Pfizer vs. Sinovac : Which Is Better Against Omicron Variant?

Posted by Dr. Adrian Wong
Date: December 31, 2021


Which works better against the Omicron variant – Pfizer COMIRNATY, or Sinovac CoronaVac?

Let’s find out what the two latest studies have shown!
Pfizer vs. Sinovac : Which Is Better Against Omicron Variant?

Everyone is worried about the new Omicron variant of COVID-19 because it has been proven to have greater ability to breakthrough vaccine protection, far more than the Delta variant!

This is not just a concern for the low-efficacy Sinovac CoronaVac vaccine, it is also a big concern for the Pfizer COMIRNATY vaccine.

So just how effective are both vaccines against the Omicron variant? Let’s find out…

If you just want the TLDR summary, here it is :
Two doses of the Pfizer vaccine will only protect 20% to 24% of fully-vaccinated individuals against Omicron.
Three doses of the Pfizer vaccine offers very good protection against the Omicron variant.
Even three (booster) doses of the Sinovac vaccine do not offer protection against Omicron.
A Pfizer booster dose offers good protection against Omicron, for individuals vaccinated with two doses of the Sinovac vaccine.

The studies show that three doses of the Pfizer vaccine are required to adequately protect against the Omicron variant, while those vaccinated with the Sinovac vaccine should opt for the Pfizer booster dose.

For those who want the details, please continue to the next section…
Pfizer vs. Sinovac Efficacy Against Omicron : 2 Doses

A recent Hong Kong University (HKU) study showed that the Omicron variant has significant vaccine escape capability in fully-vaccinated individuals.
Pfizer vaccine antibodies were able to bind to the Omicron variant only in 20% to 24% of individuals.
Sinovac vaccine antibodies were completely unable to bind to the Omicron variants.

The results suggest that mutations in its spike protein are allowing the Omicron variant to significantly block most Pfizer vaccine antibodies, and all Sinovac vaccine antibodies.

While the Pfizer vaccine will continue to offer protection to 20% to 24% of fully-vaccinated individuals, the Sinovac vaccine offers no protection at all.

The Geometric Mean Titre (GMT) results in this study also suggest that a third (booster) dose will boost the Pfizer vaccine’s neutralising antibody response against the Omicron variant.

On the other hand, the HKU study authors concluded that “whether a third dose of the present CoronaVac vaccine will enhance the neutralising antibody response against the Omicron variant remains to be determined.”

Read more : Pfizer / Sinovac vs. Omicron : What HKU Study Just Revealed!

COVID-19
Variant Seropositive Rate MN Titer (GMT)
Pfizer Sinovac Pfizer Sinovac
HKU691 Omicron 20% 0% 5.43 Min.
HKU344-R346K
Omicron
24% 0% 6.42 Min.
Delta 100% 68% 124.7 10.3
Beta 100% 0% 25.7 Min.
Alpha 100% 100% 229.4 21.7



Pfizer vs. Sinovac Efficacy Against Omicron : Booster Dose

Sinovac claimed on 15 December 2021, that three doses of their CoronaVac vaccine had a 94% neutralising antibody rate against the Omicron variant. However, they did not share the study, or even publish an official press release.

Fortunately, the medicine faculties of Hong Kong University (HKUMed) and the Chinese University of Hong Kong (CU Medicine) conducted a study of the Pfizer and Sinovac booster dose.

Here is a summary of their key findings :
Two doses of Pfizer or Sinovac vaccines do not provide sufficient protection against the Omicron variant.
Three doses of the Pfizer vaccine offers the highest level of protection against Omicron.
A Pfizer booster dose given to those who received two Sinovac vaccine doses obtain good protective antibody levels against Omicron.
Three doses of the Sinovac vaccine do not provide sufficient protection against the Omicron variant.
Antibody levels of three doses of the Sinovac vaccine were roughly equal to two doses of the Pfizer vaccine.


Pfizer vs. Sinovac Efficacy Against Omicron : What Should You Do?

The two studies from Hong Kong should serve as a sober warning for those vaccinated with the Sinovac vaccine.

The Sinovac CoronaVac vaccine has always the least efficacious COVID-19 vaccine approved – just 50.4% effective in preventing symptomatic infection by the original SARS-CoV-2 virus.

Its efficacy has further suffered against the Delta variant and the Gamma variant, but it continued to be used because there was insufficient supply of better vaccines and it still offered good protection against hospitalisation and death.

But now that these studies have shown that neither two nor three doses of the Sinovac vaccine will offer any protection against Omicron, it’s time to stop using the Sinovac vaccine.

It’s time to acknowledge what many scientists and doctors have long known – that the Sinovac vaccine was a stop-gap solution, until there was sufficient supplies of better vaccines.

We now have adequate supplies of better vaccines. There is NO REASON to continue using the Sinovac vaccine.

If you were fully-vaccinated with the Sinovac vaccine, please heed these results and opt for a Pfizer booster dose, as recommended by many health authorities.

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Dr. Adrian Wong has been writing about tech and science since 1997, even publishing a book with Prentice Hall called Breaking Through The BIOS Barrier (ISBN 978-0131455368) while in medical school.

He continues to devote countless hours every day writing about tech, medicine and science, in his pursuit of facts in a post-truth world.