidable. Yet clearly they’re not.
“If we wanted to, we’ve shown we can reduce flu deaths to pretty much zero. I don’t think that the damage we have done through lockdown is anything that anyone would support to prevent flu, but it does bring into question is there anything that we can do.”
She said that hand sanitisers should be kept available in all shops and transport hubs for the years to come, and argued that it is “worth encouraging people to wear masks” on public transport and in other busy environments during the winter months.
“I don’t know if it’s the social distancing or the mask wearing that’s done it [in reducing flu rates], but I think we should at least be having those conversations,” Prof Pagel added.
“Another thing, especially in Britain, is this attitude that if you’re sick, you still go into work. We need to change that. We’ve shown that a lot of people can work remotely.
“I think it’s an unintended consequence of Covid that we’ve realised flu isn’t this unavoidable threat that we thought it was.”
Influenza vaccination rates have meanwhile reached new heights throughout the course of the Covid-19 pandemic.
According to the latest PHE data, 80.8 per cent of people aged over 65 in England have received the latest flu jab.
Prof Pagel said the health inequalities highlighted by Covid-19 were also applicable to flu, and that a joint approach to improving the quality of care in England’s most deprived communities would help to reduce widespread infections for both diseases.
“The other thing Covid has highlighted is how big the impact of inequality is on health,” she said. “We’ve seen it with Covid in BAME and deprived communities. They have much more exposure to Covid and get sicker when they get it. Flu has a very similar gradient. The more deprived you are, the more likely you’ll get sick from flu.”