CoronaVac Vaccine By Sinovac : Your Questions Answered!

China recently approved the CoronaVac vaccine for general use, and several countries around the world have purchased it.

In this article, we will answer your frequently asked questions about this Chinese-made vaccine!

Find out how the CoronaVac vaccine works, and how effective it really is against COVID-19!


CoronaVac Vaccine : What Is It?

Developed by Sinovac Life Sciences, CoronaVac is a 2-dose inactivated virus vaccine, where the second dose delivered 14 days after the first.

Unlike the Pfizer and Moderna mRNA vaccines, CoronaVac only needs to be refrigerated at 2–8 °C (36–46 °F), which makes it easy to distribute.

On 6 February 2021, China approved the CoronaVac vaccine for general use.


CoronaVac Vaccine : How Is It Created?

CoronaVac is an inactivated virus vaccine – which is an older method of creating vaccines.

  • The SARS-CoV-2 virus (CN02 strain) is cultured (grown) in African green monkey kidney cells, also known as Vero cells *.
  • After incubation, the virus is harvested and inactivated (killed) using β-propiolactone, a sterilising agent.
  • The inactivated virus are concentrated and purified, and then adsorbed (attached) onto aluminium hydroxide.
  • The aluminium hydroxide + virus complex is then diluted in phosphate-buffered saline (basically salt water with phosphate) to match the pH, osmolarity and ion concentration of the human body.
  • Finally, the vaccine solution is sterilised and filtered, before being filled into syringes or vials.

* This is why the Sinovac CoronaVac vaccine box is labelled “SARS-CoV-2 Vaccine (Vero Cell), Inactivated“.


CoronaVac Vaccine : What Does It Contain?

The CoronaVac vaccine can come in the form of a vial, or a pre-filled syringe. Both only require refrigeration at 2–8 °C (36–46 °F).

Each dose contains 600 SU (3 µg) of inactivated SARS-CoV-2 virus and aluminium hydroxide (as adjuvant) in 0.5 ml of phosphate-buffered saline.


CoronaVac Vaccine : How Does It Work?

The CoronaVac vaccine is injected intramuscularly in two separate doses, fourteen days apart.

Once injected, the antigens on the inactivated SARS-CoV-2 virus trigger the body’s immune system, just like the actual virus would.

However, the inactivated SARS-CoV-2 virus just floats around and doesn’t infect any cells. So the immune response it generates is much weaker than an actual COVID-19 infection.

That is why it uses aluminium hydroxide as an adjuvant, and a second vaccine shot is needed to further stimulate the immune response.


CoronaVac Vaccine : What Are Its Side Effects?

According to its Phase 1 trial results, volunteers reported only these side effects :

  • injection site pain
  • fatigue
  • muscle pain
  • headache

They were generally mild (grade 1 in severity), and the volunteers recovered within 48 hours.

Only one case of acute hypersensitivity with urticaria (hives) was recorded out of 24 volunteers who received the vaccine.


CoronaVac Vaccine : Can It Make You Speak Mandarin?

After Malaysia Minister of Science, Technology and Innovation, Khairy Jamaluddin, got vaccinated with the CoronaVac vaccine, he appeared in a video speaking about it in Mandarin.

People started joking that a side effect of the vaccine was that it teaches you to speak Mandarin. To be clear, speaking Mandarin is not a side effect of the vaccine, it is just a joke!


CoronaVac Vaccine : How Effective Is It?

The efficacy of the CoronaVac vaccine is a subject of some controversy…

Butantan Study Controversy

On 24 December 2020, the Butantan Institute in Brazil announced that the CoronaVac vaccine’s efficacy was “above 50%” – the minimum threshold for approval. However, Sinovac asked them to delay releasing their results.

On 7 January 2021, the Butantan Institute announced that the CoronaVac vaccine was 78% effective.

That was “corrected” on 12 January 2021, when they announced that the 78% efficacy rate was “calculated” based on mild, moderate and severe COVID-19 cases.

When they included “very mild cases”, the actual figure was 50.38% – often rounded up as 50.4%.

Out of 12,396 volunteers, 160 who got the placebo were infected, 128 who got the vaccine were infected.

Sinovac Explains Controversy

On 14 January 2021, Sinovac senior director, Yin Weidong, explained at a Beijing press conference that the reason why the CoronaVac’s efficacy was so low was because it was tested on healthcare workers.

He noted that the other vaccines were tested on mostly ordinary citizens with lower risks of infection, even though all vaccine studies include healthcare workers who are most at risk of being infected.

Sinovac Announces Phase 3 Trial Results

On 5 February 2021 – a day before China approved CoronaVac for general use – Sinovac announced the vaccine’s Phase 3 results from Brazil and Turkey.

Brazil Trial : 12,396 healthcare workers

  • 50.65% efficacy against symptomatic disease
  • 83.70% efficacy against symptomatic disease requiring medical treatment
  • 100% efficacy against hospitalisation, severe or fatal cases

Turkey Trial : 1,322 participants

  • 91.25% efficacy against symptomatic disease

The Turkey trial was far too small, and the Brazil trial results were tainted by accusations of data manipulation. The Sinovac furthered that perception by claiming a 83.7% efficacy against medical treatment.

While that may be accurate, it muddies the already murky water and confuses people regarding its true efficacy against symptomatic COVID-19 disease.


CoronaVac Vaccine : Should You Take It?

Yes, if approved by the health authority of your country, you should take it.

The CoronaVac may have lower efficacy than the Pfizer or Moderna mRNA vaccine, but it is still an effective vaccine.

The key thing you should note is that it has been proven to prevent severe or fatal COVID-19 disease.

And it offers about 84% protection against moderate to severe COVID-19 disease that requires medical treatment.


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