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Is Sinovac + Pfizer Combo Less Effective Against Omicron?

Is Sinovac + Pfizer Combo Less Effective Against Omicron?

Was the combination of Sinovac and Pfizer proven to be less effective against the Omicron variant of COVID-19?

Let’s take a look at the claim, and find out what the facts really are!

 

Claim : Sinovac + Pfizer Combo Proven Less Effective Against Omicron

On 9 February 2022, The Edge posted an article with the title “Combination of Sinovac and Pfizer proven less effective to fight Omicron, says Pharmaniaga“.

The article covers Pharmaniaga’s statement which suggested that a third dose of Sinovac (of which they are the licensed distributor) is better than the Pfizer booster dose.

Let me share the relevant parts of the article, with key segments in bold. It’s a long read, so you can skip to the next section for the facts.

Pharmaniaga Bhd, citing a study conducted by Yale University, said that two doses of Sinovac Covid-19 vaccine with a Pfizer-BioNTech booster dose are less effective and produces a lower immune response against the Omicron variant compared with other strains.

On the other hand, Pharmaniaga, which is the licensed distributor of Sinovac vaccine in Malaysia, highlighted that a separate research by Sinovac Biotech Ltd shows that three doses of Sinovac Covid-19 vaccine produced higher neutralising antibodies in 95% of recipients compared with 3.3% by the second dose against a variant of concern (VOC), including Omicron.

 

Truth : Pfizer Booster Is Superior To Sinovac Booster Against Omicron

I have not read the actual Pharmaniaga statement, because it is still not available on their website.

However, I had earlier written about the Yale University study, and the statement as shared by The Edge appears to misrepresent what the study actually said.

It also appears to ignore what other studies have said about the poor efficacy of the Sinovac vaccine, including their own Phase 3 trial results.

Let’s go through the claims, and see what the facts really are…

Fact #1 : All Vaccines Are Less Effective Against Omicron

Because it has so many mutations, the Omicron variant is more able to escape the antibody protection that vaccines offer. This is true for all COVID-19 vaccines, not just the Pfizer vaccine.

It seems rather disingenuous for Pharmaniaga to point out that the Pfizer booster dose is less effective against Omicron, compared to other variants… when that is the case for all other vaccines, including Sinovac.

Fact #2 : Booster Dose Will Always Raise Antibody Levels

A booster dose is like a refresher course for your immune system. It will always boost antibody levels against COVID-19.

So the “separate research by Sinovac” themselves (instead of a neutral third party) only tells us that their booster dose is doing what other booster doses are doing – increasing antibody levels.

Abuthen? Did you expect a different result?

Fact #3 : What They Didn’t Say Is Interesting…

You can pick up more information if you note what Pharmaniaga did not say, assuming The Edge did not leave out anything pertinent.

For example, Pharmaniaga did not mention how much was the increase in antibody levels. Why not?

Neither did they confirm that the higher level was sufficient to protect against the Omicron variant. Why not?

They also conspicuously did not claim that the Sinovac booster dose is more effective than the Pfizer booster dose against the Omicron variant. Why not?

Fact #4 : Pfizer Booster Greatly Improves Protection

The Yale University study showed that two doses of Sinovac with a Pfizer booster dose gives protection equivalent to two mRNA vaccine doses.

However, the Pharmaniaga statement left out the very pertinent fact of what that actually meant :

  • 10.1X higher NAb levels against ancestral (original) virus : 
  • 6.3X higher NAb levels against Delta variant : 

The study also showed that two doses of Sinovac with a Pfizer booster offered 40% better protection against Omicron than two doses of the mRNA vaccines.

In other words, the Pfizer booster dose greatly improves on the mediocre protection offered by the Sinovac vaccine, but it may not be at par with 3-doses of other vaccines.

Read more : Why Sinovac Recipients May Need Two Pfizer Booster Doses!

Fact #5 : Cross Protection Not Seen With Sinovac Vaccine

According to Pharmaniaga, the Yale University study showed that no cross protection (hybrid immunity) was seen in Sinovac recipients who receive a Pfizer booster dose.

That is absolutely correct, but it does not mean what they think it means.

Professor Iwasaki specifically pointed out, “Prior infection only synergies with the mRNA vax to elevate broadly neutralizing Ab but not with inactivated vax. This may relate to the persistent GC (Germinal Centre) responses in mRNA vax”.

In other words, this synergistic boost in antibody levels from a COVID-19 infection is only seen with mRNA vaccines like the Pfizer COMIRNATY, but not seen with inactivated virus vaccines like the Sinovac vaccine.

Let me put it plainly – the Yale study showed that if you want cross protection (hybrid immunity), you will get it with the Pfizer vaccine, but not with the Sinovac vaccine.

Fact #6 : Pfizer Superior To Sinovac Against Beta, Delta + Omicron

A recent Hong Kong University (HKU) study showed that while the Pfizer vaccine is less effective against Omicron, the Sinovac vaccine is worse.

  • Sinovac vaccine antibodies were completely unable to bind to the Beta and Omicron variants.
  • Sinovac vaccine antibodies were only able to bind to the Delta variant in 68% of individuals.

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

COVID-19
Variant
Seropositive Rate
Pfizer Sinovac
Alpha 100% 100%
Beta 100% 0%
Delta 100% 68%
Omicron 20% – 24% 0%

Incidentally, the Yale University study also pointed out that there was NO detectable neutralisation against the Omicron variant in people who received two doses of the Sinovac vaccine.

Even Pharmaniaga themselves inadvertently confirmed it, when their statement mentioned that only 3.3% of people vaccinated with 2 doses of Sinovac had neutralising antibodies against variants including Omicron.

Fact #7 : 3X Sinovac Doses Not Sufficient Against Omicron

A joint study by Hong Kong University (HKU) and the Chinese University of Hong Kong (CUHK) recently showed that 3 doses of the Sinovac vaccine does not provide sufficient protection against Omicron.

  • Three doses of the Pfizer vaccine offer 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.

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

Fact #8 : Sinovac Is Least Efficacious COVID-19 Vaccine

The Sinovac CoronaVac is the least efficacious COVID-19 vaccine, barely qualifying for its EUA/EUL with a 50.4% efficacy rate in its Phase 3 trial.

Back when vaccine supply was extremely limited, some protection was better than nothing at all, which is why health authorities deployed the Sinovac vaccine.

Now that we have supplies of better vaccines – Pfizer, AstraZeneca, Sinopharm, etc., there is no longer any reason to settle for the Sinovac CoronaVac.

It is impossible for the Sinovac vaccine to improve its efficacy against the ancestral (original) COVID-19 virus, and it is certainly ludicrous to suggest that a third dose will boost its efficacy from 50.4% to 94%.

Please listen to advice from health authorities, instead of a vaccine manufacturer and/or its distributor.

CITF-B strongly recommends the Pfizer or AstraZeneca booster dose for Sinovac recipients, because they offer better protection.

Sinovac recipients are at the highest risk of a breakthrough infection, because they have the least protection. So make sure you get the best booster dose you can!

 

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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.

 

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Does Sinovac Booster Offer 94% Protection Against Omicron?

Does the Sinovac booster dose really offer 94% protection against the Omicron variant?

Let’s take a look at their claim, and find out what the facts really are!

 

Sinovac : Booster Dose 94% Protective Against Omicron!

On 15 December 2021, Sinovac claimed that three doses of their CoronaVac vaccine had a 94% neutralising antibody rate against the Omicron variant.

This was not an official announcement posted on their website, but announced through Global Times, a Chinese state media outlet.

The latest study shows three shots of Chinese biotech firm Sinovac’s inactivated vaccine can lead to a 94 percent neutralizing antibody rate against the Omicron variant, while the rate after two shots is 35 percent, the Global Times learned from the company on Wednesday.

The study was conducted by the company on 20 people who received two shots and another 48 who received three shots. Seven in the first group and 45 in the second tested positive in neutralizing antibodies against the Omicron variant, the company said in a statement to the Global Times.

Sinovac said that the data demonstrated that the administration of a booster shot of its vaccine can effectively enhance the vaccine’s neutralizing capacity to the Omicron variant, read the statement.

 

Does Sinovac Booster Offer 94% Protection Against Omicron?

Unfortunately, it does not appear that the Sinovac booster shot actually offers 94% protection against the Omicron variant.

And here are the reasons why…

Fact #1 : Sinovac Did Not Post Official Statement / Study

Most of the press blindly posted Sinovac’s claims, without bothering to fact check.

I refrained from commenting earlier, because I was waiting for Sinovac to actually post their study details, or at least an official statement.

However, it is now 1 January 2022, and Sinovac has posted neither the study results, nor an official press statement.

In case you are wondering if Sinovac actually posts such press releases, yes, they do. On 9 September 2021, they posted a press release announcing that a third dose of their vaccine is able to “effectively neutralise the SARS-CoV-2 variants of concern“.

Fact #2 : Sinovac Results Were Misleadingly Worded

If you read the Global Times report very carefully, you will notice that it was carefully worded to say one thing, but imply something else altogether.

In that report, Sinovac claimed a 94% neutralising antibody rate against the Omicron variant, suggesting that their booster dose offers 94% protection against Omicron. That is not what it actually means.

Sinovac stated that they detected neutralising antibodies against Omicron in 45 out of 48 people (93.75%) who received three doses of their vaccine, but cleverly avoided mentioning :

  • how much neutralising antibodies were present (the Geometric Mean Titre),
  • whether the quantity of neutralising antibodies was high enough to protect against Omicron, and
  • whether the 45 individuals with neutralising antibodies were able to avoid getting infected by the Omicron variant.

So while they may have detected neutralising antibodies against the Omicron variant, that does not mean that the antibodies were present in high enough quantities to deliver adequate protection.

The results certainly do NOT mean that the Sinovac booster dose is capable of offering 94% protection against the Omicron variant.

Fact #3 : Sinovac Booster Dose Proven To Be Ineffective Against Omicron

The University of Hong Kong and the Chinese University of Hong Kong recently conducted a study of the Pfizer and Sinovac booster dose.

In that study, they found that three doses of the Sinovac vaccine boosted neutralising antibodies against Omicron, compared to just two doses.

However, the amount of neutralising antibodies produced by three Sinovac doses was much TOO LOW to protect against the Omicron variant.

In fact, the three Sinovac doses were only able to deliver the equivalent antibody titre of two Pfizer doses against the Omicron variant.

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

Fact #4 : Sinovac Did Not Prove Booster Dose Protects Against Omicron

Sinovac is technically correct in claiming that the booster dose enhances protection. That’s what ALL booster doses do – they enhance protection.

However, unless they share their actual study data (particularly the antibody titre), they cannot claim their booster dose effectively protects against the Omicron variant. They offered NO EVIDENCE to prove that.

On the other hand, the recent HKU and CU study has shown that the increased antibody levels from the Sinovac booster dose is not enough to protect against the Omicron variant.

It is past time to stop using the Sinovac vaccine. It was the least efficacious COVID-19 vaccine to be approved, and it does not get much better with a third dose.

The Omicron variant is proving to be highly infectious, and those who were received the Sinovac vaccine will need to get a Pfizer booster dose to obtain sufficient protection.

If you were fully-vaccinated with the Sinovac vaccine, please opt for a Pfizer booster dose. Don’t waste your time with a third dose of the Sinovac vaccine.

 

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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.

 

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

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

 

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

How well do the Pfizer and Sinovac vaccines work against the Omicron variant? Not very well, I’m afraid.

Take a look at what a small HKU study just revealed!

 

Pfizer / Sinovac vs. Omicron : How Was HKU Study Conducted?

The University of Hong Kong recently conducted a small lab study to investigate how well the Pfizer and Sinovac vaccines work against the new Omicron variant of COVID-19.

Before I go into the study results, it is important that you understand how they conducted their study. You can also read their preprint.

The HKU team took blood samples from two groups of people who received their first dose 56 days earlier :

  • 25 people who received two doses of the Pfizer-BioNTech COMIRNATY vaccine
  • 25 people who received two doses of the Sinovac CoronaVac vaccine

They removed all cells and clotting factors from the blood samples, to derive the serum which would contain neutralising antibodies.

The HKU team then used the 50 serum samples to assess their ability to neutralise :

  • Omicron variant from South Africa (HKU691)
  • Omicron variant from Nigeria with additional R346K mutation (HKU344-R346K)
  • Alpha, Beta and Delta variants (as controls)

They basically mixed the serum with the virus sample for an hour, and then added the mixture to a Vero cell culture for 3 days, before examining them to see if the cells were infected and destroyed.

 

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

The problem with most of the reporting I’ve read is that – the writers did not actually read the preprint, only the HKU press release.

Not only did they miss a ton of details, they also missed some important points. So let me start by first summarising what the HKU team found in this table :

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

Also, take a look at the geometric mean titre (GMT) of Microneutralisation (MN) antibodies provided by the HKU team :

So what does this HKU study tell us? Let me summarise the key takeaway points :

Pfizer-BioNTech COMIRNATY Vaccine

  1. Pfizer vaccine antibodies were able to bind to the Omicron variant in 20% to 24% of samples.
  2. Pfizer vaccine antibodies were able to bind to Alpha, Beta and Delta variants in 100% of samples.
  3. Pfizer neutralisation antibody titres were highest against Alpha and Delta variants.

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

There is some protection from the Pfizer vaccine antibodies, but a third dose is necessary to boost the neutralising antibody response against the Omicron variant.

The good news is that the study shows that the Pfizer vaccine is excellent at neutralising the Alpha and Delta variants.

Sinovac CoronaVac Vaccine

  1. Sinovac vaccine antibodies were completely unable to bind to both Omicron variants, as well as the Beta variant.
  2. Sinovac vaccine antibodies were able to bind to 100% of the Alpha variant samples, but only 68% of the Delta variant samples.
  3. Sinovac neutralisation antibody titres were highest against Alpha and Delta variants, but were 10.5X to 12X lower than the Pfizer titres respectively.

The results suggest that the Omicron variant can completely evade neutralising antibodies produced by the Sinovac vaccine.

That’s why 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.

The results also confirm yet again that the Sinovac CoronaVac vaccine is far less efficacious than the Pfizer-BioNTech COMIRNATY vaccine across the board.

CAVEATS

As interesting as the HKU study results are, there are a few caveats we should be aware of :

  1. This is a very small study
  2. This is an in vitro (laboratory) study, and not a real world study
  3. It only assessed neutralising antibodies in the serum, and does not assess T cell immunity

 

Pfizer / Sinovac vs. Omicron Results : What Should You Do?

For scientists, these alarming results suggest a need for the COVID-19 vaccines to be tweaked or updated to cover the Omicron variant.

For the rest of us, it means we need to take a booster dose as soon as we are able to. The HKU team ended their study with the same advice :

[B]efore the availability of these next generation vaccines, booster doses of currently available vaccines will likely render most people having protective levels of neutralizing antibody titers.

But it is also not just getting a third dose, but a booster dose of a better vaccine. This is especially important if you earlier received a less efficacious COVID-19 vaccine like the Sinovac CoronaVac.

Those who had earlier received the Sinovac vaccine should heed these results, and opt for a Pfizer or Moderna 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.

 

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