On the 7th, 8th and 9th of December, Butantan and Sinovac will promote the CoronaVac Symposium, a free online event that brings together international experts to present and debate scientific data on the efficacy and safety of the vaccine. Three researchers from Chile will attend to discuss their results, which prove that CoronaVac was able to prevent serious cases and deaths in the country, including in the elderly, and that it generates a high level of neutralizing antibodies against the original strain of SARS-CoV-2 and against its variants. The immunizing agent corresponds to 70% of the vaccines applied to the Chilean population.
On the first day of the symposium, at 9:20 am, the advisor to the Ministry of Health of Chile, Rafael Araos, professor at the Faculty of Medicine at Universidad del Desarrollo, will give a presentation on the effectiveness of CoronaVac in the country – that is, the proven effectiveness in the “real world”, considering adversities, not only in controlled clinical studies. Araos is a specialist in infectious diseases and coordinated a survey published in The New England Journal of Medicine, which found that the immunizing agent protects more than 86% against hospitalizations and deaths caused by Covid-19.
The cohort study (observational study that follows individuals over a period to determine characteristics and evolution of the group) was carried out with 10.2 million people aged 16 years and over between February and May 2021. The research also showed the effectiveness of CoronaVac in the elderly: 66.6% for protection against SARS-CoV-2 infections, 85.3% against hospitalizations, 89.2% against admissions to the Intensive Care Unit (ICU) and 86.5 % for the prevention of disease-related death.
Protection against variants
On the second day, at 10 am, researcher Alexis Kalergis, postdoctoral fellow in immunology and director of the Millennium Institute on Immunology and Immunotherapy in Chile, will speak about the safety and effectiveness of CoronaVac in healthy adults. A study coordinated by the scientist and published in the journal Frontiers of Immunology showed that individuals who took the two doses of the vaccine had high rates of seropositivity for neutralizing antibodies against the variants: above 97% for the original strain, over 80% for the variants alpha and gamma, over 75% for delta and over 60% for beta.
Another study published in the same journal looked at CoronaVac's ability to prevent severe cases of Covid-19. Of 2,263 fully vaccinated individuals, only 45 (1.99%) reported symptomatic infection after 14 days or more of the second dose. Of these, 43 people developed the mild form of the disease, one had moderate symptoms and the other severe symptoms requiring hospitalization. Both exceptions were adults over 60 years who had comorbidities.
Immunization of children
At 9 am on the last day of the symposium, scientist Susan M. Bueno, a professor at the Pontificia Universidad Católica de Chile and an associate researcher at the Millennium Institute on Immunology and Immunotherapy, will give a lecture on the effectiveness of CoronaVac in children and adolescents, already proven by clinical trials developed by Sinovac. Last week, Chile approved the use of the vaccine in children over three years of age – the immunizing agent had already been administered since September from the age of six, after the country's Public Health Institute analyzed data from the research of the Chinese pharmaceutical company.
Currently, Chilean scientists are conducting a phase 3 clinical trial to assess the efficacy, immunogenicity and safety of CoronaVac in children and adolescents aged six months to 17 years. The randomized, double blind, placebo-controlled study will be composed of 14,000 subjects. According to information from the Chilean government, preliminary research results indicate that children have greater production of antibodies than adults and fewer adverse reactions.