People living outside cities may face greater risk from second wave
People living outside early-hit major cities may be at highest risk during a second wave of coronavirus as those living in dense population centres such as London and Glasgow may have already been infected, according to a study.
The research from scientists at the University of Sussex and the Francis Crick Institute tracks the daily Covid-19 death rates in major cities (London, New York, Madrid and Milan/lombardy) of four hard-hit countries and compares it with the corresponding nations as a whole.
They show that after lockdown – and indeed just before lockdown – death rates slowed more quickly in these early hit cities than in the rest of the population.
The researchers conclude this is because coronavirus infection became more widespread in these cities, with the result that fewer people remained susceptible to infection and therefore Covid-19 was less able to spread.
The findings show that, for all four countries, the number of people remaining susceptible to the disease has been reduced more in early-hit cities due to the disease being seeded sooner there.
In spite of the heavy death toll in these cities, this difference in remaining susceptibility means that the other areas of each country would need to brace for a higher per capita death rate in the event of a second wave. Of the cities studied, this effect is particularly large in London.
The research also indicates that more people have had Covid-19 than was previously realised. These results are derived from the disease dynamics analysis rather than serology testing for antibodies or live infections, which are both prone to selection bias, under-representative population sampling and insufficient reliability.
The data shows that as many as 45 per cent of Londoners could have been infected, compared with just under 20 per cent for the rest of the country.
In New York the findings reveal 41 per cent of the population could have had the infection, compared with only 5 per cent of the rest of the US.
Prof Peter Krüger, from the University of Sussex, said: “Our research compared daily death rates in London versus England as a whole, Madrid versus Spain, Lombardy versus Italy and New York versus the US. We show that, in these cities, the death rate dropped more steeply than elsewhere after lockdown started.
“That is because, in these early-hit cities, the spread of coronavirus infection was already beginning to slow due to fewer people remaining susceptible.
“In effect, it is as if lockdown was introduced later in the cities than in the rest of their respective countries because the pandemic had reached a more advanced stage there.”