R-0 may be the most important scientific term you have ever heard of when it comes to stopping the coronavirus pandemic.


Officials have been able to control COVID-19 transmission speeds by implementing policies that encourage residents to eat and drink, exercise and spend time with friends and loved ones at a safe distance outside.

But health experts are worried whose cases could increase again as cooler temperatures in the fall and winter force people back indoors.

The nation’s leading infectious disease expert Dr. Anthony Fauci is also concerned that upcoming holidays could increase transmission speeds and advised Americans to skip big Thanksgiving plans.

In a speech to the “CBS Evening News” on Wednesday, Fauci warned against “gathering in an indoor environment” with large groups of guests outside the city. “It’s unfortunate because it’s such a sacred part of American tradition – the family gathers around Thanksgiving,” he said. “But it’s a risk.”

Some experts suspect that indoor transmission is what facilitates the summer rise in COVID-19 cases in southern states as residents retreated to air-conditioned public places to escape the heat. The three most populous states – California, Texas and Florida – each recorded more than 500,000 infections at the height of the increase in August, according to Johns Hopkins data.

“Indoors in public spaces is one of the places where the greatest risks and transmission are likely to occur,” said William Hanage, associate professor of epidemiology and faculty member of the Center for Communicable Disease Dynamic at the Harvard TH Chan School of Public Health.

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New York City reached a milestone of recovery on Wednesday when the indoor restaurant was allowed for the first time since March. (April 30)

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‘A minority of infections lead to the majority of transmission’

Dr. Lewis Nelson, professor and chairman of emergency medicine at Rutgers New Jersey Medical School, said one of the main reasons there is a higher risk of transmission indoors than outdoors is lack of ventilation.

Natural air currents outside disperse virus particles faster and more efficiently than inside. There is minimal or no air circulation indoors, so virus particles can linger in the air or fall on surfaces with high contact.

“If I smoke a cigarette (inside), you will see the smoke particles linger,” he said. “Whereas outdoors smokes kind of leaves.”

In addition, public indoor locations have multiple surfaces. When respiratory droplets or aerosol particles fall, they land on tabletops, chairs, door handles and other objects that people often touch.

“Outdoors have smaller surfaces,” Nelson said. “No one touches the ground and then touches their eyes, nose or mouth.”

People also tend to be closer indoors because they are restricted by walls. Hanage said bars are an important source of transmission in communities because people tend to congregate there for long periods as the sentence is weakened by the consumption of alcohol.

According to the US Centers for Disease Control and Prevention, adults with confirmed COVID-19 are twice as likely to have eaten out at a restaurant in the 14 days before they became ill than those who tested negative.

Positive patients were also more likely to report going to a bar or café when the analysis was limited to those without close contact with people known to have coronavirus.

“A minority of infections lead to the majority of transmission,” he said. “If you’re at a bar, this cluster is clearly much larger as more people gather.”

How to increase airflow and ventilation indoors

Experts agree that increasing airflow in indoor environments is important to reduce the risk of transmission as it prevents virus particles from hanging in the air for too long.

Ventilation speed is the volume of outdoor air delivered per. Time unit and air change speedis the ventilation rate of a room divided by the volume of that room, according to Shelly Miller, professor of mechanical engineering at the University of Colorado Boulder.

Most air conditioners and heating systems cycle approximately 20% of fresh air into a building, while the remaining 80% is recycled for energy efficiency.

However, ventilation can be increased by opening a window and turning on a fan. Most portable air filters cannot filter out airborne virus particles, but they still facilitate air circulation that spreads the virus. Air purifiers with HEPA filtration remove more than 99 percent of airborne particles regardless of particle size and also facilitate air circulation.

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“If you can quickly remove any airborne virus, you reduce the risk of transmission,” Miller said.

While UVC devices are useful for commercial buildings such as offices and schools, experts recommend sticking to a simple fan or portable air filter for private use, as some disinfectant gadgets can be harmful if used incorrectly.

Another good way to reduce the risk of transmission is to limit the number of people in a room, which generally contributes to a better indoor climate.

“If I lose the number of students from 35 to 17 now, the ventilation gives twice as much outdoor air per. Person, and that’s great, ”Miller said.

Building consulting firm BranchPattern developed an online calculator that determines the transmission risk by entering room characteristics such as heat, ventilation, how many people are in the room and for how long. The user can also add parameters such as Masking and portable filters.

Getting back to the basics: Masks, social distance and hand hygiene

Experts say the best way to be safe indoors is through the three basic mitigation measures: masks, social distance and hand hygiene.

“If you take all of these things together and put them into decent practice, it should hopefully slow down (transmission),” Hanage said.

Masks are especially important. CDC Director Robert R. Redfield told a Senate panel in mid-September that a vaccine may not be available to the American public until the summer or fall of 2021, and that masks are “the most important, most powerful public health tool we have” – possibly even more efficiently. than a vaccine.

Dr. Sunil Sood, an infectious disease specialist at Northwell Health’s South Shore University Hospital in Bay Shore, New York, said eateries should wear masks even when eating outside.

“It’s boring … (but) you just have to do it,” he said. “The only time you have to take the mask off is when you actually bite and chew.”


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This means keeping the mask on while chatting with other eateries, waiting for food and talking to your waiter.

Dr. Chad Asplund, professor of family medicine and orthopedics at the Mayo Clinic, said these policies also apply to the gym.

He always recommends wearing a mask, wiping machines down and washing your hands. He also advises against using any exercise equipment, such as yoga mats and blocks.

“If you did intervals, it would be harder to wear a mask,” said Asplund. “It can be a good idea to get creative with times you normally go, because there are definitely times (when it gets crowded) before work and after work.”

For social distancing, Colorado’s state health department developed an online tool that calculates transmission risk using the total square footage of space and objects in space to determine how many people can safely be there at a time.

Keep an eye on transmission speeds in the community

Although masking, social distance, hand hygiene, and increased airflow can reduce the risk of transmission indoors, these mitigation efforts are not 100% effective, especially if transmission rates in society are high.

Barry Bloom, a professor of public health and former dean of the Harvard TH Chan School of Public Health, advises residents to keep an eye on transmission rates in their area to determine if it is safe to go to an indoor public setting.

“When (rates are) high, as in many parts of the states, it just asks for trouble,” he said.

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Bloom says this is happening in the UK, where the country’s confirmed number of COVID-19 cases has more than tripled in the last three weeks, with infection rates rising in all age groups and regions.

British Prime Minister Boris Johnson unveiled a new system on Monday that saw stricter measures to curb the spread of the virus three weeks after a nationwide program banning gatherings of more than six people and demanding that pubs and restaurants close early.

“It makes a big difference whether you are in a low transmission environment or a high transmission environment, how much flexibility you have to be safe,” Bloom said.

Contribution: Ramon Padilla, USA TODAY; Associated Press. Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT.

Health and patient safety coverage in the USA TODAY is made possible in part by a grant from the Masimo Foundation for ethics, innovation and competition in healthcare. Masimo Foundation does not provide editorial input.

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