Face masks have become the political hot potato. We asked Dr. Priya Sampathkumar, a Mayo Clinic physician and an infectious disease expert, some of the burning questions about masks.

RELATED: Why people refuse to wear face masks

One argument I've seen bandied about on social media is that cloth face masks are worthless and don't protect against COVID-19. Is that true?

No, that is not true. Cloth masks are not as effective as the surgical masks that are used in health care for protecting the wearer, but that is not the purpose of the cloth masks. The cloth mask is to prevent the person wearing it from infecting others. And in that, they are very good. They are almost as good as surgical masks.

If I go out shopping and I'm social distancing, but not wearing a mask, am I protecting others?

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Social distancing is much harder to do in a public place than you think it is. You might try to stay 6 feet away from each other, but people are crossing you in the aisles and reaching over you to grab something off the shelf. So 6 feet is not always possible to maintain. So that's one thing.

The second thing is, if you're not wearing a face mask, if you're talking loudly or coughing, the droplets that come out of you fall to surfaces. So, although you may walk away from there, those droplets with the virus can stay on surfaces. The next person who comes by and touches that cereal box could pick up the virus on their hands.

If everyone wore a mask, would the virus disappear?

I would say it would go down to very, very low levels. The point is that not everybody can wear a mask all the time. And the more people we can get to do it, the greater the chances are we'll be able to control this.

Some people who don't wear masks are being accused of not caring about others. If I'm not wearing a mask, am I causing the death of others?

I wouldn't go as far as that. You're definitely contributing to the risk of increased spread in the community. The point that people are making is, "Well, I know I'm not positive. So why should I wear a mask?" The real difference with this virus compared to other infections is that there is infectivity before the person has symptoms.

Anywhere from 10 to 30% of (infected) people may have no symptoms at any point in time. They can still transmit it to others. The people who do go on to have symptoms can still transmit the virus two days prior to having symptoms.

Democratic presidential candidate Joe Biden said he would mandate the wearing of face masks if he becomes president. If you were president, would you require their use?


To what extent does mask-wearing prevent the spread of COVID-19?

What I can tell you: We don't know if 80% of the people wore a mask, what would happen to transmission dynamics. Or if 70% of the population wore a mask, what would happen. What we do know is that if an individual is infected and wears a mask — the cloth mask — the risk of transmission from that individual to other people is reduced by 50% to 70%. That's a powerful number.