10 Jun professionals world health organization have tried to clarify the statement made that asymptomatic transmission of coronavirus happens in “very rare” cases, says MarketWatch.
Technical lead of the who response to COVID-19 Maria van Kerkhove said there was “a misunderstanding to claim that asymptomatic transmission in the world is very rare,” and that her comments during a briefing of news who was based on “a very small subset of research.”
“I was just answering the question; I have not said about the politics of who,” she said.
Who estimates that currently 16% of people with COVID-19 are asymptomatic and can transmit the coronavirus, while other data show that 40% of the transfer of coronavirus cases due to asymptomatic carriage.
Health officials recommended that people stay at a distance of 6 feet (approximately 2 metres) from each other. Facial masks are designed to prevent the transfer of invisible droplets of another man and thus infect him. The owner is protected from the person who might be infected COVID-19, but which has very mild symptoms or they are not.
But “there is nothing magical about six feet,” said Gregory Poland, who studies immunogenecity of vaccine reactions in adults and children at the Mayo clinic in Rochester, Minnesota, and is an expert of the American society of infectious diseases.
“The virus doesn’t measure distance, he said. For example, the viral cloud during the conversation extends to 27 feet (8.2 meters) and lingers in the air for about 30 minutes. It’s more like a flu in the sense that people transmit the virus to onset of any symptoms and some, of course, not sick.”
Asymptomatic transmission “is the Achilles heel of pandemic COVID-19 using the public health strategies that we’ve implemented at the present time”, according to a study conducted by experts from the University of California San Francisco, published may 28 in the New England Journal of Medicine.
“Screening based on symptoms is useful, but the epidemiological evaluation of outbreaks COVID-19 facility skilled nursing facility conclusively demonstrates that our current approaches are inadequate,” write the researchers, Monica Gandhi, Diane and Deborah Yokoe Hauler.
Detection of symptoms and subsequent testing to determine the procedures of isolation and quarantine was justified by the similarity between SARS-CoV-1 (the virus causing SARS SARS) and SARS-CoV-2 (the virus that causes coronavirus infection COVID-19), wrote the researchers.
Gandhi Yokoe and Havlir stated that these symptoms include a high genetic relationship of the viruses, transmission is mainly through respiratory droplets and regularity of symptoms in the lower respiratory tract (fever, cough and shortness of breath), and both infections develop in approximately 5 days after infection.
“Despite the deployment of similar measures of control, the trajectories of two epidemics turned into a completely different direction, they added. — SARS was brought under control within 8 months after SARS-CoV-1 has infected approximately 8,100 people in the limited geographical area”.
The number of confirmed cases COVID-19 continues to grow. Less than 6 months after the first reports of a new coronavirus pandemic COVID-19 was first identified in Wuhan, China, in December, infected 7 856 960 people worldwide and 2100 749 in the U.S. as of Monday, June 15. According to the Center for system science and engineering at Johns Hopkins University, in the world killed at least 434 388 people, of whom 115 827 in the United States.
Here are five reasons to worry about asymptomatic transmission of the virus:
1. COVID-19 creates a high viral load in the upper respiratory tract
A study at the University of California in San Francisco showed that there is a high viral load of SARS-CoV-2 in the upper respiratory tract, even among przecietnych patients, “which distinguishes it from SARS-CoV-1, where replication occurs mainly in the lower respiratory tract”.
“Viral load in SARS-CoV-1, associated with the onset of symptoms, peak at an average of 5 days later the viral load in SARS-CoV-2, which makes the detection of infection based on symptoms more effective in the case of SARS CoV -1”, — wrote the researchers.
Against flu, they added, “people with asymptomatic disease usually have lower quantitative viral load in secretions from the upper respiratory tract than from the lower respiratory tract, and a shorter duration of isolation of the virus than people with symptoms.”
2. The fans to run in the fresh air can create a “viral loop” up to 30 feet (9 meters)
In April, after several weeks of confusion regarding the effectiveness of face masks, the administration trump and the Centers for control and disease prevention stated that Americans should wear them. Some studies suggest that transmission is more likely without a mask.
“The running man, who does not know that he was sick, and runs in front of you is likely to infect you with a stream of air that spreads out behind it up to 30 feet — said Poland. — 6 feet of the large respiratory droplets settle to the ground.”
“Who told us that wearing a mask is not necessary, and then necessary, he added. — If in a hospital ward was ill only a few people, you can still cultivate the virus from door handles and light bulbs. It can also happen that the risk of transmission is higher when people cough and sneeze”.
3. Some experts say that the effectiveness of masks ambiguous
“If you don’t wear a PAPR, self-contained breathing apparatus, are not so straightforward security, says Poland. Is the so — called space suits. The only thing to say: this is safer than without them. You can’t be 100% safe with social distancing and mask”.
“All of these things together make the network your protection. You don’t get in the car without seat belts, brakes, tires, airbags. Even one of these things is important. The same applies to the so-called non-pharmacological interventions”.
Kent added: “I worry that people who have antibodies or who receive the vaccine will receive some kind of “right of freedom”. This virus has a very specific immunological secrets enclosed in it. We are still learning about the flu and working on it since 1940-ies”.
4. Tracking system of contacts is crucial
“Asymptomatic transmission increases the need to expand opportunities for extensive testing, and thorough contact tracing to identify asymptomatic infections, interrupt undetected chains of transmission, and further bending the curve down”, — stated in the recommendations of the CDC.
If it is established that the reason of a new pandemic coronavirus are asymptomatic or laborincome carriers of SARS-CoV-2, “may require innovations in detection and prevention of diseases in addition to an exhaustive contact tracing, mass testing and isolation of asymptomatic contacts.”
The CDC said that the need to know more, in particular, develops these people have full or partial immunity, how long does protective immunity and can be protected from re-infection and thus to pass COVID-19 another person, while remaining asymptomatic.
5. Asymptomatic and presentone for a bad combination
According to a study conducted by William Petri, Professor of medicine and Microbiology at the University of Virginia, which specializiruetsya on infectious diseases, from 10 to 43% of people infected with COVID-19 (depending on the sample group), had no symptoms of the disease.
“Asymptomatic infection with SARS-CoV-2, apparently, is widespread and will continue to complicate efforts to control the pandemic, writes Petri. — Asymptomatic carriers varies from 5% to 25% for influenza.
Since many States in the U.S. open again, Carlos de Rio, Professor of global health and epidemiology in the School of public health name of Rollins at Emory University, said that while it is best to avoid prolonged contact with others.
“Working in the office with someone that has me worried,” he said.