Xinhua News Agency, Beijing, July 23 (Reporter Feng Yujing) As the delta strain of the mutated new crown virus is raging around the world, most parts of the world are still shrouded in the shadow of the epidemic. Some countries have announced or are considering introducing new crown vaccines for some people. Three doses of strengthening shots.
However, some researchers said that although the third booster shot can enhance the immune response, it is not necessary.
Whether or not to get the third booster shot has become a topic of discussion among governments and scientific research circles in various countries.
Why do you need a booster shot?
This is because the protective effect of certain vaccines may weaken over time. In order to provide additional protection, it is necessary to re-vaccinate to stimulate the body to produce and increase antibody levels.
For many vaccines to prevent viral infections, booster shots are common, such as the flu vaccine that is boosted once a year.
Another reason people may need to get a booster shot of the new crown vaccine is virus mutation.
A spokesperson for the New Coronary Vaccine Team at the University of Oxford in the United Kingdom said that some mutant strains have evolved to avoid part of the human immune response, which means they can more easily infect people who have recovered from the new coronavirus or have been vaccinated.
However, the virus cannot avoid all immune responses in the body.
A booster shot is helpful, because it can strengthen part of the immune response that the mutant strain cannot avoid.
There is also a view that booster shots may be beneficial to the elderly or people with weakened immune systems, because their bodies may not have a strong enough immune response after the earlier vaccination, but there is still evidence to prove that they are given to these people. Strengthening needles are safe and effective.
Pfizer Pharmaceuticals Co., Ltd. of the United States and the German Biotech Company issued a joint statement on July 8, stating that the third booster shot of Pfizer vaccine (BNT162b2) is expected to help the human body to improve the human body’s exposure to a variety of mutant new coronaviruses including the Delta strain. Resilience.
The statement said that preliminary data from the trial of the third dose of the vaccine showed that the human body injected the third dose 6 months after the second dose, the body's level of neutralizing antibodies against the new coronavirus and mutant virus beta strains was higher than that of the two doses. Increase 5 to 10 times.
According to the statement, data from a recent paper published in the British journal Nature showed that the test found that the human body had a higher level of neutralizing antibodies to the Delta strain after the second dose of Pfizer vaccine.
The two companies expect that the third dose will further increase the level of these antibodies, which is currently being verified through preclinical and clinical trials.
According to data previously released by the Israeli Ministry of Health, the protective effect of Pfizer vaccine has declined 6 months after vaccination, but it still has a significant effect in preventing severe illness.
Based on existing data, the two companies believe that a third dose may need to be injected within 6 to 12 months after the completion of the two doses of vaccination to continue to provide protection for the human body.
The Israeli Ministry of Health has announced on July 12 that it will provide a third dose of the new crown vaccination for people with low immunity in the country.
With the increase in the number of people who have completed the two doses of vaccination, the British government has also begun to consider implementing the third dose booster plan as soon as possible.
According to the news released by the British Ministry of Health on June 30, the “Joint Committee on Vaccination and Immunization” of the independent government expert group recommended that the most susceptible population be given a third booster injection in September, so as to strengthen the treatment before this winter. Protection of some people.
But the British Ministry of Health also said that as data analysis continues, the final recommendations of the committee may change.
The United Kingdom is currently evaluating the effect of the new crown vaccine booster through clinical trials. It is expected that the research team will announce the preliminary results of this clinical trial in September this year.
A preprinted paper published by the US "Social Science Research Network" not long ago stated that Oxford University researchers used AstraZeneca vaccine as the research object and found that the third dose of the vaccine can greatly enhance the immune response.
But they also said that there is currently no indication that a third booster shot is needed, and they emphasized that the "priority" is to ensure that people all over the world receive the first dose of vaccine.
The World Health Organization also stated that there is currently insufficient evidence to show that a third dose of vaccine is needed.
Pharmaceutical companies such as Pfizer in the United States should focus on providing vaccines to countries that do not have the opportunity to obtain the first dose of vaccines, rather than boosting vaccines for those already vaccinated in wealthy countries.
Jay Butler, deputy director of the US Centers for Disease Control and Prevention in charge of infectious disease prevention, believes that for those who have been fully vaccinated, the third dose of the vaccine may bring a higher risk of adverse reactions.
But at this stage there is not enough data to determine whether this will happen.
The U.S. Centers for Disease Control and the U.S. Food and Drug Administration issued a joint statement on July 8 stating that Americans who have completed two doses of vaccinations do not need to receive the third dose at the moment. Also "ready."
Subsequently, the European Medicines Agency also issued a document saying that it is "too early" to determine whether and when the third dose of vaccine is needed.
Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said on July 11, “Given the data and information we currently have, we don’t need to vaccinate the public with the third dose (new crown vaccine).” “About whether and When should the intensive injection be given, many studies are being carried out now."