Why is the Efficacy of Indonesia’s Sinovac Vaccine Different from Turkey and Brazil?

Suara.com – The Indonesian Food and Drug Administration (BPOM) announced the efficacy of the Covid-19 vaccine made by Sinovac at 65.3 percent.

This figure is different from the efficacy report in Turkey of 91.25 percent and in Brazil of 78 percent.

So, why are the results different?

Professor of the Faculty of Pharmacy, Gadjah Mada University (UGM) Prof. Dr. Zullies Ikawati, Apt said this could not be separated from the character of the subject and the risk of infection in volunteers who participated in the final phase 3 clinical trial in Bandung, West Java.

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“This efficacy will be influenced by the characteristics of the test subject. If the test subject is a high-risk group, it is likely that the placebo group will be exposed more, so the calculation of the efficacy will increase,” said Prof. Zullies based on a press release received by Suara.com, Tuesday (12/1/2021).

The placebo group is the group that receives empty pills, aka pills without medicinal effects or does not contain vaccines.

This is what distinguishes study subjects who received the vaccine as a controlled group and a placebo group or an uncontrolled group.

So for example, in the Sinovac clinical trial in Bandung involving 1600 people, there were 800 subjects who received the vaccine, and 800 subjects who received a placebo.

If 26 of the vaccinated group were infected (3.25%), while from the placebo group there were 75 people who contracted Covid (9.4%), then the efficacy of the vaccine was = (0.094 – 0.0325) /0.094 x 100% = 65, 3 percent.

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So what determines is the ratio between the vaccinated and non-vaccinated groups.

For example, in the vaccine group there were 26 infected, while the placebo group increased to 120 infected, the efficacy increased to 78.3 percent.

Meanwhile, the clinical trial of the Covid-19 vaccine in Brazil used a high-risk group, namely health workers, so that its efficacy was obtained.

Meanwhile, in Indonesia, it uses the general population with a smaller risk.

“We test subjects are at low risk, let alone obey the health process, never leave the house so that not many are infected, so the comparison of the incidence of infection between the placebo group and the vaccine group is lower, and results in a lower number,” said Prof. Zullies.

It is likened that there are 26 vaccine groups infected with Covid-19 (3.25%) while in the placebo group only 40 people (5%) because of maintaining the health process strictly, the efficacy of the vaccine can fall to only 35%, which is from the count (5 – 3.25) / 5 x 100% = 35%.

“So this efficacy rate is not fixed, and can be influenced by many factors when a clinical trial is conducted. In addition, the number of test subjects and the length of observation can also influence the results. If the observation is extended to 1 year, it is possible to produce a different vaccine efficacy rate. “concluded Prof. Zullies.