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Third dose of CoronaVac regains the protection of neutralizing antibodies in 20 times, affirms chinese researcher

Publicado em: 01/01/1970

The booster dose of CoronaVacinactivated virus vaccine from Butantan and Sinovac, increases in about 20 times the levels of neutralizing antibodies, capable of not only fighting the original strain of SARS-CoV-2 but all the variants, including the new variant omicron. This is what was declared by the scientist Xiangxi Wang, the main researcher of the Infection and Immunity Lab of the Biophysics Chinese Institute of Sciences during the second day of CoronaVac Symposium this wednesday (8).

The science already concluded that, six months after the second dose of the vaccine, the production of neutralizing antibodies decreases in relation to all the immunizings. Besides, according to the researcher, the mutations on the Spike protein contained in the variants promote resistance to the vaccine. “A plausible alternative to solve this question is to administer the third dose of the vaccine between six and twelve months after the second dose, to improve and extend the protection”, affirmed the researcher.

Analysis conducted in the lab with the plasma of individuals that received the booster dose of CoronaVac proved that the third dose is capable of regenerating the production of neutralizing antibodies, raising in 17 times the level of antibodies against the variant delta and against the original strain of Wuhan, in 18 times against the variant alfa, in 19 times against the beta and in 14 times against the gama. “The titration of neutralizing antibodies maintained a stability after six months of the booster dose” emphasized Xiangxi.

The researcher also analyzed more than 200 complex structures of the coronavirus and investigated places of linkage of the six types of neutralizing antibodies anti-RBD (subdominium of the S protein from the virus). The first three kinds of antibodies, which were predominant during the beginning of the immunization, were not capable of recognizing the variants.

Opposite to that, the other three kinds of antibodies recognized the epitopes and demonstrated high neutralization against the variants, including the omicron, that contains 30 mutations in the Spike protein. “These antibodies are significantly increased after the booster dose. So, the extra dose leads to a quick and long term recuperation of the humoral immunity”, explained.