COVID-19 case numbers drop, signaling winter surge is slowing

After a harsh December and January when hospitals were running out of space to handle COVID-19 patients, the number of coronavirus cases and hospitalizations has seen a dramatic decline over the last month, according to health data.

The seven-day average of new daily cases went from a peak of nearly 246,000 on Jan. 12, to nearly 94,000 on Feb. 13, while the seven-day average for COVID-19 hospitalizations went from a peak of 132,474 on Jan. 6 to 69,283 on Feb. 13, according to data from the U.S. Centers for Disease Control and the COVID Tracking Project.

Public health experts said the end of the winter holiday season played a huge factor behind the drop, combined with the steadily increasing vaccine rollout. While the sharp declines are encouraging, they warned that country is not in the clear.

"A new variant, regardless of these factors that drove down the numbers, could drive an increase in cases and hospitalizations," Dr. John Brownstein, an epidemiologist at Boston Children's Hospital and ABC News contributor, said.

Doctors and scientists expected to see a drop in the number of cases and hospitalizations as we got farther out from the holiday season, Brownstein said, but they were not expecting the decreases to be at this level. The fewer indoor congregations meant that transmission rates were reduced, he noted.

Brownstein said vaccinations have also played a small role so far in bringing the numbers down. Roughly 52 million Americans have had one coronavirus vaccine shot so far, according to the CDC.

"It has some effect when you layer it with natural immunity," he said of getting one dose of the vaccine.

The earliest doses were given to medical professionals, Brownstein noted, and the shots for non-medical personnel didn’t really start until mid-January.

Still, he and other health experts said the increased rollout of vaccines to the public, especially to the most vulnerable Americans, would be a boon. The seven-day average of daily vaccine doses administered has risen from steadily going from around 444,000 on Jan. 6 to about 1.5 million on Feb. 9, according to the CDC.

Dr. David Larsen, an epidemiologist and associate professor of public health at Syracuse University, told ABC News that by prioritizing the most vulnerable Americans, state vaccine programs have helped to keep more patients out of hospitals.

"By increasing the doses to those groups ... that will likely continue the drop in hospitalization," he said.

Larsen and Brownstein both warned that there would likely be another jump in cases caused by the new variants discovered in countries like the United Kingdom, Brazil and South Africa. It is still too early to tell if that jump will be as significant as the winter surge, Brownstein said, but he emphasized there is a potential.

Both Pfizer and Moderna have said their vaccines are effective against the U.K. variant.

Current research out of Israel, where 6.4 million residents have received one dose and nearly 29% of the population is fully vaccinated, according to John Hopkins University's Coronavirus Resource Center, shows the vaccines are helping to alleviate potential surges, Brownstein pointed out.

"We know the U.K. variant was widely transmitted in Israel, but we’re seeing massive improvements with regards to case numbers there," he said.

In the meantime, the health experts said Americans must continue to stick to the health guidelines that have been in place since last year, especially mask wearing and social distancing, to keep the decline going.

"Transmission is still around, and there is still a risk. We’ve got to stay the course," Larsen said.