The first wave of influenza in the spring of 1918 was easy on the world: It, too, was a novel virus, but as it spread through the armed forces, sickening young men, it killed a few and spared most.
It turned out to be a “herald wave,” presaging the second wave, which had a higher fatality rate and moved quickly between countries as American soldiers mobilized for participation in the last months of World War I, said Alex Navarro, a researcher at the University of Michigan.
It ripped through the United States that following fall, causing 675,000 deaths nationwide. There were third and fourth waves that continued into 1920. Worldwide, 50 million people died.
That historic outbreak is on the mind of experts this year, as the first pandemic in 100 years hits the U.S. Many have already begun discussing the second wave of Covid-19 as an inevitability.
“We fully expect another wave of infections this fall,” the Vermont Medical Society wrote to legislators on June 17.
Commissioner Michael Schirling of the Department of Public Safety said the state is preparing for that second wave. “We’re working on our PPE stockpiles, assessing what number of days of equipment we believe we’ll need if there is a surge, and making sure we have that in the stockpile,” Schirling said.
It’s unclear whether Covid-19 will follow the course of history, given that the 1918 pandemic was a different virus at a different time. That influenza hit young people the hardest and came in many forms, causing bleeding from the nose and ears, kidney damage and abdominal pain.
But experts say when it comes to envisioning our future lives — at least until a Covid-19 vaccine is widely available — history is, in many ways, all we have to go by.
Epidemiologists say a second wave is inevitable, given the nature of a disease that can cross borders and infect broadly — especially because even the most optimistic projections show it will take many months for scientists to develop a vaccine.
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Though Vermont has so far avoided much of the physical suffering (56 deaths and 1,254 cases as of July 7) as other places fairly nearby, the virus continues to emerge in different areas of the state.
Winooski’s outbreak in early June had more than 100 cases, spread among a younger community than previous outbreaks. About a dozen workers at a quarry site in Fair Haven also contracted the virus; most of them actually lived across the border in New York.
“If left to its own devices, Vermont, like New Zealand, could probably eradicate the virus — we are close as it is,” said Richard Hopkins, a retired epidemiologist who has worked for several state health departments. “And with vigorous response to clusters like the current one in Winooski, it can stay that way. But Vermont can’t isolate itself from the rest of the U.S., or the rest of the world.”
So government officials, experts, health care workers and Vermonters are poring over the data and looking to the past to predict the future. They’re asking: Will Vermont have a second wave? When? How? And how can we prevent it?
We’re not in a second wave right now
The recent rise in cases across the United States has caused fears that the country might be in a second wave of the pandemic.
States across the South, Southwest and West of the country are seeing a rise in cases. California, Arizona, Texas and Florida have been forced to reverse their reopening plans.
Dr. Anthony Fauci, testifying in front of Congress on June 30, warned that the country could see 100,000 cases a day based on the latest trajectory.
“I am not satisfied with what’s going on because we are going in the wrong direction if you look at the curves of the new cases,” he told Congress. “So we’ve really got to do something about that and we need to do it quickly.”
While the resurgence in cases in states across the country is concerning, experts agree: We’re not in a second wave — we’re still in the first.
Timothy Sly, an epidemiologist at Ryerson University in Toronto, said we don’t have enough data to say if the curve of the epidemic is declining or rising.
“The numbers only show three months,” he said via email. “There will be peaks and drops, but a sample of three is a bit limited. With five months the picture should be clearer.”
Hopkins said even the term “second wave” is not really a useful way to talk about the outbreak, because so few Vermonters have been infected by the virus so far.
Cases in the United States have indeed begun to curve upward after a long period of national decline. But the data there can be deceptive, as the numbers at a national level were influenced by the largest site of the epidemic in New York.
While New York’s recovery has pulled the national figures down, many states have never seen a lengthy period of decline, meaning that for the recent increase is mostly the result of those states reaching new highs in the first wave of their epidemic.
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Right now, that increase is driven by Florida and Texas. In response, Miami has instituted a curfew and Texas has closed bars as cases swell.
Vermont, too, has seen an increase in cases since the beginning of June because of the Winooski and other smaller outbreaks. State officials have said the latest clusters do not indicate a “second wave,” and also questioned whether Vermont’s case growth is an indicator of any surge at all.
Part of the difficulty is analyzing such a small population (1,254 cases among a population of 623,989) can lead to statistical quagmires. For example, there’s a high “confidence interval” on Vermont’s statistics like Rt, the measure of how much the virus is spreading, said Department of Health Commissioner Mark Levine.
Confidence intervals, like a margin of error, indicate how confident researchers are that a number is within a certain limit. Vermont’s tiny figures in comparison to national data make it hard to analyze upswings and downturns. Small variations in cases — like the daily total going from 1 to 2 — can turn into big percentage changes.
Officials often use the average spread over different time periods to see if the increase is consistent. That smoothed curve can make changes look less dramatic, although it still shows a bump in recent weeks.
What does a second wave look like?
According to Dr. Ubydul Haque, an epidemiologist and biostatistician at the University of North Texas Health Science Center, there’s no single, universal definition of a “second wave” of a pandemic.
That makes it difficult to say if any region has truly had one yet. But a handful of locations have seen a resurgence in cases after seeming to eliminate the virus. One example is Beijing, which reported zero cases in early June, then saw its numbers explode again.
In Beijing’s case, the resurgence was tied to the reopening of Xinfadi, a popular food market that imports food from elsewhere in the country. The city put certain neighborhoods on lockdown and has tested thousands for the disease.
South Korea has also reported its own second wave in cases, although the caseload has been far smaller than the country’s initial peak in cases. Government officials tied the outbreaks to nightlife in the capital of Seoul.
Vermont officials have not provided a single definition for what constitutes a second wave. Easton White, a researcher at the University of Vermont, finds that concerning.
“I would like to see explicit criteria for what would be a second wave,” he said. “It should be well defined that if XX cases are seen across YY locations, then we will implement policy ZZ.”
The Department of Financial Regulation, which runs Vermont’s Covid-19 modeling, does have explicit criteria to determine whether a rise in cases is cause for concern.
The “warning flags” include: doctor’s visits for Covid-like illnesses exceeding 4%; sustained viral exponential growth in cases; the percentage of tests coming back positive hitting 5%; and less than 30% of ICU beds open for Covid-19 patients.
The state has never reached those thresholds, and it’s not clear whether hitting them would constitute a second wave.
It’s also not clear at what point the state will take action on a second wave, and what that action will look like — whether it will include the restrictive lockdown measures that devastated the economy this spring.
In response to a rising number of cases in March and April, Gov. Phil Scott closed schools, workplaces and public gatherings, issued a stay-at-home order and limited medical procedures.
Scott has recommended, but not mandated, that Vermonters wear masks in public places, which has become one of the rare points of political attack against Scott for his handling of the coronavirus shutdown and reopening.
When asked about what parameters he’ll use to decide whether to reconsider reopening, Scott has said he is keeping an eye out for outbreaks that spread to other parts of the state. If there were numerous outbreaks, he’d be concerned about moving too quickly — but “sporadic outbreaks are something that I think we have to get used to and accustomed to.”
“We don’t control the virus, the virus is controlling us,” the governor said. “All we can do is mitigate it the best we can until there’s a vaccine in place.”
When will the wave come?
In the past, the notion of “waves” of a virus referred to viral strains that would appear to disappear in the summer and reappear in the winter, as cold weather affects people’s immune systems and sticks them in close quarters.
Scientists say the virus is spread largely through respiratory droplets, which can linger in a room for several hours after people have talked, coughed or sneezed. The virus also has less of an opportunity to spread in summer because sunlight acts as a disinfectant, and people are outdoors in the open air where it is easier to meet without infecting one another. In Vermont and other cold-weather climates, winter presents new challenges to virus containment efforts.
Other viruses in the coronavirus family have followed a seasonal pattern as well, making some think Covid-19 may follow. In press conferences and interviews, Department of Health head Mark Levine has referenced the potential for a second wave coming in the fall.
But the assumption that Covid-19’s spread, specifically, will come with cold weather, isn’t backed by hard evidence, said Haque, the epidemiologist at the University of North Texas Health Science Center.
“All the studies published in science on this seldomly analyze the effect of temperature on the development of COVID-19 on a large [enough] scale,” he said. Larger studies out of China, on the other hand, don’t show any correlation with winter weather.
In fact, Covid’s spread may be more closely tied to air pollution and humidity, he said.
“There are some studies that show when air pollution is high, the transmission rate also goes high,” he said. Air pollution is dependent on a mix of environmental factors, some of which are even aggravated in warm weather.
Haque is working on a model of future case growth that factors in a number of variables, including many social distancing metrics and measures of access to health care.
Does Haque think Vermont can prevent a second wave while remaining open? Is the Winooski cluster a sign of something more serious?
“This is not the first cluster of Covid-19 in Vermont. And as we’ve stated up here, we expect it will not be the last,” he said.
Vermont has repeatedly shown its ability to test residents in outbreaks with pop-up testing sites, sometimes testing above 1,500 people a day — placing it among the highest per capita testing rates in the U.S.
Levine said of the recent clusters: “As you know, we’ve greatly expanded our testing throughout the state. And we fully expected this effort to reveal more cases.”
White, the University of Vermont researcher, said the state isn’t testing enough.
“The state does need to be doing random testing throughout the state to allow early detection of new outbreaks,” he said. “If they are waiting for people to come to testing sets or hospitals, I think this is a mistake.”
Hopkins emphasized the need for everyone — including the media — to focus on extensive contact tracing, paired with extensive testing, as part of the interim solution. “Testing by itself has never prevented a case; It’s testing combined with contact tracing isolation of cases quarantine of contact,” he said.
“We have the tools,” Hopkins said. “Isolate the cases, quarantine the contact — and really good elicitation of contacts, really identify all the exposed people — and then quarantine the exposed people. It will work.”
As the state reopens, though, it could get more difficult to do high-quality contact tracing, he said, because people will have more contacts.
A regional approach to closures might work, Haque said. He’s coming up with a way for certain zip codes to determine whether to keep their swimming pools and other public places open.
For instance, “All swimming pools in that particular zip code need to be closed to protect the public health, but other swimming pools [in the county] can be open,” he said.
If people are willing to work from home when possible, Haque said there is a chance we can use modelling to carefully track the virus while allowing for some activities. “We can probably stop a high percent of public [health] issues and open 90% or 95% of our country,” he said.
White says a major stumbling block is the public’s willingness to follow the rules for social distancing and voluntary quarantining on a regional or statewide level.
“I think a big part of the reason for governments relaxing policies was that citizens were tired of them,” he said. “People lost the will to keep implementing them. I’m not sure the appetite would be there for a second set of closures.”
That proved true for the second wave of the 1918 pandemic, when cities began to reopen — then saw their cases spike. The City of Philadelphia failed to take any quarantining precautions because of city government corruption. In five weeks, 25% of the population contracted the disease, and 16,000 people died. Even after the risks were known, due to outbreaks in cities across the country, San Francisco’s attempt to re-implement a mask order met with protests and petitions.
Sly said he expected the numbers to continue to increase largely because people are tired of social distancing, and are resuming gatherings and returning to work.
“It’s inevitable, but the objective is to let that happen slowly, while not involving the high-risk population,” he said. “Whether it becomes noticeable as a true ‘second wave’ or simply a slow increase from now until the vaccines are here depends upon how well this is managed, and how well people comply.”
Katie Jickling contributed reporting.
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