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The data of booster shot of SINOVAC (Kexing) COVID-19 Vaccine is released.
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The data of booster shot of SINOVAC (Kexing) COVID-19 Vaccine is released. How is the protection effect? Is vaccination necessary?
Although several types of COVID-19 vaccines are being deployed globally on a large scale, it is reported that after vaccination, new SARS-CoV-2 variants (B.1.1.7, B.1.351, P.1) And B.1.617.2) There is still a risk of infection.
And within 6-12 months after vaccination, the immune protection against SARS-CoV-2 generally declines.
Is the third dose of vaccine really protective at some time between 6 and 12 months after the second dose of vaccination? Is the human body’s resistance to the mutant strain better after the third dose of vaccination?
On September 5, 2021, Wang Xiangxi’s team from the Institute of Biophysics of the Chinese Academy of Sciences, together with Fudan University, Peking University and SINOVAC, published an article titled “A third dose of inactivated vaccine augments the” on the preprint platform medRxiv. Potency, breadth, and duration of anamnestic responses against SARS-CoV-2″ research paper, the study through the collection and comprehensive testing of blood samples inoculated with 3 doses of SINOVAC COVID-19 vaccine, and concluded:
1. The third dose of inactivated vaccine can enhance the body’s ability to effectively resist the COVID-19 variant strain.
2. After the third dose of booster vaccination, the neutralizing antibody maintains in the body for a longer time.
Increased neutralizing antibody response after booster vaccination
In order to assess immune function, the researchers recruited 22 COVID-19 recovered patients, 6 healthy subjects (SARS-CoV-2 negative, confirmed by RT-PCR) and 38 received 2 or 3 doses of SINOVAC inactivated vaccine Of volunteers.
The measurement of plasma neutralization activity showed that compared with two doses, the neutralization activity of wild SARS-CoV-2 after three doses was about 60% higher, which was 20% higher than that of recovered patients.
Compared with WT, for blood samples from recovered patients, 2-dose and 3-dose vaccinators, the neutralization titer for B.1.351 was reduced by an average of 7.7 times, 5.7 times, and 3.0 times, respectively.
Similarly, the reduction folds of the neutralization titer against P.1 and B.1.617.2 in the three groups of blood samples were 5.3 times, 4.3 times, and 3.1 times, and 5.3 times, 3.7 times, and 2.3 times, respectively.
This fully shows that after the third dose inoculation, not only the neutralization response to wild SARS-CoV-2 can be enhanced, but the neutralization response to the mutant strain is also greatly improved.
Humoral immune response is enhanced after booster vaccination
The S-specific IgA, IgM and IgG titers and the neutralizing activity against SARS-CoV-2 variants were monitored before and 4 weeks after the third immunization. Six months after the second vaccination, about 80~90% of the anti-S IgG titers against WT decreased, while the third vaccination of SINOVAC vaccine increased these titers by nearly 20 times after 4 weeks.
In order to further characterize the rapidity, lifespan, and immune dynamics of the immune memory response stimulated by the third dose, the researchers determined the neutralizing efficacy at 0, 7, 14, 28, 90 and 180 days after the third dose of vaccination. .
It is worth noting that the NAb titer soared by 8 times (from 7 to 53) in the first week, and reached a peak of 25 times (up to 177) in the second week after the third boost, and with the passage of time decline slowly.
It is worth noting that 180 days after the third boost, the NAb titer remained around 60, which was comparable to the high-level NAb titer caused by the 2 doses. This indicates that after the booster vaccination, not only the humoral immune response is enhanced, but the time that the neutralizing antibody is maintained in the body is also greatly prolonged.
Recently, the B.1.617.2 variant has led to another surge in COVID-19 cases worldwide, accounting for about 90% of new cases in the UK and more than 40% of new cases in the United States. More and more studies have shown that the effectiveness of VOC is related to the state of full vaccination and the time elapsed after vaccination. Due to the decline in immunity, the effectiveness of the vaccine begins to decline several months after vaccination.
The results of this article show that the third booster of inactivated vaccines can trigger a rapid, powerful and long-lasting humoral response. With the continuous accumulation of somatic mutations, the emergence of new clones and the increasing affinity of antibodies to antigens, this The humoral response will continue to develop, thereby enhancing the effectiveness and breadth of neutralization.
In general, these research results prove that the vaccination schedule for the third dose of vaccine is reasonable.
(source:internet, reference only)