Covid, there is a study in which participants were voluntarily infected

In the mare magnum of studies on Sars-CoV-2 and Covid-19 there is one, still in preprint, which is causing discussion. This is a British survey of 34 healthy individuals aged 18 to 30 deliberately infected with the coronavirus. A so-called “human challenge“, Or rather controlled human infection, a type of research developed with the aim of reaching the marketing of a certain drug or more careful observation in a shorter time frame, and also on the basis of broader and more comparative knowledge elements the evolution of a certain pathology. But that obviously brings with it strong ethical doubts.

He recently talked about it Naturereporting the results of the first study of its kind in which the volunteers reported mild symptoms or, in most cases, no symptoms. ‘Such studies represent a unique opportunity to study viral infections in detail from start to finish but they are controversial because of the risks they pose to participants»Writes the scientific journal. However, he adds that the UK survey demonstrates how these studies can be conducted safely and set the stage for more in-depth investigations into vaccines, antivirals and immune responses to infection.

The trial was announced as early as October 2020 and the first volunteers were exposed to the virus in the first part of 2021.Imperial College of London and a Dublin-based clinical research organization, Open Orphantogether with its London subsidiary I live. Each person received £ 4,565, around € 5,400, for participation, which included at least two weeks of quarantine in an isolation ward at the British capital’s Royal Free Hospital.

Almost half of the participants received a low dose of the virus was not infected and some of those infected had no symptoms. Participants who instead developed Covid-19 reported mild to moderate symptomsincluding sore throat, nasal congestion and loss of smell and taste. “These studies are important on how to evaluate the future vaccine and the effectiveness of drugs – he explained to Nature Miles Davenportimmunologist at the University of New South Wales in Sydney, Australia – they open up a number of important possibilities for studying immunity in a controlled environment“. However, some researchers question whether the information obtained so far from the study is important enough to justify risks to participants, such as the potential for long-term side effects. “It’s still not entirely clear in my mind whether these studies are ethically justified and I’m waiting to see what else they found,” says Seema Shah, a bioethicist at Northwestern University in Chicago, Illinois.

This type of study has been used for decades to study influenza, malaria, and numerous other infectious diseases. “Some researchers have spoken out in favor of conducting such studies with Sars-CoV-2 in the first months of the pandemic, as a way to accelerate the development of vaccines – recalls Natu on the debate of recent years – but others considered the challenges too dangerous to be acceptable, when so little was known about the virus and few, if any, effective treatments were available. ‘

The first participants received a very low dose of the virus, the equivalent of the amount of pathogen present in a single droplet of nasal fluid. The strain was the one that circulated in the UK at the beginning of 2020, hence the one originally from Wuhan. That minimal dose, it is worth remembering with exposure in the laboratory and not in the real world, was still enough to infect half of the participants in which it replicated and produced the first symptoms on average. two days after exposure. This information strongly contrasts with what, especially for the first strains, we believed with respect to the time lapse between exposure and symptoms, that is about five days. Viral levels remained sustained for about 9 days, and in some cases up to 12. It must be remembered that this was a different strain from the one currently dominant.

Among the most frequent symptoms were those typical of other respiratory infections: dry throat, stuffy nose and some sort of cold with sneezing. The fever appeared less frequently and, curiously, no one developed that cough which, on the other hand, we know to have been for months one of the most frequent symptoms in the population affected by the infection. About 70% of those infected lost taste and smell to varying degrees of severity, and in some cases for up to 6 or 9 months. Some people did not develop any symptoms, although their viral load in the upper respiratory tract was equal to that of the symptoms.