Rapid tests for Covid, RSV and flu are available in Europe. What’s stopping them in the US?

Sander Brus didn’t expect a photo of his friend’s grandfather’s flu diagnosis to go viral. But when he shared the image on Twitter in December, he was bombarded with messages, he said.

People in the US wanted to know how to buy the rapid test pictured, which checked people for three common respiratory viruses at once: Covid, respiratory syncytial virus (RSV), and two types of flu, A and B.

The viruses have been circulating widely this winter and share many of the same symptoms, meaning they’re often indistinguishable without a diagnostic test. But unlike Covid tests, which are available over the counter, RSV and flu tests must be done at a doctor’s office or ordered via prescription. And the FDA hasn’t authorized an at-home test that could quickly detect all three viruses simultaneously.

The rapid test from Brus’ photo, however, is available in the European Union and the manufacturer has certified that it meets EU health and safety standards.

Brus is the founder of Measie, a diagnostics vendor that sells the test online. The test costs 6.5 euros ($6.92) and the company has sold about 10,000 of them so far, Brus said.

The manufacturer of the test, Shenzhen Microprofit Biotech Co. Ltd., says it captures 100% of negative cases for Covid, influenza or RSV, meaning it will not produce false positives, and it captures 90% of influenza B cases, 92% of influenza A cases, 93% of Covid cases and 95% of RSV cases.

Brus said that performance should be sufficient to obtain authorization in the United States

“A test done in Amsterdam, where I’m from, will give exactly the same result as a test done in New York. There shouldn’t be a difference based on geography,” he said. “But still, people in the United States can’t use it and I can.”

Dr. Susan Butler-Wu, an associate professor of clinical pathology at the University of Southern California, said rapid tests for multiple viruses are “the way of the future” and would help more people access the appropriate treatments. But the United States has historically lagged behind Europe in terms of licensing new diagnoses, he said.

“It’s not unusual to see things that have been approved in other countries that are great products and we don’t have them here. That’s just the reality of the situation,” he said. It takes time to go through the process and get approved.”

The Food and Drug Administration has cleared a non-prescription test that allows people to be swabbed for flu, Covid and RSV simultaneously, but the swab must be shipped to Labcorp for the results, which can take one to two days. The test also costs $169 for people without insurance.

The FDA said it strongly supports home testing for respiratory viruses, including combined testing for flu and Covid. But the agency declined to comment on whether it had received or was considering any applications for these tests from manufacturers.

“When the data is solid, the FDA hasn’t hesitated to move quickly to authorize testing, with home testing of all areas being a top priority for the agency,” an FDA spokesperson said.

The agency has pointed to a roadblock, however: At-home flu tests have traditionally required people to swab high in the nose, which usually means a doctor would have to administer them.

Unlike Covid tests, Butler-Wu said, there have been fewer opportunities to study whether rapid flu tests can be administered into the shallowest part of the nose and maintain their accuracy.

“You don’t want people just touching the outside of their nose and not actually getting the benefit of the test,” said Joshua Sharfstein, a former FDA deputy commissioner who is now a professor of health policy and management at Johns Hopkins University.

Dr. Michael Mina, chief science officer at home testing company eMed, said the FDA tends to have stringent requirements for over-the-counter testing. The agency often asks manufacturers to conduct studies showing people can properly administer the tests at home, a process that can cost millions of dollars and delay test approval by months or years, Mina said.

“It has taken a long time in the past to get new self-tests, like HIV tests or even pregnancy tests, approved,” she said. “It took years and years and years and years. We have a rather conservative regulatory approach.”

In real life, Mina isn’t concerned that the combined tests for respiratory viruses are easy to use.

“We know Americans can swab their noses because it’s been done millions and millions and millions and millions of times for Covid,” he said.

Even if a doctor does a rapid test, however, the FDA may still have reservations about its accuracy. Butler-Wu said rapid flu tests provided by medical professionals are usually about 60 percent sensitive, meaning they produce false negatives about 40 percent of the time. For RSV, that performance is “a little better” but still unreliable, he said.

“There are long-standing problems with the performance of influenza and RSV antigen tests that have been extremely well documented,” Butler-Wu said. “In 2009, when the new H1N1 emerged, the sensitivity of influenza A antigen tests was a coin flip. We’re talking 50 percent.”

As long as a test is accurate and easy to use, however, the FDA’s data requirements “aren’t that onerous,” Sharfstein said. The agency is usually able to make a decision about a test within months of submitting an application, he added.

“Tests with high sensitivity and specificity will have no difficulty getting approved by the FDA, but it’s important for the FDA to understand how it was determined, what the procedures were, and to actually look at the data,” Sharfstein said.

Mina said she hopes the FDA authorizes a combined at-home Covid and flu test this month or next, but it may not look like the version in Europe. The test could still involve two separate swabs, one for each virus, packaged together, he said.

“The FDA is a little less comfortable with getting that totally combined test into people’s homes right away,” Mina said. “I don’t really understand that part. I don’t think there’s a good logic behind it.”

But public health experts have not given up hope that a combined rapid test for Covid, flu and RSV will one day reach consumers.

The FDA “feels a lot of pressure from Americans,” Mina said. “Americans and now they’re seeing Europeans have these tests available, and just like in Covid, there’s now a push to say, ‘Why don’t we have them? Why aren’t they available to us?’ The agency is starting to figure that out and is actually somewhat open to working with the producers to see them come to fruition.”

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