Norwegian health authority reported that 33 people had died after receiving the first dose of Pfizer-BioNTech Covid-19 vaccine [1]. The news has generated concern and even fear among the general community. However, my evaluation suggests that the fear is not founded.
It is hard to make sense out of the 33 deaths without knowing the number of vaccinated people. According to The Age, Norway has vaccinated approximately 42,000 elderly people, mostly in nursing homes. Thus, the one-week risk of mortality is 0.078%.
Is the 0.078% risk too high? No. In a study published in PLoS ONE, the investigators followed 690 Norwegian nursing home residents for 3 years, and they found that the risk of mortality during the first 6 months was 17% [2]. This translates into a risk of 0.65% …
Australian experts are debating about the efficacy of AstraZeneca vaccine. Some argue that the efficacy (VE) of the vaccine is not good enough for herd immunity; others say that it is better than … face mask. I think the debate has been misled by the heavy reliance on the average. In this note, I want to make 3 comments on the true value of VE and its implication for herd immunity.
Australia is about to implement a COVID-19 vaccine program, with Oxford/AstraZeneca vaccine being the intervention of choice. It is expected that up to 80,000 people will be vaccinated by week 4, and 4 million by the end of March 2021. …
I have always struggled to make the community and patients appreciate the risk of mortality after a fracture. Well, I think “Skeletal Age” is a way to convey the impact of fracture on mortality.
Here is a well-known fact: the hazard of mortality after a hip fracture is increased by 2.9-fold (95% CI, 2.5 to 3.3) in women and 3.7-fold (3.3 to 4.1) in men [1]. The issue is how to convey this increased risk to patients and the general community.
What does ‘risk’ mean anyway? In the frequentist sense, risk is the probability that an adverse event will occur in a duration of time. Thus, the numerator of risk is the number of events, and the denominator is the number of at-risk people. However, such a definition is hardly applicable to an individual, because for an individual the denominator is 1, and the individual either will or will not have the event. …
The 2020 Vietnam’s beauty contest has concluded, and Miss Đỗ Thị Hà has been crowned Miss Vietnam 2020 [1]. The 19 yr old girl stands at a proud 175 cm tall, but her weight was only 55 kg. She and her fellow beauty contestants are classified as ‘underweight’.
I have over the years collected data pertaining to basic anthropometric parameters of Miss Vietnam titleholders. The data show that their height has increased over time. …
In the famous study, DANMASK, the authors conclude that wearing surgical mask together with social distancing practice did not reduce the risk of SARS-Cov-2 infection. However, using a Bayesian inference, I show that their result is consistent with a risk reduction of up to 28%.
Rarely a scientific study generates a lot of controversies, but that is the case for the DANMASK study [1]. In this study, the authors found that face mask wearing did not reduce the risk of infection with SARS-Cov-2 (odds ratio, 0.82; 95% CI, 0.54 to 1.23; P = 0.33) [1]. However, most newspapers and health experts were not swayed by the evidence, and they categorically say that “you need to wear them anyway” [2]. …
Pfizer has just announced that their vaccine trial had concluded with an impressive result: 95% efficacy [1]. One does not need to do any fancy analysis to see that the efficacy is real. Here, I would like to offer a Bayesian interpretation of the efficacy.
Briefly, the trial has enrolled 43,661 volunteers, and as of 13/11/2020 41135 volunteers have received a second dose of the vaccine. Assuming that half the 41135 participants have been randomly assigned to the vaccine group, and the rest to placebo. According to the press release, 170 participants were infected with SARS-Cov-2, and among whom, only 8 were in the vaccinated group compared with 162 in the placebo group. …
Vietnam is the 15th most populous country in the world. The country’s population is rapidly aging with significant changes in lifestyle and dietary habits. About 28% of women and 16% of men aged 50 and older are having osteoporosis, but most of them are undiagnosed and not treated.
Vietnam is a developing country, with per-capita GDP being around $2600 (2018 figure). Vietnam has a population of ~97 million, making it the 15th largest country in the world [1]. The country’s population is aging: at present the proportion of population aged 60 years and older is 12%, but this is expected to increase to 25% in 2049 [2]. …
The encouraging results of Pfizer’s vaccine against Covid-19 has renewed the idea of herd immunity. Central to the idea is the question “how many people in the general community need to be vaccinated to create herd immunity?” This note will answer that question.
By now, most people probably know what is herd immunity (also referred to as herd protection). Briefly, the idea of herd immunity is based on the conjecture that when a large proportion of people is immune to an infectious disease, these people will provide indirect protection to those not immune to the disease (see illustration). So, if 70% of a population is immune to, say, SARS-Cov-2, then 7 out of every 10 people who contact someone with the disease will not be infected. Consequently, the disease will not spread further and the epidemic is controlled. …
On November 9, Pfizer and BioNTech announced that their modifed RNA vaccine against Covid-19 had a “90% effective” [1]. That is absolutely a great news in the mid of the third wave of Covid-19 pandemic. However, there have been a lot of misunderstandings of the 90% efficacy. This commentary explains the source and the meaning of that number.
It is unfortunate that the Pfizer’s data have not been peer-reviewed by independent experts or published in a medical journal. And, that is why the data are open to misinterpretation. Many people, including those in the medical community, understand that a vaccine efficacy of 90% means 9 out of 10 people got the jab will not be infected. Indeed, a commentary in the Conversation states that “The Pfizer/BioNTech vaccine reports 90% efficacy, which means that their vaccine prevented COVID-19 symptoms for 90% of volunteers that received the vaccine compared to placebo” [2]. …
Despite the pop title, “Calling Bullshit: The Art of Skepticism in a Data-Driven World” is actually a tough-minded guide to spot, deconstruct and refute misinformation, fake news, and false data that abound in our society. To me, the materials and ideas covered in the book can also serve as an educational resource for epidemiology students.
Coming from a non-English speaking background, I have always thought that ‘bullshit’ is a kind of foul language. And, I was somewhat shocked to see the word in the book’s title. However, it turns out that this interesting word is well accepted in scientific and philosophical discourse. Harry G. Frankfurt is perhaps the most important philosopher who has laid the theoretical foundation for the study of bullshit. In his bestseller treatise, On Bullshit, Professor Frankfurst does not exactly define what bullshit is, but he considers that bullshit is a by-product of public life where “people are frequently impelled — whether by their own propensities or by the demands of others — to speak extensively about matters of which they are to some degree ignorant.” Bullshitting is different from lying: liars know the truth but engage in a conscious act of deception, bullshiters don’t care about the truth and don’t consciously deceive. …
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