Flu cases in Australia were down in 2020, according to national statistics – and it’s a pattern witnessed globally.
Data from the UK’s RCGP’s Research and Surveillance Centre suggests community prevalence of flu is around 95% lower than normal at this time of year in England, when compared to the five-year average.
With much of the UK still in lockdown, it’s perhaps no surprise that cases of influenza have dropped so much. Professor Martin Marshall, RCGP chair, says: “Whilst a staggering figure, it makes sense when you consider the lockdown restrictions, social distancing measures, and increased focus on maintaining good hygiene practices we are seeing at the moment – which will work to stop the spread of contagious illnesses such as colds and flu, as well as Covid-19.”
This year has also seen huge numbers of people opt in for the flu vaccine. According to Public Health England (PHE), 80% of people aged 65 and over have had the flu vaccine – the highest uptake ever achieved – as well as 51% of those under 65 in a clinical risk group.
Among children, more than half of two and three year-olds have also had the vaccine.
The expanded flu vaccination programme is ongoing, and GPs are encouraging eligible patients – now including 50-64 year olds – to have the jab.
“Flu can be a nasty illness and the flu jab is the best protection we have against it,” says Prof Marshall. “The last thing we want is to see an increase in flu cases whilst we continue to tackle the Covid-19 pandemic.”
Flu viruses are less transmissible than Covid-19, but both are thought to spread in similar ways – droplets carrying the virus can spread from one person to another when infected people breath out, cough or sneeze, says Professor Christl Donnelly, an expert in statistical epidemiology at Imperial College London and professor of applied statistics at University of Oxford.
“Social distancing measures which limit the transmission of Covid-19 therefore limit the transmission of influenza,” she says. “We come into contact with fewer people therefore there are fewer opportunities to transmit these viruses.”
The coronavirus lockdown measures have meant more of us are hand-washing and more regularly – so any flu virus you might pick up on commonly-used objects is reduced to a minimum.
People keeping two metres apart in indoor settings (where possible) and fewer close contact interactions reduces the risk of larger droplets wielding flu from landing on you. Face masks also help to reduce the number of droplets we expel – wearing one doesn’t just protect others, but also ourselves.
PHE estimates that, on average, around 17,000 people die from flu in England annually. These numbers can vary greatly from year to year, depending on the severity of the season and the strains knocking around.
Last flu season saw relatively low levels of influenza activity in the UK, according to data from Public Health England (PHE). But this year, we’re seeing even lower figures. The Times reports levels are the lowest they’ve been for 130 years.
Professor Rowland Kao, an expert in epidemiology and data science from the University of Edinburgh, tells HuffPost UK it is “very likely” both the coronavirus measures and a push for greater vaccine uptake have reduced flu levels.
“Of these, the bigger impact is likely the Covid restrictions,” he says. “Increases in flu vaccination has been considerable, but given that flu vaccination is mainly aimed at the elderly and vulnerable and does not prevent circulation of flu in the community, this would not in itself be enough to cause numbers to drop down dramatically – though it would of course prevent deaths.”
He adds that reduced travel might also prevent some infections from entering the UK, but so long as there is circulating virus within the UK, “it is unlikely to have a major impact”.
This reduced level of flu is looking similar across much of the world. The World Health Organisation (WHO) laboratories tested more than 200,863 specimens between 21 December 2020 and 3 January 2021. Of these, they found a total of 409 specimens were positive for influenza viruses.
Professor Paul Hunter, from the Norwich School of Medicine at the University of East Anglia, confirms that influenza cases were reduced “in many countries in the southern hemisphere during their winter and in Northern countries now.” However, we should not be complacent about encouraging takeup of the flu vaccine, he adds, “as there is good evidence that those few people who got influenza and Covid at about the same time were rather more likely to die.”
Flu tends to spread in the winter months due to a number of factors, Prof Hunter notes, including increased opportunities for transmission with people spending more time indoors and waning population immunity since the last influenza seasons.
This might mean that future flu seasons come back stronger. “Given that population immunity to influenza will have declined more than normal as we miss at least one and possibly two influenza seasons before we are back to normal, it is highly likely that we then see a more severe influenza peak than we would otherwise have expected,” he says.