Omicron sub-variants push up Covid hospitalisations in Europe and US

Hospital admissions are rising across Europe and the US as highly transmissible Covid-19 variants drive infections, but the resulting illness is less likely to be severe or cause death than in previous waves, according to data analysed by the Financial Times and health experts.

The number of new Covid admissions has grown by 40 per cent in the last week in France, 34 per cent in England and more than 20 per cent in several other European countries. The wave has been fuelled by the BA.5 Omicron sub-variant.

Maurizio Cecconi, president of the European Society of Intensive Care Medicine, said cases were rising in France, Italy and Germany. However, he added that cases had fallen in Portugal, which was in the vanguard of a fifth Covid wave in Europe.

The rate of increased hospital admissions in the US is currently slower than in Europe at 6 per cent. This reflects the decline of the BA.2 variant in the US, the FT’s data analysis suggests. But as the BA.5 variant becomes dominant, the overall rate of growth is likely to accelerate.

BA.4 and BA.5 currently make up around half of all infections in the US, estimated Dr Robert Wachter, professor and chair of the Department of Medicine at the University of California, San Francisco (UCSF).

Despite signs that the variants are more able than predecessors to evade the protection of both vaccines and prior infections, the FT’s analysis found that in countries experiencing BA.5 waves deaths showed only very small increases relative to hospitalisations, which themselves remain well below record highs.

Several experts said sufferers were less likely to require treatment in intensive care than in earlier phases of the pandemic and a greater proportion were only incidentally testing positive after admission for other reasons than in previous waves.

Cecconi, who is an intensive care doctor in the Italian region of Lombardy, said “very few” people were being admitted to intensive care. He added that in his region between 10 and 15 per cent of patients required intensive care at the start of the pandemic in March 2020. By the fourth wave this had fallen to 8 per cent and currently “we are probably between 2 and 3 per cent of patients . . . so it’s a very different wave from the past”.

He said it was unclear whether lower numbers of intensive care admissions suggested BA.4 and BA.5 were intrinsically milder sublineages, or simply that two years into the pandemic the majority of people were either vaccinated or had some protection against severe disease through prior infection. “The population is very different. It’s very difficult to find people that are completely naive to the virus, or to immunity from vaccination, and this is helping a lot [in reducing] the number of patients that are very sick,” he added.

In the US, Wachter also said there was evidence that the new variants might produce less severe illness. Six months ago, about two-thirds of patients at UCSF who tested positive for Covid-19 had been admitted because of complications of the infection, while a third had only incidentally been found to have the disease, he said. The breakdown was now 50:50, suggesting that fewer people were becoming so sick from the virus that they needed hospital care.

The FT’s analysis suggests that the bulk of each new variant’s advantage over older variants now comes from its ability to evade immunity, rather than from greater transmissibility. With different combinations of variant and vaccine-specific immunity in different places, the analysis also suggests that it is difficult to use data from one country to predict what is happening elsewhere.

In South Africa, where the latest versions of Omicron first took off, the BA.4/BA.5 wave was less than half the size of its original Omicron wave last winter, the data suggests. In Denmark, whose BA.2 wave was by the far its largest of the pandemic, the BA.5 wave looks to be topping out at around one-fifth of the previous peak. However, UK hospital admissions are already 77 per cent of the way to their 2022 high point and still rising.