Recently, the adenovirus vector recombinant new crown vaccine, which only needs one injection in the whole process, has begun to be vaccinated in Shanghai.
With the steady progress of COVID-19 vaccination, more and more people are joining the ranks of vaccination. Many people have such a question, what is the difference between 1, 2 and 3 doses of the new crown virus vaccine?
Data chart Courtesy of Xinhua News Agency
1 dose of vaccine:
On May 16, it was learned from the Shanghai Municipal Center for Disease Control and Prevention that since May 13, all districts in Shanghai have begun to supply the vaccine. The vaccine was developed by CanSino Biologics in collaboration with the team of Academician Chen Wei of the Institute of Biological Engineering of the Academy of Military Medicine of the People's Liberation Army Academy of Military Sciences of Chinese, and was the first clinical study in the world on March 16, 2020. On February 25 this year, the vaccine was approved by the State Drug Administration for conditional marketing in China.
The Shanghai Municipal Center for Disease Control and Prevention revealed that compared with the three inactivated vaccines of the new crown virus used in Shanghai before, the adenovirus vector vaccine produced by CanSino is completely different in terms of technical principles and vaccination procedures, but it is the same in terms of vaccination method, vaccination age range and safety.
The first is that the technical principle is different, the adenovirus vector of this vaccine is to eliminate the gene associated with replication in the adenovirus (here the human adenovirus type 5, Ad5) is eliminated, so that the virus does not replicate in the human body. Then insert the gene for the new coronavirus spike protein (S protein) into it. This new insert gene allows the reassembled virus to enter the human body, can replicate the new crown virus spike protein in the body, our immune system will start the immune response after discovering the spike protein, while remembering what it looks like, the next time it encounters the real new crown virus, it will immediately react to clear them.
This technology has previously been successfully used by Academician Chen Wei in the research and development of Ebola virus vaccines.
Image courtesy of Shanghai CDC
The inactivated vaccine of the new crown virus that we are familiar with is to directly make the new crown virus lose its infectivity and replication through chemical and other methods, while retaining the active part that can cause the human immune response.
Secondly, the vaccination schedule is different, the basic immunization of the adenovirus vector vaccine is 1 dose (0.5 ml); the current recommended basic immunization procedure for the new crown virus inactivated vaccine is 2 doses (0.5 ml per dose), and the interval between vaccinations is recommended to be 3-8 weeks. Data from the phase III clinical trial of adenovirus vector vaccine showed that after 28 days of single vaccination, the total protective efficacy of the vaccine against all symptoms was 65.28% and the protective effect against severe disease was 90.07%. Judging from the results of the current neutralizing antibody crossover experiment, the vaccine has a protective effect on the mutant strain.
However, the Shanghai Municipal Center for Disease Control and Prevention revealed that this vaccine is the same as the previous three inactivated vaccines in terms of vaccination method, age range and safety, and the vaccinators are injected with deltoid muscle in the upper arm, and the applicable objects are 18 years old and above.
At the same time, whether from the results of clinical trial studies, emergency use studies, and post-marketing monitoring, COVID-19 vaccines, including adenovirus vector vaccines and inactivated vaccines, have been conditionally approved for marketing, and have good safety. After vaccination, the adverse reactions are the same as other vaccines, mainly redness, swelling, induration, pain, etc. at the vaccination site, but also fever, fatigue, nausea, headache, muscle soreness and so on. Generally, no special treatment is required, and if necessary, the vaccination site can be contacted, and the latter will give disposal guidance.
Experts from the Shanghai Municipal Center for Disease Control and Prevention said that the vaccination contraindications to this vaccine are similar to the three inactivated vaccines used in Shanghai before, but it is particularly important to remind that patients with self-immune system diseases such as HIV infection, scleroderma, dermatomyositis and lupus erythematosus are not recommended at this stage.
At the same time, diabetic patients and those with a history of convulsions, epilepsy, encephalopathy or psychiatric disease or family history should be used with caution; those with asthma should be used with caution; patients with thrombocytopenia and any coagulation dysfunction, intramuscular injection of this product may cause bleeding, need to be used with caution.
How long can the protective effects of adenovirus vector vaccines last?
The Shanghai Municipal Center for Disease Control and Prevention revealed that the effectiveness data collected so far prove that the protection time of the Cansino adenovirus vector vaccine can reach more than 6 months, and because the vaccine development time is not long, the continuous observation of the durability of vaccine immunity is still in progress. Previously, immune persistence observations of Ebola vaccines using the same adenovirus vector technology showed that they were still adequately protected after two years of vaccination.
Shanghai municipal disease control experts suggest that those who have received 1 dose of inactivated vaccine are recommended to use inactivated vaccine to complete the whole process of vaccination; those who have completed 2 doses of inactivated vaccine are not recommended to use adenovirus vaccine to strengthen.
In addition, experts also recommend that the vaccine is not recommended to be vaccinated with other vaccines at the moment. The interval between other vaccines and COVID-19 vaccines should be greater than 14 days. When rabies vaccine, tetanus vaccine, immunoglobulin are required for animal injuries, trauma and other reasons, the interval between vaccination and the new crown virus vaccine may not be considered.
2 doses of vaccine:
The COVID-19 inactivated vaccine (Vero cells) requires 2 doses: the interval between doses is recommended ≥ 3 weeks, and the second dose is completed as early as possible within 8 weeks. That is, the second dose is completed within 21 to 56 days after the first dose.
3-dose vaccine:
The recombinant COVID-19 vaccine (CHO cells) requires 3 doses: the interval between the adjacent 2 doses is recommended ≥ 4 weeks. The second dose should be completed within 8 weeks after the first dose and the third dose should be completed within 6 months after the first dose.
Popular explanation: the immune system is equivalent to a kindergarten child, and the virus is equivalent to a bad person, as a policeman (vaccine researcher), how can you let your child know the bad guy in a safe situation?
1 injection
Adenovirus vector vaccine
The policeman uncle pretended to be a bad guy to recognize the child. That is, in the kindergarten to do exercises, the police uncle disguised as a bad guy, as far as possible to imitate the characteristics of the bad guy, so that the children can identify.
Inactivated vaccines
Confess the body of the bad guy to the child. It is to use high temperature or chemical methods to kill the virus, and then inject the dead virus into the human body to see if you can know him.
2 injections
3 injections
Recombinant COVID-19 vaccine
It's the equivalent of showing children pictures of bad guys. This is easy to understand, the bad guy has many characteristics, such as this bad guy has small eyes, a big beard, a bald head, and a scar on his face. We send these pictures to the children for them to recognize.
How do I choose?
Domestically produced COVID-19 vaccines have been approved for use by the management department.
The clinical trial data of China's new crown virus vaccine and the occurrence of adverse reactions after hundreds of millions of doses have been vaccinated at home and abroad have shown that China's new crown virus vaccine is very safe. There is no need for everyone to deliberately wait for a long time in order to choose which new crown vaccine brand, missing the best time to vaccinate, after all, one day earlier vaccination, one day earlier benefits.
Source: Healthy Hebei Guanwei
Source: Beijing Radio and Television Station