Although the action of the coronavirus has not yet been fully deciphered, the scientists have already reached consensus on fundamental aspects
After several months of facing the coronavirus pandemic around the world, scientists finally have clearer guidelines on how people actually spread.
Experts say it is not common to get Covid-19 from a contaminated surface and that the disease is also unlikely to be acquired in fleeting encounters with other people outdoors, according to a publication in the US newspaper The Wall Street Journal.
Scientists indicate that the main cause disease spread is person-to-person interaction for a long time. This risk is maximized when it occurs in crowded events, with poorly ventilated areas and people speaking out loud or singing.
This new information has been very useful for companies and governments, which seek to implement strategies that allow economic recovery, while still protecting public health. For this reason, in many places, separation screens have been placed, requiring the use of masks, having good ventilation systems and keeping windows open whenever possible.
Orders to stay home, a ban on large meetings, and the closure of businesses prevented further spread of the virus and the death of many people, according to two large studies. However, scientists and public health experts point out that There is already more knowledge available to implement new measures to limit the spread of the disease.
They added that this calls for increased care “for nursing home residents and multi-generational families living in overcrowded conditions.” It was also emphasized that physical distance, the use of masks and limitations to meetings in closed spaces should be maintained.
After initial controversies, all countries adopted the use of face masks as a preventive measure.
“We shouldn’t be thinking about a shutdown, but about ways to increase physical distance,” said Tom Frieden, executive director of Resolve to Save Lives, a nonprofit public health initiative. “This may include allowing outside activities, walking or biking to an office with physically distant people, picking up on the sidewalk in stores, and other innovative methods that can facilitate resumption of economic activity without reigniting the outbreak.”
Reopening recommendations include widespread testing, contact tracing, and isolation of infected or exposed individuals.
An important factor in transmission is that seemingly harmless activities such as talking and breathing produce respiratory fragments of different sizes that can spread throughout air currents and potentially infect people nearby.
Until now, contact with respiratory drops has been identified by health agencies as the primary mode of transmission for Covid-19. These large drops of liquid can transfer viruses from one person to another if they fall into the eyes, nose, or mouth. But they tend to fall to the ground or onto other surfaces fairly quickly.
Some researchers note that the new coronavirus can also be transmitted through tiny droplets that float in the air longer than large droplets., these can also be inhaled directly.
He believes this may have happened at a restaurant in Guangzhou, China, where an infected diner who was not yet symptomatic infected five people who were sitting at adjacent tables. Ventilation in the space was poor, with the exhaust fans turned off, according to a study looking at conditions in the restaurant.
Tiny drops of your breath or that you released while talking could have accumulated and the strong airflow from an air conditioner in the wall may have helped recirculate the particles in the air, according to the study authors.
Great ventilation in the places people visit and work is very important, said Yuguo Li, one of the authors and professor of engineering at the University of Hong Kong. Proper ventilation, such as forcing air into the ceiling and pumping it out, or bringing fresh air into a room, dilutes the amount of virus in a space, reducing the risk of infection.
Last March 10, at a church choir practice in Washington state, 87% of attendees were infected, said Lea Hamner, an epidemiologist and lead author of a study.
Choir members changed places four times during the two-and-a-half-hour practice, were squeezed into a confined space, and were mostly older and therefore more vulnerable to disease, she said. In total, 53 of the 61 practice attendees were infected, including at least one person who had symptoms. Two died.
Several factors conspired, Hamner said. When singing, people can emit many large and small respiratory particles. Singers also breathe deeply, increasing the chance of inhaling infectious particles.
In Japan, of 61 cases of contagion between January 15 and April 4, many involved shortness of breath near, karaoke parties, club entertainment, speaking in bars and exercising in gyms, according to a recent study published in the Emerging Infectious Diseases magazine.
The so-called attack rate, the percentage of people infected in a specific place and time, can be very high in crowded events, homes and other spaces where many people are in close and prolonged contact.
It is estimated that 10% of people with Covid-19 are responsible for approximately 80% of transmissions., according to a study recently published in Wellcome Open Research.
Some people with the virus may have a higher viral load, or produce more drops when they breathe or speak, or they may be in a confined space with many people and poor ventilation when they are at the most infectious point of their disease, Jamie Lloyd said -Smith, professor at the University of California, Los Angeles studying the ecology of infectious diseases.
But overall, “the risk that a certain infected person will spread to people is pretty low,” said Scott Dowell, deputy director who oversees the Covid-19 response from the Bill and Melinda Gates Foundation. “For every supercontag event you have many times that no one gets infected.”
The Covid-19 attack rate in homes ranges from 4.6% to 19.3%, according to several studies. It was higher for spouses, at 27.8%, than for other household members, at 17.3%, in a study in China.
Rosanna Díaz lives in a three-bedroom apartment in New York City with five other family members. The 37-year-old mother was hospitalized with a stroke, which her doctors attributed to Covid-19, and was still coughing when she returned home two days later.
She pushed to get home quickly, she said, because her 4-year-old son has autism and needed it. He kept his distance from the other members of his family, covered his mouth by coughing, and washed his hands frequently. No one else in the department has been sick. “No one approached me when I was sick,” she said.
Being outdoors is generally safer, experts say, because viral particles dilute faster. But small and large droplets pose a risk even outdoors when people are in close and prolonged contact, says Linsey Marr, a Virginia Tech professor of environmental engineering who studies airborne virus transmission.
“Based on our experiment, it would assume that something above that number would be required for infectivity,” said Clemens Wendtner, one of the study’s lead authors and head of the department of infectious diseases and tropical medicine at München Klinik Schwabing, a university hospital from Munich.
He and his colleagues found samples from infectious patients with virus levels up to 1,000 times higher, which could help explain why the virus is so infectious under the right conditions: much lower levels of virus may be required than those found. in a sick patient to infect someone else.
Countries take new measures
With this new panorama, some policies are changing in various countries. The standard procedure for someone who tests positive is to quarantine them at home. Some cities offer free temporary accommodation and social services where infected people can stay on a voluntary basis, to avoid transmitting the virus to family members.
The Center for Disease Control and Prevention (CDC) recently urged Americans to continue to wear face masks and to maintain social distance as their economies re-activate.
“The more you interact with others, the longer the interaction lasts and the greater the number of people involved in the interaction, the greater the risk of Covid-19 spreading,” said Jay Butler, manager of Covid response incidents- 19 of the CDC.
If the number of Covid-19 cases begins to increase dramatically as states reopen, “more extensive mitigation efforts may be needed again, such as what was implemented in March,” a decision that would be made. locally, he said.
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