The United States has a blind spot in the count of covid-19 cases

(CNN) — Official Covid-19 case metrics severely underestimate the true number of infections, leaving the United States with a critical blind spot as the most transmissible strain of coronavirus gains ground.

The BA.5 subvariant of omicron became the dominant variant in the United States last week, according to data from the US Centers for Disease Control and Prevention (CDC), and the subvariant carries key mutations that help it evade antibodies generated by vaccines and previous infection, aiding its rapid spread.

With that will come “an increasing number of cases and more hospitalizations,” Dr. Eric Topol, a cardiologist and professor of molecular medicine at Scripps Research, said Monday. “A good thing is that it doesn’t seem to be accompanied by intensive care admissions and deaths like previous variants, but this is definitely worrying.”

However, if you look at the official case count, it’s hard to tell.

The proportion of cases being officially reported is at an “all-time low,” said Dr. Michael Mina, an epidemiologist and chief scientific officer of the telehealth company eMed. “There is no doubt about it.”

Covid-19 cases have been somewhat underestimated throughout the pandemic for reasons including a lack of available testing in some locations and asymptomatic cases that may have been missed. But as people increasingly rely on rapid tests done at home, and as attitudes toward the pandemic change across the board, the US hasn’t come up with a reliable way to track transmission levels.

An estimate from the Institute for Health Metrics, a research center at the University of Washington, suggests that the actual numbers of infections in the first week of July were about seven times higher than the reported cases, which have been an average of about 107,000 daily. in the last two weeks, according to data from Johns Hopkins University.

Before the CDC lifted the requirement that international travelers take a COVID-19 test before entering the country last month, Mina said, it was an “incredible opportunity” to monitor the status of COVID-19 in across the US among a group of mostly asymptomatic people. About 5% of travelers tested positive for the entire month of May, which he said likely translates to at least a million new daily infections in the general US population, 10 times more than the official count.

Now that the BA.5 subvariant is here, “we know there’s going to be a surge in the fall, there’s almost no doubt about it, if not sooner. So you really have to be aware that that’s what can happen.” Mina said.

But with so many variables at play, it doesn’t necessarily make sense to compare the current state of affairs to other times in the pandemic.

“We really don’t have a good idea of ​​what the baseline is,” said Dr. Marcus Plescia, chief medical officer for the Association of State and Territorial Health Officials. “To say ‘this is where we are, right now in 2022, compared to 2021,’ is not a fair comparison.”

To gauge your individual risk of Covid-19 as a new variant gains traction, counting cases among friends and family may be a better indicator than official data, experts say.

“People are asking each other, sharing stories, and it’s probably not a bad source of evidence,” says Baruch Fischhoff, a Carnegie Mellon University professor and founding chair of the Food and Drug Association’s Risk Communication Advisory Committee. United States (FDA).

Our social networks have probably remained more consistent than national surveillance systems, he said, and “if more people than you hear about in your circle are getting the disease now than in the past, and your circle size is about the itself, so presumably there are much more infections now than before.”

Serious results don’t tell the whole story

At White House Covid-19 Response Team briefings, the most recent of which took place more than two weeks ago, CDC Director Dr. Rochelle Walensky presented trends in undone cases. Reference these important data caveats.

Months ago, the CDC moved away from COVID-19 transmission levels, which ranked risk based on case counts and test positivity rates, to focus on community COVID-19 levels, which are based on to a greater extent in metrics related to hospitalizations.

During this winter’s omicron surge, hospitalizations and deaths did not follow the same steep trend line as cases, a major change from previous waves of the pandemic.

But the fact that serious results continue to occur is reason enough to keep paying attention to the
cases, experts say.

“If we ever get to a state where people get infected but no longer cause any severe disease, maybe it’s a new variant that’s much less severe, or it won’t cause prolonged covid, if there weren’t really adverse health outcomes.” significant, then we wouldn’t worry so much about cases anymore,” said Jason Salemi, an epidemiologist and associate professor at the University of South Florida.

“But let me be clear, we’re not there yet.”

There is no evidence that the BA.5 subvariant causes more severe disease, but studies have shown that it can evade antibodies from vaccination or previous infection, even from another omicron subvariant. The vaccines are expected to continue to provide protection against severe disease, and for the fall, vaccine manufacturers are developing updated booster vaccines that incorporate the BA.4 and BA.5 omicron subvariants.

There are treatments available, such as the antiviral pill Paxlovid, that dramatically reduce the risk of death or serious illness. And high-quality masks, ventilation, distancing, and quarantine and isolation can continue to help reduce the spread of any variant, including BA.5.

But currently, more than 5,000 people are admitted to the hospital with Covid-19 each day, according to CDC data, and more than 300 die each day, according to data from Johns Hopkins University.

Focusing on these “lagging indicators” costs “significant time to start curbing people’s behavior and prevent a lot of morbidity and mortality,” Salemi said.

If 1 in 5 covid-19 infections results in long-term covid, and actual infections are seven times higher than reported, the number of people with long-term covid could be growing by 100,000 every day.

Work on the blind spots

For now, the US is in a “sustained management phase,” with continued efforts to keep things under control, compared to “what was a much more reactive and emergent approach in the past,” Plescia said.

But the federal government recently reallocated testing resources because Congress failed to approve additional funding for Covid, a move that Mina said will leave the US “pretty blind as we move into the fall.”

Some surveillance programs are underway, such as sewage monitoring that tracks the amount of virus present in sewage. But he says they’re “minimal,” and “overall, they’re not giving us a good picture of what’s really going on across the United States.”

“In a way, we just got through this big spurt,” Mina said, referring to the previously dominant omicron subvariants. “But I would say we shouldn’t let our guard down, because with BA.5, I expect it to be a very different story.”