As Europe prepares to enter its second winter of the pandemic era, the spectre of another catastrophe looms on the horizon.
In the highly vaccinated nations of Western and Central Europe, there is good reason to be hopeful. The virus may have returned, but it is not what it once was. In the UK, where more than 67 per cent of people at the time of writing are fully vaccinated, 3.2 million people have been infected in the last three months, the same volume of infections as last winter. Seventy-six thousand died from Covid-19 then, but the last three months have seen fewer than 11,000 deaths from the disease.
In Eastern Europe, where vaccination campaigns have been sluggish, the picture could not be more different. In many of these countries the link between infections and deaths is growing stronger, not weaker.
Consider the contrast between Finland and Ukraine, which have both recently experienced waves of infection approximately 60 per cent larger than their winter peaks.
In Finland, where 70 per cent of the population is fully vaccinated, deaths peaked just over half their winter level – a 63 per cent fall in the ratio of deaths to cases, which is one way of estimating the case fatality rate (CFR). In Ukraine, where only 18 per cent are fully vaccinated, deaths have reached almost triple their winter height – a 70 per cent increase in the CFR.
Ukraine is not alone – Russia, Belarus, Romania, Moldova, Bosnia-Herzegovina and Serbia have all seen a higher CFR in their recent peaks than they saw last winter. Russia’s recent wave of infections has reached a level 30 per cent higher than that seen over winter, but the country’s deaths (lagged by eight days to account for the incubation period of the virus) are more than double the levels they reached last winter.
Is Covid-19 actually becoming deadlier in Eastern Europe?
Every country measures cases and deaths differently, and all measures are flawed. These estimates of the CFR do not assume that countries are perfect at capturing all deaths and cases, or even that they are equally bad at it.
What they do assume is that, for any given country, the share of cases and deaths that are captured in the data has remained broadly the same since its winter peak. If a country has become markedly worse at capturing cases, for instance, the ratio of deaths to cases would falsely appear to increase.
One sign of insufficient testing capacity is a high share of tests returning positive results, known as the test positivity rate. Test positivity rates are driven both by the prevalence of infection and by the comprehensiveness of a country’s testing regime. Comparing the test positivity rate of a country at two points in time with similar infection levels should therefore give an indication of any change in the testing capacity.
Of the countries for which the data suggests an increased case fatality rate, none have seen a substantial increase in their test positivity rate since their winter peaks (data for Moldova is not available).
Test positivity rates in Bosnia-Herzegovina, Serbia and Romania are in fact much lower this time around, making it highly unlikely that cases are being missed at a higher rate than in winter.
Why is this happening?
One thing all these countries have in common is a low vaccine uptake. Of the eight European countries in which less than 35 per cent of residents are fully vaccinated, six have seen their CFR increase significantly. For the other two, the data is far from clear.
Bulgaria’s data shows a fall in the case fatality rate since winter, but the country’s test positivity is far lower now than during its winter peak, suggesting that case numbers may have previously been underestimated and CFR consequently overestimated. The only other under-vaccinated country for which data suggests a falling CFR, Albania, has not reported sufficient test positivity data to rule out similar issues.
What we may be witnessing are the consequences of Delta – the variant that has been dominant across Europe since the spring – encountering largely unvaccinated populations.
Delta is known to be more deadly than the variants behind previous waves. A recent study in Canada found that the risk of death from Delta in unvaccinated people was more than twice as high as for the original Covid-19 variant.
“Deaths have increased significantly in these countries, and that’s essentially due to poor vaccination rates,” said Raghib Ali, a senior clinical research associate at the University of Cambridge’s MRC Epidemiology Unit.
“Even with that, however, you wouldn’t expect the CFR to be worse than last year – even any level of vaccination should help. But if the CFR really has risen, then one possible explanation is Delta, because Delta may have a higher fatality rate. The second is the overwhelming of healthcare capacity.”
“Hopefully it’s very unlikely for a country with high vaccination rates in higher risk groups to have a similar winter to last winter given their very high effectiveness against hospitalisation and death,” said Ali.
“I don’t see how you can get to the same level of deaths as we had last winter unless you had an immune escape variant, which seems unlikely given that it hasn’t happened so far – but not impossible.
“But in countries with low rates of vaccination, the combination of Delta and insufficient hospital capacity is a serious one, and [that] is why this winter unfortunately is likely to be worse than last winter.”