As Covid-19 infections drop to pre-Omicron levels and hospital visits for the disease decline, Vermont officials have begun to discuss how the virus could be dealt with as a permanent fixture in everyday life.
“Many of us in public health believe Omicron has hastened our pathway to the endemic state, meaning a time when the virus is constantly present in our population,” but in a milder state, said Health Commissioner Mark Levine at a recent press conference.
He compared that phase of the coronavirus to another, more well-known disease that strikes every year: the flu.
“When Covid is less disruptive,” he said, it will be “much like the flu, a virus that can be dangerous but is largely managed through regular vaccinations and good prevention practices.”
There are some straightforward similarities between the two diseases. Both are infectious, airborne respiratory viruses that can be transmitted when a person is incubating or asymptomatic. Both have been tackled through public health strategies such as vaccination and encouraging people to stay home when they’re sick.
And both have caused deadly pandemics within the past century — although the way Vermont managed the 1918 flu pandemic was very different from how it has tackled Covid in the past two years.
“It turns out that influenza and Covid are more like each other than we had originally thought,” said Richard Hopkins, a former epidemiologist who worked in Colorado, West Virginia and Florida and now lives in Middlebury.
But there are fundamental differences in how the two diseases have been treated, partly because of the flu’s status as a seasonal endemic virus. To Vermonters accustomed to the metrics of Covid cases, hospitalizations and testing reported each day, the Vermont Department of Health’s weekly flu surveillance reports are nearly unrecognizable.
And although public health officials have decades of experience dealing with the flu, the disease has remained tricky to handle. The flu still kills thousands of people each year nationwide.
“Influenza surveillance and influenza control has always been difficult,” Hopkins said.
“Having people with experience under their belt, doing the surveillance and looking at the data, really is important, and then having the appropriate analytical tools and surveillance tools is really important. But it’s not all one or the other,” he said. “Part of it is judgment; part of it is systematically collected data.”
How Vermont tracks the flu
The flu season in Vermont tends to begin around late September or early October, according to health department reports. But monitoring the flu begins months before that, as public health officials in the United States watch what happens in the winter in the Southern Hemisphere, said Laura Ann Nicolai, deputy state epidemiologist.
That data helps to shape an educated guess about which strains are going to circulate during the flu season and which vaccines to use to prepare for it, in combination with data from previous American winters, she said.
So far this year, Vermont appears to be having a mild winter for the flu. Flu activity was “minimal” in the state as of the end of January, according to the most recent health department report. Although other states reported nasty flu seasons to the Centers for Disease Control and Prevention earlier in the winter, the activity level has been dropping for the past few weeks.
But the Vermont health department doesn’t track every new flu infection in the state; it doesn’t even try. Instead, it uses several measures that inform the department about the relative level of the virus — and several key data points that shed light on how it’s affecting the state.
“Individual cases are not required to be reported to us, but if we have enough data points from our overall surveillance system, the goal would be then that we can know when and where flu activity is occurring,” Nicolai said.
That’s a big contrast to the department’s Covid data dashboard, which reports the number of new infections, deaths and PCR tests performed, and the number of Covid patients in the hospital at any one time.
But officials have increasingly warned that daily cases are not the best way to measure Vermont’s progress with the Covid virus.
Mike Pieciak, commissioner of the Department of Financial Regulation, which keeps the state’s statistics, said recently that each Covid-19 case reported by the health department probably translated to four or five undetected cases under Omicron, either because of asymptomatic cases, symptomatic people who never got tested, or people who never reported a positive take-home test to the health department.
Levine signaled that the health department’s data collection could shift even further as Covid transitions into an endemic virus.
“As part of our evolving pandemic response, we’re continually assessing the most effective use of our public health resources,” he said, as part of an announcement that the department would no longer update its dashboard on weekends.
The most prominent data for tracking the flu is the percentage of emergency department visits related to “influenza-like illness,” patients at the hospital with symptoms that match the flu, Nicolai said.
So far this year, those visits have been fewer than 1% of the total emergency department visits, compared to about 6% of visits during the peak of the 2019-20 season, according to the report.
The state also collects flu data from “sentinel providers,” or doctor’s offices scattered throughout Vermont that report the number of visits they get with patients who may have the flu, and it tracks a few details about the cases, such as the age distribution of patients, according to the report.
But Nicolai said the department enrolled only 10 providers for this flu season, and their participation has been spotty. “This is less than we would prefer, but we understand providers are working through extra challenges due to Covid,” she said via email.
State labs also test a subset of viral samples to see which strains are circulating with PCR tests, but that was affected by Covid last year, too: Labs tested only 28 samples, compared to more than 200 in 2019-20, the department reported.
“It is likely the Covid-19 global pandemic contributed to a decrease in tests performed in the 2020-21 season by the Vermont Department of Health Laboratory and Vermont hospitals compared to the previous flu season,” the department said in its report.
Still, other data points suggest that the flu was unusually mild last year because of the many measures – masking, closures and isolation – taken across the country to deal with Covid, Hopkins said.
The CDC reported only one pediatric death nationwide from the flu last year, far below the more than 100 deaths typically reported each season.
Hopkins said the goals of flu surveillance are threefold: To see when it begins, peaks and ends; to measure its severity and pressure on the health care system; and to see whether it’s a strain covered by the vaccine.
“You don’t need to keep track of every individual case to meet those objectives. In fact, it’s counterproductive to do that, probably,” he said.
Each component of the system — hospital visits, lab testing and mortality reporting — helps to tell the story of the flu. “And going forward with Covid, we’ll probably need those three components as well,” he said.
Nicolai told VTDigger it’s “unfortunate” that the flu surveillance system is “in retrospect, looking back at the data that has just occurred,” rather than providing real-time context, but it still could serve a role during the season itself.
“It is just trying to help us ascertain … the burden of flu on our communities, and then also, using that to inform the public that, ‘oh, hey, you know, flu activity is still really low. It’s not too late to get your flu shot,’” she said.
Lessons from the flu — and from Covid
Hopkins has some experience with nasty flu years. He served as Florida’s state epidemiologist in 2009, when H1N1, better known as swine flu, reached America’s shores.
His team made plans to close schools and take other measures to control spread should the strain turn into a widespread crisis. But swine flu turned out to be less severe than they had feared, in part because older Americans had immunity from long-dormant strains of the flu virus.
As with Covid, people with influenza can be infectious for a day or two before they get sick. That makes contact tracing very difficult to implement, he said.
Vermont performed contact tracing with the original strain and started doing it with Delta, but it announced it would stop most contact tracing in November as infections rose.
“Both diseases have this problem, and it’s really hard to do with influenza. You can’t know about all the people in the community who have influenza,” Hopkins said. “The number that we know about is only the tip of the iceberg. It’s only a tiny fraction of the total number of infections out there. That was very unsatisfying for people, but it’s true.”
Hopkins said that one of the challenges in dealing with the flu has been the lack of institutional memory over the decades. There have been shifts in the nature and virulence of the virus in the United States about once every 10 years, such as in 1947, 1957, 1968 and 1977.
The 10- to 20-year intervals between these major shifts “means that the public health staff turned over,” he said. “They certainly didn’t have … the same people doing influenza response in 2009 that they had in ’77.”
Vaccines were also largely useless against the disease in 2009. Cases began in Florida in April and reached a peak in September, while vaccines weren’t available until October. Vaccines “had no impact on it whatsoever, because it was going away of its own accord,” he said.
Not only does the flu vaccine take months to prepare, it can be less effective than the Covid vaccine — anywhere from 40 to 70% effective — and fewer people, even older people, get the flu vaccine compared to the Covid vaccine.
So Hopkins is heartened to see the progress Vermont has made on administering the Covid shot. “The population-level immunity (to Covid) has been driven very largely by the vaccine,” rather than just natural immunity, he said.
“Superficially, the impact of Covid on our communities might look like a bad influenza year, but it’s an impact that is moderated by the very high vaccine coverage that we have,” he said.
Pharmaceutical companies have taken the lessons from the Covid vaccine to heart. Trials are underway for an mRNA vaccine for the flu, which would speed up the production process and allow the vaccine to better match the dominant strain.
Another practice from the Covid pandemic that may shift to flu surveillance is wastewater monitoring, where municipalities test their wastewater for viral fragments. Burlington used that method to detect the Delta and Omicron variants before they became widespread.
Nicolai said the department is looking into testing for other pathogens in addition to Covid. “That is kind of a new and exciting opportunity,” she said.
She said the Covid pandemic was a reminder for Vermonters to follow the practices that help with both diseases. “I just don’t want people to think it’s normal and acceptable to continue to live out in the community, and go to work, and interact with folks if they do have either flu-like illness, or Covid-like illness,” she said.
“At the end of the day, both flu and Covid can be serious illnesses for others, especially folks who might have underlying health conditions, and what might seem like a more minor illness for an individual like you could have very serious repercussions for others,” Nicolai said.
Correction: About 100 pediatric flu deaths are reported nationwide each year. An earlier version of this article conflated state and national statistics.
