With so much attention paid to avoiding SARS-CoV-2, the virus that causes ­COVID-19, it’s easy to put flu prevention on the back burner. But with flu season just around the corner, integrative medicine specialist Leo Galland, MD, answers important questions to help you stay healthy against both viruses… 

When should I get a flu shot this year? October is always ideal. Though you might be tempted to get it as soon as possible, summertime is too early. The vaccine’s effectiveness diminishes with each passing month, and flu season is often roaring in January and February. 

Important: Don’t get a flu shot if you are sick with an acute illness, even if it’s just a cold, and even if you are positive for COVID-19 infection but ­asymptomatic. While the tests are not foolproof and are prone to false-­negatives, it still is worth getting tested if you think you may have been exposed to the coronavirus before having any vaccine.

With all the different flu vaccines available, should I ask for one in particular? Each flu season brings new combinations of vaccines that are aimed at protecting people from what public health ­experts predict will be the most prevalent strains of both influenza A and influenza B. There are numerous flu vaccines from different manufacturers. The best are quadrivalent, which means they target four flu strains (two A and two B) and provide the broadest protection possible. Trivalent vaccines still are available (targeting three strains of flu) but now are mainly used when quadrivalent vaccines are not available.

The Flucelvax Quadrivalent vaccine, which was newly available during last year’s flu season, is completely egg-free. It is made with a new technique using a cell-based production process involving mammalian cells ­instead of eggs. This process may yield vaccines that have a stronger immune response than standard vaccines—and therefore are more beneficial for ­everyone, not just those who are ­allergic to eggs.

Should I get any other vaccines? If you haven’t been vaccinated for pneumonia, it is worthwhile to defend against the most common bacteria that cause pneumonia. Although protecting yourself against flu also helps protect against the pneumonia that often follows flu (see below), the flu vaccine is, at best, 40% to 60% effective according to the CDC, so it is not reliable protection against flu-related pneumonia.

Also, COVID-19 can lead to pneumonia in two ways. Viral pneumonia can result from the virus infecting lung cells. Then, like with the flu, a secondary pneumonia, usually bacterial, can accompany COVID-19. Many people hospitalized with COVID-19 have more than one type of pneumonia. 

The pneumonia vaccine is given as one or two doses (each is a different formula), depending on your age and your health status. Talk to your doctor about whether you need one or both of the vaccines and the right timing of the doses for you. Both vaccines are for those age 65 and over as well as for people with certain chronic conditions, such as diabetes, heart or lung disease, or some types of cancer—conditions that also make you more vulnerable to severe ­COVID-19. 

What extra steps can I take to protect myself? As I said above, the flu vaccine is, at best, 40% to 60% effective—so you can’t rely on that alone to avoid the flu. There are many ways to help yourself ward off the flu or mitigate how sick you get if you catch it. 

Boring basics: Follow a well-­balanced diet—avoid sugar, refined carbs and alcohol…stay well-hydrated…get enough sleep…exercise for about 30 minutes a day—but be aware that ­intense exercise actually can impair the immune response. These steps all help keep your immune system operating at its best. Of course, physical distancing, regular hand-washing and wearing a face mask will reduce the risk of getting or transmitting any virus. 

Given how depleted the immune systems of many people are from stress, poor nutrition, poor sleep and a sedentary lifestyle, certain nutritional supplements can strengthen your ability to defend against cold and flu viruses. While it’s possible that these supplements may also defend against the new coronavirus, so far only ­vitamin D has been shown to have a COVID correlation. I advise taking the following supplements from ­September through May or year-round if you don’t get daily sun exposure in the summer…

Vitamin D. A simple blood test will indicate your vitamin D level and help your doctor to determine the daily amount that you need, usually between 1,200 international units (IU) and 5,000 IU. For immune function, the optimal level of vitamin D in blood is between 40 ng/mL and 50 ng/mL. Take vitamin D supplements with your largest meal of the day, because the vitamin needs fat to be properly absorbed. Vitamin D at a dose of 1,000 IU/day has been shown to prevent many types of respiratory infections, including the flu, though I often recommend higher doses for ­patients who need the additional boost. Early studies show that, among patients hospitalized with COVID-19, the lower their vitamin D levels, the worse their outcomes. 

NAC (N-acetylcysteine), an amino acid and antioxidant, also helps ward off flu or minimize symptoms if you do get it. Dosage: 600 mg twice a day with or without food. 

Extract of American ginseng (Panax quinquefolium). Take 200 mg twice a day on an empty stomach through the winter to lower your risk for flu as well as the common cold—or reduce its ­severity, should you catch either. 

What about vitamin C? Vitamin C—at a dose of 1,000 mg/day—can ­decrease the frequency of colds, but there’s no data indicating that it wards off the flu.

Some symptoms of COVID-19 and the flu are the same—how can I tell the difference? Typically flu symptoms come on pretty quickly, whereas ­COVID-19 develops gradually over a period of a few days and then ­either fades out or gets worse. Common shared symptoms include fever, sore throat, muscle aches, cough, headache, fatigue and even chest pain. Pinkeye (conjunctivitis) and a dry cough are ­associated with COVID-19, while we now think that a fever is more likely with the flu, as are diarrhea and nausea. Many people are having their temperatures taken these days before entering public spaces. But fever occurs in only half of COVID-19 cases. Fever does not rule out COVID-19, but the absence of fever makes flu unlikely. 

You’re also unlikely to have a runny or stuffy nose with the flu, but you may with COVID-19. What sometimes happens within the nose with COVID-19 is loss of smell and, often as a consequence, loss of taste, too. This is thought to be from ­COVID-19–related swelling in the nose that puts pressure on the olfactory nerve, which communicates smell to the brain. 

Can someone have the flu and ­COVID-19 at the same time? Yes. We know this from people hospitalized with COVID-19 who were found to carry other respiratory pathogens. If you think you’re sick, ask your doctor about getting the COVID-19 Combination ­Diagnostic Test that can detect SARS-CoV-2 and influenza, among other ­respiratory organisms, to determine which infection or infections you have. 

Does having had the flu help ward off COVID-19 or vice versa? It’s doubtful that there’s any cross immunity. We still don’t even know whether having COVID-19 truly offers immunity from getting it again—there now are some cases of people getting it twice. In terms of the flu, it’s possible to get sick more than once from different strains. 

Nothing replaces the prevention steps mentioned above. You’re not only protecting yourself but also protecting those around you, loved ones and strangers alike. 

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