Results for the first human active infection challenge test with new coronavirus

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Results for the first human active infection challenge test with new coronavirus

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Result for the first human active infection challenge test with new coronavirus, revealing the attack and transmission mode of the new coronavirus.

Recently, a new round of COVID-19 epidemics appeared in Shanghai and Jilin and other places. The COVID-19 Omicron mutant strain that caused this round of epidemics.

According to the current published data, the proportion of asymptomatic infections greatly exceeds that of confirmed cases. cases, which also proves that the symptoms caused by the Omicron mutant strain are milder, but asymptomatic infections also have the ability to spread, which further increases the difficulty of epidemic prevention and control.

On March 31, 2022, researchers from Imperial College London published a research paper titled: Safety, tolerability and viral kinetics during SARS-CoV-2 human challenge in youngadults in the top international medical journal Nature Medincine .

The study recruited 36 young, healthy volunteers to participate in the first-ever COVID-19 challenge study in humans . A small liquid containing the original strain of the new coronavirus was dropped into the noses of volunteers through a dropper to expose them to the new coronavirus. , 18 of them were infected, all of which were mild, about 83% of the patients lost their sense of smell, and the most severe cases lost their sense of smell for more than six months.

What’s more, the study found that a droplet smaller than 10 microns “fired” by an infected person by coughing or sneezing is enough to infect a person, and it only takes two days for a person to start spreading the virus after being infected. That is, the patient is already shedding a lot of the virus before showing symptoms.

For many years, controlled human infection models (CHIMs) have been used to study disease pathogenesis and evaluate preventive and therapeutic approaches. Simply put, the CHIMs test is equivalent to directly exposing healthy volunteers to pathogens, so as to intuitively reflect the infection process of the virus and test the efficacy of newly developed vaccines and drugs.

In fact, as early as March 2020, researchers from Rutgers University, Harvard T.H. Chan School of Public Health, and the London School of Hygiene and Tropical Medicine published a preprint titled: Human Challenge Studies to Accelerate Coronavirus Vaccine Licensure article.

Once the article was published, it caused widespread controversy. The paper proposes exposing about 100 healthy young people to the new coronavirus to see whether those who have been vaccinated with candidate vaccines can avoid infection, thereby speeding up the development of COVID-19 vaccines.

In young people, infection with Covid-19 is often mild or asymptomatic, but this may drive community transmission, although the detailed time course and contagiousness of early infection is not yet fully understood. In response, young, healthy, low-risk volunteers were artificially vaccinated with the virus to provide precise longitudinal measurements of viral kinetics, immune responses, and transmission dynamics under tightly controlled conditions.

In this latest study, the research team recruited 36 healthy adults aged 18-29 to participate in the challenge trial. These volunteers had not previously been infected with the new coronavirus and had not been vaccinated against the COVID-19 virus. The researchers infected the volunteers with a low dose of the wild-type new coronavirus strain via nasal inoculation.

Research flow chart

Of the 34 seronegative volunteers, 18 (53%) were infected, the viral load peaked 5 days after vaccination, and all infected individuals developed specific IgG and neutralizing antibodies against SARS-CoV-2. At the beginning, the researchers detected live new coronavirus in the throat of the patient, and then the virus rose to higher titers in the nose for 10 days.

What’s more, the study found that the volunteers spread the virus for an average of 6.5 days and up to 12 days, even if they were asymptomatic.

Virus transmission peaks rapidly after a short incubation period after infection

Of the 18 infected, 2 (11%) were asymptomatic, and most of the others had mild symptoms. These patients had mild nasal congestion, nasal congestion, sneezing, and sore throat, but none of them had mild symptoms. The patient has lung problems.

In addition, about 83 percent of patients lost their sense of smell — at least partially, and six months after the study ended, one patient’s sense of smell had not returned but was improving.

Human COVID-19 challenge can induce mild to moderate symptoms

Now, the research team plans to conduct another challenging study in vaccinated populations infected with the Delta mutant strain.

Dr Christopher Chiu , the study’s corresponding author , said: “In fact, no other type of study has done this, because often patients only pay attention when they develop symptoms, so early signs of infection are often missed. All data.”

In conclusion, this study establishes the viral dynamics during the initial and early infection of 2019-nCoV through the first detailed description and safety analysis of the challenge study of 2019-nCoV infection in young healthy adults, and public health recommendations and strategies for 2019-nCoV transmission. Control strategy has far-reaching effects.

It is worth noting that these “human challenge studies” are controversial because they carry certain risks – does direct infection with the new coronavirus pose unpredictable dangers to volunteers? In addition, it remains to be verified whether such a small-scale trial with a highly controlled and uniform nature can be generalized to the population.

But in any case, in the context of the COVID-19 pandemic, controlled human infection models (CHIMs) can be used to initially evaluate vaccines and prioritize those that look the most promising.

It is hoped that in the future, this experimental model can be effectively used to speed up the evaluation of vaccines, specific drugs and diagnostic methods, and quickly deploy them to the community to add strength to the fight against the new coronavirus!

Reference:
https://www.nature.com/articles/s41591-022-01780-9
https://www.nature.com/articles/d41586-020-00927-3

Result for the first human active infection challenge test with new coronavirus

(source:internet, reference only)

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