As Covid Emergency Ends, Surveillance Shifts to the Sewers

The coronavirus won’t go away when the Covid-19 public health emergency is lifted in the United States on Thursday. But many of the data streams that have helped the American public monitor the virus will be turned upside down.

The Centers for Disease Control and Prevention will cease regional-level tallies of COVID-19 and will no longer request specific case information from hospitals or laboratory data from laboratories. And as free testing is curtailed, the official case count, which has become less reliable as Americans shift to testing at home, may diverge further from reality.

But sewage still remains a valuable option for professionals who want to monitor the virus.

Because people infected with coronavirus shed the pathogen in their stools, whether they are tested for COVID-19 or receive medical care, authorities have tracked virus levels in communities over time to help identify new variants. Appearances can be monitored.

This approach expanded rapidly during the pandemic.of National Wastewater Monitoring SystemEstablished by the CDC in late 2020, the data now includes data from more than 1,400 sampling sites across 50 states, three territories and 12 tribal communities, said program director Amy Kirby. said. The data covers approximately 138 million people, more than 40% of the U.S. population.

And while other tracking efforts are curtailing, some communities are racing to set up sewage monitoring programs for the first time, Dr. Kirby noted. “This actually makes wastewater even more interesting,” she said.

Scientists say monitoring wastewater will become even more important in the coming months, helping authorities spot early outbreaks.

But sewage monitoring is still not done in many communities and more work is needed to transform what began as an ad hoc emergency effort into a sustainable national system, experts say. Stated. And as the pandemic continues to evolve, authorities will need to think carefully about how data is used.

“Wastewater must be improved,” says virologist David O’Connor of the University of Wisconsin-Madison. “And we need to be a little more savvy about interpreting what the wastewater data is telling us.”

Over the past three years, the value of wastewater monitoring has been repeatedly proven. At a time when testing was widely available, trends in wastewater mirrored official COVID-19 cases. When testing was scarce, spikes in viral concentrations in sewage were an early warning of an upcoming virus surge, allowing authorities to reallocate public health resources and hospitals to prepare for an influx of infected cases.

Wastewater sampling can help scientists determine when new variants have arrived in particular communities, and when clinicians use specific treatments that may not work against all versions of the virus. It helped me make a more informed decision about whether to

“Regarding SARS-CoV-2, our wastewater monitoring system is pretty robust right now.” said Marisa Eisenberg, an infectious disease epidemiologist at the University of Michigan. “We’ve gotten past that pace to some extent.”

For example, Houston currently has a large Wastewater monitoring We collect weekly samples from all 39 wastewater treatment plants in the city and from individual schools, shelters, nursing homes and prisons. Lauren Hopkins, chief environmental science officer for the Houston Department of Health and a statistician at Rice University, said the city has no plans to downsize.

“I really don’t know what will happen with the new coronavirus,” she says. “We will continue to investigate how much virus is present in the sewage.”

The CDC will continue to track deaths and hospitalizations, but they tend to be lagging indicators. Wastewater is therefore likely to remain an important early warning system for both authorities and the public in the future.

“It can help people who are especially vulnerable because they have weakened immune systems,” said Alexandria Boehm, an environmental engineer and research director at Stanford University. Wastewater SCAN, Sewage Monitoring Initiative. “It helps me decide between wearing a mask and going to a crowded concert.”

Scientists said that monitoring effluents will also be an important strategy for monitoring new variants and gauging the threat they pose as clinical testing dwindles. For example, a variant that rapidly overruns a sewer system, or a local hospitalization rate that rises after its spread, may warrant increased surveillance.

Still, data is not available everywhere. Existing wastewater monitoring systems have emerged in a somewhat haphazard manner with interested jurisdictions agreeing, resulting in uneven coverage in the country. Wastewater sampling sites tend to be sparse or non-existent in many rural areas and parts of the South and West.

And collecting wastewater data is only the first step. Scientists warn that it could be even more difficult to understand.

Among the challenges they cited is that many Americans have acquired some degree of immunity to the virus, so a surge in wastewater will not necessarily lead to the wave of hospitalizations expected at some facilities. Thing. And scientists don’t yet know if all subspecies are equally detectable in wastewater.

Furthermore, just finding new mutants in wastewater does not necessarily portend problems. For example, since 2021, University of Missouri virologist Mark Johnson and his colleagues have discovered dozens of unusual variants in wastewater samples across the United States.

Some of these variants are fundamentally different from Omicron and could theoretically pose new public health risks. But at least for now, these variants don’t seem to be spreading. Dr. Johnson said these likely come from individual ultra-dropout patients with long-term coronavirus infections.

“Wastewater is great because it gives us a comprehensive picture of what is going on,” said Dr. Johnson. But “it can be misleading,” he says.

And while a decline in tracing COVID-19 cases was probably inevitable, sewage monitoring is most beneficial when combined with other sources of public health data, scientists said. “I like to think of it as a complementary data stream,” Dr. Eisenberg said.

Dr. Kirby said wastewater monitoring will continue to evolve. The CDC is in talks with some states about how to optimize its network of sampling sites. That process may involve both adding new sites and downsizing areas where multiple sampling locations provide inherently redundant data.

“We expect some reductions in facility numbers in some of these states,” Dr. Kirby said. “However, we will work with them strategically to ensure that we do not lose any information.”

The official explore other possibilities, that too. as part of the CDC Traveler Genome Surveillance ProgramFor example, Ginkgo Bioworks, a Boston-based biotech company, Currently testing wastewater samples From a plane landing in the international terminal at San Francisco International Airport.

“As other forms of testing begin to wane, it’s very important to have these indirect mechanisms in place that allow us to see what’s going on in the world,” said the firm’s Concentric by Gingo. Business Development Director Andrew Franklin said. Biosecurity and Public Health Department.

Dr. Kirby said the American Rescue Plan has provided sufficient funding to implement wastewater monitoring in all states and territories through 2025.

But maintaining sewage monitoring will require ongoing funding over the long term and ongoing buy-in from local officials who may lose interest as the pandemic emergency subsides. “There will be dropouts due to fatigue,” said Guy Palmer, an infectious disease pathologist at Washington State University and chairman of the Wastewater Oversight Board at the National Academy of Sciences, Engineering, and Medicine.

So proponents of wastewater monitoring want to demonstrate its continued utility against both COVID-19 and other diseases. Some jurisdictions are already using wastewater to track flu and other pathogens, and the CDC hopes to roll out expanded testing protocols by the end of the year, Dr. Kirby said.

“This is part of our long-term surveillance portfolio,” Dr. Kirby said. “I think when this emergency period is over, we will really see how powerful it is.”

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