Coronavirus FAQs: Can I Go Running? Is Food Shopping Too Risky? What's Herd Immunity?

This is part of a series looking at pressing coronavirus questions of the week. We'd like to hear what you're curious about. Email us at goatsandsoda@npr.org with the subject line: "Weekly Coronavirus Questions."

The global spread of COVID-19 cases continues, with cases around the world and increasingly strict measures to control its spread. Authorities in the U.S. and other countries have banned or discouraged large gatherings and are urging social distancing and frequent hand-washing.

To answer this week's questions, we spoke with Albert Ko at the Yale School of Public Health and others for guidance.

I heard that the U.K. was talking about using a "herd immunity" approach to the coronavirus. What exactly is herd immunity, and could it work against coronavirus?

Last week, the U.K. government signaled that it might be considering a different approach to coronavirus control than the rest of the world — in essence, allowing a large percentage of the population to become infected in order to develop a "herd immunity" that would eventually end the epidemic.

Herd immunity occurs when enough people in a population are immune to disease — either because they've been infected and recovered or they've been vaccinated against it. The idea is that the pool of people who can catch the disease has been reduced, reducing the risk to the so-far unaffected.

Sir Patrick Vallance, the U.K. government's chief scientific adviser, said that about 60% of the population would need to get the coronavirus in order to get a herd immunity effect.

But using such an approach would raise a big question: During that spread, how do you protect the most vulnerable groups – the elderly and those with underlying medical conditions?

Herd immunity works with contagious diseases like measles, for which a vaccine exists. But the idea that the U.K. would not immediately work to suppress the number of cases, especially as there are no approved treatments for COVID-19 yet and the disease has killed thousands in Italy, stirred an immediate public backlash.

The government quickly backtracked, and on Friday, Prime Minister Boris Johnson said all restaurants, pubs and gyms would close for the foreseeable future to reduce transmission.

And there is no certainty that herd immunity would even work for coronavirus. That approach "assumes that people being infected are immune and cannot get re-infected. And we don't know that as of yet," says Albert Ko, professor of epidemiology and medicine at the Yale School of Public Health.

People who go outside to exercise are sometimes shamed on TV and on social media for risky behavior. Is it okay to go outside for a walk, run or bike ride?

The White House coronavirus guidelines for the 15-day period that started Monday advise avoiding "discretionary travel, shopping trips and social visits," as well as "social gatherings in groups of more than 10 people." But outdoor exercise is not on the list.

So unless local guidelines instruct otherwise, fresh air and outdoor exercise are allowed – though it's important to keep some distance between yourself and others. The coronavirus is thought to spread primarily through close contact between people – within about six feet.

The primary mode of transmission is through respiratory droplets.

There is better airflow outside than in confined spaces. That air flow outside reduces the risk of one person transmitting the virus to another through droplets in the air, says Albert Ko, the Yale epidemiologist. "So if you're going out and you're hiking or biking or running and you're not within, say, six feet or 10 feet of another person, I would consider that a healthy, safe practice."

Ko also points to the significant mental health issues that can be caused or exacerbated when people are cooped up.

"My personal feeling is that if people are practicing sound respiratory hygiene, sound hand hygiene, they're distancing themselves physically from others outside, and you're exercising and walking in the park — I think that's actually a good public health practice."

I've heard that taking drugs like ibuprofen to ease COVID-19 symptoms could actually worsen the progress of the illness. Is that true?

The World Health Organization and many infectious disease experts say that there is no good scientific evidence establishing a link between ibuprofen and worsening of COVID‑19.

The notion that such a link exists was sparked last weekend when a tweet by the French health minister warned people not to take nonsteroidal anti-inflammatory drugs — a category of pain relievers and fever reducers that includes ibuprofen — because, he said, some French COVID-19 patients had experienced serious side effects. The warning was also included in a bulletin from the French health ministry, which counseled that patients should instead use acetaminophen, the generic name for Tylenol.

But experts say that warning isn't based on data.

"Based on currently available information, WHO does not recommend against the use of ibuprofen," the WHO stated on its official Twitter account, adding, "'We are also consulting with physicians treating COVID-19 patients and are not aware of reports of any negative effects of ibuprofen, beyond the usual known side effects that limit its use in certain populations."

Dr. Angela Rogers, a pulmonologist at the Stanford University Medical Center and chair of its intensive care unit's COVID-19 task force, notes that Tylenol is the go-to medication for patients who are sick enough to be hospitalized for any infection. That's because these patients are at higher risk of damage to internal organs, including kidneys. And kidney damage can be a side effect of ibuprofen for some patients who use it long-term in higher doses, says Rogers, whose research focuses on the kind of acute respiratory distress experienced by the most severe COVID-19 cases.

Tylenol, like any medicine, isn't risk-free either; Rogers notes that acetaminophen can cause serious liver damage in high doses. In low doses, though, she says, Tylenol is "very effective" for reducing fever and "very safe."

How do I manage any risks while grocery shopping?

With new research that suggests the new coronavirus can live on surfaces for hours or days, the prospect of going grocery shopping can seem daunting.

But you can manage the risk.

First of all, the viability of the virus goes down over time and it's sensitive to temperature – so it dies off more quickly in room temperature than it does in the cold.

Second, when you go to a grocery store, people aren't generally touching all the cans on the shelf — although there tends to be more handling of individual items in the produce section.

Among the things you can do to protect yourself and others are:

• Wash your hands before and after going to the store.
• Shop at off-peak hours so it's easier to keep a distance from others.
• If you're over 60, see if stores in your neighborhood are offering shopping exclusively for seniors an hour before opening to all.
• Don't touch something at the store and then touch your face.
• Use a sanitizing wipe to disinfect the shopping cart or basket handle. Many stores now provide wipes, but you might want to come with your own supply just in case they're out.

Ko says it helps to understand the differing levels of risk in different situations. Coming into close contact with a person who is infected with coronavirus carries greater risk than touching a shopping cart that might have been touched by an infected person hours or days earlier.

When it comes to disinfecting things, it makes sense to focus on high-touch surfaces. Ko says you should worry more about disinfecting bathroom doorknobs and faucets at home than about a can of tomato soup from the supermarket.

"There's never anything that has zero risk," Ko says, "but the risk is so much lower than [surfaces] that are more frequently touched."

NPR's Geoff Brumfiel and Scott Neuman contributed to this report.

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