There are a lot of unknowns about Covid-19. This makes sense, because despite six months of the most amazing scientific effort of our lifetimes, the coronavirus is a novel disease which means that we are constantly finding out new things about it. Even now, the debate about the most likely method of spread of the disease rages on, in part because the idea of masks has in many places become somehow a political decision rather than a scientific one.

Sometimes 2020 feels like living in the Bad Place (but with less frozen yoghurt).

But the worry about unknowns doesn’t end at whether you should be sporting pandemic chic. One claim that has been flying around the airwaves, as we move from the early stages of Covid-19 to the endless ennui of an ongoing outbreak, is the idea that, since only a small proportion of people die from the disease, the rest of us should stop worrying about it and carry on. The idea is pervasive, and has been repeated worldwide – since only 1% of people are going to be killed by the coronavirus, the 99% of us who aren’t going to die will be totally fine.

This is, unfortunately, completely off the mark.

Firstly, let’s look at the facts. A colleague and I have looked into the infection-fatality rate of Covid-19, using data from dozens of studies, and our conclusion is that about 0.7% of people who catch the disease will die. So broadly speaking, saying that only 1% of people who get the disease will die isn’t entirely wrong.

But there’s a problem. Dying isn’t the only issue that a disease can cause. Measles kills about 0.2% of people who catch it, but it leaves some people deaf, others with brain damage, and may cause permanent immune system damage to boot. Polio, the disease that causes terrifying paralysis, is entirely asymptomatic in upwards of 70% of people who catch it.

Similarly, the impact of Covid-19 can’t be boiled down to a single number. For some, it causes death. For others, it causes lengthy ICU stays, which are themselves dangerous. Long-term mechanical ventilation, while hailed as the saviour of humanity early in this crisis, is associated with a host of serious health problems such as bacterial infections, ulcers and more. Even for those not admitted to ICU, there are worrying trends emerging indicating the potential for long-term organ damage such as kidney injury, or severe psychiatric issues.

Worse still, there are increasingly reports that these impacts are not wholly confined to people with severe infections. Some patients with mild symptoms are saying that they have had symptoms for weeks or months, a far cry from our usual ideas of “mild” disease. There is some evidence that symptoms like fatigue, which can be very long-lasting, are hitting people who barely had any issue earlier on in their affliction.

All in all, it’s not a pretty picture. Death may be the most easily identifiable outcome of coronavirus infection, but it’s certainly not the only one.

Which brings us back to that 99% figure. As the threat of a second wave looms, people are beginning to get tired of the ongoing government action. “Wouldn’t it be easier”, they say “to just let the disease roll through the population? It’s only going to kill 1% anyway”.

Perhaps, although it’s worth noting that in Australia and the UK a death rate of 1% would imply hundreds of thousands of deaths before the virus burned itself out. Moreover, those who are hospitalised – a significant proportion of Covid-19 patients – will certainly suffer. And even those with more mild disease may not be exempt from long-term harm. While government restrictions are starting to feel onerous, the fact is that we simply do not know enough about this disease to be sure that even the lowest risk is acceptable. We’ve got a handle on short-term, acute issues – the things that we see in a hospital – but we’re still only just discovering what the long-term issues that this disease causes might be.

Unfortunately, the damage that Covid-19 causes is almost certainly not confined entirely to the death rate. We may not know for some time exactly what else it causes, but even now we have enough evidence to know that there are other problems out there. Letting everyone get infected is a strategy that, even ignoring the enormous death toll, could leave us much worse off as a society.

I wish I could end with an uplifting message, but really all there’s left to say is simple: we’re in this for the long haul. I hate to be the bearer of bad news, but it seems like that’s what 2020 is about for epidemiologists.

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