The rate of COVID-19 cases in Washington is improving but not enough for the public to stop masking up and social distancing, according to the state Department of Health.

The department (DOH), in a report released May 7, said there are signs that cases may be starting to flatten, but disease activity remains high. That means vaccination efforts, wearing face masks, and keeping physical distance are still critical to fighting the pandemic, officials said.

Statewide case counts showed some flattening starting in late April, but case counts have remained high following increases in late March and most of April. As of April 22, case trends varied more from county to county than in previous weeks. Many counties were continuing to see increases, but quite a few were experiencing flattening trends.

DOH estimates the vast majority of cases in the state are now associated with variants of COVID. As of May 6, officials estimated more than 80 percent of all cases were likely due to the B.1.1.7 variant and about 10 percent were due to the P.1 variant.

Immunity is playing a bigger role in slowing the spread of the virus as vaccination increases, but transmission was still on the rise as of mid-April. The estimated percentage of Washingtonians with active COVID-19 infections almost doubled between April 2 and April 16, reaching a level only slightly lower than peak estimates in November 2020. This percentage is known as overall prevalence, and the estimate includes identified cases as well as people who have COVID-19 but don’t have symptoms and may not have been tested. High prevalence means a lot of people may need healthcare or could be passing the virus to others, according to DOH.

As of April 22, case and hospital admission rates were increasing across all ages except people 70 and older, who are also the most likely to have been vaccinated. People 20 to 29 years old had the highest case rates and sharpest increases in case rates. Cases were also increasing sharply among people ages 10 to 19 and 30 to 59.

While overall hospital admissions continued to increase through April 22, vaccination is helping keep admission rates in check, DOH reported. The increase in admissions has been driven by hospitalizations in people who are not vaccinated. Among those 65 and older, the hospital admission rate for unvaccinated people is about nine times higher than for people who are fully vaccinated.

“We are cautiously optimistic about a possible plateau in the most recent data, but we are still in a fourth wave and seeing a number of concerning signs. DOH will continue monitoring these trends closely,” said Scott Lindquist, the state’s acting health officer. “No matter what, we all need to keep taking precautions like wearing masks and gathering outside. If you haven’t been vaccinated, now is the time to protect yourself, your loved ones and your community. We can all help by talking to people we know about vaccination. Every vaccine makes a difference.”

The DOH report and others like it is a joint effort of the state, the Institute for Disease Modeling, Fred Hutchinson Cancer Research Center, University of Washington, and the Microsoft AI for Health. COVID-19 data is online at doh.wa.gov.