The first COVID-19 Human Challenge study provides insights

April 1, 2022-Small droplets containing coronavirus can infect COVID-19. Recent results From the first COVID-19 Human Challenge study published in the journal Nature medicine..

Human Challenge Trials deliberately infect healthy volunteers to understand how the infection occurs and progresses. In COVID-19’s first human challenge study, people were infected with the SARS-CoV-2 virus to better understand what happened during the pandemic.

“In fact, there are no other types of studies that can do that. Usually, patients only get your attention when symptoms appear, so you miss all the days before the infection.” , Christopher Chiu, Principal Research Author and Infectious Disease Doctor and Immunologist, Imperial College London, Told to CNN..

Since March 2021, Chiu et al. Carefully selected 36 volunteers aged 18-30 years who are free of severe COVID-19 risk factors such as overweight and kidney, liver, heart, lung, and blood problems. Participants also signed a wide range of informed consent forms, CNN reported.

Approximately 83% of participants infected with COVID-19 lost their sense of smell to some extent, and 9 could not smell at all. Most participants’ symptoms improved within 90 days, but about 6 months after the end of the study, one person was still unable to fully regain the sense of smell.

The research team reported several other discoveries:

• A small amount of virus can make someone sick. About 10 microns, or the amount of a drop that someone sneezes or coughs, can lead to infection.
• Approximately 40 hours after the virus was inserted into the nose of the participants, the virus was detected in the back of the throat.
• It took about 58 hours for the virus to appear from the nose to the swab, and eventually the viral load increased further.
• The incubation period of COVID-19 is short. After infection, it takes about two days for someone to start shedding the virus to others.
• People are transmitted before they show symptoms and shed large amounts of the virus.
• In addition, infected people can shed high levels of the virus without symptoms.
• Research volunteers shed the virus for about 6 days on average, but some volunteers shed the virus for up to 12 days without symptoms.
• Lateral flow tests, which are used for rapid home tests, work well when the infected person is contagious. These tests can diagnose infection before 70% to 80% of viable viruses are produced.

Now the research team is conducting another human challenge trial, including vaccinated people infected with the delta variant. Researchers intend to study the participants’ immune responses, which may provide valuable insights into new mutants and vaccines.

“Although there are differences in infectivity due to the emergence of variants such as Delta and Omicron, this is basically the same disease and the same factors are responsible for protecting it,” Chiu said. In the statement..

The research team will also study 18 participants who did not get sick in the first human challenge test. Despite receiving the same amount of virus as the sick, they did not develop antibodies, Chiu told CNN.

Prior to the study, all participants were screened for antibodies to other viruses, such as the original SARS virus. This means that volunteers were not mutually protected, and other factors could influence why some people are not infected with COVID-19. Future research may help researchers provide better protection advice in the event of new variants or future pandemics.

“There are many other things that can help protect us,” Chiu said. “There are barriers in the nose. There are different types of proteins and some that are very old and primitive protection systems … and we are really interested in trying to understand what they are. I have.”