The White House and many Americans are hoping to “rapidly” develop a vaccine to defeat the Covid-19 pandemic. But some scientific experts warned that they all expected too much and too early.
“Everyone thinks that Covid-19 will eliminate vaccines,” said William Haseltine, chairman and president of Access Health International, an organization that advocates for affordable care.
The ongoing clinical trials mainly aim to show whether the candidate Covid-19 vaccine can prevent any symptoms of the disease-which may be as mild as a sore throat or cough. However, the trial will study 30,000 to 60,000 volunteers, but the time is too short and the scale is too small to prove that the vaccine will stop people’s most worried thing-hospitalization or death when the first batch of vaccine manufacturers apply for emergency use authorization. Haseltine said it is expected to happen later this year.
Haseltine said that the United States should insist on seeking an optimal vaccine with more mature capabilities. Others say that the heavy cost of the pandemic has caused at least 225,000 deaths. Although the disease still has major problems after its release, the country still requires the country to accept the best it can achieve in the next few months. vaccine.
“There is tension between getting every piece of information and getting vaccinated [out] Save lives in time,” said Dr. William Schaffner, Professor of Medical Cancer Preventive Medicine and Health Policy at Vanderbilt University.
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Dr. Peter Lurie, a former Food and Drug Administration official who chairs the Science Center in the Public Interest, said: “We want to know whether vaccines can reduce disease or mortality? Of course. But this is immediate pressure. This is a pandemic. It is It’s explosive.”
At the public meeting of the FDA Vaccine Advisory Committee on Thursday, researchers debated how to rigorously test Covid-19 vaccine candidates.
Peter Doshi, an associate professor in the School of Pharmacy at the University of Maryland, said: “It is not enough to prevent mild cases and may not prove the risks associated with vaccination.”
But vaccine experts say there are good reasons to focus on the lighter Covid-19 cases.
Dr. Arnold Monto, an epidemiologist at the University of Michigan School of Public Health and interim chair of the Vaccine Committee, said that vaccines that prevent mild diseases usually also prevent serious diseases.
If you put out a small fire in the kitchen, you don’t have to worry about the entire house catching fire.
Dr. Kathleen Neuzil, director of the Center for Vaccine Development and Global Health at the University of Maryland, said, for example, the original research on the measles vaccine showed that it can only prevent measles, not hospitalization or death.
Later studies found that the measles vaccine can greatly reduce mortality. According to data from the World Health Organization, from 2000 to 2018, the number of deaths from measles worldwide decreased by 73%.
Dr. Philip Krauss, deputy director of the Office of Vaccines at the FDA’s Center for Biologics Evaluation and Research, said: “There is no example in the vaccinology of vaccines for mild diseases, and there is no more effective vaccine for serious diseases.” At the hearing.
Dr. Paul Offit, who developed a rotavirus vaccine, compares prevention of the coronavirus with fighting fires.
Offit, a member of the FDA advisory committee, said: “If you put out a small fire in the kitchen, you don’t have to worry about the whole house catching fire.
Proving that vaccines can prevent serious illness and death is more difficult than proving that it can prevent mild illness, because hospitalization and death are much less frequent. Schaffner said this is especially true among health-conscious people who voluntarily participate in vaccine trials, who may wear masks and social distance more than others.
Neuzier said: “When we check the elderly for influenza in hospitals, these trials will last for two years.” In an ongoing study, “we are looking for a typhoid vaccine for nearly 30,000 children, which is a two-year period. Years of experimentation.”
Dr. Amesh said that the Covid-19 pandemic has officially infected about 8.7 million people in the United States. Considering that the actual number of people infected is estimated to be 6 to 10 times higher than the reported number, the mortality rate is about 0.6%. Adalja, a senior scholar at Johns Hopkins University Health Security Center.
Dr. Corey Casper, chief executive officer of the Fred Hutchinson Cancer Research Center and Infectious Disease Research, said that scientists believe that the ideal vaccine can provide “bactericidal immunity”, which not only means preventing disease symptoms, It can also prevent virus infection. Seattle Research Institute.
For example, two doses of measles vaccine can prevent 97% of people from contracting the virus.
Few people expect the Covid-19 vaccine to be so effective. Casper said: “We are working hard to lower this threshold and determine an acceptable reduction.”
Casper said that preventing mild diseases can curb and prevent diseases.
He said: “We may not have the perfect vaccine.” “But I do think that we are likely to have vaccines, and if we can prove that they are safe, we can set a turning point for this pandemic….I Think, even for mild disease.”
Casper said that the flu vaccine is not super effective. The annual effective rate increases from 19% to 70%, but it is still very useful.
According to the Centers for Disease Control and Prevention, during the 2018-19 U.S. flu season, vaccination prevented approximately 4.4 million flu illnesses, 2.3 million doctor visits, 58,000 hospitalizations, and 3,500 flu-related deaths.
According to historical standards, trials of 30,000 to 60,000 people have been considerable. Krauss said that within a tight time frame, it is impractical to dramatically expand this range.
He said at the meeting: “If the endpoint of the trial is a serious disease, the trial scale may need to be close to 10 times.” “And these trials are not feasible, we will never get a vaccine.”
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On the other hand, Klaus said: “If there is a vaccine that appears to be highly effective or that seems to be able to save lives, then if it has a great chance of saving lives, I don’t want to stop this vaccine.”
Neuzil said that although coronavirus vaccine trials are measuring serious illness or death, they are “secondary endpoints,” meaning that the current research scale is not enough to produce statistically significant answers.
She said that after the vaccine is distributed, whether the vaccine can reduce serious illness and death will become more clear in future studies.
Offit said the debate revolved around a question: “Knowing that we are facing a virus that makes us surrender, how much uncertainty are we willing to endure?”