Sinovac – Efficacy rate of vaccines – The Manila Times
NORMALLY, fake news, disinformation and cognitive dissonance irritate me. It is bad enough that they affect people’s intelligence and judgment. However, with Covid-19, when they affect people’s lives, then that is evil. For me, whether through ignorance, prejudice, sloth or malevolence, it cannot be tolerated as just a difference of opinion as lives are in peril and the well-being of the people and country are at risk. It is sad when these peddlers are so blind or bigoted that they cannot or refuse to see how malevolent and mendacious their sources are or in the rare event they quote a mainstream source, they strain the context where a circle becomes a rectangle that is obvious to anyone with an average IQ. There is no delusion greater than self-delusion as anyone who knows the story of the emperor’s new clothes can attest. People should not die for a lie.
Corollary to that, I suspect very few people actually understand what the efficacy rate of a vaccine means. Many, including Covid deniers and anti-vaxxers, think it is the percentage that are protected or not. Many erroneously think a 95-percent and 75-percent efficacy rate means 5 percent or 30 percent will get infected or not be protected. Not so as it is more complicated.
There is a reason why the World Health Organization (WHO) sets 50 percent as the acceptable standard for vaccine efficacy, and it is not to only protect half. They also differentiate between what happened in tests, the circumstances behind them and how conditions may have altered since. Plus, the results of actual mass application. The point is not that this is better or worse or whatever.
The question we now face is if there is no choice except one, should I choose that over waiting? I got a Moderna shot in the US, which, while excellent, was my last choice (I am not complaining and am happy I had access to that vaccine). I wanted J&J so I would be one and done. Failing that, Pfizer so I would only have to wait 21 days for the final shot. Moderna is what was available and took 28 days later to get my second shot. If I waited for Pfizer or J&J to be available, I might still be waiting for my second shot or even my first. Now I am fully vaccinated. I encouraged my family back home to take the Sinovac vaccine, and they did. I would have done the same if still home. The choice was getting vaccinated or waiting an indefinite period. In the Philippines, circumstances are far worse than the US for vaccine choice or availability, so the question is not am I going to eat lechon or lugaw, it is will I eat or starve? That is the context to weigh on getting vaccinated now or wait until whenever. The other issues are secondary even if valid. The same mentality of risk reward led to the lifting of the suspension of both AstraZeneca and J&J’s vaccines in Europe and the US and the partial lifting of outdoor masks in the US given the high levels of adult vaccinations and that outdoor air is very safe if not crowded. I noticed the biased columnist may have a racist or colonial mindset as he only criticizes Sinovac, even though AstraZeneca and J&J have had similar issues and results.
Back to the efficacy rate. If Pfizer and Moderna have 95-percent efficacy against moderate symptoms and Sinovac has about 70 percent (as does Astra and J&J), it is not the case that 5 percent and 30 percent of those vaccinated will not be protected. It is a lot more subtle and complex. Unlike some others, I am not a clipping service that cuts and pastes or lifts entire articles, and never hit job propaganda. I do my best to use well-reasoned points and explanations from people and publications I respect, learn from them, and share as part of my article to illuminate my analysis. I try to use them to illustrate and elaborate on the points I aim to make. Not in lieu of actually writing a column or the bulk of it.
To be precise, here is the definition of vaccine efficacy from The Lancet, the leading medical journal in the UK in an article by Piero Olliaro published on Feb. 17, 2021.
“It is imperative to dispel any ambiguity about how vaccine efficacy shown in trials translates into protecting individuals and populations. The mRNA-based Pfizer and Moderna vaccines were shown to have 94-95 percent efficacy in preventing symptomatic Covid-19, calculated as 100 × (1 minus the attack rate with vaccine divided by the attack rate with placebo). It means that in a population such as the one enrolled in the trials, with a cumulated Covid-19 attack rate over a period of three months of about 1 percent without a vaccine, we would expect roughly 0·05 percent of vaccinated people would get diseased. It does not mean that 95 percent of people are protected from disease with the vaccine — a general misconception of vaccine protection also found in a Lancet Infectious Diseases editorial.
“In the examples used in the editorial, those protected are those who would have become diseased with Covid-19 had they not been vaccinated. This distinction is all the more important as, although we know the risk reduction achieved by these vaccines under trial conditions, we do not know whether and how it could vary if the vaccines were deployed on populations with different exposures, transmission levels, and attack rates.
“Simple mathematics helps. If we vaccinated a population of 100,000 and protected 95 percent of them, that would leave 5,000 individuals diseased over three months, which is almost the current overall Covid-19 case rate in the UK. Rather, a 95-percent vaccine efficacy means that instead of 1,000 Covid-19 cases in a population of 100,000 without vaccine (from the placebo arm of the abovementioned trials, approximately 1 percent would be ill with Covid-19 and 99 percent would not), we would expect 50 cases (99-95 percent of the population is disease-free, at least for three months).”
What it means for PH
What does this mean for example for the Philippines? We have over 1 million cases and 17,000 deaths, or an infection rate given the population of about 110 million of around 1 percent and a death rate of about 15 per 100,000 or 0.0015 percent. That is a lot better than the 5 percent in the UK and 9.7 percent in the US. The efficacy rate of 95 percent for Pfizer does not imply 5 percent would be ill as that is just like what was happening to the country pre-vaccine in the UK and higher than the Philippines’ actual infection rate to date. It asks what is the percentage that would get infected versus those who will get infected without the vaccine. If instead you vaccinated all of them, then of those that would get sick 95 percent no longer would. Not 95 percent will not but 95 percent of those who would have otherwise gotten infected will not. In the case of Sinovac, AstraZeneca or J&J, about 70 percent of those who would have otherwise gotten infected would not. That is very different.
So, in the case of the Philippines if we vaccinated 100 million people it does not mean 30 million will get Covid if there is 70-percent efficacy. That would even be worse than doing nothing. It means if we assume the control group who got the placebo would have, say, gotten infected at a rate of the UK’s 5 percent instead of our lower 1 percent, then if there was no vaccine about 5 million people would get infected. If 95 percent, then only 250,000 would get infected. Even if 70 percent, then only 1.5 million. Instead of 5 million infected. Definitely not 30 million infected
Also, for example, the Philippines infection rate of 1 percent is fantastic compared to the 5 percent in the UK and nearly 10 percent in the US. One could reasonably argue it is “only” 1 percent because of the restrictions imposed by the various quarantine rules so we would not have only 1 percent if we answered the right wing’s wet dream and aped Trump’s shambolic stewardship last year and opened up, threw away masks and stopped social distancing. So, a better guess would be the rate of the US. It is probably the best example as for nearly a year they had the “let’s inject bleach” administration of Donald Trump and two major infection waves, while some governors did the best they could. Perhaps their stats of about 10 percent infected and 0.2 percent deaths of the total population would be reasonable estimates. Reducing that from 10 percent infected to 3 percent or 0.5 percent is worthwhile and a good risk-reward trade-off for vaccinating to enable opening up safely. Especially given the effectivity is around 100 percent for death and hospitalization regardless of which vaccine so the health care system will not be strained. What this means if we assume 10 percent is the natural infection rate, if we did nothing and acted like it was 2019, a plausible estimate is the Philippines would have about 10 million infected and 200,000 dead before natural herd immunity took effect. With 10 percent infection rate, mass vaccination with 70 percent and 95 percent efficacy implies there would be only 3 million and 500,000 infections, respectively with 70 percent and 95 percent efficacy. Not 30 to 5 million.
Stage 3 tests
The caveat to this is they are comparing the results of the extensive but limited as to time and participants, stage 3 mass test of the control group that got the placebo and the test group that got the vaccine. It is a test and thus, is a mere estimate but a very good one of what will happen when rolled out to the population in a mass vaccination. The results will vary and not be an exact replica but will be close unless something unexpected or unprecedented happens.
That is why health departments and pharma companies do not just stop at the stage 3 test. They continue evaluating and fine-tuning the results of all the vaccinations. That is how they were able to determine that at least Pfizer and Moderna, while not 95 percent, have over 70 percent efficacy against the new variants and mutations. Also, that protection seems to last at least nine months instead of the estimated six months. One would assume the same continuing tests are being done for J&J, AstraZeneca, Sinovac, Sputnik V and others. There are many other effects that they are uncertain of, hence the authorization for the vaccines being “emergency” authorization, not regular. Normally, a vaccine will not be allowed to be administered broadly in so fast a time with the tests limited to what we had, but this is a pandemic and emergency.
To repeat, if 70-percent efficacy means 30 percent of the population vaccinated gets infected, that assumes 100 percent will get infected without vaccines. That is not the case. If it was, then humans should be extinct as we should all have died from the bubonic and other plagues that happened before germs and viruses were understood and vaccines developed.
To repeat, the efficacy rate means the percentage who will be protected out of the total population that would likely be infected without vaccines. For example, if the likely infection rate of the general population is 10 percent, then 70-percent efficacy rate means 70 percent of the 10 percent will be protected and 90 percent would probably not get infected even if exposed tangentially, so there will only be 3 percent infected, not 30 percent of the population vaccinated. That is why the WHO guideline for a viable vaccine is 50 percent or higher and the 70- to 95-percent rate for moderate symptoms and practically 100 percent against hospitalization and death is a spectacular success.
At this point I can imagine some anti-vaxxers, especially the prejudiced ones saying the equivalent of see, you do not know and cannot be sure of what will happen if you take the vaccine. Yet we do know generally what will happen, but yes, we might not know all of what may happen. That is true, but compared to what? This is where risk-reward comes in. That is why their false god Donald Trump took experimental drugs when he got Covid. His doctors and his view were versus what? Stay very sick or die? Same thing with vaccines. Efficacy against hospitalization and death so far based on the trials for all the major vaccines is practically 100 percent. The variation is for minor effects and on the variants and mutations. Still, vastly better than no protection. The worst case is I will get some mild symptoms? I will take that over dying or getting hospitalized. I would prefer a 95-percent efficacy vaccine over a 70 percent for mild symptoms, but I would rather take a vaccine that will keep me from dying than wait for the perfect or better vaccine to arrive. Especially when the worthwhile is at least partially available and the date the other vaccines will arrive is uncertain.
Ignorance is not bliss and lies are worse. Please stay safe by staying smart and sane. Know what you are doing and what is being done, versus listening to bloviating, ignorant and malevolent cranks with biases and agendas. You are only risking your life and health after all. Probably your sanity too.
Sinovac – Efficacy rate of vaccines – The Manila Times