The third dose of CoronaVac is capable of maintaining the neutralizing antibodies against Covid-19 high for at least a year and, when administered eight months after the second dose, can provide a long-term immunity in relation to the primary vaccinal scheme. These are some of the conclusions of the study shared by the researcher Hongjie Yu, from the Fudan University in China, during the last day of the CoronaVac Symposium, that happened this Thursday (9).
“The homologous reinforcement is capable of generating long-term immunity and higher antibodies levels, but extra studies must be made”, punctuated the scientist. Online and free , the event is an initiative from Butantan and Sinovac and discusses the main researches and discoveries regarding CoronaVac with specialists from several countries.
The study presented by Hingjie Yu evaluated the immunogenicity of CoronaVac between healthy adults from 18 to 59 years of age and eldery (over 350 people), analyzing the administration of the third dose of CoronaVac two months after the second dose and eight months after the second dose.
According to Yu, the study revealed that a third dose given until two months after the second dose generated a moderate increase in the immunity of adults from 18 to 59 years of age, but the neutralizing antibodies decreased close to the seropositivity limit six months after the third dose. On the third dose given after six months, however, the decrease of the neutralizing antibodies happened at a minor level in adults that had up to 59 years of age. But when the third dose of CoronaVac was administered eight months after the second dose, the titer levels of antibodies (GMT) increased.
On elderly the research pointed out that the levels of neutralizing antibodies decreases to a limit smaller than the seropositive six months after the second dose. But when the third dose was administered eight months after the second dose, there was an increase of antibodies to a limit higher than after the second one.
Yu emphasized that the study did not report any adverse effect among the volunteers. “The second dose of CoronaVac causes a good immunological memory that decreases to a level similar to a seropositive individual after six months. But the administration of a third dose from CoronaVac eight months after the second dose generates a great boost in immunity”, said the chinese researcher.