Should you get the flu shot this fall?
| By Dr. Ronald Hoffman
With the coronavirus pandemic still raging, and temperatures plummeting, public health officials are urging everyone to get a flu shot. For example, a recent article from the University of California at San Francisco exhorts “Why COVID-19 Means You Need a Flu Shot This Year.” In recent weeks, I’m getting a record number of questions from patients and listeners: “Should I take it?”
There’s said to be a dual rationale: First, with COVID-19 gearing up for a dreaded “second wave”, it’s claimed we need to minimize the confusion and drain on medical resources that might result from a flu epidemic superimposed on a still-raging pandemic. It’s hard to distinguish between the symptoms of COVID-19 and influenza; there’s considerable overlap in symptoms like fever, cough, body aches, etc. That could get messy as thousands of people come down with ambiguous complaints.
Secondly, it’s not yet known what happens when you get the flu at the same time you contract coronavirus; could it be the “perfect storm” that results in thousands more hospitalizations and deaths?
But there’s no certainty to these assertions.
As to the first, although cooler weather driving people inside generally creates conditions conducive to spread of the flu, it’s likely that the very precautions we’ve taken to contain the coronavirus—masking, social distancing, handwashing, and staying home when sick—will blunt the impact of the flu.
In fact, that appears to be happening. It’s been reported that “Flu in the Southern Hemisphere has ‘practically disappeared’.” Our summer is their prime respiratory disease season, and COVID-19 lockdowns in countries like Australia, New Zealand, Argentina, South Africa and Chile have severely blunted the usual impact of the flu this year.
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As to whether you can catch the flu and COVID-19 simultaneously, we simply don’t have enough experience to say. But previous studies looking at the prospect of coinfection with ordinary coronaviruses responsible for colds, and influenza, provide strong evidence that the viruses that cause the illnesses may interfere with each other. In fact, there’s speculation that having the flu prevents or delays the onset of a cold, and vice versa. It’s as if the body’s immune response to one pathogen prepares it to fend off the other.
Of course, there’s the alternative hypothesis that if you’re rendered weak by the flu, you’ll be that much more likely to succumb to a double whammy when you contract COVID-19. We’ll only know more by spring 2021.
In the past, as during the 2009 H1N1 “swine flu” pandemic, I patriotically urged people to get vaccinated even though the shot was likely to be a mismatch for the looming new flu strain, if only as a mitigation step. But not since.
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I’ve become a flu shot “agnostic”, as in the dictionary definition: “not taking a stand on something, especially not holding either of two usually strongly opposed positions.”
It turns out swine flu vaccine was about 50% effective, but it didn’t offer much protection to people 50 or older—those most vulnerable to the serious adverse effects of the flu.
Each year, the flu shot represents vaccine developers’ best guess as to what form the rapidly-mutating flu virus will take. Some years it’s moderately effective, other years its protection may be as low as 20%. And the problem remains that people with the most compromised immune systems—the elderly, frail, and people with predisposing conditions like diabetes, heart disease, and chronic respiratory conditions are least likely to be its beneficiaries.
It’s been said that the flu shot could render you more susceptible to COVID-19. This claim is based on a much-circulated Department of Defense study which showed that previous vaccination for the flu was associated with “virus interference”, i.e. there was some evidence a flu shot recipient might be more vulnerable to a coronavirus. But this finding was generalized to coronaviruses overall and didn’t specifically address immunity to COVID-19.
A recent study assuages some of these concerns:
“The researchers studied more than 13,000 patients who were tested for COVID-19 at Cleveland Clinic between early March and mid-April. They then compared individuals who received a flu vaccine in the fall or winter of 2019 (4,138 patients) with those who didn’t (9,082 patients) . . . There was no evidence that suggested the patients’ flu vaccine increased their chances of catching COVID-19 or having a severe case. The vaccine also did not raise risks of hospitalization, admission to the intensive care unit or mortality from the disease.”
Is there a downside to taking the flu shot? Besides transient reactions like local arm soreness, redness and swelling, body aches, fever and flu-like malaise, dire side effects are rare. There’s concern that people with a history of the neurological disease Guillain-Barré Syndrome might experience reactivation due to the vaccine. Some people have allergies to constituents of the vaccine—although egg allergy is no longer considered an absolute contraindication.
Others argue more generally that interrupting the body’s natural acquisition of routine pathogens has a debilitating effect on the immune system. The “hygiene hypothesis” contends that getting exposed to germs is a sort of “boot camp” for cultivating immune system resilience. When I get sick, I console myself that my white blood cells are getting “schooled”, and I’ll be rendered less susceptible to subsequent illness. A hotly-debated subject remains whether immunity acquired via natural illness is superior to artificially-induced resistance conferred by synthetic vaccines.
If your concern is mercury, note that single-dose vials of current flu shots contain no thimerosal; it’s the multi-dose vials that use this substance as a preservative. 87% of this year’s flu vaccine offerings will be mercury-free.
An oft-ignored factor, as we face down the flu season, is that Americans, as never before, have been alerted to the importance of natural immune support. Millions more are taking adequate amounts of vitamin D, C, zinc and selenium, and nutraceuticals like mushroom extracts and elderberry, in an effort to fortify against COVID-19. While not rendering them invulnerable, they may do much to reduce the impact of other common seasonal respiratory viruses, as research has amply demonstrated. It’s also been shown that deficiencies in key vitamins and minerals reduce the likelihood that a vaccine will “take”, and that supplements help promote a stronger immune response to the flu shot.
So I’m recommending that my patients with high susceptibility to the consequences of the flu—e.g., those with insulin-dependent diabetes, compromised lung function, or heart conditions—take the flu shot. For others in high-touch professions, like health workers and home attendants caring for the vulnerable sick or elderly, the flu shot may be desirable (if not already employer-mandated). For remaining folks, taking the shot should be at one’s personal discretion.
Timing of the flu shot may be important. It takes a couple of weeks for the immune response to develop, but conversely, taking the jab too early may allow its protection to wane. Watch the CDC reports on whether the flu is surging in your locale and act accordingly, usually by the end of October.
Despite dire predictions, we may have a milder flu season this year, regardless.
