The new crown vaccination has exceeded 400 million doses. Did you get the second shot?
Pay attention to the new crown vaccination
According to the official website of the National Health Commission, as of May 16, 2021, 31 provinces (autonomous regions and municipalities) and the Xinjiang Production and Construction Corps have reported a total of 406.9938 million doses of COVID-19 vaccine.
More than 400 million doses of new crown vaccination!
In addition to vaccination with only one injection of adenovirus vector vaccine, many people have entered the "time window" for the second injection.
Among people who have been or will be vaccinated, the interval between the first and second shots of the new crown vaccine varies: among those who were vaccinated at the beginning of the year, many people were vaccinated at 14 days intervals; March 29 The Technical Guidelines for Vaccination (First Edition) also stipulates that the recommended interval between two injections of inactivated vaccine is 3-8 weeks, and the recommended interval between two adjacent injections of recombinant protein vaccine is 4-8 weeks. The injection is best completed within 6 months after opening the vaccination.
What is going on with these intervals of varying lengths?
What effect does the interval length have on the efficacy of the new crown vaccine?
Research shows that the effect is better after 3 weeks
The second dose of the new crown vaccine changed from the original shortest interval of 14 days to the completion of the vaccination within 3-8 weeks. Why?
In response to this problem, Zhu Fengcai, a clinical vaccinology expert and deputy director of the Jiangsu Provincial Center for Disease Control and Prevention, replied to the reporter of Science and Technology Daily: The effect will be better.
Under different vaccination procedures, the effect of vaccines in stimulating antibodies can be obtained by designing clinical trials, for example, by testing relevant data including the concentration of neutralizing antibodies.
"The protection efficiency of vaccines will be affected by many factors including vaccine immunization procedures. We have indeed observed in Phase III clinical trials that if a longer vaccination interval is used, the protection effect may be better." Kexing Holdings Biotechnology Co., Ltd. spokesperson Liu Peicheng said that although the immunization program in the clinical research phase was a 14-day interval program, the follow-up adjustment is a recommended vaccination program of more than 3 weeks.
Sinopharm Sino Biotech has also explored different vaccination procedures and different vaccination doses in the clinical trial phase. The results also show that the effect is the best at intervals of 3 and 4 weeks, with the durability of immunity, the level of antibody positive, and the average antibody All indicators such as value are better than the interval of one week and two weeks.
It’s a response in one or two days, so why don’t you continue to plant for three or four weeks?
So why is there a difference between two weeks and three weeks?
Many people may be wondering: The response occurs within a day or two after the first injection. Why does it take several weeks for the antibody to work?
In fact, after the vaccine enters the body, many things happen in the cells, including telling the body that there is an invasion (vaccine is a harmless invasion that mimics a virus), starting to produce antibodies, screening the most effective antibodies, and mass-producing antibodies, etc. Many steps.
The entry of the vaccine initiates a series of chain reactions in the body.
B cells recognize antigens and transform themselves into "plasma cells", which can produce a large amount of neutralizing antibodies.
However, there are usually very few such plasma cells. At a critical moment, the momentum of "many and powerful" must be formed. B cells first proliferate by themselves and produce a large number of cells that can produce antibodies.
Subsequently, these cells began to produce antibodies.
These work cycles with full horsepower are relatively long.
The body feels fatigued and has mild cold symptoms because the immune cells just recognized that there is an infection in the body at that time, and sound the "assembly number" by releasing type I interferon to gather the existing "guard".
This process is relatively short.
A basic immunologist explained to a reporter from Science and Technology Daily that the massive production of type I interferon is one of the important factors that make people feel tired.
It can be seen that fatigue response and the production of neutralizing antibodies are two different processes.
The former is more like the rapid assembly of "frontier troops" for early-stage resistance, while the latter includes the entire process of conscription, military training, and targeted assembly to form specific batches of neutralizing antibodies against the new coronavirus.
Knowing what changes have occurred when the vaccine enters the body, it is not difficult to understand why the second shot will not be in vain even if it is overtime. There is no need to start the vaccination again, because the specific neutralizing antibodies in the body have already been produced, and the second shot just urges the immune system to restart. Work harder.
It is also for this reason that a slightly longer and shorter interval between the two doses will not have a particularly large impact on the protective efficacy of the vaccine.
In general, according to the results of the existing phase III clinical trials, the inactivated vaccine can produce high-titer antibodies 14 days after the completion of all two injections, forming effective protection, and the positive conversion rate of neutralizing antibodies in the whole population reaches 99%.
Group vaccination arrangements require comprehensive scheduling
The herd immunization strategy of the new crown vaccine requires overall coordination work involving many aspects such as vaccine production, vaccination services, and vaccination organization.
To produce such a large number of vaccines in a short time, not only the production work needs to be completed in an orderly and intense manner, but also the scheduling and vaccination work deployment must be implemented in an organized manner.
Therefore, the public may experience a slightly longer interval compared with the interval between doses when the second dose is inoculated.
In response to the public's complaints about the difficulty of the second dose of vaccine, Wang Bin, the inspector of the National Health Commission’s Disease Control Bureau, said at the press conference of the State Council’s Joint Prevention and Control Mechanism that the second dose of vaccine is relevant. On the one hand, the department prioritizes the need for the second dose of vaccine when formulating the vaccine distribution plan. On the other hand, in accordance with the requirements of the "New Coronary Vaccination Technical Guidelines (First Edition)", the second dose of inactivated vaccine can be The first dose of vaccination will be completed within 3-8 weeks. Under special circumstances, the vaccines of different manufacturers with the same technical route can be replaced.
Our reporter Zhang Jiaxing