Jan 08, 2021 05:30 AM

Sinovac’s Covid Shot Proves 78% Effective in Brazil Trial

A box of Sinovac Biotech Ltd. coronavirus trial vaccine in Sao Paulo
A box of Sinovac Biotech Ltd. coronavirus trial vaccine in Sao Paulo

(Bloomberg) — An experimental vaccine developed by China’s Sinovac Biotech Ltd. was shown to be 78% effective against Covid-19 in late-stage Brazil trials, the most definitive result so far on the shot’s efficacy after previous data sparked confusion and doubt.

The protection rate, which was reported by the newspaper Folha de Sao Paulo Thursday and confirmed by Sao Paulo state officials, was derived from Sinovac’s most advanced phase III trials in Brazil, involving about 13,000 participants. The number is below the nearly 95% effectiveness reported for the mRNA vaccines developed by Pfizer Inc. and Moderna Inc.

Sao Paulo Governor Joao Doria is attempting to move quickly while the central government delays setting concrete vaccination dates. Almost 11 million doses of Sinovac’s vaccine, called CoronaVac, have already been shipped to the country. Doria, a political rival of Brazil President Jair Bolsonaro, plans to obtain swift approval and begin vaccinating the state’s 45 million people Jan. 25. Pressure from other governors led the health ministry to include the shot, which has been publicly shunned by Bolsonaro, in the country’s vaccination plans.

Conflicting and incomplete information from Sinovac’s trials last month created confusion over exactly how effective its shot is in protecting people from becoming sickened by the novel coronavirus. Researchers in Brazil delayed releasing complete data on the CoronaVac shot in late December, saying only that it was found to be more than 50% effective. Sao Paulo state Health Secretary Jean Gorinchteyn later said the vaccine “didn’t reach 90%” efficacy. Further confusing matters, Turkey said its trial showed an estimated efficacy rate of 91.25%, though that was based on only 29 cases.

Shore up confidence

The release of more definitive data on the vaccine’s effectiveness was delayed because the Beijing-based vaccine developer needed to reconcile results from different trials using varying protocols, according to a person familiar with the matter.

While Sinovac’s disclosure provides a clear picture of its vaccine’s effectiveness and should shore up confidence in countries like Indonesia and Brazil where it has inked supply deals, Chinese developers’ lack of timely and clear disclosures have contributed to a lack of trust in their inoculations.

China has already administered more than 4.5 million doses under emergency use authorization and is aiming to inoculate 50 million people against the virus by early February, before the annual Lunar New Year holiday.

Both Sinovac and state-owned developer China National Biotec Group Co., whose shot last week became the country’s first to be approved for the general public, have disclosed conflicting data on their vaccines. CNBG said its vaccine is effective in preventing Covid-19 in 79.3% of people, less than the 86% reported earlier from its trials in the United Arab Emirates.

600 million doses

Sinovac can make more than 600 million doses a year at its production facilities in China. The company has orders from countries involved in vaccine trials, including Brazil, Turkey and Indonesia, and will also supply Singapore and Hong Kong in addition to the Chinese mainland.

Sinovac and CNBG’s inactivated vaccines use a killed version of the coronavirus to stimulate the body’s immune response. They can be stored at refrigerator temperatures (2–8 degrees Celsius), making them potentially better choices for distribution and use in the developing world than the mRNA vaccines from Pfizer and Moderna that require deep freezing.

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