Brazil finds disappointing 50.4% efficacy for China’s Sinovac vaccine

The Chinese vaccine Coronavac developed by Sinovac Biotech is 50.4% effective in preventing symptomatic infections according to a Brazilian study, just enough to pass the regulation and well below the rate recently announced by the Butantan Institute based in São Paulo.

New ‘general efficacy’ figure comes after pressure for more transparency.

The results are certainly disappointing for Brazilian health authorities who have relied on the vaccine developed by Oxford University and AstraZeneca Plc, and the Chinese vaccine to initiate immunization during the second wave of the COVID-19 epidemic.

Many scientists and observers have lashed out at the Butantan biomedical center which had released partial data in recent days, generating unrealistic expectations.

Last week, Brazilian researchers celebrated results that showed 78% effectiveness against cases considered mild to severe of COVID-19.

Ricardo Palácios, medical director of clinical research at Butantan, said the lower efficacy rate was caused by the inclusion of patients who were infected with the novel coronavirus but showed only “very mild” symptoms.

Turkish authorities last month claimed CoronaVac was 91.25% effective, while Indonesian authorities said it had 65% effectiveness.

The COVID-19 vaccines in use manufactured by Pfizer Inc with BioNTech SE and Moderna Inc are approximately 95% effective in preventing the disease.

More than 200,000 people have died in Brazil from the coronavirus, the second-largest death toll after the United States.

Featured image: São Paulo State Secretary of Health Jean Gorinchteyn (left) and Instituto Butantan chairman Dimas Covas (right) holding single-dose prefilled syringes of CoronaVac, part of the fourth shipment of Sinovac-manufactured vaccine to arrive in Brazil (source)