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What makes flu lethal?
Flu’s familiarity belies its deadliness. This year marks the centenary of the deadliest pandemic of recent years, the Spanish flu of 1918 that killed up to 100 million, some 5 per cent of humanity at the time.
The way flu kills directly is mostly by causing viral pneumonia, a deep infection that damages the lungs’ oxygen-absorbing membranes. Pneumonia can also happen indirectly if the flu virus wipes out immune cells that normally keep bacteria in your lungs at bay, triggering a bacterial infection. Compromised immune systems, for example in elderly people and pregnant women, allow the virus to replicate more freely and make flu more dangerous.
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Winter flu: All the essential facts you need to know
Especially in elderly people flu can also cause excessive levels of inflammation, normally a broad immune defence against germs. Each year, right after flu season, there is a second, broadly equal wave of deaths from inflammation-triggered conditions such as heart attack and stroke. Chronic conditions that boost inflammation such as obesity can make flu more dangerous.
Pneumonia linked to flu is the fourth biggest killer of women in the UK, and the sixth biggest killer of men (see diagram). According to the first worldwide direct estimate, published by the World Health Organization (WHO) in December 2017, the , and 1.3 million from all causes – twice what we thought. “If we had another vaccine-preventable virus killing that many people we’d be outraged,” says of FluPal Consultancy in Amsterdam.
Should I get a flu jab?
Yes. Ignore people who swear the vaccine gave them flu: the virus in the vaccine is dead, or so crippled it can’t replicate. That said, very recent observations suggest that past vaccination may sometimes mean worse flu in years when the vaccine doesn’t closely match the circulating virus. While virologists don’t quite know what to make of this yet, it is clear that flu vaccines can protect, especially if you are .
Unfortunately, flu vaccination isn’t effective or popular enough to stop flu entirely through “herd immunity”. Each person vaccinated has about a 60 per cent chance of being protected, and even in the US, where vaccination is recommended for everyone over 6 months old, . Numbers are similar overall in Europe. , at over 70 per cent for the over 65s.
The vaccine takes two weeks to kick in, so get it soon. Consider the which protects against post-flu bacterial pneumonia. Children shed more virus for longer, and respond better to the vaccine, so vaccinating them , creating a kind of herd immunity within households.
Children don’t even face a needle: the UK and other countries give them nose drops containing weakened live virus. This induces a broader range of immune reactions and so offers better protection, but official caution about giving live vaccine to elderly people or pregnant women, and the small number of manufacturers, have otherwise limited its use.
The antiviral drug Tamiflu can help if you are severely ill. But you should start taking it within two days of symptoms starting, which is generally before you know whether it will be bad.
Is this the flu or just a cold?
If you are ill outside the local flu season, it is unlikely to be flu, but colds happen when flu is around and can have similar symptoms. Flu feels worse and is more likely to feature fever, headache, muscle pain, a dry cough and a sore throat, and perhaps eye and joint pain, plus sudden fatigue. Trouble breathing or other severe symptoms .
Children might have vomiting and diarrhoea with flu, although adults usually don’t – “stomach flu” is probably something else. If children become extremely irritable, have trouble breathing, have a fever with a rash, bluish skin or trouble waking, get help. In babies, the warning signs are , no tears when crying and trouble breathing.
At any age, if you seem to get better, then get sick again with a worse cough, see a doctor. Flu cannot be treated with antibiotics, but a secondary bacterial lung infection can be. New diagnostic tests can distinguish colds, flu and bacterial lung infections, but are not in general use, which is a major factor in antibiotic misuse.
How else can I protect myself and others?
Vaccination is the best way to reduce your likelihood of getting flu, or getting it badly – but there are a few other do’s and don’ts to limit the risk to yourself and those around you
DO: Wash your hands.
Hands pick up virus when you touch contaminated surfaces, then infect you when you touch your mouth or nose, something we all do constantly (try not to for a minute).
¶Ů°ż±·â€™T: Use a face mask.
Only an N95-rated hospital-grade mask keeps virus out, and these make it so hard to breathe that hospitals requiring front line staff to get vaccinated or wear one quietly report a jump in vaccination rates.
DO: Elbow-bump instead of shaking hands.
Or cover coughs and sneezes with a sleeve, not the hand you are about to touch a doorknob or shake with.
¶Ů°ż±·â€™T: Go to work.
Presenteeism is not a virtue if you are infectious, so work from home for the duration – usually about a week.
DO: Migrate.
Avoiding winter entirely by moving between northern and southern hemispheres every six months will reduce your exposure – although watch out crossing the tropics, as flu can crop up sporadically there all year round.
¶Ů°ż±·â€™T: Use most flu “remedies”.
Painkillers and decongestants can make flu’s symptoms more bearable, but they can’t shorten the misery. Eat sensibly, drink fluids (sorry, no alcohol, but yes to chicken soup) and rest.
This article appeared in print under the headline “Winter flu: Everything you need to know”
