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


Officials have managed to control the transmission rate of COVID-19 by implementing policies that encourage residents to eat and drink, play sports and spend time with friends and relatives at a safe distance outside.

But health experts are worried that the cases could jump again, as lower temperatures in the fall and winter are forcing people to return indoors.

The country’s leading infectious disease expert, Dr. Anthony Fauci, is also concerned about the upcoming holiday celebrations and could increase the speed of transmission and advised Americans to miss big plans for Thanksgiving.

Speaking to CBS Evening News on Wednesday, Fowsey warned against “gathering indoors” with large groups of guests outside the city. “It’s unfortunate because it’s such a sacred part of the American tradition – family reunion around Thanksgiving,” he said.

Some experts suspect that the indoor broadcast is what has eased the summer influx of COVID-19 cases in the southern states, as residents retreat to public places with air conditioning to avoid the heat. The three most populous states – California, Texas and Florida – collected more than 500,000 infections in the midst of the wave in August, according to John Hopkins.

“Indoors in public is one of the places where the greatest risks and transmission can occur,” said William Hanaj, an associate professor of epidemiology and a professor at the Center for the Dynamics of Infectious Diseases at Harvard’s TH School School of Public Health.

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“A small proportion of infections lead to the majority of transmission”

Dr. Louis Nelson, professor and president of emergency medicine at Rutgers Medical School in New Jersey, said one of the main reasons for the higher risk of indoor transmission than outdoor is the lack of ventilation.

Natural air currents from the outside disperse viral particles faster and more efficiently than inside. Indoors there is minimal or no air circulation, which allows viral particles to remain in the air or fall on high-contact surfaces.

“If I have to smoke a cigarette (inside), you will see how the smoke particles are retained,” he said. “While the smoke is out in the open.”

In addition, indoor public places have more surfaces. As respiratory droplets or aerosol particles fall, they land on table tops, chairs, door handles, and other objects that people often touch.

“There are fewer surfaces outdoors,” Nelson said. “No one touches the ground, and then their eyes, nose or mouth.”

People also tend to be closer indoors because they are enclosed by walls. Hanage said bars are a major source of proliferation in communities, as people tend to gather there for long periods of time because judgment is impaired by alcohol consumption.

According to the US Centers for Disease Control and Prevention, adults with confirmed COVID-19 are twice as likely to dine at a restaurant on the 14 days before they fall ill than those with a negative result.

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

“A small proportion of infections lead to the majority of transmission,” he said. “Obviously, if you’re in a bar, this cluster tends to be much bigger as more people get together.”

How to increase airflow and indoor ventilation

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

Ventilation speed is the volume of outside air provided per unit time and air change rateis the degree of ventilation of a space divided by the volume of that space, according to Shelley Miller, a professor of mechanical engineering at the University of Colorado Boulder.

Most air conditioning and heating systems cycle about 20% of clean air in a building, while recycling the remaining about 80% for energy efficiency.

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

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“If you can quickly clear any airborne viruses, you’ll 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 household use, as some disinfectant gadgets can be harmful if used improperly.

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

“If you reduce the number of students from 35 to 17 now, ventilation provides twice as much outside air per person, and that’s great,” Miller said.

Construction consulting firm BranchPattern has developed an online calculator that determines the risk of transmission by entering space characteristics such as heating, ventilation, how many people are in the room and for how long. The user can also add parameters such as wearing a mask and portable filters.

Return to basics: Masks, social distancing and hand hygiene

Experts say that the best way to be safe indoors is through the three main mitigation efforts: masks, social distancing and hand hygiene.

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

Masks are especially important. CDC Director Robert R. Redfield told the Senate committee in mid-September that the vaccine may not be available to the U.S. public until the summer or fall of 2021, and that masks are “the most important, powerful tool for public health.” which we have “- probably even more effective than a vaccine.

Dr. Sunil Sud, a specialist in infectious diseases at Southwell Health University Hospital in Bay Shore, New York, said diners should wear masks even when eating out.

“It’s annoying … (but) you just have to do it,” he said. “The only time you have to take off your mask is when you’re actually biting and chewing.”


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

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

He recommends wearing a mask at all times, wiping machines and washing your hands. He also advises not to use some fitness equipment, such as yoga mats and blocks.

“If you take intervals, it becomes harder to wear a mask,” Asplund said. “You may want to get creative with the time you usually walk, because there are definitely times (when it’s crowded) before and after work.”

For social exclusion, Colorado’s state health department has developed an online tool that calculates the risk of transmission, using the total area of ​​space and objects in the room to determine how many people can be safely there at one time.

Track the percentage of community broadcasts

Although wearing masks, social distancing, hand hygiene, and increased airflow can reduce the risk of indoor transmission, these mitigation efforts are not 100% effective, especially if the transmission rate in the community is high.

Barry Bloom, a professor of public health and former dean of the Harvard School of Public Health at TH Chan, advises residents to monitor the transmission rate in their area to determine if it is safe to go indoors.

“When (rates are) high, as in many parts of the state, problems are just wanted,” he said.

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

British Prime Minister Boris Johnson unveiled a new system Monday that sets out gradually tougher measures to slow the spread of the virus, three weeks after a national program banned gatherings of more than six people and required pubs and restaurants to close earlier.

“It makes a big difference whether you’re in a low-transmission or high-transmission environment, how flexible you need to be safe,” Bloom said.

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

Patient health and safety coverage at USA TODAY is made possible in part through a grant from the Masimo Foundation for Health Ethics, Innovation and Competition. The Masimo Foundation does not provide editorial data.

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