Experts who have spent the last year forecasting Covid-19 transmission across the US are now considering scenarios for the spread of new, more infectious strains of the coronavirus.

At the same time, the US continues to lag in surveillance for coronavirus variants, despite having among the most well-developed genomic sequencing infrastructure in the world.

The warnings come as the US appears to have crested a devastating winter wave of infections, which at one time saw more than 300,000 new infections and 4,000 deaths a day. Even though daily infections have more than halved from the peak, with death rates expected to drop soon also, the threat of the more infectious variants has some considering the possibility of a fresh surge.

“It’s a grim projection, unfortunately,” said Ali Mokdad, professor at the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, one of the leading academic forecasters of Covid-19. “I’m concerned about a spike due to the new variant and the relaxation of social distancing,” he said. “People are tired. People are very tired.”

Forecasters still do not consider this the most likely scenario, nor do they see it as the worst-case scenario. But the addition of the model is a recognition of how dangerous new variants can be, even in an environment where hospitalization and death rates are expected to decline.

IHME’s “rapid variant spread” model predicts total deaths could increase by 26,000 over the most likely scenario by May. Such a forecast would result in a total of more than 620,000 Covid-19 deaths by that time.

Notably, the most accurate are often “ensemble” forecasts, which draw in many individual projections. The ensemble forecast published by the CDC makes a prediction only through 27 February, when it estimates up to 534,000 deaths could occur. IHME also estimates universal masking could save 31,000 lives.

On Monday, the US surpassed 27m confirmed coronavirus cases, with the country’s death toll nearing 465,000. Both figures are by far the highest in the world, according to the John Hopkins Coronavirus Resource Center.

The most well-understood variant of concern is the B117 strain, first detected in the United Kingdom. B117 is believed to be as much as 50% more transmissible and to be now circulating in the US, where 541 cases have been found in 33 states, according to the Centers for Disease Control and Prevention (CDC).

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Read more: https://www.theguardian.com/us-news/2021/feb/08/covid-19-variants-deaths-us-tracking