June 2, 2023

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SINOVAC COVID-19 vaccines: Insufficient resistance to some mutant strains

SINOVAC COVID-19 vaccines: Insufficient resistance to some mutant strains



SINOVAC COVID-19 vaccines: Insufficient resistance to some mutant strains.  The COVID-19 variant is too fierce? Chinese study found that SINOVAC (Kexing) inactivated vaccines have insufficient resistance to some mutant strains.

The new coronavirus mutates quickly, how effective is the inactivated vaccine against the mutant strain? A study by the Nanjing University Gulou Hospital team is worthy of attention.


SINOVAC’s inactivated vaccine is currently one of the new coronavirus vaccines currently used on a large scale in China, and it has been proven to be effective in preventing COVID-19 in a phase 3 clinical trial.


But nowadays, a variety of variants of COVID-19 have caused epidemics in different regions of the world. Among them, the main target of the neutralizing antibody-the S protein has mutations, and the effectiveness of humoral immune protection caused by vaccination may be reduced, which has aroused people’s concerns.


The Nanjing University Gulou Hospital team recently published a newsletter in the infectious disease sub-journal of The Lancet.


SINOVAC COVID-19 vaccines: Insufficient resistance to some mutant strains

Original title published in The Lancet Infectious Diseases Sub-Journal

They tested the neutralizing activity of the vaccine against a variety of new coronavirus variants on 93 health care workers who received two injections of SINOVAC vaccine, using a pseudovirus containing the S protein of the Wuhan wild-type virus as a control. These variants include D614G. , B.1.1.7 (first appearing in the UK), B.1.351 (first appearing in South Africa), P.1 (first appearing in Brazil), B.1.429 (first appearing in California, USA), B.1.526 (first appearing in California), B.1.526 (first appearing in South Africa) In New York, USA), no neutralization reaction was detected in the serum of subjects before vaccination.


After two injections of SINOVAC vaccine, 82% of subjects’ serum samples were able to neutralize wild-type pseudoviruses, which were equally effective against D614G, B.1.1.7 and B.1.429 mutant strains, but it was effective against B.1.526, B.1.526, The serum neutralization efficiency of P.1, B1.351 was significantly reduced, and only a small part of the subjects’ serum could achieve effective neutralization, and the neutralization efficiency of B.1.526, P.1, B1.351 was only 26 %, 34%, 5%.


Compared with the wild-type pseudovirus, the specific neutralization of E484K by IgG in the subjects’ serum was significantly reduced, which may be the reason for the immune escape of many mutant strains that produce E484K mutation.


Although E484K mutations occur in many new coronavirus variants, some variants, such as B.1.1.7 and B.1.429, can still be effectively neutralized by inactivated vaccines, while the neutralization efficiency of other variants is significantly reduced.


In this regard, the Nanjing University Gulou Hospital team emphasized that it is necessary to strengthen the surveillance of the virus, especially for the mutant strains with E484K mutations, to strengthen the evaluation of the effectiveness of the existing approved vaccines against the mutant strains, and to seriously examine the vaccine’s resistance to the mutant strains. Insufficient problem


(source:internet, reference only)

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