In September I caught a cold so severe I couldn’t get out of bed. After three days of shivering and sneezing under a duvet, mainlining Lemsip and trying to summon the energy to eat some toast, I recovered. But then I caught something else the next week that sent me straight back to bed. A few weeks later, the same thing happened again.
In the aftermath of a pandemic that has claimed millions of lives worldwide and brought the global economy to a standstill, all this might sound rather trivial. But while I’m not looking for sympathy, I was curious. In less than three months I’d taken as many days off work due to illness as I had in the six years prior to the Covid crisis. What was wrong with me?
Whatever it was, I wasn’t alone. Anecdotes might not be reliable data, but I couldn’t help notice how my Twitter feed was full of people struck down by coughs and colds that they felt were unexpectedly severe, lamenting “I never used to get ill like this!” Colleagues at the New Statesman were dropping like flies. So were their children. We didn’t have Covid (we were testing), but the symptoms we did have seemed so much worse than normal.
With every day bringing news of more pressure piling up on the health service, from backlogs to strikes to the worsening winter crisis, I got more anxious. What if ordinary winter bugs had somehow become much more virulent after two and a half years of lockdowns and social distancing? Or what if Covid (which, by now, most people in the UK will have been exposed to) had damaged our immune systems? It was possible, I mused, that having suffered the prolonged trauma of the pandemic we had all become hyper-alert to any kind of illness and were overreacting to symptoms that three years ago we would have ignored. But then I got ill again and realised it definitely was not in my head.
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“It’s a combination of things,” said David Matthews, professor of virology at the University of Bristol. The psychological element, he told me, might be one factor in the collective assessment that we all seem less than healthy this winter than we used to be. But he pointed to the latest data from the UK Health Security Agency (UKHSA) which shows that something else is going on too. The GP sentinel swabbing scheme, whereby GPs take samples from patients presenting with flu-like symptoms and send them off for national testing, found a significant rise in both influenza and respiratory syncytial virus (RSV) compared with this time last year. UKHSA’s FluDetector, a model that tracks internet searches for “influenza-like illness”, also suggests an increase in people googling flu symptoms compared with previous years.
According to Phil Whitaker, GP and medical editor for the New Statesman, viruses such as flu, RSV and milder rhinoviruses that cause the so-called common cold are very likely “having a field day”. The winter of 2020-21 was spent in various forms of lockdown, and while the UK government held off imposing further restrictions this time last year, the rules still mandated people self-isolate if they tested positive and public health messaging encouraged reducing social contact in the run-up to Christmas. This, Whitaker said, “seriously curtailed the ‘usual’ respiratory viruses that we get in circulation, so they’ve been effectively locked up for a couple of years and now they’ve been let out to play.”
That’s one reason why we might be catching colds more frequently than in recent years, but it doesn’t explain why our symptoms feel more severe. “I don’t know of any evidence to suggest that this year’s common cold-causing viruses have become more virulent,” Matthews reassured me, allaying my fears of super-strong bugs. What is probably happening is that two winters of social distancing have reduced what he calls our “immune memory”.
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When we catch a new virus for the first time the infection takes hold while our immune system works out how to fight it. (This is why infants and small children come down with bad coughs and colds so frequently compared with adults.) The next time we’re exposed to that same virus, our immune system recognises it and leaps into action before we even feel it. If we’re exposed each year, our immune system will get a memory jog every time and we’re unlikely to experience symptoms from that virus again. But immune memory fades over time. Someone who caught a particular virus in autumn 2019 might not have been exposed to it for three full years as they socially distanced to avoid spreading Covid. If they catch it now, “it will take longer for your immune system to get off its backside and do something”, as Matthews put it.
Then there’s the impact of Covid itself to consider. Whitaker said people might be “a bit immunosuppressed for a few months after a bad bout of Covid – we know this happens with chickenpox, for example”. This is, however, probably temporary. Some viruses, such as measles, can erase your immune memory almost completely, making you far more susceptible to severe infection from pathogens you’ve already been exposed to. But there doesn’t seem to be any evidence yet that Covid does the same, meaning the damage to our immune systems is reversible, at least for most people. It’s possible sufferers of Long Covid will be more susceptible to long-term immune dysfunction, but so far there isn’t conclusive research.
More worrying is the risk that the high number of viral infections going around at the moment could cause an increase in secondary bacterial infections. When our immune systems are weakened from fighting one bug, there’s a higher chance that another one might take hold. (The influenza virus, for example, can lead to bacterial pneumonia in vulnerable patients.) There is particular concern at the moment about Strep A bacterial disease – eight children in England and Wales have died since September of Strep A, which is not usually fatal. An email from UKHSA over the weekend warned GPs that “current invasive Group A streptococcus (iGAS) infection notifications remain unusually high for this time of year, particularly in children”, continuing that “a high burden of co-circulating viral infections may be contributing to the increased severity and complications through co-infection”.
Overall, the consensus is that the suppression of normal seasonal viruses during the pandemic is to blame for higher rates now. The good news is that it’s probably not permanent. Matthews predicted that the lockdown effect will gradually disappear over the next few years if behaviour returns to pre-Covid levels, especially among children who are catching up now on all the bugs they missed. In the meantime, anyone eligible should get the flu vaccine, and we should continue with hand-washing and remain at home if we feel ill rather than braving it by going into the office – even if we don’t have Covid.
Since my three bouts of knockout illness, I haven’t been bedridden again. But I keep having days of intense cold symptoms that suggest severe illness is coming, only to fully recover overnight. (It was one of these days that prompted me to write this article.) Now I know I’m not being a hypochondriac; I imagine my immune system gradually learning how to work again, like an old machine creaking into action after years of disuse. Each time, hopefully, will be a little faster than the last.
[See also: Covid-stretched NHS has led to deadly consequences for heart care]