Flu Season Raises Concerns

Every winter, flu makes its rounds, but this year, things seem a bit off.

A flu virus unexpectedly mutated over the summer. This variant seems to bypass some immunity we’ve built up, leading to a flu season that’s kicking off more than a month early. Historically, this type of flu tends to be more severe.

In light of this, the NHS has put out a “flu jab SOS” as worries mount about the potential severity of this winter’s flu season.

It’s all a bit nuanced, and there’s a fair amount of uncertainty. Yet, leading experts in flu research caution that we might be facing the worst flu season in decades.

“We haven’t encountered a virus like this in some time. The dynamics are unusual,” says Prof. Nicola Lewis, who directs the World Influenza Centre at the Francis Crick Institute. She adds, “I’m not panicking, but yes, I am concerned.”

What’s Happening?

This leads us to wonder: what’s going on, and what can we do about it?

Scientists keep a close watch on how flu viruses evolve since they mutate constantly. Each year, the flu vaccine needs to be updated accordingly.

This evolution takes place in a pattern known as “shift and drift.” Usually, the virus drifts along with minor changes, but occasionally, there’s a major shift where it mutates significantly. This year, that notable shift occurred in June.

Seven mutations appeared in an H3N2 strain, causing a rapid increase in cases, according to Prof. Derek Smith, who leads the Centre for Pathogen Evolution at the University of Cambridge.

Unusually, this mutation occurred during a summer month, well outside the typical flu season. Prof. Smith believes it’s likely to spread globally, and it’s starting to show signs of an uptick as children went back to school and temperatures cooled.

While scientists are still investigating the exact role of these mutations, they likely contribute to the virus’s ability to evade some of the immunity built through years of vaccinations and past infections.

This means the virus is spreading more easily, which explains why the flu season is beginning earlier in the UK and countries like Japan.

Flu’s R Number

If the virus can spread more readily, it doesn’t need to wait for colder weather to make its presence felt. Prof. Lewis notes, “We’re ahead of the game, and I think we’re in for a robust flu season.” She reminds us of the R numbers—the way we measure how infective a virus is—indicating this new strain has an edge. Seasonal flu typically has an R number of around 1.2, but early estimates for this year are pegged at 1.4.

So, hypothetically, if 100 individuals have the flu, they could pass it to 120 people in a regular year and 140 this year.

Could This Be the Worst Season Yet?

Prof. Christophe Fraser from the Pandemic Sciences Institute at the University of Oxford warns that it’s likely to be a severe flu season that’s already underway. Indicators suggest it might surpass some of the intense flu seasons we’ve experienced in the last decade.

Typically, about one in five people get infected during flu season, but this year, that could be higher. Still, there’s a cloud of uncertainty surrounding these predictions.

Australia had its worst flu season ever, but they didn’t deal with the same H3N2 mutations we’re facing. There’s considerable current spread among children, particularly in schools, but immunity levels differ significantly between a 10-year-old and their grandparents, who may have faced multiple flu seasons.

A Potentially More Severe Virus

Historically, the type of influenza we are seeing this year tends to be more severe, especially in older individuals. You may have heard of various flu strains like H1N1 or H5N1. The recent mutations are occurring in the H3N2 group.

“H3 is generally a more aggressive virus—it impacts the population more significantly,” notes Prof. Lewis. Some might get flu without showing symptoms, while others experience high fever, body aches, and fatigue, but the virus can be deadly for the vulnerable. Just last year, nearly 8,000 flu-related deaths were reported, and the previous season saw roughly 16,000 fatalities.

The NHS is already gearing up for what looks to be a challenging flu season. The clear recommendation is to get the seasonal flu vaccine—currently, they’ve issued a “flu jab SOS,” indicating that 2.4 million vaccine appointments are available soon.

Prof. Lewis suggests this is “the most crucial year” to get vaccinated and urges those called by their GP to act quickly.

However, this year’s vaccine isn’t a perfect match for the mutated virus. The design decisions were finalized in February to allow sufficient time for production, with the mutations surfacing later in June.

Some protection is better than none, yet Prof. Fraser acknowledges that the effectiveness of this year’s vaccine might not be as high as in years where the match was more precise. It will generate antibodies, but the real benefit is expected in terms of reducing illness severity rather than outright preventing infection.

Meanwhile, doctors have been reminded that early antiviral treatments can reduce flu-related complications.

Japan is also experiencing an early flu season and has taken steps like temporarily closing schools to limit outbreaks—not quite lockdowns like Covid, but targeted measures to disrupt the virus’s spread.

No one can predict precisely what’s ahead in the coming months. “It could all subside by next week,” says Prof. Lewis, “but I doubt it.”