Sinovac Vaccine: Data show 100% effectiveness in preventing severe cases

The Chinese company Sinovac's Covid-19 vaccine is 100% effective in preventing severe and moderate infections, 77.96% effective in preventing mild cases and has an overall efficacy of 50.4%, according to the results of Brazil's final-stage trials released by researchers.

Experts said the result was acceptable keeping in mind that almost all participants in Brazil were high-risk medical workers, reports The Star of Malaysia. 

The 77.96% efficacy in mild-cases means that the vaccine can reduce 78% of people from needing hospitalization, according to vaccine experts. 

"The vaccine was able to 100% prevent severe illness in such a high-risk population, and effectively control the morbidity, and protect at least 50% of people from infection, which is good enough," Wang Guiqiang, director of the Infectious Disease Department at Peking University First Hospital, told the Global Times of China on Tuesday.

"Currently, the manufacturer [CoronaVac] requires a 0-14 vaccination doses program [second dose 14 days after the first one], but this probably cannot bring the highest level of antibody which then partly lowered the efficacy result. That's why some manufacturers ask for a 0-21 vaccination program. But overall, its protective effects in such a high-risk population is good enough," Wang emphasized.

The most common systemic effects were headache and myalgia and even those were mild and did not affect the participants' daily routine.

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Notably, there were no severe events associated with the Sinovac vaccine.

Dimas Covas, director of the Butantan Institute, which cooperates with Sinovac on the Brazil trials, during a news conference on Tuesday said adverse events were very rare.

A higher efficacy will be seen in community use, he remarked. 

The Sinovac vaccine will have a very high effectiveness among the general population, he added. 

The authorities concerned have been conducting phase III clinical trials of Sinovac’s vaccine in Brazil, Indonesia and Turkey. These countries have designed different clinical plans based on their own domestic conditions. 

Vaccines from the same batch and immunization schedule achieved different results of efficacy — 91.3% in Turkey; 100% protection against severe symptoms and 78% for mild cases in Brazil; and 65.3% in Turkey, which is normal and shows objectivity of clinical trials, according to a document the Global Times obtained from Sinovac.

Despite the discrepancies, the general inference is that the vaccine is protective, particularly in preventing medium and severe symptoms, as mentioned in the Sinovac document.