Anthony Fauci of the National Institute of Allergy and Infectious Diseases in the US is of the opinion that 50% of people have passed or already have COVID 19. Chinese scientists claim 60% of the population. What was the flu that the world went through in January and February this year and should the people who passed it be tested for antibodies?
As COVID 19 continues its march around the world, it is being observed day by day that a large number of cases have mild symptoms of its involvement, or no symptoms at all.
However, people with these symptoms can still spread the virus and spread the disease, but at the same time they are causing a lot of confusion in the debate about the real percentage of those affected worldwide.
Assessments for asymptomatic cases have sparked controversy among virologists. Last Sunday, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases in the United States, hypothesized that the number of asymptomatic patients could be twice as high as reported. Fauci said 50% of people already have or have had coronavirus.
This is twice as much as reported by the National Center for Disease Control and Prevention. Other studies have reported lower figures. 18% asymptomatic was the percentage of people infected on the Diamond Princess ship, while 42% resulted in the number of those evacuated from Wuhani to China.
Chinese officials go further when they report a rate of 60% this month, from the tracking they have done to asymptomatic people “the different percentage depends on the behavior of the coronavirus in different populations, but the study model or time is also important. when the assessments were made, ”said Keiji Fukuda of Hong Kong University, who also heads some of the teams responding to the outbreak of pandemics at the World Health Organization.
But fortunately it is possible to find out who carries a hidden infection. Serological tests, or tests that look for and find proteins called antibodies in people's blood, can tell if a person is infected without realizing it and long after the infection has left their body.
Serological tests have been a fundamental feature of the medical scene in the last 50 years in the fight against epidemics. Antibody testing is different from the tests used for people who show symptoms.
These diagnostic tests work by recognizing parts of the coronavirus genome, and they require the virus to be present in the individual's body. The virus usually disappears from the human body once it has healed.
But the immune system produces antibodies that develop pathogens to destroy various bacteria or viruses, and they stay inside us for years, giving us the immunity we need.
A well-known and simple method to look for antibodies is enzyme-linked immunosorbent assay (ELISA), which is ideal for rapid testing that can produce results for dozens of people in the same time.
This quick method helped solve a mystery in Singapore, where two people with mild symptoms were considered responsible for the outbreak of two outbreaks of infection in two religious communities, and infecting more than two dozen people.
"ELISA analysis can be done in half a day," says Danielle Anderson, Virologe of the Duke-NUS Medical School in Singapore, who led the development of serological test-related tests related to outbreaks in religious communities. more accurate and safer as staff will not have direct contact with the virus, ”she added.
To perform an ELISA-type analysis, small test tubes are placed on a plastic plate lined with coronavirus protein and sampled from the blood of individuals. If that specimen has the right antibodies, then they stay in the coronavirus proteins and start a chemical reaction that changes color.
"You can see it with the naked eye," said Fatima Amanat, a graduate student at Mount Sinai Icahn School of Medicine who conducted an immuno-experiment for SARS-CoV-2 in early March. As monsters she used the blood of patients who had fought and passed the disease for at least ten days to make sure the test identified the right proteins.
"So serological evaluations are more helpful as an infection has passed the maturation stage," says Elitza Thell, director of the Infectious Diseases Serology Laboratory at the Mayo Clinic.
Searching for these antibodies and asymptomatic ones, too early before the immune system can develop them, can lead to false results.
Recently, scientists studying patients who tested positive for COVID 19 in China reported that it took 11 to 14 days for antibodies to be detected."Time is everything when it comes to accuracy of results," warns Thell.
Many laboratories are already conducting serological tests, as the US Department of Health and Human Services has issued a series of regulations regulating the normal development of such tests.
In the United States, the first commercial license was granted on April 2, and the agency has hired a long list of laboratory or academic executives who have extensive knowledge of the subject.
To do enough tests, it is essential to track the hidden spread of coronavirus in a nation. Epidemiologists are of the opinion that testing by a small sample, taken at random in perhaps 1 percent of the entire population, may be sufficient to detect the extent of the pandemic in the United States. we know the number of infected people, the more specific we will be about the recommendations we can give, ”says Samuel Scarpino, who heads the Epidemic Emergency Laboratory at Northeastern University.
And efforts to identify the extent of the spread of the infection have begun. Italian authorities tested each resident in the quarantined city with 3,000 Vo residents and found that approximately half of the people there were asymptomatic.
In Telluride, Colorado, the United Biomedical Biotechnical Company is offering serological assessments to all 8,000 residents of the county. Large-scale testing is being conducted in Iceland, the Netherlands, Singapore, Germany or even the United Kingdom.
On April 10, the U.S. National Institute of Allergy and Infectious Diseases began recruiting 10,000 random volunteers to participate in a study using serological analysis.
Calculating undiagnosed, asymptomatic, or mild cases of COVID 19 in a population can help identify people who are already immune and can return to work.
This information can be especially important for healthcare workers or those who are on the front line of response. But such testing is being widely sought after by businesses that are facing ongoing activity blockages.
"I've received dozens and dozens of emails, or text messages from different people telling me that in January or February they had this or that serious respiratory illness, or other symptoms caused by COVID 19. They want to be tested if they have they had and have passed SARS-CoV-2, ”says Robert Garry, a virologist at Tulane University who conducts serological tests.
"We have to go and get the blood sample from these people, and see what we had to do with January this year," he said.
But on the other hand, immune testing can determine how resistant a population is to the second wave of infection expected in the fall. If a large part is resistant then the disease is unlikely to spread. But if the percentage of resistance is low, then the removal of restrictive measures and socialization increases the possibility of another explosion.
"The consequences of misinformation about the percentage of infected people are really great. We need to do some national research as soon as possible, ”says Scarpini
Serological tests would also help us understand how deadly COVID really is 19. "Currently the death rate is likely to be bloated," says epidemiologist Martin Hibberd of the London School of Hygiene and Tropical Medicine.
"Most of the cases so far have been diagnosed when patients seek medical attention, scientists have basically assessed the mortality rate of those who have been hospitalized. But the increase in cases of mild or asymptomatic cases should reduce the total mortality rate that this pandemic has brought, "he says.
In conclusion, scientists already have it in hand to gather the right information about the immunity that societies have developed for SARS-CoV-2. What remains unclear at the moment is how long this immunity can last.
But comparisons with the similar SARS virus and the results obtained so far from COVID-19 predict that immunity in the human body can last more than a year without developing the vaccine.
"Immunity of the peoples, this is the end of this pandemic," says Christackis of Yale University. "The virus will infect us until it reaches every potential person and he can do it. The only way to stop it is to develop natural immunity or vaccination.
Source: Nationalgeographic
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