‘Human challenge’ study offers valuable insights on Covid infection

It only takes about two days for a person infected Covid-19 to start shedding the virus, a recent ‘human challenge’ study of the SARS-CoV-2 virus has confirmed. Apart from the virus’ very brief incubation period, the study also showed that it takes a very tiny virus-laden droplet to infect someone with Covid.
The ‘Challenge’ study, where volunteers are deliberately infected with a virus or pathogen to understand its full effects, offers valuable insights on the course of the infection. The findings were published in the journal Nature Medicine on Thursday.
The study, which began in March 2021, included a carefully screened group of 36 volunteers between the ages of 18 and 30. They were only permitted to participate in the study if they didn’t have any risk factors associated with severe Covid-19. The study was conducted in phases, with the first 10 infected volunteers receiving the antiviral drug remdesivir to reduce the risk of severe disease. Monoclonal antibodies were also available at hand in case any of the volunteers took a turn for the worse, the study stated. However, they did not end up using needing the antibodies.
“Really, there’s no other type of study where you can do that, because normally, patients only come to your attention if they have developed symptoms, and so you miss all of those preceding days when the infection is brewing,” the study’s lead author, Dr. Chropher Chiu, an infectious disease physician at Imperial College London, told CNN.
A tiny drop of fluid containing the originally detected strain of the virus was adminered on each participant through a thin tube inserted into their nose, CNN reported. The study notes that a total of 18 participants became infected, two of whom were asymptomatic. The people who did get sick, developed only mild symptoms, including stuffy noses, congestion and sore throats.
Most participants ended up losing their sense of smell, at least to a degree. Nine couldn’t smell at all.
Notably, the study found that it only takes around 10 microns — which is about the same amount found in a single droplet when someone coughs or sneezes — to infect somebody. The study also confirmed that infected people begin to shed high amounts of the virus even before they first start to show symptoms.

At-home tests work well for detecting when a person is contagious, the study claims. These tests are able to diagnose the infection before 70% to 80% of viable virus had been generated.
According to the study’s authors, it confirmed what a lot of epidemiologs have already figured out about the disease, CNN reported.