Europe's rising Covid-19 caseloads could foreshadow second Omicron surge in the US

NEW YORK (NYTIMES) - Experts warn that another coronavirus wave may be imminent in the United States, fuelled by a more contagious Omicron subvariant that is spreading rapidly in Europe, although they said the trend was more a cause for caution than alarm.

The Omicron variant this month began its second sweep through Europe, where past virus surges have been a harbinger of what was to come in the US. Many countries thought they were free of the worst of Covid-19 and raced to lift restrictions in February and March, but a highly transmissible Omicron subvariant, BA.2, is contributing to the new surge.

The surges have not led to a widespread rise in hospitalisations in Europe, although the number of Covid-19 patients is on the rise in a few countries, including Austria, Britain and the Netherlands, according to Our World in Data. BA.2 does not appear to cause more severe illness than BA.1, and existing vaccines are effective against it.

Some countries, including Germany and Austria, are again approaching record levels of caseloads or have even exceeded them.

Cases per capita in Europe were already far higher than any other region in the world when they began creeping up again earlier this month.

The continent is now recording 95 cases every 100,000 people, after bottoming out at 87 on March 3; the US and Canada, by comparison, are recording 10 cases per 100,000 people, according to a New York Times database.

On Thursday (March 17), Dr Anthony Fauci, the government's top infectious disease expert, told Politico that "you've got to at least be prepared that we may see something similar here with some differences", regarding the surge of cases in Europe.

"We've got to not ignore it. We've got to monitor it very carefully," he added.

All 50 US states made the same choice by the beginning of this month, lifting their universal indoor mask mandates after the winter Omicron surge retreated.

Caseloads in the country have continued to drop since then, reaching levels this week not seen since last summer, according to the Times database.

But throughout the pandemic, Covid-19 trends in the US have lagged Europe's by a few weeks. And US wastewater data is already showing signs of a new increase.

Dr Wafaa El-Sadr, a professor of epidemiology and medicine at Columbia University, said that the data was a sign that people should be cautious.

"But I would not say that people should be alarmed as of yet," she said on Wednesday.

Because people excrete the virus through their stool, wastewater can be used to predict where the coronavirus is or will be prevalent and if a new variant is circulating.

About 38 per cent of active US wastewater sampling sites reported an increase in coronavirus levels from Feb 26 to March 12, according to the Centres for Disease Control and Prevention's (CDC) wastewater data tracker, which surveys 698 wastewater sites across the country.

The BA.1 subvariant remains the predominant Omicron subvariant in the US, but BA.2 is more contagious and spreading fast, so Dr El-Sadr said it was important for Americans to be vaccinated and boosted.

"This will protect us from what is coming next," she said.

BA.2 is responsible for only a fraction of coronavirus cases in the US, but that share is growing, according to estimates from the CDC. The subvariant's spread in the US depends on a number of factors, including people's existing immunity and the subvariant's severity.

Dr Maria Van Kerkhove, the World Health Organisation's technical lead for coronavirus response, said that BA.2 was one of the factors driving the recent global uptick in cases, fuelled by high caseloads in Asia and Europe. Other factors include lifting pandemic restrictions, vaccine resistance and misinformation.

"We have huge amounts of misinformation that is out there," she said at a news briefing on Wednesday. "The misinformation that Omicron is mild, misinformation that the pandemic is over, misinformation that this is the last variant that we will have to deal with."