Coronavirus Health

WHO sees 17% drop in cases, but experts say Covid-19 variants pose new threats

The WHO’s latest tally recorded 3.15 million new cases of Covid-19 worldwide in one week – a 17 percent drop from the previous week and the fourth consecutive week of declines.

But between the appearance of more contagious Covid-19 variants, the setbacks seen in vaccination campaignsacross Europe and the vast populations subjected to rolling lockdowns or travel bans, the pandemic seems as virulent as ever.

The WHO suggests there may be a vast difference between the real Covid-19 situation and what is perceived, even while reporting that weekly case tallies have fallen in Africa, the Americas, Southeast Asia, Europe, the Eastern Mediterranean and the Western Pacific, all six of the organisation’s regions. However, the declines are more distinct in countries such as India, Japan and Spain, and much less so in France and Germany. 

“It’s certainly not bad news, but we still don’t know how good it is,” virologist Jonathan Stoye, the head of research at the Francis Crick Institute in London, told news agency FRANCE 24.

The overall decrease in new cases is mainly due to large countries that account for the lion’s share of reported infections. Infections have been falling in the UK (which reported a 25 percent drop), the US (20 percent) and Brazil (10 percent).

These declines, significant in terms of volume, can “give a misleading impression of a general decline”, Stoye said. The WHO data do not fully reflect “the situation in other countries that lack the means to organise major screening campaigns, and thus, only provide incomplete data”, he said.

While the WHO’s announcement of a decline in new cases at the global level offers only mitigated cause for optimism, the fact remains that the dips seem to be real in some larger countries.

“The effect of implementing more restrictive health measures at the end of 2020 is now being felt. This gives the impression that as far as a public health response goes, we are beginning to know how to control the virus’ spread,” epidemiologist Jean-Marie Milleliri said to FRANCE 24.

This is particularly evident in the United States. The drop in new infections since January “seems to be the direct result of the stricter health measures taken by President Joe Biden”, said Daniel Dunia, a virologist at the pathophysiology centre of Inserm, France’s national institute of health and medical research, in comments to FRANCE 24.

Biden signed executive orders to require quarantine for all air travellers arriving in the US and to extend mask rules on interstate travel shortly after his January 20 inauguration. 

The benefit of health measures is also evident in Spain and in the UK, “where reinforced lockdowns have been introduced”, said Stoye.

What about the variants?

But there is another factor in the equation. The virus is receding “not only because of social distancing and lockdowns, but also because, once the virus is in the air, there are fewer individuals to infect – as some of them are immune because they have already had it”, said Jean-Stéphane Dhersin, the deputy scientific director of France’s National Institute of Mathematical Sciences and a specialist in modelling epidemics, in an interview with French news agency FRANCE 24.

But Dhersin points out that the WHO data still only tell part of the story: the numbers essentially show the trajectory of “classic” Covid-19 without reflecting the emergence of variants. “What is apparent in the figures is the evolution of cases of infections with the majority strain of the virus, which is still the original form of Covid-19,” he said.

The WHO’s most recent weekly epidemiological update includes three distinct maps that show which countries have reported cases of Covid-19 variants, but its country-by-country infection tallies do not distinguish between strains. 

For Dhersin, the world could in fact be at a tipping point – the original variant may be nearing the end of its run because authorities have managed to control it, as WHO figures show, but the new forms of Covid-19 could be ready to take over.  

To gain a more realistic vision of the pandemic’s evolution, “one would need to carry out a massive sequencing of the virus in the infected population to know as quickly as possible when a new ‘mutant’ appears and if it is more contagious or dangerous”, Dhersin said. Without this knowledge, we risk continuing to rely on WHO figures that cannot take into account these mutations, which are gradually becoming more widespread.

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