Q and A

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A highly contagious form of the coronavirus known as the Delta variant is spreading rapidly and becoming increasingly prevalent around the world. First identified in India in December, Delta has now been identified in 111 countries.

In the United States, the variant now accounts for 83% of sequenced COVID-19 cases, said Rochelle Walensky, director of the Centers for Disease Control and Prevention, at a July 20 Senate hearing. In May, Delta was responsible for just 3% of U.S. cases. The World Health Organization projects that Delta will become the dominant variant globally over the coming months.

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Emily Mullin
Emily Mullin is a science and biotech journalist whose work has appeared in The Washington Post, New York Times, Wall Street Journal, Scientific American, National Geographic and Smithsonian Magazine.
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Frequent, thorough handwashing is essential to protecting yourself from infection.

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What's the case-fatality rate?

Currently, the official rate is 3.4%. But this is likely way too high. China was hit particularly hard, and their healthcare system was overwhelmed. The best data we have is from South Korea. The Koreans tested 210,000 people and detected the virus in 7,478 patients. So far, the death toll is 53, which is a case-fatality rate of 0.7%. This is seven times worse than the seasonal flu (which has a case-fatality rate of 0.1%).

What's the best way to clean your hands? Soap and water? Hand sanitizer?

Soap and water is always best. Be sure to wash your hands thoroughly. (The CDC recommends 20 seconds.) If soap and water are not available, the CDC says to use hand sanitizer that is at least 60% alcohol. The problem with hand sanitizer, however, is that people neither use enough nor spread it over their hands properly. Also, the sanitizer should be covering your hands for 10-15 seconds, not evaporating before that.

How often should I wash my hands?

You should wash your hands after being in a public place, before you eat, and before you touch your face. It's a good idea to wash your hands after handling money and your cell phone, too.

How long can coronavirus live on surfaces?

It depends on the surface. According to the New York Times, "[C]old and flu viruses survive longer on inanimate surfaces that are nonporous, like metal, plastic and wood, and less on porous surfaces, like clothing, paper and tissue." According to the Journal of Hospital Infection, human coronaviruses "can persist on inanimate surfaces like metal, glass or plastic for up to 9 days, but can be efficiently inactivated by surface disinfection procedures with 62–71% ethanol, 0.5% hydrogen peroxide or 0.1% sodium hypochlorite within 1 minute." (Note: Sodium hypochlorite is bleach.)

Can Lysol wipes kill it?

Maybe not. It depends on the active ingredient. Many Lysol products use benzalkonium chloride, which the aforementioned Journal of Hospital Infection paper said was "less effective." The EPA has released a list of disinfectants recommended for use against coronavirus.

Should you wear a mask in public?

The CDC does not recommend that healthy people wear a mask in public. The benefit is likely small. However, if you are sick, then you should wear a mask to help catch respiratory droplets as you exhale.

Will pets give it to you?

That can't be ruled out. There is a documented case of human-to-canine transmission. However, an article in LiveScience explains that canine-to-human is unlikely.

Are there any "normal" things we are doing that make things worse?

Yes! Not washing your hands!!

What does it mean that previously cleared people are getting sick again? Is it the virus within or have they caught it via contamination?

It's not entirely clear. It could be that the virus was never cleared to begin with. Or it could be that the person was simply infected again. That could happen if the antibodies generated don't last long.

Will the virus go away with the weather/summer?

Quite likely, yes. Cold and flu viruses don't do well outside in summer weather. (For influenza, the warm weather causes the viral envelope to become a liquid, and it can no longer protect the virus.) That's why cold and flu season is always during the late fall and winter. However, some experts think that it is a "false hope" that the coronavirus will disappear during the summer. We'll have to wait and see.

And will it come back in the fall/winter?

That's a likely outcome. Again, we'll have to wait and see. Some epidemiologists think that COVID-19 will become seasonal like influenza.

Does dry or humid air make a difference?

Flu viruses prefer cold, dry weather. That could be true of coronaviruses, too.

What is the incubation period?

According to the World Health Organization, it's about 5 days. But it could be anywhere from 1 to 14 days.

Should you worry about sitting next to asymptomatic people on a plane or train?

It's not possible to tell if an asymptomatic person is infected or not. That's what makes asymptomatic people tricky. Just be cautious. If you're worried, treat everyone like they might be infected. Don't let them get too close or cough in your face. Be sure to wash your hands.

Should you cancel air travel planned in the next 1-2 months in the U.S.?

There are no hard and fast rules. Use common sense. Avoid hotspots of infection. If you have a trip planned to Wuhan, you might want to wait on that one. If you have a trip planned to Seattle and you're over the age of 60 and/or have an underlying health condition, you may want to hold off on that, too. If you do fly on a plane, former FDA commissioner Dr. Scott Gottlieb recommends cleaning the back of your seat and other close contact areas with antiseptic wipes. He also refuses to take anything handed out by flight attendants, since he says the biggest route of transmission comes from touching contaminated surfaces (and then touching your face).

There have been reports of an escalation of hate crimes towards Asian Americans. Can the microbiologist help illuminate that this disease has impacted all racial groups?

People might be racist, but COVID-19 is not. It can infect anyone. Older people (i.e., 60 years and older) and those with underlying health conditions are most at risk. Interestingly, young people (aged 9 and under) are minimally impacted.

To what extent/if any should toddlers -- who put everything in mouth -- avoid group classes like Gymboree?

If they get infected, toddlers will probably experience only a mild illness. The problem is if the toddler then infects somebody at higher risk, like grandpa or grandma.

Should I avoid events like concerts or theater performances if I live in a place where there is known coronavirus?

It's not an unreasonable thing to do.

Any special advice or concerns for pregnant women?

There isn't good data on this. Previous evidence, reported by the CDC, suggests that pregnant women may be more susceptible to respiratory viruses.

Advice for residents of long-term care facilities/nursing homes?

Remind the nurse or aide to constantly wash their hands.

Can we eat at Chinese restaurants? Does eating onions kill viruses? Can I take an Uber and be safe from infection?

Yes. No. Does the Uber driver or previous passengers have coronavirus? It's not possible to tell. So, treat an Uber like a public space and behave accordingly.

What public spaces should we avoid?

That's hard to say. Some people avoid large gatherings, others avoid leaving the house. Ultimately, it's going to depend on who you are and what sort of risk you're willing to take. (For example, are you young and healthy or old and sick?) I would be willing to do things that I would advise older people avoid, like going to a sporting event.

What are the differences between the L strain and the S strain?

That's not entirely clear, and it's not even clear that they are separate strains. There are some genetic differences between them. However, just because RNA viruses mutate doesn't necessarily mean that the virus will mutate to something more dangerous or unrecognizable by our immune system. The measles virus mutates, but it more or less remains the same, which is why a single vaccine could eradicate it – if enough people actually were willing to get a measles shot.

Should I wear disposable gloves while traveling?

No. If you touch something that's contaminated, the virus will be on your glove instead of your hand. If you then touch your face, you still might get sick.

Alex Berezow
Dr. Alex Berezow is a science writer, a U.S./European political affairs writer, and Senior Fellow of Biomedical Science at the American Council on Science and Health. Formerly, he was founding editor of RealClearScience. He has published in numerous outlets, such as BBC, CNN, Wall Street Journal, The Economist, and USA Today, where he serves on the Board of Contributors. He is the author of two books, Little Black Book of Junk Science and Science Left Behind, and holds a PhD in microbiology.