It is one of the studies most questioned of the last time. A group of volunteers had to be intentionally infected with Covid, albeit in a controlled space, which generated an ethical debate regarding how it would be carried out.
But beyond the moral questions, the research showed that the current pandemic has been surrounded by certain beliefs and myths that have finally been disproved.
The study, published last week in the magazine Nature Medicinefound that only a tiny amount of the virus is needed to infect a person, as much as a single drop in the air from a person who sneezes, coughs or speaks, contrary to what was believed until now.
It also found that, despite what most people have been told, viral shedding and transmissibility occurs at high levels when a person is infected, regardless of whether you have severe or mild symptoms.
The study was carried out University College London Hospitalthe Imperial College London and the Oxford Universityand among other conclusions, it also reinforced the idea of the importance of the mask.
The scientists concluded that Sars-CoV-2, the coronavirus that produces Covidis “present at significantly higher (levels) in the nose than in the throat”, a finding they said provides “Clear evidence emphasizing the critical importance of wearing face coverings over the nose and mouth.” Many people wear the mask under the nose, under the mistaken belief that the greatest danger of contagion occurs in the mouth.
© Andy Wong
Photo: AP
“Deliberate human infection of low-risk volunteers allows accurate longitudinal measurement of viral kinetics, immune responses, transmission dynamics, and duration of infectious shedding following a fixed dose of a well-characterized virus,” the authors wrote. , justifying the decision to infect a group of volunteers.
“Experimental challenge with human pathogens requires careful ethical scrutiny and regulation, but it can provide unprecedented information that can inform clinical policy and the refinement of infection control measures,” they added.
The disputed study
The study began in March 2021, the date the scientists recruited to 36 volunteers. As a precautionary measure, only people between 18 and 30 years old were admitted and that they did not have any risk factor for severe Covid-19, as overweighthave reduced kidney or liver function, or have any heart, lung, or blood problems. They also signed an extensive informed consent form to participate.
To further reduce the risks and prevent them from becoming seriously ill, the researchers conducted the study in phases. The first 10 infected volunteers received remdesiviran antiviral that is believed to reduce the chance of serious illness.
The volunteers received a small drop of liquid containing the virus strain originally detected through a long, thin tube inserted into the nose.
They were medically monitored 24 hours a day and stayed for two weeks in rooms at the Royal Free Hospital Londonin which they had a special air flow to prevent the virus from escaping.
Half were infected
A total of 18 participants became infectedtwo of whom never developed symptoms and among all the people who did get sick, they had a mild clinical picture, which included congestion, sneezing and sore throat.
The researchers also looked at how Covid-19 affects a person’s sense of smell.
To do this, they used odor identification tests with the help of University of Pennsylvania and found that 15 of the 18 infected participants reported “some degree of impaired smell.” Even, nine participants experienced a complete loss of smell, known as anosmiabut the researchers said “they improved markedly before day 28″. However, six months following the study ended, there is still one participant who has not been able to recover his full sense of smell.
This now well-known symptom improved for most people, but six months following the study ended there is a person whose sense of smell has not returned to normal, although the scientists assured that it is improving.
The researchers found that 18 participants, or 53 percent, became infected with a viral load that “it increased abruptly and peaked five days following inoculation.” They noted that the virus “was first detected in the throat, but it increased to significantly higher levels in the nose.”
© Michael Probst
Photo: AP
“Viable virus might be recovered from the nose up to 10 days following inoculation, on average,” the research noted.
The scientists also discovered that most of those infected recovered quickly. There were no serious adverse events and16 of the 18 infected participants reported mild to moderate symptoms. The other two who were infected remained asymptomatic.
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