By Robert Roy Britt
With that in mind, this year’s flu vaccine could serve as a vital shot in the arm for public health and society’s efforts to avoid dual epidemics that could overwhelm the already overburdened healthcare system and its exhausted doctors and nurses.
“This is the year that everyone should be getting the flu shot,” says Richard Ellison, MD, a professor of medicine and an expert in infectious diseases and immunology at the University of Massachusetts Medical School.
With Covid-19 infections, hospitalisations and deaths rising across the US, experts fear that the pandemic will worsen this autumn, when cooler weather drives people indoors.
Flu season starts in October and peaks from December into February. The severity can’t be predicted, but in recent years flu deaths have ranged from roughly 12,000 to 61,000, with as many as 800,000 hospitalisations in a bad year.
Experts say no Covid-19 vaccine is expected until at best early next year. But the flu vaccine will be available in September.
Ellison and other infectious-disease experts say that researchers don’t know the likelihood of catching the flu and coronavirus at once, but it definitely can happen.
Dual infections are generally not uncommon. It’s known, for example, that people can contract a flu virus atop a cold virus, or vice versa, says virologist Andrea Amalfitano, dean of the College of Osteopathic Medicine at Michigan State University.
When people die of the flu, it’s usually because they get a secondary infection of bacterial pneumonia, he points out.
Ellison explains that the flu actually predisposes a person to getting that bacterial infection, because it debilitates hair-like “barrier” cells in the upper airways that would normally sweep the bacteria away.
He says it’s not known if the flu would predispose someone to catching Covid-19, adding that the possibility can’t however be ruled out.
What is clear is that having Covid-19 and the flu simultaneously “is really going to increase the risk that someone ends up in the intensive care unit or on a ventilator”, Ellison says. He adds that it would also make a person even more susceptible to bacterial pneumonia, and having all three “would be particularly devastating”.
Amalfitano says enduring the flu prior to contracting Covid-19 could be likened to the risks of other comorbidities, like diabetes or obesity, which are known to increase the severity of Covid-19 infections.
“You’re already debilitated, you’re already weak, just like if you have underlying health conditions,” he says, adding: “Having an infection prior to catching another infection increases your risk that your body just can’t take all these different insults at once.”
And insults they are, says Julia Hurwitz, PhD, an infectious disease expert who studies immune responses and vaccine development at St. Jude Children’s Research Hospital in Memphis. Our first line of defence against respiratory viruses comprises those sweeper cells that line our airways, she explains in an email.
“If the barrier cells are weakened by one virus infection (or any insult, such as that caused by smoking), cells will have more trouble protecting us from another insult,” she says, adding: “Our front line will be weakened like soldiers in a war. We may then lose the battle when another enemy (virus) comes along.”
How effective is the flu shot?
The flu vaccine’s effectiveness varies each year, as it’s re-engineered for the various flu strains expected. On average it’s thought to be about 50 per cent effective at reducing infections and severity of infections in healthy adults up to age 64. Precise figures don’t exist, because people who get mild cases typically don’t visit a doctor and so are never counted.
However, a vaccinated person who still gets the flu and ends up in the ICU spends, on average, four fewer days in the hospital than someone who had not been vaccinated.
The flu shot cuts the risk of flu-related death in half for children with underlying high-risk medical conditions, and reduces it by 65 per cent in healthy children.
While the vaccine “may not completely prevent you from getting the flu, you tend to be less sick and miss fewer days of work due to illness,” Ellison says.
Also, each prevented infection reduces the risk of spread for everyone else. “If you’re a young healthy person, it will help you to protect your grandparents,” he says.
If enough people get the flu vaccine, herd immunity can kick in, Ellison explains. The virus has almost nowhere to go, because most of the herd is protected, and the spread is greatly reduced or even eliminated. Various estimates put the threshold for herd immunity for influenza in the 35 per cent to 75 per cent range, depending on how virulent a given strain is, and the effectiveness of each year’s vaccine.
Who should get the vaccine?
The US Centres for Disease Control and Prevention (CDC) recommends flu vaccines for everyone six months and older – with rare exceptions, including people with severe allergic reactions to the ingredients, among them eggs.
“Getting a flu vaccine this autumn will be more important than ever not only to reduce your risk from flu but also to help conserve potentially scarce health care resources,” the agency states.
However, only about 45 per cent of US adults and 63 per cent of children were vaccinated during the 2018-2019 season. Even at those less-than-hoped-for levels, the CDC estimates that 4.4 million flu cases were prevented, along with 58,000 hospitalisations and 3,500 deaths.
Addressing the prospect of dual epidemics this autumn, a recent opinion article in the Journal of the American Medical Association calls on the US federal government to “fund an evidence-based mass communication campaign, focusing on public benefit and personal obligation” of getting the flu shot this year.
It also recommends that states consider requiring flu vaccines for schoolchildren, just as they require vaccines for chickenpox, measles and a handful of other diseases.
“I personally take every vaccine that I am offered because I want to protect myself from outside invaders that can make me sick. I hate being sick,” Hurwitz says:
- A report in initially published in Elemental, a new Medium publication about health and wellness. Robert Roy Britt is a science & health journalist, author and former editor-in-chief of LiveScience & Space dot com.