Scientists’ Advice for Ways to Ward Off the Coronavirus
Nine months since the disease now known as COVID-19 first crept into the headlines, standard advice for avoiding it—such as wearing a mask, avoiding crowds, and washing hands well and often—has become familiar. But as winter approaches in the northern hemisphere, and with it an anticipated surge in cases, we sought out additional science-backed tactics to lower the chances of becoming infected, or of developing severe disease. The Scientist spoke with experts in virology, immunology, and medicine about the measures they’re taking themselves and recommending to others that may boost defenses against the novel coronavirus and other pathogens. None yet meet the gold standard for clinical evidence—a randomized controlled trial showing they reduce COVID-19 transmission or severity—but for each, there’s a scientific rationale for thinking they may provide some protection.
As we anxiously await a proven vaccine for SARS-CoV-2, studies indicate that certain existing vaccines—namely, those made with live, attenuated pathogens—confer some degree of temporary protection against germs they weren’t designed to target. For example, a trial published last month in Cell found that 25 percent of elderly people randomized to receive the tuberculosis vaccine bacille Calmette-Guérin (BCG) developed any kind of infection over the following year, compared with 42 percent of those who got a placebo shot. The vaccine appeared to be most protective against viral respiratory infections.
Trials are now underway to test whether BCG and two other live vaccines, oral polio and measles, mumps, and rubella (MMR), provide some protection against COVID-19. Robert Gallo, who directs the Institute of Human Virology at the University of Maryland School of Medicine and chairs the international scientific leadership board of the Global Virus Network, has advocated for testing oral polio in particular against the coronavirus. It’s cheap, easy to administer, and readily available, he says, adding that he expects other live vaccines would likewise provide bonus protections, including the intranasal flu vaccine, “which I’d love to take myself for the flu season.” He is unfortunately over the age limit—it’s only approved for people between 2 and 49 years old.
The conventional flu shot is not a live vaccine, but the protection any flu vaccine provides against influenza itself is particularly important this year, notes Rachel Roper, who studies SARS-CoV-1, SARS-CoV-2, and other viruses at Eastern Carolina University. You don’t want to get the flu and need medical attention at a time when the healthcare system may be overwhelmed with COVID-19 cases, she writes in an email to The Scientist. “If you get flu and have to go to the doctor, you may be exposed to people who have COVID and catch it yourself!”
Get some sunshine (or a supplement)
Far from being only important for bone health, the hormone vitamin D “affects many, many, many systems and cells throughout the body,” including innate and adaptive immunity, says Carol Wagner, a neonatologist at the Medical University of South Carolina who studies the vitamin in clinical trials. “I, of course, have all my family members and friends taking vitamin D.” Wagner and others now have clinical trials underway to test whether supplements of vitamin D—which can also be obtained through sun exposure and some foods—reduces the risk of SARS-CoV-2 infection or of developing severe COVID-19. In the meantime, some observational studies have pointed to an effect, such as an analysis published last month that compared 191,779 US patients’ SARS-CoV-2 test results with a vitamin D blood test they’d undergone within the past 12 months. That study found an inverse relationship between levels of vitamin D in the blood and the chances of SARS-CoV-2 infection, which persisted after researchers adjusted their model for demographic factors.
Taking extremely high doses of vitamin D supplements can cause toxicity, but Wagner says that based on studies she’s done, it’s “very safe” at the doses she recommends, namely, 4,000–6,000 international units (IU) per day for adults, depending on their BMI. Children, she says, should take about 50 IU per kilogram of body weight until they’re big enough to take the adult dose. The goal for both is to get to a concentration of between 40–60 nanograms per microliter in the blood, Wagner says.