Answers to Yours Sinovac Vaccine

Chee Loh
4 min readApr 27, 2021


The efficacy of the Sinovac vaccine (officially named CoronaVac, but more popularly known by the name of its developer Beijing-based biopharmaceutical company Sinovac Biotech Limited) has been found to be to be 50.4% in preventing symptomatic Covid-19 by researchers in Brazil.

Photo by Mufid Majnun on Unsplash

The director of the Chinese Center for Disease Control and Prevention himself has said that “Chinese vaccines don’t have very high protection rates”, and that the Chinese government is considering mixing the vaccines to give their efficacy a boost.

In China, more than 34 million people have received two doses of a Covid-19 vaccine already.

Only China-made vaccines have been used and none developed by foreign pharmaceutical companies have been registered there.

However, results from a phase 3 clinical trial conducted in Turkey showed that Sinovac has an 83.5% efficacy in preventing symptomatic Covid-19.

Meanwhile, interim results from a clinical trial in Indonesia has cited 65.3% efficacy.

Is 50.4% considered a good number?

You should not consider this number on its own, but compare it to the results of the other clinical trials that have been announced.

Ultimately, a meta-analysis of all the clinical trials should be done to group all the results together and determine the true efficacy of the vaccine.

This is as the larger the number of people tested, the more accurate the results will be.

Let us take a deeper look at the Brazilian results.

It is 50.4% in preventing symptomatic infections.

However, it is 78% effective in preventing mild cases that require some form of treatment, and 100% effective in preventing severe cases of Covid-19.

This means that if you get the Sinovac vaccine, you are virtually guaranteed not to develop a severe case of Covid-19.

Is the Sinovac vaccine made with mRNA technology?

No, the Sinovac vaccine is made by inactivated virus technology, which is the traditional method of making vaccines.

There are several methods of making vaccines these days.

The Pfizer/BioNTech and Moderna vaccines are fully made with mRNA (messenger ribonucleic acid) technology.

The important thing, especially for tropical countries, is that the Sinovac vaccine does not need to be deep-frozen.

It can be transported and refrigerated at 2–8°C, which is refrigerator temperature.

What about the Sputnik vaccine?

It is actually called the Sputnik V vaccine, and is registered under the name Gam-COVID-Vac.

It is an adenovirus vector vaccine, which contains the gene for the SARS-CoV-2 virus’ spike protein, which will be the trigger for our immune system to develop antibodies against.

The Lancet, one of the most prestigious medical journals in the world, stated that they have reviewed the clinical trial results for the vaccine and it has a 91.6% efficacy without any significant side effects.

The Sputnik V vaccine was initially met with scepticism because of its fast approval in Russia.

But for me, if The Lancet has reviewed it, then that is the highest authority in the world for evidence-based doctors.

What about the Johnson and Johnson vaccine? I heard it is only one shot and that would be more convenient for me.

The Johnson and Johnson vaccine was actually developed by Janssen Pharmaceuticals in the Netherlands, which is owned by the United States-based Johnson and Johnson.

It is an adenovirus vector vaccine similar to the AstraZeneca/Oxford and Sputnik V vaccines.

In a clinical trial, the vaccine was 66% effective after one dose in preventing symptomatic Covid-19.

It has an 85% efficacy in preventing severe Covid-19, but is 100% effective against preventing hospitalisation or death due to the disease.

I am hearing so much about blood clots associated with the Covid-19 vaccines. What is the truth about this?

The European Medicines Agency (EMA) has announced that there is a possible link between blood clots and the AstraZeneca/Oxford Covid-19 vaccine.

But it is extremely uncommon, according to the New England Journal of Medicine.

In fact, the chances of developing a blood clot due to the vaccine is so rare that the benefits of getting the vaccine far outweigh any risk of such a side effect.

This means that the chances of you dying from Covid-19 is much greater than you dying from the side effects of the AstraZeneca/Oxford vaccine, so you should still take the vaccine.

Take this analogy for example: the necessity and convenience for you to drive out to buy groceries far outweighs the risk of you getting into a car accident.

So, you will still drive out to buy your groceries, right?

(Actually, the risk of you being in a road traffic accident is far greater than you getting a blood clot from a Covid-19 vaccine.)

How does the Covid-19 vaccine cause blood clots?

According to reports, the blood clots appeared in the brain and lungs, as well as unusual parts of the body, such as the abdomen.

Most blood clots tend to occur in the legs.

Not enough is known at this time about the vaccine-related blood clots.

This phenomenon appears to be very similar to heparin-induced thrombocytopenia (HIT).

Heparin is an anticoagulant (blood thinner) drug, while thrombocytopenia occurs when platelets are low.

HIT is thought be caused by an immune reaction that affects a lot of platelets.