This fall and winter, health experts expect two types of deadly viruses to be circulating widely in the US. But they don’t yet know what the extent of the damage will be when the two collide.
In the absence of a coherent federal response, the novel coronavirus continues to spread across the country, with several states still battling active outbreaks. Experts estimate it could continue to hospitalize thousands and kill hundreds of people a day into September — likely with more spikes in the coming months.
We’re also now staring down the annual flu season, which typically starts in October and burdens the health care system even in normal years. The 2018–2019 flu season in the US, for example, resulted in about half a million hospitalizations and more than 34,000 deaths. The previous season, deaths were double that. And communities of color, which have already been disproportionately impacted by Covid-19, historically have also been more likely to have chronic health conditions that put them at higher risk of influenza-related complications.
In the Southern Hemisphere this year, where the seasons are opposite those in the US, there has been less fall and winter flu activity (possibly due to effective Covid-19 measures, which can also limit the spread of other respiratory viruses). But not all experts are counting on that same scenario in the US.
Which means the months ahead could be bleak. “Based on all the current trends in the US, and our inability to control Covid-19 spread, especially in some parts of the country, I think we are in for a rough fall and winter,” Tony Moody, an immunologist at Duke University Medical Center and the Duke Human Vaccine Institute, told Vox in an email. “If we have Covid-19 on top of the usual seasonal rise in hospital admissions due to influenza and other illnesses, we could overwhelm the health care system.”
Stephen Morse, an epidemiologist at Columbia University Mailman School of Public Health, is also worried: “Adding another half million [flu] patients needing hospitalization, some requiring ICU beds, is a recipe for disaster. It could stretch our health care systems and personnel close to the breaking point.”
One problem is that because influenza and Covid-19 are both respiratory viruses, severe cases will be treated on much of the same limited medical equipment, like ventilators. And because they can have overlapping symptoms, figuring out whether someone has the flu or Covid-19 — or neither — will be tricky but also important.
Fortunately, we already have a safe vaccine for the flu, and nearly 200 million doses are slated to be available in the coming months.
The Centers for Disease Control and Prevention (CDC) says that everyone 6 months and older (with very rare exceptions, like a life-threatening egg allergy) should get a flu shot. And this year, it is more crucial than ever to get one, experts say, to reduce the spread of the virus and keep the health care system from being overtaxed with continued surges of Covid-19.
Yet the barriers will also be higher than usual. Many workplaces that typically offer flu shot clinics either aren’t open or are reducing their size. Mass vaccination events, like those at schools, community centers, and religious institutions, have also been scaled back this fall due to physical distancing precautions. Instead, many individuals will need to get their vaccine this year by visiting their doctor’s office or an urgent care clinic, pharmacy, or local health department.
It’s clear this year’s flu season in the midst of a pandemic promises to be especially fraught. Let’s take a closer look at why that is — and why flu shots even under difficult circumstances should be worth the effort.
Why this year’s flu season is extra unpredictable
Uncertainty looms over flu season every year, but this time there are even more unknowns than usual — from precisely what strains will be circulating to how the virus will interact with Covid-19 to whether our new pandemic habits will impact its spread. “This year, in particular, we don’t know what to expect,” says Stacey Schultz-Cherry, an influenza researcher at St. Jude’s Children’s Research Hospital.
The influenza virus is a mercurial one. It mutates quickly, and multiple strains circulate at any given time, some more harmful than others. This is why each year’s flu shot hedges its bets by fending off a few different strains — and why you need to get a new flu shot every year.
This rapid evolution is also why it’s hard to develop a vaccine that is a precise match for the strains of flu that end up circulating. Vaccines take months to manufacture in such large quantities, so the process of designing the year’s vaccine begins way before flu season hits the US.
Early in the year, scientists start looking at what strains of influenza are circulating around the world, especially south of the equator, just before their full flu season starts. But this year, we are largely missing this crucial piece to the puzzle because the Southern Hemisphere has seen very little flu.
The paucity of flu cases in the Southern Hemisphere this year also means that we haven’t been able to learn much about how Covid-19 interacts with influenza.
Some case reports from early in the pandemic, when the flu was still circulating in China over the winter, showed that some people did have simultaneous infections.
“We really don’t know what a co-infection would look like,” Schultz-Cherry says. But, she says, “I wouldn’t want to have the lungs that would find that out.” She does hypothesize that it would be “a more significant infection” — especially in those at a higher risk for severe Covid-19 and for severe flu illness (including older adults and people with heart disease or cancer).
Other researchers have proposed a model by which familiar seasonal viruses, like the flu, might actually out-compete the novel coronavirus SARS-CoV-2 in the body (due in part to its relatively slower replication rate), thus potentially making full-blown Covid-19 less likely. And a preliminary report from China proposes limited clinical evidence for this idea.
Still other small reports have documented similar outcomes for patients with co-infections of the flu and Covid-19 as those who only had Covid-19.
Moody notes that gathering more of this important data is going to take time. “We expect that we will see co-infections once influenza season gets underway. Unfortunately, we will probably be deep into influenza season before we can say if outcomes are worse if you have both,” he says. “For this reason, we are encouraging people to get their influenza vaccine this season — to blunt this risk.”
We also don’t know how much our restrictions to reduce the spread of SARS-CoV-2, such as mask-wearing and physical distancing, will impact the spread of influenza this year. Many experts attribute the decrease in flu cases in many Southern Hemisphere countries this year, including Chile, South Africa, and New Zealand, to these measures. But it’s not clear whether the US, which has had patchwork restrictions on things like mask-wearing, will see the same trend.
“I would be hesitant to compare ourselves to New Zealand,” says Schultz-Cherry, where they have had virtually no flu this winter — but also went months without a single local transmission of Covid-19. (The country spiked a high of 95 new daily Covid-19 cases at the end of March and has recently had some new cases.)
James Quinn, an emergency medicine professor at the Stanford University Medical Center, says he is optimistic “that our overall flu and common cold virus season will be much better this year,” he wrote to Vox in an email. “I hope it will provide some relief to the surge in Covid-19 that we will undoubtedly see.”
No, the flu shot won’t give you the flu — and it could save a life
Each year, only about half of people in the US get a flu shot. One of the major blocks to higher uptake has been rampant misperceptions about it — and lack of understanding of how deadly the seasonal flu can be.
For example, contrary to popular belief, the flu shot cannot actually give you the flu.
But it does have its share of shortcomings. Researchers fully acknowledge that they cannot always predict which strains they will need to fend off months ahead of time. But, says, Schultz-Cherry, “even if one of the components [in the seasonal flu shot] isn’t a good match, you’re still protected against the other circulating strains.”
The flu shot also doesn’t always keep people from getting the flu (and of course doesn’t protect against other respiratory viruses). But it does help keep their cases milder, including reducing the risk of getting admitted to the ICU.
Schultz-Cherry is constantly reminding people of this. “People come up to me and argue all of the time” that they got a flu shot but still caught the flu that season. Her response: “Yeah, you got the flu. But you didn’t die.”
This plays out on the population level, too. For the 2018–2019 flu season, even with only about half of the US population getting a flu shot, it prevented about 4.4 million cases of the flu, 58,000 hospitalizations, and 3,500 deaths, according to a CDC analysis. And this year, many of those additional hospital beds will likely be needed to treat Covid-19 patients.
“We know flu vaccines aren’t perfect, but they do help, and can help blunt the onslaught,” Morse says. “Anything that helps reduce disease is a terrific return on the investment.”
The power of the flu shot to prevent illness is so well-documented that many more workplaces and education systems are mandating it this year. The entire University of California system, for example, announced that it is requiring all students and staff to get a flu shot by November 1. (Universities often already require students to have certain vaccinations, such as the one for measles, mumps, and rubella.) And some experts have argued that it is actually a smart business move to mandate flu vaccines for employees; the CDC estimates that the US loses about 17 million workdays a year due to people getting sick with the flu. And many health care systems already do this.
How overlapping Covid-19 and flu symptoms are going to make this season very confusing
As US Surgeon General Jerome Adams noted in a radio interview earlier this month, “This is the most important flu season that we’ve faced, I’d say, in my lifetime.”
Beyond pushing hospitalization capacity, flu season also has the potential to overwhelm clinics and testing resources. “Both Covid-19 and the flu are contagious respiratory illnesses that present with similar symptoms,” Libby Richards, who teaches nursing at Purdue University and studies individual health behavior, wrote to Vox in an email.
It is important to know whether someone has Covid-19, influenza, or neither, because treatment can look very different, such as administering specific antiviral drugs for influenza. And “that puts even greater demand on our already-limited diagnostic testing capacity,” Morse says. “Anything you can do to reduce the need for further testing is good. The flu vaccine won’t prevent this, but hopefully it will reduce the problem by lowering flu incidence.”
A large part of the testing concern is that tests for influenza often rely on the same techniques and equipment as those we are now using for Covid-19. “Many of the lab tests for influenza use the same swabs and viral transport media that we use for SARS-CoV-2 testing,” Melissa Stockwell, division chief of child and adolescent health at Columbia University who also studies population and family health, wrote to Vox in an email.
Major national testing companies are still figuring out how they will balance testing for Covid-19 and influenza at the same time. “Laboratories continue to navigate supply constraints,” Julie Khani, president of the American Clinical Laboratory Association, whose members include Quest, LabCorp, and other major testing companies, said in an email statement to Vox. So “boosting vaccination rates for the flu is just one way communities can do their part to minimize the burden on the health system and the labs performing critical Covid-19 testing.”
The very real potential for co-infection with the flu (or a cold) and Covid-19 also makes testing important and diagnosis tricky. Things like a runny nose or sore throat aren’t all that common with Covid-19, but as the authors of one paper on the topic noted, that doesn’t mean you definitely don’t also have the coronavirus. They saw some patients with flu and Covid-19, who “may be a reminder to those who had [those symptoms] not to ignore the possibility of Covid-19 infection.” And they caution health care providers not to overlook this possibility either, “to make sure that we could provide the best and the most comprehensive treatment to the patients.”
In an effort to ease some of the testing burden ahead of flu season this year, the US Food and Drug Administration has approved a new PCR-based test that can look for Covid-19 and influenza in a single analysis. This could not only save on testing resources but also give patients and health care professionals the best information for how to proceed. So far, though, this test has only been made available to CDC-supported public health laboratories (and not the many private laboratory companies, such as Quest or LabCorp, that are currently processing the bulk of the country’s Covid-19 tests).
But experts are not hanging their hats on dual testing or reduced spread due to physical distancing this year. “As Covid-19 sweeps through the country, local health care systems have been stretched to capacity in unimaginable ways. It is hard to imagine how adding yearly influenza to that can be handled,” Stockwell says. “It is something we are very worried about. … It is extremely important that people protect themselves in all ways that they can.”
Flu shots can only save lives if people can get them
Although the pandemic has disrupted global medical supply chains, experts say that we should have a steady supply of flu vaccines in September and October. Because companies have to start making the vaccine so early, and because they have to do it every year, “the supply chain for that process is secured well in advance” of when they get distributed, explains Moody, who also is a principal investigator at the Duke Collaborative Influenza Vaccine Innovation Centers.
But even with ample supply, the barriers to getting a flu shot will be higher this year. “Unfortunately, efforts to reduce the spread of Covid-19, such as stay-at-home orders, have led to a decreased use of preventive health care services, such as vaccines,” Richards says. And this sort of “routine vaccination, including the flu shot, will prevent not only illness but also reduces unnecessary medical visits and hospitalizations.”
Uptake of the flu shot will also probably take an additional hit because many people are accustomed to getting it at their workplaces or other large flu shot events. “The mass flu shot clinics that people may usually depend on may not be available or have decreased capacity due to the need for social distancing,” Stockwell notes.
Instead, this year, more people will need to make a concerted effort to get their flu shot by, for example, making an appointment with a doctor, nurse, or local health department, or going to a pharmacy or urgent care clinic (which, Richards says, are “taking proper precautions to reduce the risk of disease transmission”). For those worried about visiting a doctor’s office or pharmacy while the coronavirus is circulating, Richards says, “I think it is a greater risk to not get a flu shot.” And drive-through flu shot offerings could also be good options, especially for people looking to minimize their exposure, she notes.
Also, you might not want to get your seasonal flu shot just yet, according to experts at Harvard University. Some studies have shown the vaccine’s efficacy can start to fade after four to six months. And if peak flu season happens later in the winter, an August shot’s power could already be waning by then. They recommend early October as a good target, especially for older adults, whose immune systems tend to be weaker.
Even with the slightly higher barriers this year, Schultz-Cherry says, relatively speaking, “this is a pretty easy thing. It’s a vaccine-preventable disease. Get a vaccine.”
The annual flu shot is also an equity and health care access issue. Historically, many people of color have been less likely to have gotten a flu vaccine. Richards notes that about 48 percent of white adults have typically gotten a flu shot; that rate drops to about 39 percent for Black adults and 37 percent for Latinx adults. Which packs an additional punch because people of color have also been more likely to have had reduced access to health care and preexisting conditions that put them at higher risk of complications from the flu.
And the pandemic might well drive these flu vaccination rates lower. Richards notes that nonwhite individuals have been more likely to lose income and health insurance during the pandemic. “This will likely impact vaccination rates, as those who are uninsured are less likely to receive a flu shot.” (She points out, though, that local health departments and community clinics offer low-cost or free flu vaccines for people without insurance.)
If this trend continues, it could add to the devastation many communities of color have experienced in vastly higher rates of hospitalization and death from Covid-19.
“Many people of color have lost faith in the health system,” Lawrence Gostin, an expert on health law and policy at Georgetown Law and co-author of a JAMA letter on the collision of Covid-19 and influenza, wrote to Vox in an email. “Covid-19 amplified distrust and highlighted unconscionable health inequalities. It is likely to keep people away from vaccine clinics and doctors’ offices. This is a major health concern.”
The CDC has noted that it will be focusing more efforts to improve public health messaging around the flu shot this year, particularly in higher-risk and underserved groups. Stockwell recommends that “underscoring the importance of the flu vaccine as well as countering misperceptions about the flu — such as it ‘just being a bad cold’ — as well as the vaccine — such as that it ‘causes the flu’ — can be helpful.” It might also help lay the groundwork for crucial vaccine use in the future.
Public health messaging about the flu shot could be stronger
In recent years, the US has seen a downturn in people getting vaccines of all kinds. We are even now teetering on the edge of losing our nation’s measles eradication status because of people not vaccinating their children. “We need to socialize the idea of vaccinations,” Adams said in his radio interview. “We’ve been backsliding in terms of vaccine confidence over the last several years.”
Many experts worry that these attitudes will carry over once a Covid-19 vaccine becomes available, leading to more unnecessary illness, disability, and death. Not only that, but many questions remain about our country’s preparedness to widely deploy an effective Covid-19 vaccine once one becomes available. Researchers estimate we will need at least 55 percent of people (and possibly up to 82 percent) to get the vaccine (or be otherwise immune) before we can keep the virus in check without major societal restrictions.
But reimagining flu vaccine distribution and communication this season could also help bolster uptake of the Covid-19 vaccine, Gostin and his co-author note in their JAMA letter. For one, they advocate for improving health messaging around flu shots, “focusing on public benefit and personal obligation,” they write.
They also propose the federal government commit to purchasing additional flu vaccine this year (between 194 million and 198 million doses are expected to be available this flu season, based on estimates from private manufacturers; although that is at least 7 million more than last year, it is not enough to vaccinate everyone who should get it).
This government commitment would help avoid shortages and allow more Americans to get a flu shot. But it would also set a precedent for it placing orders for a future Covid-19 vaccine. “At the very least,” they note, “all levels of government should develop evidence-based immunization plans, appealing to individual’s ethical responsibilities to protect themselves, health care workers, family members, and vulnerable populations.”
By developing more effective and efficient ways of getting the flu vaccine to more people — and by honing public health communication around it — we could find ourselves better prepared not only for more protection this fall and winter, but also for a future in which we could get the Covid-19 vaccine to more people, faster.
In the meantime, Stockwell notes, “as we are all awaiting a SARS-CoV-2 vaccine, the influenza vaccine is something we have now that we know helps prevent influenza-related hospitalization and death.”
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