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COVID-19 vaccine update | Uncertainty over Sinovac shot’s effectiveness an issue despite trail results in Brazil, Turkey

On Thursday, Sao Paulo state Health Secretary Jean Gorinchteyn confirmed that China's Sinovac vaccine "didn’t reach 90%" efficacy, making it less successful than those developed by Pfizer Inc. and Moderna Inc.

December 25, 2020 / 04:05 PM IST
Workers unloading the 1.2 million doses of COVID-19 vaccine made by Sinovac, upon its arrival from Beijing at Jakarta's international airport in Tangerang on December 6, 2020. (PC-AFP)

Workers unloading the 1.2 million doses of COVID-19 vaccine made by Sinovac, upon its arrival from Beijing at Jakarta's international airport in Tangerang on December 6, 2020. (PC-AFP)

Amid the final phase of trials for China-based Sinovac Biotech Ltd.’s coronavirus vaccine in Brazil and Turkey, uncertainty over the effectiveness of the shot in protecting people from the deadly virus has become an issue. Though Sinovac claims a protection rate on either side of 90 percent.

Sinovac, which is finalising results of phase III trials -- carried out in Brazil, Chile, Turkey, and Indonesia -- has conducted tests independently in these countries from each other under different protocols, rather than subjecting to unified norms, Bloomberg reported.

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Earlier this week, Brazilian researchers delayed releasing complete information on Sinovac’s vaccine and stated that the vaccine is found to be over 50 percent effective. On Thursday, Sao Paulo state Health Secretary Jean Gorinchteyn confirmed that Sinovac vaccine "didn’t reach 90%" efficacy, making it less successful than those developed by Pfizer Inc. and Moderna Inc.

"We don’t know how much more than 50% it was, whether it was 60%, 70% or 80%, but it’s at levels that allow us to reduce the impact of the disease on our population. We knew that the effectiveness would never reach 90%," Bloomberg quoted Gorinchteyn saying in an interview with Brazil’s CBN Radio.

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COVID-19 Vaccine

Frequently Asked Questions

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How does a vaccine work?

A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.

How many types of vaccines are there?

There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.

What does it take to develop a vaccine of this kind?

Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.

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Meanwhile, the Turkish administration had stated that the Sinovac vaccine's trial showed an estimated efficacy rate of 91.25 percent, which is based on only 29 cases. While Sinovac spokesman has not commented on this issue.

Considering the case of Sinovac vaccine's less requirement against Pfizer and Moderna, the Chinese drug can be proved more effective to inoculate more people around the world and save lives, especially in developing countries like Brazil. Sinovac's COVID-19 vaccine shots can be kept at normal refrigerator temperatures, unlike Pfizer and Moderna which require deep-freezers.

Since China's Sinovac began its trail in Brazil, President Jair Bolsonaro had kept saying that the vaccine from China can’t be trusted. "I want to make it very clear that the label of this vaccine will be ‘we are not responsible for any side effect.’ Responsibility is yours," he maintained.
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