Sinovac Efficacy Is Being Questioned. What Does Data Say?

It's at the forefront of the Philippine rollout.

Sinovac was the top trending topic on Twitter Monday as soon as the Philippines delivered the first jab, setting into motion a long-delayed vaccination program against COVID-19.

The posts questioned Sinovac's 50% efficacy rate, which pales compared rival vaccines from Pfizer (94%) and AstraZeneca (70%). All three have been certified for emergency by Filipino authorities and the China-made drug was first to arrive.

What is Sinovac's efficacy rate?

CoronaVac has an efficacy rate 50.4 percent, according to its manufacturer, Sinovac. As the name implies, it's a measure of how effective a vaccine against a disease, in this case, COVID-19.

Edsel Salvana, who heads the Institute of Molecular Biology and Biotechnology at the National Institute of Health, got the Sinovac vaccine on Monday. He is also part of the government's technical working group on vaccines.

In March 2020, Salvana wrote that the Philippines was managing the pandemic well. He branded as "myths" the public's concerns that we weren't testing enough people and downplayed community transmission. Then, in April 2020, Salvana wrote that the Philippines should not prioritize mass testing

The Sinovac jab is 50% efficacious for mild cases, 78% efficacious for moderate cases and 100% efficacious for severe cases, he said.

What does this mean?

Should an entire population catch the virus, say the common cold and they all get vaccinated with a jab that is 50% efficacious, 50% of them will get colds and the remaining 50% will not get sick. Of the 50% who will get sick, some of them could infect others. No one is likely to die, Salvana said.

Salvana based his explanation on his experience at the frontlines of the pandemic since it started last year. The NIH body that he heads was involved in processing RT-PCR or swab tests. He also said he had access to confidential papers.


Questions on Sinovac's efficacy stemmed mostly from the refusal of its makers to immediately disclose the results of their own human trials. Data on its efficacy have been released by countries that used CoronaVac.

It has been found to be up to 91.25% effective in trials in Turkey but other, more robust trials in Brazil only demonstrated an efficacy rate of around 50.4%.

Sinovac is 50% effective, will it help fight COVID?

Salvana illustrated Sinovac's efficacy this way: It will reduce a lion into a cat.

It makes sense to get the most readily accessible vaccine to protect oneself now versus waiting for a higher efficacy vaccine and leaving oneself vulnerable to infection in the process, he said.

"The best vaccine is the vaccine that's in your arm," he said. "Tanggapin po natin kung anong bakuna nandyan dahil po ito ay makakasalba ng buhay."

Some healthcare workers have protested the use of Sinovac saying they were promised the Pfizer jab. The first Sinovac jab was given to Dr. Gerardo Legaspi, the Philippine General Hospital director.

"Yung leon po, ginagawa nating kuting. We are turning COVID-19 from a deadly disease that shut down the whole world into a common cold," he said.

"Wala pong takot sa sipon. Madami pong takot sa COVID. Yan ang ginagawa natin, tatanggalan natin ng pangil ang COVID para hindi na siya nakakatakot," he said.

This story originally appeared on reportr. Minor edits have been made by the editors.

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