British studies intentionally infect volunteers to test viral vaccines

London — Imperial College London scientists plan to intentionally infect volunteers with the coronavirus early next year, and how vaccinated people were intentionally exposed to the virus. We will launch the world’s first effort to study how it responds, paving the way for new uncertainties in identifying effective vaccines.

The· A fiercely contested strategyKnown as the Human Challenge Trial, it has the potential to reduce decisive time in the race to screen out many vaccine candidates. Rather than conducting the type of trials currently underway around the world, where scientists wait for vaccinated people to encounter the virus at home or in the community, researchers intend in a hospital isolation unit. Infects the target.

Scientists have been using this method for decades to test vaccines for typhoid fever, cholera, and other illnesses. However, while infected people can cure these diseases, scientists are in the UK in an almost unknown ethical area, as Covid-19 has few widely used treatments and no known treatments. I am in charge of research.

Scientists start with small doses and first administer the virus to a small group of unvaccinated volunteers to determine the minimum dose of virus that will definitely infect. This process, scheduled to begin in a hospital in northern London in January, will be followed by tests in which volunteers are vaccinated and intentionally exposed to this carefully adjusted amount of virus.

The study is led by scientists at Imperial College London and hVivo, a company specializing in Human Challenge Trials. It still requires approval from the UK drug regulator, but the government said on Tuesday that it would allocate £ 34m, or $ 44m million in public funding.

In the first round of volunteering up to 90 healthy adults between the ages of 18 and 30, the virus is dropped into the nose without vaccination. If a sufficient number of participants are not infected, scientists will try to expose these early-stage volunteers to higher doses and repeat this process until they have identified the required exposure level of the virus.

After scientists have decided on the dose to be given by the end of spring, they begin the process of comparing vaccine candidates by immunizing the next volunteer group and then exposing them to the virus.

Although some of the vaccine candidates currently under study have already been approved by then, researchers have added direct evidence of the effectiveness of the challenge trial and compared the performance of different vaccines. I hope it helps you to.

“The intentional transmission of known human pathogens to volunteers is never light,” said immunologist and collaborator Peter Openshaw. “But such studies, even well-studied ones like Covid-19, are very informative about the disease.”

Many important research questions remain unanswered. The UK Government’s Vaccine Task Force, which selects the first vaccine candidates to include in the Human Challenge Trial, has not yet announced its plans.

The idea for the Human Challenge Trial has received warm welcome from several major vaccine manufacturers, including Johnson & Johnson and Moderna, and analysts are uncertain about which company’s vaccines will be included.

And it’s not yet clear how European and US regulators will evaluate the results of human challenge trials, or whether such studies will accelerate the vaccine approval process.

For strategic proponents, it is a moral imperative to potentially speed up vaccine development and save lives by promoting understanding of the virus. Those scientists and bioethicists say that the risk of the coronavirus seriously ill or killing young and healthy volunteers (such as those who become infected) is low enough that it could save tens of thousands of lives. It is said that it exceeds.

“I’m surprised that it wasn’t used before,” said Professor Julian Savlesk, director of the Oxford Center for Practical Ethics. “Delaying vaccine development and effective treatment kills an additional 5,000 people each day. It helps to screen for ineffective vaccines and understand the immune response.”

Skeptics urged scientists to wait or abandon their approach altogether. A young patient had a case of a serious illness of unknown cause, the long-term effects of the infection were unknown, and the pandemic began only a few months ago. It is also difficult to make a broad estimate from human challenge trials. For example, it is unclear whether studies of healthy young adults can reliably predict the effectiveness of vaccines in the elderly and people with pre-existing conditions.

Scientists also warn of the challenge of mimicking real-world transparency in the laboratory. This can make it difficult for researchers to know if a vaccine that could protect volunteers from intentional hospital exposure would do the same for people who encounter the virus at work or at home. There is.

“Did it exhale and sneeze, do you sniff it all with one fallen mass of virus that comes to you?” John Moore, a professor of microbiology and immunology at Weil Cornell Medical College Said. “No one really knows. It’s very difficult to model. Blowing a bolus of virus into the nose is an incomplete model of natural infection.”

The debate split the advisory board to the World Health Organization. Guidelines The safest way to do a challenge trial in June. In the United States, the National Institutes of Health has no plans to support such trials, saying that randomized clinical trials are sufficient.

But Britain took a different view.

Prime Minister Boris Johnson, Barrage of criticism of dealing with a pandemic What made Britain the highest death toll in Europe was its attempt to cast Britain as being at the forefront of scientific progress in the coronavirus.Oxford University researchers Developed one of the leading vaccine candidates, the same as One of the most promising treatments, A steroid called dexamethasone.

Some scientists questioned whether the fierce competition for the first development of an effective vaccine had overly influenced the planning of human challenge trials.

“It definitely has to do with vaccine nationalism,” Moore said. “It’s a race for money and glory. That’s the reality.”

The scientists who oversee the trial Antiviral drug remdesivir Treat volunteers as soon as they begin to detect a viral infection, even before symptoms appear. However, the drug has been found to have little benefit. Some analysts also said that treatment is needed, but limits the ability of researchers to determine whether the vaccine candidates being evaluated have reduced the severity of the disease.

Volunteers in London will be paid the UK minimum wage of approximately £ 9 ($ 11) per hour to attend trials and spend 2-3 weeks on forced quarantine. Researchers said they were wary of providing additional incentives that could overshadow volunteer decisions.

Thousands of people in the UK are already interested in participating in a coronavirus challenge trial through 1Day Sooner, an American group advocating such research.

But as the virus surges again in parts of Europe and the United States, some scientists say that people enrolled in regular vaccine trials are still exposed to the virus under natural conditions. Insist.

“This is not a rare disease,” said Dr. Paul Offit, a professor at the University of Pennsylvania and a member of the Food and Drug Administration’s Vaccine Advisory Board. “You can probably find a hotspot to do a vaccine test.”