Not a single case of flu detected by Public Health England this year as Covid restrictions suppress virus

Not a single case of influenza has been detected by public health officials in England for the past seven weeks, with infection rates at historic lows amid the ongoing Covid-19 restrictions.

The social restrictions brought in to curb transmission of coronavirus, combined with increased uptake of the flu vaccine, have both been credited with driving down infections.

Thousands of swab samples are processed and analysed by scientists at Public Health England (PHE) every week 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 to 31 December 2020, just one case of flu was confirmed by laboratory analysis.

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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 the Royal College of General Practitioners’(RCGP) research and surveillance centre has shown that the rate 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 strain. In comparison, the basic R value for Sars-CoV-2 – the virus that causes Covid-19 – is estimated to be around 2.5-3.0.

This means influenza is far less infectious and easily spread than coronavirus, helping to further explain its low 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 the idea of whether there is anything that we can do.”

She said that hand sanitiser 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 in to 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 are 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.”

Dr Stephen Griffin, a virologist at the University of Leeds, said it was unclear whether flu cases would surge later this year after being subdued over the recent winter months.

“Hopefully some of the good habits in relation to social distancing and hygiene might help again in the future as well,” he told The Independent.

Prof Griffin warned there could be an issue in terms of surveillance and vaccine development. “If there’s very little [flu] circulating it’s harder to predict which strains might be dominant and so need to be incorporated into the vaccine,” he added.