Lorraine Williamson
Spain’s flu curve is starting to ease nationally, but the winter threat hasn’t disappeared — it has shifted. New research highlighted by the Instituto de Salud Carlos III (ISCIII) suggests the flu vaccine may help in a place many people don’t think about: reducing the danger of secondary bacterial infections that can follow influenza.
That matters because, even as overall flu incidence dips, infections are still rising among older adults — the very group most vulnerable to complications.
A vaccine story that goes beyond “stopping the flu”
The ISCIII-backed research, conducted in a preclinical mouse model, examined the interaction between influenza and bacteria such as Streptococcus pneumoniae, a common cause of severe pneumonia.
In the study, a single dose of trivalent inactivated influenza vaccine (TIV) reduced mortality in “coinfections” (simultaneous infections with flu and bacteria) from 50% to 15%. In “superinfections” — where the bacterial infection struck a week after the viral one — mortality fell from 100% to 50%.
Researchers also reported lower viral and bacterial loads, less lung inflammation, and immune changes suggesting a more controlled response in vaccinated animals.
Why secondary bacterial infections are so feared
Flu doesn’t always end with a fever and a week on the sofa. In higher-risk people, it can open the door to bacterial infections that hit hard and fast, including pneumococcal disease.
That’s one reason winter messaging often focuses on vaccination, even when people feel they “usually cope fine” with the flu. The point isn’t only avoiding infection. It’s reducing the odds of the dangerous spiral that can follow.
The authors stress this is not a human clinical trial. But it adds weight to a long-standing concern in respiratory medicine: flu and bacteria can be a lethal partnership, and prevention may soften the blow.
Flu in Spain is dipping — except among older adults
The latest surveillance snapshot for 15–21 December shows Spain’s overall flu-like syndrome rate edging down from 197.6 to 192.6 cases per 100,000 people.
But among those aged 60 and over, incidence moved the other way. Rates rose in the 60–69 bracket (from 96.6 to 115.3), in 70–79 (from 84.7 to 106.5), and slightly in the 80+ group (from 91 to 93.5).
Those numbers remain below the national average. Even so, they are a warning light, because age increases the risk of severe illness and complications.
Hospitals are stable — but pressure can change quickly
Hospital admissions linked to flu have remained broadly steady, with only slight week-to-week movement reported in the same surveillance window.
The bigger risk is what happens after holiday mixing: crowded travel days, multi-generation meals, and house parties where “it’s just a cough” spreads quickly. The infection curve can rise again in January.
The mask moment that suddenly makes sense
So far this winter, our own household has dodged the flu. Plenty of friends haven’t been so lucky. It often seems to start with the children, then ripple through the adults a few days later.
That’s why a small moment at Hospital Costa del Sol stuck with me. At a recent appointment, I was simply handed a face mask and asked to wear it. It wasn’t inconvenient, and if it made the waiting room feel safer for someone older or unwell, it felt like a reasonable trade-off. I’ve also noticed more masks again in supermarkets and shopping centres — a quiet sign that people sense winter viruses are back in circulation.
A winter reminder for families with older relatives
The new study doesn’t claim the flu jab is a shield against every complication in humans. But it strengthens the argument that vaccination may matter even when flu rates begin to fall.
For families visiting older relatives over the coming days, the basics still count. Don’t “push through” symptoms, ventilate indoor spaces, and take a sudden worsening seriously — particularly breathing difficulty, chest pain, confusion, or signs of dehydration.
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