The unseen covid-19 risk for unvaccinated people

As more people receive vaccines, covid-19 cases are occurring mostly in the increasingly narrow slice of the unprotected population. So The Washington Post adjusted its case, death and hospitalization rates to account for that - and found that in some places, the virus continues to rage among those who haven't received a shot.

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The rosy national figures showing declining case numbers led the Centers for Disease Control and Prevention to loosen mask recommendations two weeks ago and President Joe Biden to advise people to take off their masks and smile.

But adjustments for vaccinations show the rate among susceptible, unvaccinated people is 73% higher than the standard figures being publicized. With that adjustment, the national death rate is roughly the same as it was two months ago and is barely inching down. The adjusted hospitalization rate is as high as it was three months ago. The case rate is still declining after the adjustment.

Unvaccinated people are getting the wrong message, experts said.

Related: Advice for parents as kids get vaccinated against COVID-19

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"They think it's safe to take off the mask. It's not," said Lynn Goldman, dean of the Milken Institute School of Public Health at George Washington University. "It looks like fewer numbers, looks like it's getting better, but it's not necessarily better for those who aren't vaccinated."

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States with high rates among unvaccinated people

The adjusted rates in several states show the pandemic is spreading as fast among the unvaccinated as it did during the winter surge. Maine, Colorado, Rhode Island and Washington state all have covid-19 case spikes among the unvaccinated, with adjusted rates about double the adjusted national rate. The adjusted rates of Wyoming, West Virginia, Oregon, Florida, Michigan and Pennsylvania are slightly lower than the highest states.

Maryland, Virginia and the District of Columbia have adjusted rates below the national average. In the region, however, lower vaccination rates in the Black community have concentrated cases there to an extraordinary degree. Before vaccines, Black people were about one third of new covid-19 patients in Maryland and half in the Distrit. In the latest data, Black people are just under half of the new cases in Maryland and more than 80% in the District.

Oregon's current surge is driven in part by a covid-19 variant known as B.1.1.7, which is 50% more contagious, said Tom Jeanne, a deputy state epidemiologist and a senior health adviser, in an interview.

It is characterized by outbreaks traced to social gatherings with unvaccinated people and no masks.

"They're at very high risk for infection," Jeanne said.

Washington state officials say they are caught between applauding the optimism that comes with vaccination and warning everyone who isn't vaccinated that it's still dangerous.

"Things are getting safer for those who are vaccinated," the state's secretary of health, Umair A. Shah, told The Post. "For those who are unvaccinated, they remain at risk. We have to make sure that nuanced message is getting to our community."

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States with high death rates

In addition to cases, several states still have relatively high death rates.

Coronavirus vaccines are virtually perfect in preventing deaths, so the decline in deaths nationally hides the steady covid death rate among unvaccinated people.

Michigan, Pennsylvania, New Jersey, Maine, Florida and Illinois all have adjusted death rates about 50% higher than the national adjusted rate.

Looking at the death rate is not a good measure of the current spread of the pandemic, experts said, because it is a "lagging indicator" - people dying are usually infected at least a month earlier, which means deaths don't reflect current community spread of the disease. The steady adjusted death rate, however, shows that unvaccinated people are not yet getting safer.

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People more likely to end up in the hospital

Experts often point to hospitalization rates as a critical measure of the pandemic, because they reflect people getting very sick and aren't dependent on how much coronavirus testing a community is doing. When current hospitalizations are spread across only the unvaccinated population, the District and Michigan have rates about twice as high as the adjusted national rate. Pennsylvania, Maryland, Florida and Rhode Island have rates about 50% higher than the adjusted national hospitalization rate.

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Tale of two societies

Unvaccinated young adults in Maryland have the same infection rate as they had in the January surge, according to a state analysis. Even worse, the risk of hospitalization among the infected has more than doubled, possibly because of widespread coronavirus variants, said Ted Delbridge, executive director of the Maryland Institute for Emergency Medical Services Systems.

Washington state has been publicizing the extreme threat of hospitalization for unvaccinated people. It said unvaccinated seniors are 11 times as likely to get hospitalized than seniors who got the shot. For unvaccinated people age 45 to 64, the chance of covid-19 hospitalization is 18 times higher.

Shah, the state secretary of health, worries people are being left behind while others feel the pandemic is past.

"I hope this does not become a tale of two societies," he said. "The people who are vaccinated and are protected can resume their lives, taking off their masks.

"The people who are not vaccinated are the ones who are not wearing a mask or washing their hands. Those are the very people who often times will socialize and be around similar like-minded people. You're going to have the pandemic continue in those clusters."

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About this report: The Post adjusted covid-19 rates for cases, deaths and hospitalization over time by combining Centers for Disease Control and Prevention data on cases, hospitalization and vaccinations. The Post used a rolling seven-day average of daily cases, deaths and hospitalization. For vaccination, The Post used the number of people who had received at least one shot as of each date.

For events like covid-19 infection, rates are usually calculated by dividing the number of cases by the number of people in the population. For example, if there are 12 cases among a population of 100 people, the rate would be 12 people per 100. The Post reduced the denominator to exclude most vaccinated people. So if 20 people got vaccinated, that would mean there were 12 cases out of the remaining 80 unvaccinated people, for an adjusted rate of 15 cases per 100 people.

Vaccination is not perfect in preventing infections, however, so The Post did not subtract the entire population of vaccinated people. Data shows vaccines are about 90% effective in preventing cases among people who have received the shot. Cases among vaccinated people are called breakthrough cases. To be conservative, The Post estimated that up to 15% of the vaccinated population could still be infected.

So, in the example above, instead of removing all 20 vaccinated people, The Post removed 17. That would leave 12 cases among 83 people, for an adjusted rate of 14.5 cases per 100 people.

The Post calculated the adjusted rates of cases, deaths and hospitalization for the nation and each state since the start of vaccination in December. Covid-19 case and death rates released by states are sometimes subject to time lags. State also sometimes review older cases and issue updated figures that reflect a backlog of old cases rather than a surge on that day.