What did the world’s first COVID-19 human Challenge test discover?
On February 1, the world’s first human challenge to COVID-19 trial was published in the UK in a pre-print.Let’s start with the human challenge test itself: Many of you don’t know that the human challenge test has been around for a long time. It has been used against more than a dozen pathogens, from flu to malaria.■ Who also published a guidance in 2016 on how to use human testing to guide vaccine development: Human Challenge testing for Vaccine Development: Regulatory considerations.■ Since the outbreak began, WHO has assembled a panel of experts to make recommendations for conducting COVID-19 human challenge trials in volunteers, with guidance published in the journal Clinical Infectious Diseases.■ The British trial was approved after many layers of medical ethics.In conclusion, despite the uncertainties surrounding the new virus, the human trial was based on long-term scientific research, professionally designed and evaluated.Here’s how the study was done: The results came from 34 healthy young adults, ages 18 to 29, who had not had COVID-19 or been vaccinated.In the spring of 2021, they were given a close approximation of the original Novel Coronavirus strain through the nose.The researchers carefully designed the doses.In the past, we did the human challenge test for influenza and other respiratory infections, because most people have been infected and have resistance, so we used a relatively high dose of virus.But now these people are a blank sheet of paper to draw the most beautiful pictures, so the researchers give them a very low dose, the plan is to get 50 to 70 percent of them infected.They did: After receiving the virus, each subject stayed comfortably in a separate room with negative pressure, so the virus could not be transmitted.The results are from 18 people who were infected, 53%.(Vichie81 / iStock) Finally, the results of the experiment.■ Most importantly, the test tracked the progression of the virus: the virus was detected first in the throat and then in the nasopharynx after about two days.The virus load peaked after about 5 days, with a higher load in the nasopharynx than in the throat, and it seemed to make sense to take a sample from the nasopharynx.On average, there is no live virus after 10 days.The time when the live virus was available coincided with the time when rapid antigens could be detected, suggesting that antigen tests can be used to diagnose whether a person is infectious and help decide when to come out of isolation.Interestingly, 14 days after the expected end, the NUCLEIC acid test was still positive, and the subjects had to be kept home for an additional five days.By 28 days, 33 percent and 11 percent had tested positive for NUCLEIC acid in the throat and nasopharynx.So if you just look at the nucleic acid results, you might put someone who’s not contagious for a few more weeks.■ Antibodies produced by the sick: neutralizing antibodies reached 425 on 14 days, but doubled to 864 on 28 days.IgG was 193 and 1549 at 14 and 28 days.Looks like 28 days could be the peak antibody.■ Symptoms: 89% of infected people have symptoms, but they are quite mild.Symptoms begin two days after the virus is detected, and the peak of symptoms corresponds to the peak of the virus amount.Previous modelling also found that up to 44 per cent of infections occur before symptoms appear, so the novel coronavirus is typically spread quietly before symptoms appear.However, the amount of virus and the severity of symptoms are not consistent, and may vary greatly from person to person.Although they did a chest C.T., they didn’t have pneumonia.Tried a couple of guys to hit Remdesivir first. No difference.■ Olfactory effects: twelve people had some olfactory changes that appeared 6 to 7 days after peak symptoms.Note that not total loss of smell, but any degree of change.After half an year still have 5 people report olfactory did not restore completely, but lighter.All in all, it was a carefully done and meaningful experiment.The purpose of this article is to convey additional information and does not reflect the views or positions of this issue.If related to copyright and other issues, please contact to delete.