Coronavirus cases and deaths are making a “dramatic” decline that is faster than expected, an influential forecasting team said in an update Thursday. The team projects that 574,000 people will have died of Covid-19 in the US by June 1.

Cases and deaths are dropping more quickly than expected – a drop of 70% over the past five weeks, the team at the Institute of Health Metrics and Evaluation (IHME) at the University of Washington reported.

“Daily reported cases in the last week decreased to 65,200 per day on average compared to 96,800 the week before,” the IHME said in its new report.

In its last forecast, the IHME predicted 562,000 Americans will have died by April 1. Currently, according to Johns Hopkins University, 507,806 Americans have died of Covid-19. 

“Despite increasing mobility and the spread of new variants, particularly B.1.1.7, daily cases continue a dramatic decline that began in the second week of January. While the decrease is likely driven by declining seasonality and rising vaccination, it is faster than expected,” it added.

The B.1.1.7 variant, first seen in the UK, has been found across the US and experts fear it might fuel a new surge as it appears to be more contagious. There’s little sign it’s doing so yet, the IHME said.

“Daily deaths are also declining, but the decline is half the size of daily cases,” the IHME said. That may partly be because of a rising ratio of deaths in Alabama, Arizona, California, Delaware, and Georgia. But the number of daily deaths has dropped nearly 35% in the last five weeks.

“In our reference scenario, which represents what we think is most likely to happen, our model projects 574,000 cumulative deaths on June 1. This represents 76,000 additional deaths from February 22 to June 1,” it said.

“Daily deaths are expected to decline steadily until June 1. By June 1, we project that 88,600 lives will be saved by the projected vaccine rollout.”

One other big factor in the slowed spread: Americans are wearing masks. “Mask use has fortunately remained high, with more than three-quarters of adults reporting they wear a mask when leaving home. As new variants likely spread, the behavioral response will be critical in determining if there will be an increase in cases and deaths in April and May. In our worse scenario, where mask use begins to decline this month, infections and detected cases may remain at current levels until late April,” the IHME said.

IHME estimates that 165.82 million Americans will have been vaccinated by June 1 – close to half the population. 

“COVID-19 remains the number 1 cause of death in the United States of America this week,” the IHME said. “We estimated that 19% of people in the United States of America have been infected as of February 22.”