Recently, the Omicron strain continues to spread around the world, and there are still many scientific questions to be answered about such a devastating variant.
Although there are already more than a dozen vaccines in clinical use, in the face of new virus variants, a very urgent scientific question lies ahead, that is, whether these vaccines can prevent the Omiljun strain.
In response to the above problems, Gao Fu, director of the Chinese Center for Disease Control and Prevention, and other experts recently jointly released an academic paper in BioRxiv, and Omi kerong did have serious immune escape in the serum of recovered patients, but in vaccinators who received three-dose inactivated vaccines or protein subunit vaccines, neutralization activity was better preserved. Among them, the ZF2001 group remained 100% positive for the neutralization of the Omiljung strain, and the neutralizing antibody (NAb) titer was only reduced by 3.1 times.
Three doses of the vaccine are mostly useful
The COVID-19 pandemic continues to pose a threat to global public health, with the Opmi Kerong variant (VOC) mentioned on 24 November having been detected in 58 countries and territories. Because, its spike (S) protein has 32 mutations, including 15 mutations in the receptor binding domain (RBD), the immune escape of Omi kerong has attracted great attention.
As of December 2021, more than 8.4 billion doses of vaccines have been injected worldwide, of which more than 2.6 billion doses have been given in China. At present, inactivated vaccines such as CoronaVac of Kexing Group and BBIBP-CoV of Sinopharm Group, as well as protein subunit vaccines such as ZF2001 of Zhifei Bio, have been widely used in China and some other countries.
As a result, Gao Fu et al. tested conjugated antibody titers (ELISA) and neutralizing antibody titers (pseudoviral neutralization tests) on the serums of convalescent and vaccine recipients who received inactivated or protein subunit vaccines (CoronaVac, or BBIBP-CoV, or ZF2001).
Specifically, the researchers analyzed binding and neutralizing antibodies (NAbs) caused by the three-dose subunit vaccine ZF2001 or three-dose inactivated vaccine (CoronaVac or BBIBPCoV). Serum from ZF2001 vaccinators was also divided into two groups: one group had a shorter interval between the second and third doses (given at 0, 1, and 2 months) and the other group had a longer interval (around 0, 1, and 5 months).
Inactivated vaccine vaccinators were given a third dose more than 6 months after the second dose, and the binding antibody to the prototype (WH-01) or Omilon's trimer S protein was analyzed by elisa.
In addition, the researchers tested serum samples against SARS-CoV-2 prototypes and VOCs including Omikeron neutralizing antibodies (NAbs) using pseudoviral neutralization. Fifteen of the 16 serum samples from recovered patients tested negative for Omilon neutralizing antibodies, indicating that Omilon's immune escape was severe, consistent with other recent unpublished serological and monoclonal antibody analyses.
According to this trial, Omi kerong did have severe immune escape in the serum of recovered patients, and 15 out of 16 people were neutralized negative. In contrast, most of those who received the three-shot inactivated vaccine or protein subunit vaccine were able to maintain a neutralizing effect on Theomexon.
Extend the interval between the second and third stitches
In particular, the article mentions that in the ZF2001 group, the second and third injections were extended (4 to 6 months), remained 100% positive in the neutralization of the Omiljung strain, and the neutralizing antibody (NAb) titer was only reduced by 3.1 times.
62.5% of those who had received three doses of inactivated vaccine, 56.25% of ZF2001 (0, 1, 2 regimens) and 100% of ZF2001 (0, 1, 5 regimens) were positive for Omikeron neutralizing antibodies. As for neutralizing antibody titers, the serum group of recovered patients declined 17.4 times from prototype to Omilon. The inactivated vaccine group was reduced by a factor of 5.1, the ZF2001 (0,1,2) group by a factor of 10.6, and the ZF2001 (0,1,5) group had only a 3-fold reduction in the NAB titer of Omikeron.
In addition, as reported above, a longer interval between the second and third needles can cause higher antibody titers and better neutralization of all variants.
●According to the data, on March 24, 2021, The Lancet reported the results of the Phase 1 and Phase 2 clinical trials of the recombinant protein subunit vaccine (ZF2001) developed by Anhui ZhifeiLongkema Biopharmaceutical Co., Ltd., a subsidiary of the Institute of Microbiology of the Chinese Academy of Sciences and Zhifei Biologics (300122). The trial results showed that the vaccine was safe and there were no serious adverse events associated with the vaccine, and 97% of the enrollees who received 3 doses of the 25 μg vaccine produced neutralizing antibodies that could block the live virus, and the level of neutralizing antibodies exceeded the serum of recovered patients; in the same month, the State Drug Administration organized a demonstration to agree to the emergency use of the vaccine.
Based on the above findings, the researchers were prompted to consider that multiple intensifications and extensions of the time interval between vaccinations may be beneficial in dealing with variants of severe variation, such as Omilon. This is consistent with studies of mRNA vaccines, which have shown that people who received three doses of the vaccine were more likely to maintain a neutralizing effect on the Omilon variant.
In this case, the researchers note that people who have already had two injections or who have been infected with SARS-CoV-2 should be advised to undergo booster injections. For vaccines like ZF2001 that already have a three-dose regimen, extending the interval between the second and third doses would be beneficial, and multiple boosting strategies that promote immune maturation would facilitate neutralizing antibodies against destructive variants such as the Omiljun strain. At the same time, a next-generation COVID-19 vaccine with broad protection is also needed, but more real-world data is needed to make accurate judgments.
(Editor-in-charge: Zhang Qianye)
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