COVID-19, The Astonishing Results of the First Ever Human Experiment [Reading Science]

UK Research Team Conducts Direct Injection Experiment on 36 People
Half Uninfected... "Possibly Due to Similar Virus Experience or Innate Immunity"
"Significant Progress in Vaccine and Treatment Development Research"

[Asia Economy Reporter Kim Bong-su] A research team in the UK has conducted the world's first experiment of directly injecting the COVID-19 virus into humans and has released the results. About half of the participants were not infected at all, and the rest only experienced mild symptoms. Scientists are paying attention to the fact that half of the participants were not infected despite being directly exposed to the COVID-19 virus, as this could help in the future development of vaccines and treatments.

The research team from Imperial College London conducted an experiment in early last year involving healthy volunteers aged 18 to 30, injecting a small amount of the COVID-19 virus into their bodies and observing the progress. The related paper was published on June 2 on the preprint site 'Research Square.'

The participants were given a small dose of the virus that was prevalent in the UK during the early stages of the 2020 COVID-19 pandemic. As a result, only 18 out of 36 participants were infected, while the rest were not. No one experienced severe symptoms. Among the 18 infected, only 16 reported mild to moderate symptoms 2 to 4 days after virus exposure. Regarding symptoms, 67% (12 people) of the infected complained of olfactory dysfunction. The infected experienced sore throat, runny nose, loss of smell and taste. No correlation was found between the amount of virus and symptoms. In other words, even asymptomatic infected individuals carried a large amount of the virus.

In particular, the high infectivity of the COVID-19 virus was confirmed. Participants were given a small amount of virus equivalent to a single respiratory droplet. Researchers had expected that a larger amount would be necessary for infection, but this was not the case. Infected individuals began to show symptoms in less than two days and tested positive in PCR tests. This progression was much faster than the usual incubation period of about five days for COVID-19. The highest viral load was observed on the fifth day after infection, and it remained high enough to be contagious until days 9 to 12. The virus administered was first detected in the throat, then quickly spread to the nose and multiplied rapidly. The viral load in the nose returned to normal only after 10 days post-infection.

Researchers are focusing on why half of the participants were not infected despite direct injection of the COVID-19 virus. Notably, some of these uninfected individuals carried low levels of the virus for a short period, which may indicate that their immune systems fought off and defeated the virus. Relatedly, researchers suggest that these participants might have gained resistance to COVID-19 after recovering from common colds, or they might have had inherently strong immune systems regardless. Professor Christopher Chiu of Imperial College London said, "We are studying how some people can have immunity to a virus they have never been exposed to before." He added, "We also plan to conduct experiments directly injecting the Delta variant into people to study immune factors that can prevent breakthrough infections even after vaccination."

The research results have sparked debate in the scientific community. Some support it as an important tool for vaccine and treatment research. Professor Miles Davenport, an immunologist at the University of New South Wales, Australia, welcomed the study, saying, "It is a significant advancement that could potentially improve experiments to evaluate future vaccine and treatment efficacy," and "It opens many possibilities for studying immunity in a controlled environment."

On the other hand, ethical concerns have been raised. Professor Shima Shah, a bioethicist at Lurie Children's Hospital and Northwestern University in Chicago, USA, questioned, "Was this experiment important enough to justify the risk of participants suffering long-term aftereffects?" and pointed out, "It is uncertain whether this research is morally justified."