Vaccine Leak – Sinovac vaccine was 50.4% effective in Brazil

This was announced by the scientists of the Butantan Institute of Sao Paulo when requesting the emergency approval of the inoculant.

Sinovac vaccine was 50.4% effective in Brazil

The COVID-19 Coronavac vaccine showed an overall efficacy against the disease of 50.38 percent in large-scale trials in Brazil, the Butantan Institute of Sao Paulo announced on Tuesday.

The figure was released after the effectiveness of the inoculant was mired in controversy for a week. On January 7, the health authorities indicated that this oscillated between 78 and 100 percent. On Tuesday, they clarified that these figures apply to mild and moderate or severe cases, respectively, and that when taking into account those that do not require medical attention and are considered “very mild”, the general drops to 50.38 percent.

The trial of the vaccine, developed by Chinese pharmaceutical company Sinovac, began in July 2020 and involved more than 13,000 volunteers. All of them were health workers of legal age, which meant greater exposure to the virus.


218 people contracted the disease throughout the test. 158 of them had received a placebo and 60 the vaccine. The study did not take into account potential asymptomatic cases, which are believed to account for half of the COVID-19 cases globally.

The Butantan Institute requested the emergency approval of the vaccine from the health regulator Agência Nacional de Vigilância Sanitária (Anvisa), in order to start immunization on January 25. Indonesia is also preparing to begin inoculating its population with the Coronavac vaccine.

Although the effectiveness of CoronaVac is well below the success rate of more than 90% of vaccines from Moderna or Pfizer and its partner BioNTech, it is easier to transport and can be stored at normal refrigerator temperatures.

Sinovac also has supply agreements with Turkey, Chile, Singapore, Ukraine, and Thailand. In fact, Turkish researchers had announced in December that provisional studies showed that the inoculant was 91.25 percent effective in preventing infections.

It is not clear if these figures referred to mild and moderate or severe cases, such as those mentioned by the Brazilian authorities last week, or referred to the general efficacy, which would throw a wide discrepancy with the numbers reported this Tuesday in the South American country.

Anvisa has a period of ten days from the placing of the order to give its answer. The agreement between the Butantan Institute and Sinovac provides for the shipment of doses to Brazil and the transfer of technology for the local production of the vaccine.

Beijing has already sent 10.7 million doses and supplies to São Paulo to manufacture another 40 million doses. Days ago, Health Minister Eduardo Pazuello indicated that the country is in the process of closing an agreement for up to 100 million doses.

Brazil is one of the countries most affected by the pandemic globally. It has reported the third-highest number of positive cases – more than 8.1 million – and is only behind India and the United States. Additionally, it ranks second on the grim death list, with more than 203,500. The United States, with almost 378,000, is the only nation with the most deaths.

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