Is the bivalent vaccine not much different from the original sequence? Physician: It can reduce bed occupancy and has strategic significance for population
Bivalent vaccine may be ineffective if there is little difference? Medical: Helps protect medical energy
The epidemic of the BA.5 virus strain has resurfaced, and the command center predicts that the number of confirmed cases will reach a new peak in mid-September. At the same time, the Taiwan Food and Drug Administration granted EUA (emergency use authorization) for Moderna’s bivalent vaccine, and the command center announced that vaccination will be available to qualified persons after the supply is available at the end of September. However, some people are worried that the Moderna bivalent vaccine combination of “original strain + BA.1” is not much different from previous vaccines and will not have a significant effect on preventing the currently circulating BA.5 virus strain.
Jiang Guanyu, an attending physician at the Department of Integrated Medicine and Care at the Taipei City Hospital Zhongxing Branch, posted on the social media that he believed that the view that “the effect of the bivalent vaccine is not much different from the original sequence” is not correct. Judging from the selection of bivalent vaccines in the United Kingdom and the United States (Editor’s note: the bivalent vaccine approved by Moderna in the United Kingdom is the original sequence + BA.1; the Moderna and Pfizer next-generation vaccines approved by the United States are the original sequence + BA. .5), Australian scholar Deborah Cromer used the immune bridging model to estimate that the UK’s bivalent vaccine option is still beneficial in the epidemic prevention strategy.
Dr. Jiang Guanyu explained that the difference between the bivalent vaccination and the original sequence booster seems very small, but for the entire group, every 5% increase in protection can reduce more infections. When mutant strains become more and more contagious to individuals, the enhanced protection provided by the bivalent vaccine will play a certain role in reducing bed occupancy in medical institutions and protecting the amount of medical treatment. The number of hospitalizations is expected to be “strategically reduced.” Taking the bivalent vaccine administered to 1,000 people as an example, as long as there are 8 fewer severe hospitalized patients than the original strain, the population strategy makes sense.
Differences in bivalent vaccines between the UK and the US reflect coverage and protection considerations over time
Dr. Jiang Guanyu also pointed out that the difference in body protection and subsequent effects among groups considering receiving the bivalent vaccine may be the reason why the United States has ordered the BA.5 vaccine. Since the American people were vaccinated earlier, for groups whose protection has been delayed for a long time or even has insufficient coverage, the bivalent vaccine with the latest variant sequence should have a significant protective effect compared to the bivalent vaccine with the older variant sequence. Vaccines are more effective.
However, if the protection has not been too long since the last vaccination, has faded too much, or is like in areas with high three-dose vaccine coverage in Taiwan, there will be almost no significant difference in effectiveness even if the latest variant is updated.
Can senior citizens get the fourth dose? The next generation of vaccines should pay attention to popularization among young people
Dr. Jiang Guanyu reminded that the BA.5 epidemic in Taiwan is expected to peak in mid-September. Elderly people are rushing to take the fourth dose of the original sequence, which actually still has protective effects. First, under high community coverage, the protective effects are similar. Secondly, if we wait until a large-scale epidemic breaks out before additional vaccination is carried out, the protective effect will not be effective. Hong Kong is an obvious example.
As for young people, Dr. Jiang Guanyu believes that if there was no infection in the last wave of BA.2 strains, it means that the protective power of the third dose has faded. However, vaccination with the traditional fourth dose is not very effective for young people. Repeating the same sequence will not be effective. It may cause T cell immunity fatigue and reduce its effectiveness. It is recommended that the command center prepares to purchase next-generation vaccines and spread them among young people as soon as possible.
Should Taiwan purchase the next-generation vaccine of BA.5 in the future? Dr. Jiang Guanyu said that the BA.5 part of the vaccine is still controversial because it only has animal data and no human trial data. In addition, in the original high coverage areas, the expected protective effect of BA.1 and BA.5 is not great. At the same time, We must also consider the commercial relationship with pharmaceutical companies competing for vaccine shipments to various countries.
“It’s still the same. The vaccine that can be administered to you is the best vaccine!” Dr. Jiang Guanyu reminded that those who are eligible for vaccination should pay attention to the information released by the command center and properly vaccinate with the next-generation bivalent vaccine, which can still help individuals and community groups. Correct concept of health.
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