On May 25, residents in Lane 200, Zhaohua East Road, Changning District, Shanghai, waited in the outdoor observation area after being vaccinated. Photography/Yin Liqin
Should the fourth shot be given? How to type
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As large-scale infections driven by Omicron and its various mutant subtypes spread around the world, the effectiveness of the original new crown vaccine has declined to varying degrees. A clinical trial published in The Lancet showed that after two doses of the Johnson & Johnson adenovirus vector vaccine and one dose of the Pfizer vaccine as a booster shot, the vaccine effectiveness dropped to 8.8% after 25 weeks; even after three doses Pfizer 's mRNA vaccine, after 10 weeks, the effectiveness of the vaccine is still not high, falling to 45.7%. When dealing with the original strain of the virus, the effectiveness of one shot of the mRNA vaccine is as high as 90%. Under such circumstances, more and more countries have begun to plan or launch the fourth dose of the new crown vaccine, including Japan, Italy, the United Kingdom, Israel, Singapore, Denmark and Chile. As BA.5 takes hold in Israel, Israeli experts say the possibility of including a fifth shot for the elderly and immunocompromised people should be considered.
On January 3 this year, the Israeli government launched a project to vaccinate high-risk groups with the fourth dose of the Pfizer vaccine. People over 60 years old or with immune deficiencies can be vaccinated 4 months after the third injection. So far, more than 700,000 people in Israel have received their fourth dose of the Pfizer vaccine.
In March of this year, the results of a study released by Israel's Sheba Medical Center included data from more than 1.25 million subjects over the age of 60 who had received at least three doses of the Pfizer vaccine. Research results show that after receiving the fourth dose of the Pfizer vaccine, the infection rate and severe disease rate of COVID-19 are lower than those after only receiving three doses of the vaccine. Research also shows that the infection-preventing effect of the fourth dose of the vaccine is short-lived, and the effect of preventing severe disease is not diminished.
It is worth noting that so far, the fourth shot of the Pfizer vaccine administered in Israel was not specifically developed for the Omicron strain . At the end of January this year, Pfizer/BioNTech revealed that it had launched clinical trials of a new coronavirus vaccine specifically targeting the Omicron strain. But so far, the two companies have not released relevant experimental data or results.
"Judging from the attenuation speed of antibodies in the body after vaccination, booster shots need to be vaccinated every year." Chen Xi said, but this is not for all age groups. Specifically, in the United States, you are eligible for a second booster dose if you are 50 years or older and 4 months or older since your first booster dose, or if you are 12 years and older and have an immune-compromising condition. Currently, people in the United States over the age of 65 and those with underlying diseases are recommended to receive the fourth shot. The optimal time for vaccination is in autumn and winter. Chen Xi said that this is because autumn and winter are also high-incidence periods for influenza and influenza, and vaccination with the second booster dose can prevent medical resources from being overburdened. Moreover, this time point was chosen because the antibodies in the vaccinators have dropped to a certain level and need to be strengthened.
Jin Dongyan pointed out that for the country, vaccination with three shots of the inactivated vaccine is a basic plan. As for whether and what kind of fourth shot should be given, it depends on further disclosure of specific data. There is no specific data on the fourth shot of the inactivated vaccine. The top priority right now is to get the third shot. “The domestic third shot vaccination rate has not yet reached a very high level.”
Jin Dongyan said that if the second-generation vaccine against Omicron is used as a fourth booster in the future, the effect will naturally be better than the existing vaccine, because it is "prescribing the right medicine." Domestic elderly people over 60 years old and people with immunodeficiency can consider getting the fourth shot. In the future, it may be developed to determine whether the shot is needed by measuring the antibody level in the body.
A domestic public health expert who did not want to be named told " China News Weekly " that according to his understanding, several domestic research and development pipelines are stepping up the development of new second-generation vaccines against the Omicron strain, but he does not know whether Can we get the results before October?
On May 31, Hong Kong University School of Medicine and Sinopharm announced a cooperation to launch a clinical trial of the second-generation Omicron strain vaccine to study the safety and immune response of the vaccine as a booster in adults, with a target recruitment of 1,800 people. Adult volunteers who have received two or three doses of inactivated or mRNA COVID-19 vaccine. According to Jin Dongyan’s understanding, the above-mentioned clinical trials should disclose relatively complete data in 2 to 3 months. By then, it will be autumn and winter, and this vaccine is expected to be useful.
On June 8, Moderna announced the interim clinical results of the bivalent vaccine under development against the Omicron strain and the original strain. Research results show that when this vaccine is used as the fourth dose, the increase in the neutralizing antibody against the Omicron strain is 1.75 times higher than that of the original vaccine. Moderna also mentioned that the vaccine was generally well tolerated as a booster shot, with side effects comparable to the original vaccine at the 50 microgram dose level.
From the current point of view, the vaccination rate of booster shots for the elderly in China is far from enough. Chen Xi believes that the fourth shot of the vaccine is more targeted at those elderly people who are at high risk of infection or have underlying diseases. The subsequent development of the second-generation vaccine against the Omicron strain has entered the clinical phase III and needs to include a large number of subjects. After the epidemic is brought under control in China, there will be a shortage of personnel to participate in clinical trials. If you choose to conduct clinical trials abroad, there will also be problems such as racial disparities and fewer high-risk and elderly people with underlying diseases abroad.
Vaccine demand encounters "bottleneck"
Chen Xi analyzed that now vaccine companies are more on the sidelines. When factors such as the emergence of new variants and rising case fatality rates, the corresponding market size of the new coronavirus vaccine will naturally grow. Manufacturers will adjust the vaccine through genetic sequencing and invest heavily in research and development. Otherwise, companies will most likely choose to "stand still."
On June 15, local time, the U.S. Food and Drug Administration approved the vaccination of children 6 months to 5 years old with the mRNA COVID-19 vaccine developed by Pfizer and Moderna, which means that the vaccination group for the COVID-19 vaccine will be expanded to approximately 19 million people in the United States. Suitable for infants, toddlers and preschool children. But Chen Xi believes that this market is limited. He revealed that the United States had conducted an internal survey and found that less than one-third of parents were willing to vaccinate their children under the age of 5 against the COVID-19 vaccine.
"In Germany, the bivalent vaccine against Omicron is expected to be released in September this year, but it is unlikely that large-scale universal vaccination will follow." Lu Mengji believes that if this time point is missed, even if the subsequent vaccine is launched, the significance will be the same. The value will also be greatly reduced. In Lu Mengji's view, the emergence of the above-mentioned second-generation vaccines will definitely play a role in promoting the market, but in the long run, this role will gradually fade because the impact of the new coronavirus will gradually decrease. "For most people, the fourth dose may be the upper limit."
"The vaccine market with a large influx of capital is more like a short-lived phased thing. If the technology itself has no long-term competitiveness, for these vaccine manufacturers, this wave of dividends will dissipate sooner or later. For those whose production capacity has reached a certain level, For enterprises, the damage will undoubtedly be huge under the trend of shrinking demand," Lu Mengji said.
Many people believe that the new coronavirus epidemic may eventually become an endemic disease. In a large-sample study led by , Zhang Wenhong, and others, it was mentioned that in the face of the highly transmissible Omicron virus strain, the most important thing is to identify patients with mild symptoms, identify vulnerable groups, and take measures to deal with vulnerable groups. A series of protective measures, including adequate vaccine coverage and special protection for vulnerable groups during the epidemic period, will be able to significantly and continuously reduce the severe illness rate and mortality rate of vulnerable groups, and minimize the harm caused by Omicron. .
Source: China News Network
Editor: Intern reporter Zhao Xinqiu
