The US is facing a unique season of respiratory virus transmission: flu cases are rising earlier than usual, and RSV case rates are extremely high, even after an “unprecedented” surge this summer. And Covid-19 is still a public health emergency.
Public health experts expected a break from typical seasonal trends amid a pandemic that has disrupted “normal” in many ways. Some of the results would be unexpected.
But one thing that can help public health officials better prepare for and respond to these unusual surges is comprehensive, real-time disease surveillance that more closely tracks transmission trends and other key data. It is especially critical now as the country faces what will be a particularly harsh winter when virus trends have changed.
“The system has adequately detected the changes, but the change itself is more unpredictable,” said Janet Hamilton, executive director of the Council of State and Territorial Epidemiologists.
The Covid-19 pandemic revealed how broken and underutilized the health data infrastructure in the United States is, and data lags made it difficult to respond quickly to the coronavirus. Ultimately, the frequency of Covid-19 reporting (daily updates, sometimes hourly updates) created a deluge of information that was shared throughout most of the pandemic.
But that was special.
Surveillance systems for viruses such as influenza and RSV were established long before Covid to track trends, with data generally updated weekly. The national data is based on voluntary reports from a dozen laboratories representing about one-tenth of the population, and is then shared by the US Centers for Disease Control and Prevention.
In normal years, this system captures what it means.
“In many ways, it works very well because you can often determine a lot from a sampling strategy,” Hamilton said, especially with diseases that have been consistent over the years.
“For things like the flu and RSV, you don’t necessarily need to know about every single person. But it’s important to know when you start seeing traffic, if it’s increasing, how long we’ve been seeing traffic, when it’s peaking and when it’s going down.”
In atypical years like this, more real-time information is critical, but early indications of major outbreaks were not shared through surveillance data.
Pediatric hospitals are among the hardest hit by this unusual virus season.
About three-quarters of pediatric hospital beds are used across the country, well above the average in recent years. Rhode Island, Minnesota, Maine and Texas, as well as Washington, D.C., are more than 90 percent full, according to data from the U.S. Department of Health and Human Services.
Hospitals are constantly assessing capacity needs, preparing for infectious disease outbreaks by ensuring there are enough beds available and enough supplies to support those in need. But when it comes to planning ahead, experts say getting more labs to participate in the national surveillance system isn’t hospitals’ most pressing need.
“For hospitals [using CDC data], it’s like looking in the rearview mirror. “They’re already starting to experience that increase in cases before they’re even showing up in the federal data,” said Nancy Foster, vice president of quality and patient safety at the American Hospital Association.
“We’re talking about data that’s collected inside the hospital, transmitted through a data path to the federal government, analyzed there, and sent back to the hospitals.”
Instead, hospitals rely on informal networks of physicians, public health officials, and others to share more immediate information about recent experiences to help make planning decisions.
Perhaps there are efforts to identify and build on critical lessons learned from the Covid-19 pandemic to help make key data immediately available and make reaction times more efficient, Foster said.
“Within those conversations, some of those clinic-to-clinic conversations and how to leverage what you’re seeing on social media to more realistically identify potential spikes or other issues like supply shortages so you can address them more quickly,” he said.
One way to supplement traditional surveillance methods became more popular throughout the pandemic: monitoring the level of viruses released into local sewage systems.
Weeks before the surge in RSV infections began to spread across the United States, researchers at WastewaterSCAN, a national wastewater monitoring initiative based at Stanford University, noted a significant increase in detections of the virus in wastewater across the country.
“We found that the onset of RSV started around mid-August of this year,” said Marlene Wolfe, assistant professor of environmental health at Emory University and principal investigator of WastewaterSCAN. “If we are seeing it in the waste water, the infections are there. We had the data before we reported the clinical positivity data.”
Wastewater surveillance can help hospitals plan for capacity because they can track community wastewater data to determine when the circulation of a particular infectious disease may increase and prepare for an increase in sick people, Wolfe said. “One of the really important ways to look at using wastewater data is through capacity planning. You can get a lot of public health responses from knowing there’s an uptick in a disease.’
Also, since most people don’t get tested for RSV (especially adults, whose symptoms mimic the common cold), wastewater monitoring can help monitor when and where the virus is circulating.
Wastewater monitoring tests sewage, feces and other human waste in untreated water to see if it contains the genetic material of viruses or bacteria that can make people sick. This material, RNA or DNA, can be detected in the waste, but does not indicate whether the pathogen is infectious in the water itself.
The WastewaterSCAN initiative, which provides results to the CDC’s separate wastewater surveillance system, was launched in November 2020 to test wastewater samples for SARS-CoV-2, the virus that causes Covid-19. Since then, the program has expanded to monitor dozens of sewage plants across the country and to monitor additional pathogens, including RSV testing, in 70 city and county sewage systems in 20 states.
“You can track RSV in wastewater. We have abundant evidence that we have been able to do this effectively for about a year now, and this season, this outbreak, provides us with good information that matches RSV and other sources of information. It gives us a little jump to make sure we have good information to prepare our communities,” Wolfe said.
“And the patterns we’re seeing across the country where transmission is particularly high is consistent with what we’re seeing across the country where those levels are particularly high in wastewater,” he said. “So we’re going to continue to build and expand the system so that we can provide that network of sites across the country that tell us where the hot spots are for these different diseases, whether it’s RSV, influenza or Covid.”
Regardless, experts say local data is the key to public health success.
“I always want to have more detailed data and information, especially since we’re coming out of Covid and we’ve had such unusual respiratory disease seasons that having more detailed data available would be helpful to pinpoint exactly where we’re seeing disparities,” he said. said Hamilton.
“People respond more to local data. If people feel that they are really close and with them, they are often ready to make behavioral changes that you don’t see if the danger is not present.’
States and jurisdictions with stronger surveillance systems noticed something unusual in their local trends in previous years and “pooled funding” because they knew they needed to do more to understand it, he said.
But now, trends have become unusual in most places, and robust systems are not well understood.
Changing that requires funding.
“We can do more and we’d like to do more,” Hamilton said, but “it’s really scary how under-resourced RSV surveillance is.”