Happy Nice Mall

When the highly contagious Omicron variant of the coronavirus reached the United States last fall, it pushed the number of new cases to unprecedented heights.

Even then, the record wave of recorded infections was a significant undercount for the truth.

In New York, for example, authorities recorded more than 538,000 new cases between January and mid-March, which represents about 6 percent of the city’s population. But a recent survey of New York City adults suggests there may be more than 1.3 million additional cases that were either never detected or never reported, and 27 percent of adults in the city may have been infected during these months.

The official count of coronavirus infections in the United States has always been underestimated.. But as Americans increasingly turning to home tests, Specifies shutter mass test sites and institutions reduce surveillance testsScientists say the number of cases is becoming an increasingly unreliable measure of the true cost of the virus.

“Blind spots seem to get worse over time,” said Denis Nash, an epidemiologist at the CUNY Institute for Public Health and Health Policy and who led the preliminary and yet-to-be-published New York City analysis.

This could leave officials increasingly in the dark about the spread of Omicron’s new highly contagious subvariant known as BA.2, he said. “We are more likely to be surprised.” On Wednesday, New York officials announced two new Omicron sub-variantsboth are descendants of BA.2, have been circulating in the state for weeks and are spreading even faster than the original version of BA.2.

The official number of cases can still catch up with the main trends and has started to rise again as BA.2 spreads. But experts said undercounts will be a bigger problem in the coming weeks, and mass testing sites and widespread surveillance testing may never return.

“This is the reality we find ourselves in,” said Kristian Andersen, a virologist at the Scripps Research Institute in San Diego. “We don’t have as much eyes on the pandemic as we used to,” he said.

To monitor BA.2 and future variants, authorities will need to take whatever information they can from a range of available indicators, including hospitalization rates and wastewater data. But truly tracking the virus will require more creative thinking and investment, the scientists said.

For now, some scientists said, people can measure their risk using a lower-tech tool: by noting whether people they know have contracted the virus.

“If you hear that friends and colleagues are getting sick, that means your risk is increased, and that means you probably need to test and mask,” said Samuel Scarpino, vice president of pathogen surveillance at the Rockefeller Foundation’s Pandemic. Prevention Institute.

Problem with testing

Tracking the virus has been difficult since the early days of the pandemic, when testing was severely restricted. Even when testing improved, many people didn’t have the time or resources to research it – or they had asymptomatic infections that never presented themselves.

When the Omicron hit, a new challenge loomed: Home testing eventually became more common, and many Americans relied on them to get through the winter holidays. Many of these outcomes have never been reported.

“We haven’t done the groundwork to systematically capture these cases at the national level,” said Katelyn Jetelina, an epidemiologist at the University of Texas Health Sciences Center in Houston.

Some jurisdictions and test manufacturers have developed digital tools that allow people to report test results. But a recent study suggests that getting people to use them can be labor-intensive. Residents of six communities across the country were invited to use an app or an online platform to order free tests, record their results, and then send that data to their state health departments if they wanted to.

About 180,000 households used the digital assistant to order the tests, but only 8 percent logged in Researchers found no results on the platform, and only three-quarters of those reports were sent to health authorities.

Experts said that, in addition to general Covid fatigue, the vaccine’s protection against severe symptoms could prompt fewer people to get tested. And citing a lack of funding, the federal government recently announced stop reimbursing healthcare providers for the cost of testing uninsured patients, asking for some providers to stop offering these tests for free. Dr. This could make uninsured Americans particularly reluctant to test, Jetelina said.

“The poorest neighborhoods will have more depressive cases than high-income neighborhoods,” he said.

Experts said that monitoring case trends remains important. “If we see an increase in cases, it’s an indication that something has changed – and something has changed, such as a new variant, most likely due to a bigger shock to the system,” said public health policy expert Alyssa Bilinski. Brown University School of Public Health.

But experts said more modest increases in transmission may not be reflected in the case count, meaning it may take longer for authorities to detect new fluctuations. The problem may be exacerbated by the fact that some jurisdictions have already started. updating case data less frequently.

Dr. Nash and colleagues are exploring ways to overcome some of these challenges. To estimate how many New Yorkers might be infected during the winter Omicron surge, they surveyed a diverse sample of 1,030 adults about their testing behavior and outcomes and potential Covid-19 exposures and symptoms.

Persons who reported testing positive for the virus in tests administered by healthcare or testing providers were counted as cases that could be caught by standard surveillance systems. Only those who tested positive at home and those with possibly unreported infections (a group that included both people with Covid-19-like symptoms and those known to have been exposed to the virus) were counted as latent cases.

The researchers used the responses to calculate how many infections could escape detection, and weighted the data to fit the demographics of the city’s adult population.

The study has limitations. It is based on self-reported data and does not include children as well as adults living in institutional settings, including nursing homes. However, Dr. Nash said health departments could use the same approach to try to fill in some of the blind spots in surveillance, particularly during surges.

“You can do these surveys daily or weekly and quickly correct prevalence estimates in real time,” he said.

Another approach would be to repeat what Britain did. regularly tested a random choice hundreds of thousands of residents. “This is really the Cadillac of surveillance methods,” said Natalie Dean, a biostatistician at Emory University.

However, the method is expensive and the UK has recently downsize their efforts. Dr. “This is something that should be part of our arsenal in the future,” Dean said. “It’s unclear what people’s appetites are.”

disease burden

The spread of Omicron, which easily infects even vaccinated people and often causes milder illness than the previous Delta variant, has caused some officials to place greater emphasis on hospitalization rates.

“If our goal is to monitor serious illness from the virus, I think that’s a good way to do it,” said epidemiologist Jason Salemi of the University of South Florida.

But hospitalization rates are lagging indicators and may not catch the real toll of the virus, causing serious disruptions and Covid-19 for a long time without sending people to hospital, said Dr. Salem.

Indeed, different measures can create very different portraits of risk. In February, the Centers for Disease Control and Prevention began using local hospitalization rates and hospital capacity measures in addition to new case counts. “Covid-19 community levels” is designed to help people decide whether to wear a mask or take other precautions. more than that 95 percent of US states they currently have low community levels of Covid-19 relative to this measure.

But the CDC’s community transfer map, based only on local case and test positivity rates, shows that: Only 29 percent of U.S. states There is currently a low level of viral transmission.

Hospitalization data may be reported differently from one place to another. Because Omicron is so contagious, some areas are trying to distinguish patients specifically hospitalized. for They catch Covid-19 and the virus by chance.

New Hampshire Department chief medical officer Dr. “Due to the unique factors of the virus we see currently circulating in our area, we felt we needed to update our measurements,” said Jonathan Ballard. Health and Human Services.

New Hampshire’s until late last month Covid-19 online dashboard showed all inpatients with active coronavirus infection. It now instead shows the number of hospitalized Covid-19 patients who received two frontline treatments, either remdesivir or dexamethasone. (Data on all confirmed infections in hospitalized patients remains available through New Hampshire Hospital Association, Dr. Ballard noted.)

Another solution is to use approaches that do not rely on testing or access to healthcare, such as wastewater surveillance. People with coronavirus infections shed the virus in their faeces; Monitoring levels of the virus in wastewater is an indication of how prevalent it is in a community.

Working with colleagues to track the virus in San Diego’s wastewater, Dr. “And then you combine that with sequencing so you get an idea of ​​what variants are in circulation,” Andersen said.

CDC recently added wastewater data hundreds of sampling sites To the Covid-19 dashboard, however, coverage is quite uneven and some states report no up-to-date data. If wastewater surveillance is to fill testing gaps, it needs to be expanded and data published in near real-time, the scientists said.

Dr. “Wastewater is no problem for me,” Andersen said. “It gives us a really good, substantial passive surveillance system that can scale. But only if we realize that this is what we have to do.”

From the Pandemic Prevention Institute, Dr. Scarpino said there are other sources of data authorities can leverage, including information on school closures, flight cancellations and geographic mobility.

Dr. “One of the things we don’t do well enough is put them together in a thoughtful and coordinated way,” Scarpino said.