The CoronaVac COVID-19 vaccine developed by China’s Sinovac Biotech Ltd showed efficacy between 50 percent and 90 percent in Brazilian trials, Sao Paulo's state health secretary said, and its Brazilian producer said full trial results will be released by January 7.
Results of trials in Brazil are known exclusively by Sao Paulo state's Butantan Institute biomedical research center, which has an agreement with Sinovac to produce the vaccine, said health secretary Jean Gorinchteyn.
First trials showed efficacy above 50 percent, the minimum required by Brazilian health regulator Anvisa, and below 90 percent, Gorinchteyn said in an interview with CBN radio aired late on Thursday.
At Sinovac's request, Sao Paulo's health department has not received the Chinese drugmaker's full trial results, he said, adding that the company will review the data before announcing final results.
Butantan will disclose the data trial results in up to 15 days, or by Jan. 7, the institute said in a note on Friday.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
The South American country has registered 7,448,560 confirmed coronavirus cases and 190,488 deaths from COVID-19, the country's Health ministry said on Friday.
On Wednesday, Butantan had declined to specify the efficacy rate from a trial with 13,000 volunteers, citing contractual obligations with Sinovac, raising questions about transparency.
The CoronaVac vaccine showed 91.25 percent efficacy in Turkey, according to an announcement on Thursday of interim data from a late-stage trial in the country.