Just as more students head back to school, health experts are worried about a disturbing trend in much of the country: decreasing testing combined with high test positivity rates.

In other words, Covid-19 is still spreading rampantly, but there’s less testing to find and isolate cases.

The number of tests performed each day in the US has dropped by an average of 68,000 compared to the daily rate in late July, according to data from the Covid Tracking Project.

Fifteen states have conducted fewer tests this past week compared to the previous week: Mississippi, Louisiana, North Carolina, Washington state, Rhode Island, Wisconsin, Minnesota, Colorado, New Mexico, Arizona, Utah, Nevada, Idaho, Montana and Alaska.

Yet test positivity rates — the percentage of tests that are positive — are still higher than the recommended 5% in more than 30 states, according to data from Johns Hopkins University.

“The testing situation is not good in the United States. What we’re not picking up is people who are contagious,” said William Haseltine, chairman and president of ACCESS Health International.

“We’re probably missing 8 out of 10 people who are contagious. And any decrease in testing is worrisome because we’re not already doing well. And if you don’t pick people out of a crowd who are contagious, then the epidemic spreads. … This epidemic is still spreading widely.”

Why are some states testing less?

Medical experts say there could be several reasons.

“One of the reasons that testing is decreasing is that supplies aren’t being shipped to places that can test. I think it’s part of a strategy not to count how many people are infected,” Haseltine said.

Another reason is that people may be less motivated to get tested, knowing it can take several days or longer to get results. And major delays can make some tests “borderline useless.”

Dr. Kent Sepkowitz said he’s worried some states may be taking cues from President Donald Trump, who said “when you do more testing, you find more cases,” which might make the US “look bad.”

Sepkowitz noted that several states that have touted decreased case counts also had some of the highest test positivity rates — an indicator that the virus is spreading rampantly.

“So even as the rates are worsening, many states have decided to reduce their efforts to find cases,” he wrote. “As a result, by looking less, they are finding fewer cases and sure enough, the case numbers are going down.”

Covid-19 is now the No. 3 cause of death in the US

A disease that didn’t even exist a year ago has now infected more than 5.4 million Americans and killed more than 170,000.

In fact, the US has averaged more than 1,000 coronavirus deaths per day over the past three weeks.

“Covid is now the No. 3 cause of death in the US — ahead of accidents, injuries, lung disease, diabetes, Alzheimer’s, and many, many other causes,” said Dr. Thomas Frieden, a former director of the Centers for Disease Control and Prevention.

The rate of deaths from Covid-19 is also much greater in the US than in many other countries,” Frieden said.

“Last week, Americans were eight times more likely to get killed by Covid than were Europeans,” he said.

A fast, inexpensive test just got emergency approval

There is some good news: A new saliva test could give Americans a quick way of learning if they have Covid-19 — and if they need to isolate to help prevent the spread.

Researchers from the Yale School of Public Health created the SalivaDirect test, which received emergency use authorization from the Food and Drug Administration on Saturday.

“If cheap alternatives like SalivaDirect can be implemented across the country, we may finally get a handle on this pandemic, even before a vaccine,” said Nathan Grubaugh, a Yale assistant professor of epidemiology.

Unlike some other tests that require specialized supplies, the SalivaDirect test doesn’t require a specific swab or collection device. It can also be used with reagents from multiple vendors.

“We simplified the test so that it only costs a couple of dollars for reagents, and we expect that labs will only charge about $10 per sample,” Grubaugh said.

Researchers said the new test can produce results in less than three hours, and the accuracy is on par with results from traditional nasal swabbing. They said SalivaDirect tests could become publicly available in the coming weeks.

‘We’ve got to break through to our young people’

Shortly after their classrooms reopened, thousands of students must stay home and quarantine after coronavirus clusters at their schools.

Health experts are urging younger Americans to take precautions seriously, especially after the CDC said Covid-19 cases among children have been “steadily increasing” from March to July.

“Recent evidence suggests that children likely have the same or higher viral loads in their nasopharynx compared with adults and that children can spread the virus effectively in households and camp settings,” the CDC said.

Outbreaks have also emerged at colleges and universities.

Oklahoma State University said Sunday that at least 23 sorority members in an off-campus house tested positive for the virus. The entire house is in isolation or quarantine and “will be prohibited from leaving the facility,” the university said.

Less than a week after starting classes, the University of North Carolina at Chapel Hill announced its fourth cluster of coronavirus. The clusters were located at two residence halls, a private apartment complex that serves students and the Sigma Nu fraternity.

The North Carolina Department of Health and Human Services defines a cluster as five or more cases in close proximity.

“We’ve got to break through to our young people that they are not immune to the virus,” Chicago Mayor Lori Lightfoot said.

The city has seen a steady increase in cases, which she attributed to 18 to 29-year-olds.