Unless it happens to contain your birthday, we’re willing to bet that January is probably not your favorite month. The holiday fun is over, but the Northern Hemisphere winter has barely begun, and for many of us that means several more weeks of dark nights and bad weather. Oh, and another thing: it’s the peak of the flu season. And in some places at least, this season is shaping up to be a bad one.
What’s going on with flu around the world?
In the Northern Hemisphere, flu season is typically between October and March, during the wintertime. The Southern Hemisphere, predictably, sees the opposite pattern, with the peak of infections during their winter between April and September. In tropical regions nearer to the equator, the pattern is less obviously seasonal, and flu can circulate all year round.
Countries plan their seasonal flu vaccination programs to fit this pattern, with the aim of getting as many flu shots into people as possible before infections start to ramp up. Increased time spent indoors as the weather worsens, as well as lots of socializing during the holiday season, means that a rise in cases during December and early January is not unexpected.
But is this year worse than previous ones?
In Japan, you’d have to say yes. AFP reports that the country saw its biggest flu outbreak in 25 years at the end of December. A record 317,812 cases of flu were diagnosed between December 23 and 29, three times the number logged during the same period in 2023.
Alarms are being raised in the UK as well, with leading figures in the health service telling the BBC that the pressure on hospitals right now is similar to what was seen at the height of the COVID-19 pandemic. At time of writing, the latest data from the UK Health Security Agency shows that flu activity “remains at high levels”, and that while hospital admissions were “stable”, they were also at high levels.
Across other European countries, the picture is similar. One GP from France told Euronews, “It’s been a long time since I’ve seen such a major epidemic.
In the US, it’s not just the flu that authorities are highlighting. At time of writing, the Centers for Disease Control and Prevention (CDC) data up to January 3 showed that flu and COVID-19 activity were increasing across the country, and RSV was circulating at high levels, especially in young children. CBS reports high hospital admissions in some states – a spokesperson for Oregon Health & Science University Hospital told reporter Alexander Tin that flu cases had been “significantly higher than last year.”
The role of vaccines
It’s worth remembering that the availability of vaccines – the best defense we have against influenza viruses – varies from country to country, and these different strategies could impact the number of flu cases seen.
In the US, the CDC recommends that everyone over the age of 6 months get a flu shot. There are a few different options available depending on circumstances, including nasal sprays and injections, and vaccines are typically available at pharmacies, doctor’s offices, and clinics.
In the UK, flu vaccines are offered free of charge through the National Health Service to groups deemed to be high risk, including young children, older adults, healthcare workers, and people with a range of chronic health conditions. For everyone else, if they would like to get a vaccine they may be able to pay for one privately at a pharmacy. It’s a similar story in France.
In Japan, only injectable vaccines are approved, so there’s no nasal spray option.
A 2023 study raised questions about how flu shots have traditionally been administered in the country. The global recommendations for these shots are that they be injected directly into a muscle, usually in the upper arm; but in Japan, inactivated vaccines had been traditionally administered just below the skin instead. The authors recommended that Japan align with the global standard of intramuscular injection, citing research showing a better immune response and fewer side effects.
Of course, these preventative strategies rely on people actually taking up the offer of a vaccine in the first place. The data for this year will have to be analyzed when the season is over, but a recent study in the US found low uptake of both flu shots and COVID boosters among healthcare workers in 2023-24.
How do scientists predict how a flu season will go?
Forecasting how a flu season will play out, what virus strains will be circulating, and which ones should be included in a vaccine is a bit of a guessing game.
Back in 2013, the CDC ran a “Predict the Influenza Season Challenge” to recruit help from academics and industry researchers, and since then teams of scientists have collaborated each year to develop these forecasts.
Scientists don’t always get it right – the efficacy of seasonal flu shots varies from year to year, for example – but this data is still valuable to help health systems prepare as best they can.
The Southern Hemisphere will certainly be keeping a close eye on the current season as it continues to play out, as it’s probably a fairly accurate heads-up for what they might be facing come wintertime.
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