I was quite surprise to see our Ministry of Health (MOH) put up a infographic that purportedly compares the efficacy between Pfizer and Sinovac.

In the infographic, it says that

  1. Sinovac prevents 65.9% of the disease, Pfizer 64% Yes, the efficacy of Sinovac is higher in this regard (!!??)
  2. Sinovac reduces hospitalization by 87.5%, Pfizer 93%
  3. Sinovac reduces ICU cases by 90.3%, Pfizer by 93%
  4. Sinovac prevents 86.3% death, as for Pfizer, no data on this.

To make the figure looks more authoritative, MOH even cites a source from New England Journal of Medicine. So it should be enough to establish the efficacy of the Sinovac, once and for all, right?

But if Sinovac efficacy is really on par with Pfizer, why on earth would the government phased out Sinovac Vaccine earlier? Action speaks louder than words.

To understand the whole thing, it’s useful to start with the New England Journal of Medicine source. It turns out that on 7/7/2021, there really is an study titled Effectiveness of an Inactivated SARS-CoV-2 Vaccine in Chile, where MOH got their Sinovac data. A summary of the above journal article can be also found at major news outlet, such as The Edge.

Reading the above study ( or just The Edge summary) carefully, we can notice that while MOH did cite the Sinovac data correctly, it didn’t cite the Pfizer data from the same study, which stands at 92.6% prevention, 95.1% hospitalization and 96.2% ICU admission. A comparative effectiveness  data can be found at The Edge article above, and is reproduce below:

 Covid-19HospitalizationICU admissionDeath
CoronaVac65.9%87.5%90.3%86.3%
Pfizer-BioNTech92.6%95.1%96.2%91.0%

It’s pretty clear that the Chile study that MOH cites doesn’t support the conclusion that Sinovac’s effectiveness is on par with Pfizer, as implied by MOH in the above infographic. Citing one half of the study but not the other half is not exactly lying, but it’s not too far from that.

Secondly, although MOH doesn’t say, but we can tell where the 64% Pfizer efficacy is coming from; it is from the data released by the Israeli government around the same time ( on 6/7/2021). But is it the only data concerning Pfizer? Obviously no, the phase 3 study of Pfizer efficacy has established the efficacy of 95%, way higher than the 64% efficacy. On the other hand, the phase 3 study of Sinovac at Brazil put its its efficacy level at 50.7%. If MOH really did want to compare fairly, it should compare among phase 3 studies as these are the tightly controlled experiments and represent our best chance for an apple to apple comparison.

Why are we witnessing a drop of the efficacy of Pfizer? It largely has to do with delta variant. The “64% data” was collected at the time when the all-infectious delta variant was ravaging Israel. But the above Chile study doesn’t even address the efficacy of Sinovac against this strain of virus ( only alpha and beta). Isn’t it a further unfairness to compare between the two vaccines based on unequal condition?

Furthermore, there are other studies that establish the efficacy of Pfizer more favorably, at 88%. A British study,  found that two doses of the Pfizer vaccine were 88% effective against stopping symptomatic infection, even against the Delta variant. Why is MOH not citing this data?

Basic intellectual honesty would demand MOH to compare between apple and apple, or at the better yet, compare the efficacy of both vaccines against the delta variant, for it is the dominant one now. The fact is that although the data concerning delta variant is abound for Pfizer, there is no corresponding data for Sinovac, which doesn’t look too good on Sinovac. But cherry-picking the data and comparing vaccines based different conditions, and then use it to justify that “all vaccines are safe and effective, the best is the one that is being offered” is just blatant dishonesty, and betray the trust of the public. I don’t expect MOH to stoop this low, but here we are.

Maybe MOH want to assuage the public that Sinovac is still safe to use after the government decided to phase it out ( no wonder people are worried), or maybe MOH want to appease the Big Brother who supply them with Sinovac. But whatever the motives, it doesn’t excuse MOH.

It’s not MOH’s fault to use Sinovac in the first place– no one could have foreseen the rise of delta. But I don’t see how misleading the public is an ethical or even a helpful thing to do. An ethical thing to do is to just tell us the truth and provide remedies. After all, we are talking about LIVES here.

So you still want to tell me Malaysia government is making Covid-19 related decision based on science?

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