The research and development of the new global crown vaccine is currently entering a critical clinical trial stage. Before the vaccine is put into production, key large-scale clinical Phase III effectiveness trials are yet to be verified. With the spread of the new crown epidemic in the northern hemisphere under control, this has brought new challenges to vaccine clinical trials.
A number of researchers engaged in the research and development of first-line vaccines told the First Financial Reporter that they now need to answer the question of how to recruit large-scale subjects in phase III clinical trials.
Large-scale clinical targeting overseas
A latest statistical report on global vaccines published in The Lancet magazine shows that China’s adenoviral vector vaccine has entered clinical phase II trials; the remaining four inactivated vaccines are also in clinical phase I or II trials . These vaccines are expected to complete phase II clinical trials in July this year, and the question to be faced next is how to carry out large-scale phase III clinical trials.
Safety, effectiveness and accessibility are the hallmarks of vaccine success. The clinical phase I and phase II trials are mainly to verify the safety of the vaccine, and the vaccine as a key factor in ending the epidemic, its ultimate success is based on large-scale phase III clinical trials.
This is a huge challenge for most northern hemisphere countries where the first wave of epidemics is gradually declining. If you want to go to the southern hemisphere for clinical trials, the cost will also be very high, because you need to send someone to carry out relevant work locally. This may hinder clinical trials.
In the past few months, the embarrassing situation caused by the slowdown of the epidemic has been encountered in the clinical trial of ridxivir. In the course of clinical trials of vaccines, researchers will face similar problems.
A virologist told the First Financial Reporter that the phase III clinical trials often required tens of thousands of people. It is understood that the United States plans to launch large-scale clinical trials of vaccines in July, and each vaccine will recruit 20,000 to 30,000 volunteers to be tested. The vaccine at the Jenner Laboratory in Oxford University in the UK is also planning to recruit 10,000 subjects in the second clinical trial.
At present, European and American manufacturers have also targeted overseas countries as test fields, especially in Africa or South America where the epidemic situation is still high.
The Brazilian Ministry of Health has stated that it is negotiating clinical trials with vaccine developers including Moderna in the United States and Oxford University in the United Kingdom, with the goal of providing a vaccine to Brazilians in the shortest possible time.
Hot discussion on the challenge test
Vaccine clinical trials come at the cost of volunteers bearing the risk of infection. Because the clinical trial was set as a control group, one group was vaccinated and the other group was vaccinated with a placebo, and then they returned to the community where the virus was spread. After a period of time, their infection rates were compared. If the vaccination group had a lower infection rate , Then the vaccine has played a protective role.
“But if there is no infection in the community, then the clinical trial control is meaningless.” The above experts told the first financial reporter.
In this context, some companies and academics have begun to call for clinical trials of virus attacks, but because of the greater risk, the initiative may have difficulty passing the ethics committee.
The so-called virus attack test refers to vaccinating participants and then artificially infecting them with the virus to verify the effectiveness of the vaccine. Opponents believe that the risk of such an attack test is too great when the knowledge of the new coronavirus is still limited. high.
Overseas, AstraZeneca CEO Pascal Soriot (Pascal Soriot) said that his research team is considering this virus attack method, if approved, will set a precedent for a new clinical trial of crown epidemic.
Zhu Tongyu, director of the Shanghai Public Health Clinical Center, told the First Financial Reporter that in the United States and Europe, the law has allowed clinical trials of influenza vaccines to use influenza virus attack tests. However, considering that the risk of the new coronavirus is uncontrollable, it is still debatable whether this virus attack method is feasible.
Zhu Tongyu believes that there is another compromise method to verify the effectiveness of the vaccine through alternative indicators. “For example, after being vaccinated, it can produce a certain titer of neutralizing antibody level, then in theory it can be regarded as a protective effect. In this way, there is no need for a challenge test or a large-scale population test.” Zhu Tongyu To the first financial reporter. He also said that other alternative indicators include specific T cell activity indicators.
But he emphasized that the above method is based on the verification of the protective effect of neutralizing antibodies. At present, China has published a number of clinical research results of neutralizing antibodies, which will have important guiding significance for the development of vaccines.