- 专家开始讨论何时以及如何更新现有的Covid-19-19-19疫苗以及何时提供其他助推器。
- No decision was made on whether boosters will be recommended in the fall, similar to how flu shots are recommended to the general public on an annual basis.
- The meeting comes after the FDA authorized people over 50 to get a second booster dose.
The Food and Drug Administration’s (FDA) vaccine advisory panel met Wednesday to discuss future COVID-19 booster doses and how to prepare for new strains of the coronavirus that may emerge.
No decision was made at the meeting on whether boosters will be recommended in the fall in preparation for a potential winter surge. A follow-up meeting is expected by early summer for further discussions.
在会议期间，专家概述了在已经发展为多种变体的病毒之前的挑战，有些是高度传播的，有些能够克服疫苗和先前感染产生的免疫保护。
这次会议是在FDA授权的second booster dosesfor adults over age 50 and certain people with weakened immune systems, and as the agency is set toconsiderCOVID-19 vaccines for very young children.
All viruses can mutate and give rise to new strains, but they do so at different rates. SARS-CoV-2, the coronavirus that causes COVID-19, has been especially adept at this process.
在咨询委员会会议期间，Trevor Bedford, PhD, a researcher at the Fred Hutchinson Cancer Center in Seattle, said that in terms of evolution, the coronavirus has accomplished in two years the equivalent of five years of seasonal flu evolution.
自SARS-COV-2于2019年底首次出现以来
一些更可传播的变体（例如三角洲和Omicron）席卷了人群，迅速取代了现有菌株。其他人，例如β，已经显示出逃避疫苗或感染获得的免疫力的能力。
但是，即使经过两年的SARS-COV-2研究，科学家也犹豫要预测冠状病毒的下一步。
贝德福德说：“确切地评估这里的概率非常困难。”
他提供了两个可能ble scenarios — a slightly different variant could develop from one of the currently circulating ones, or a variant with many mutations could come out of nowhere, as did Omicron.
第一种情况类似于季节性流感病毒的发展方式。
贝德福德说，从目前循环的Omicron Sublineages之一开始，新的菌株更有可能发展。但是，他补充说，每1.5至10。5年可能会出现一个截然不同的冠状病毒变体。
Scientists can use blood from people who have been vaccinated to see if an existing vaccine is likely to work against a variant. This method would work for a variant that has already been identified.
但是要保持领先不断发展的冠状病毒，有一种方法可以预测疫苗是否会与尚未出现的新变体作用。
During the meeting,
“直到我们知道更多关于病毒将另一个星球ve], we have to know how to react to a new strain that may arise,” he said.
The current COVID-19 vaccines are based on the original strain of the virus. But the vaccines also work against all of the variants that have arisen — to varying degrees.
The NIAID is running a临床试验in which people will be given a COVID-19 vaccine based on the original strain of the coronavirus or other known variants. Some people will also receive a booster.
Scientists will measure how well the antibodies in the blood of those people work against the existing variants.
They can predict how well the vaccines or vaccine-booster combinations might work against new variants that might arise, based on how similar those potential variants are to existing ones.
This work is based on the ability of antibodies produced in response to vaccination to target a variant. However, antibodies are just one part of the immune response.
小组成员Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia, suggested that measures of T cells might provide a better idea of how well the vaccines might work against a new variant, in particular the protection offered against severe illness.
Seasonal flu vaccines are
但是，流感季节非常规律，使科学家更容易做出预测。冠状病毒可能并非如此。
“我不确定数据是否支持Covid-19的季节性。我们的时间表可能与流感不同。”亚当·伯杰（Adam Berger），博士, director of Clinical and Healthcare Research Policy at the National Institutes of Health.
In addition, there are many different platforms for the COVID-19 vaccines, including mRNA, adenovirus, and protein subunit. These technologies complicate the vaccine update process.
Another challenge of updating the COVID-19 vaccines is manufacturing capacity. Even if a vaccine had high efficacy against a new variant, if vaccine makers couldn’t make enough doses, this vaccine would do little to help the world.
伯杰还提出了一个问题，即制造商是否能够生产足够剂量的现有疫苗，同时还生产原型疫苗，以测试针对新变体的测试。
One of the advantages of the mRNA vaccines, though, is that they can be rapidly redesigned. However, designing the vaccine and producing enough doses are separate problems to be solved.
One of the challenges outlined during the meeting is knowing when to update the existing vaccines to target a new variant or possibly to target multiple variants.
在向公众推出新疫苗之前，FDA需要进行临床试验。这需要时间。
小组成员迈克尔·尼尔森博士, a professor of medicine at UVA Health, said if clinical trials had been started shortly after the arrival of the Omicron variant, by the time the clinical trials were done, the wave would have passed.
他说，这种方法不仅有缺少当前浪潮的危险，而且还有一种无法防止未来变体的疫苗。
Another way to think about whether to modify the existing vaccines is to look at how well they are working against the existing variants in circulation.
或者，作为小组成员Dr. Cody Meissner, a pediatrician at Tufts University School of Medicine, put it: “At what point will we say the vaccine isn’t working well enough?”
This can be done by testing the blood of vaccinated people to see how well antibodies in their blood recognize and neutralize a particular variant.
许多研究都进行了这种分析。但是，科学家还没有清楚地了解中和活动的“足够”。这也称为“保护的相关性”。
此外，虽然抗体活性的水平可以很好地了解疫苗可以防止感染的能力，但它可能无法预测其保护人们免受严重疾病的影响。
For that, scientists turn to data from real-world vaccine effectiveness studies.
当前的研究表明，现有的三剂MRNA Covid-19疫苗继续提供强烈的保护，以防止严重疾病，住院和死亡。
So the question that would need to be decided is how low does this protection have to drop in order for vaccines to need to be modified.
如果保护下降，现有疫苗的助推器可以恢复一些免疫保护，以防止感染和严重疾病。
However,
“Given that our effectiveness against hospitalization in immunocompetent individuals is over 80 percent, and that’s in older adults and in persons with chronic medical conditions, I think we may have to accept that level of protection, and then use other alternative ways to protect individuals with therapeutics and other measures,” she said.
This question was discussed at the meeting, but panel members made no decision.
The advisory group is expected to meet again, likely by early summer, said
During that meeting, panel members will review additional clinical and laboratory studies data that might help guide their decisions.
They will also discuss whether additional boosters should be offered in the fall before a possible winter surge and the framework needed for deciding when and how to update the existing vaccines.