Throughout this year, the biggest worry for healthcare planners has been what happens if a second wave of Covid-19 coincides with a winter flu epidemic. We are now in what looks like a second wave of Covid-19 – and October is the month when flu cases tend to start rising. So are we on the edge of a vast deep abyss?

Not if the experience of the southern hemisphere winter is anything to go by. A paper in the Lancet led by the Medical Research Institute of New Zealand analyses this year’s influenza season – and observes that it was virtually non-existent.

The researchers looked up cases of flu reported on FluNet, the global influenza surveillance and response system and found remarkably low levels of the disease this year. Australia, for example, registered 21,156 cases and 36 deaths – compared with 298,120 cases and 812 deaths at this stage in 2019. To date, incidentally, Australia has recorded 905 Covid-19 deaths – only ten per cent more than died from flu last year. Have cases of flu been missed because attention was deflected to Covid-19? Not at all – the researchers note that the number of tests for influenza actually increased this year.

Similarly low rates of flu have been recorded in other southern hemisphere countries. The US Centers for Disease Control (CDC) noted in September the virtual non-existence of flu this year in Chile, where 12 out 21,178 tests proved positive and South Africa, where six out of 2098 tests were positive.

Why did flu disappear and will it similarly disappear in the northern hemisphere this winter? The authors of the Lancet study speculate that the reason for declining cases of flu is because social distancing has stopped it spreading just as it has tempered the spread of Covid-19. If people are coming into contact with fewer people than normal it stands to reason that they are less likely to pass on all kinds of infectious diseases.

In other words we have reason to be optimistic that this year’s flu season in Britain will be similarly suppressed. What, though, might that mean for longer term for healthcare policy? Assume, for a moment, that a Covid-19 vaccine is soon approved, proves highly effective and that the pandemic is largely over by this time next year (a very large assumption).

Would we then go back to living as we did up until the spring of this year – or would there be pressure to keep some kind of social distancing forever after in order to tackle the perennial menace of seasonal flu? While some people have sought to dismiss those who have compared Covid-19 with seasonal flu, the latter has always killed large numbers of people – without the kind of reaction we have seen to Covid-19. According to the CDC, the annual global death toll from flu ranges from 290,000 to 660,000. Covid-19 deaths, by contrast, are currently 1.16 million.

Has our attitude towards infectious diseases shifted for good, so that we no longer look upon the annual death toll from flu as a price we are prepared to pay for unrestricted lifestyles? If so, we might expect a future in which, Covid or no Covid, we end up with a degree of social distancing rules to be put in place every winter. It is hard to imagine that there will not be at least some people in public health who will not be pushing for this.