10 votes

BNT162b2 mRNA Covid-19 Vaccine efficacy after 1st dose - explain the statistics

The paper itself describes how this is calculated (see the Methods section), but also see this Q&A at Biology.SE talking more broadly about how efficacy has been defined in these vaccine trials: ...
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7 votes
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Multiple Sclerosis and Chemotherapy

Is there any truth behind chemotherapy actually curing Multiple Sclerosis? Unfortunately, no. Multiple sclerosis (MS) is a chronic illness - meaning that it cannot be completely cured. There are, ...
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  • 2,823
6 votes
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Does vaccination weaken the immune system ? Studies?

I have found a couple of papers which debunk this myth. The links here go directly to free PDF copies and there are DOI links in the references in case the PDF links die. The most recent paper I can ...
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  • 5,872
6 votes
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Are there scientific studies that support the daily usage of xylitol to prevent oral problems?

Original Answer This comes from my high-school chemistry book (in German): Hexanhexol (sorbitol) is common in apples, cherries and other fruits. The sweet taste comes from the OH-Groups within ...
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  • 6,594
6 votes

BNT162b2 mRNA Covid-19 Vaccine efficacy after 1st dose - explain the statistics

The formula used for vaccine efficacy is as follows: VE = (ARU - ARV) / ARU (VE: vaccine efficacy, ARU: attack rate in unvaccinated participants, ARV: attack rate in vaccinated participants) This is ...
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  • 2,331
5 votes
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Does melatonin have an effect on the treatment of type 1 diabetes?

It appears that melatonin decreases blood pressure in a way that occurs nocturnally in normal persons. Interestingly, it is being investigated as a possible anti-hypertensive in Type 2 diabetics. It ...
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5 votes
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Are there current studies about long term development of WPW in children?

There are the following newer studies which are related to that one from 1990: 1992: Usefulness of predischarge electrophysiologic study in predicting late outcome after surgical ablation of the ...
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  • 4,697
5 votes

Did covid vaccine studies use an active placebo (with side effects)?

The AstraZeneca COVID-19 vaccine approved by EU and UK regulatory authorities used a meningitis vaccine as the control in phase 2/3 trials. From the methods section of their paper: Participants were ...
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  • 3,153
4 votes
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Do side effects spoil blind studies?

If a drug produces noticeable side effects, it is likely that studies will suffer from an unblinding effect which will cause overstatement of efficacy of the drug. This is because in a properly ...
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  • 282
4 votes
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What does "Primary Purpose: Treatment" mean in a clinical study?

Your interpretation is basically correct. The formal definition is: https://prsinfo.clinicaltrials.gov/definitions.html#IntPurpose Primary Purpose *§ Definition: The main objective of the ...
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  • 9,345
4 votes
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Are "data cut off" and "data lock" the same thing in a clinical trial?

I don't think they are both specific terms that will apply consistently across all studies, you will have to use the surrounding context. "Data lock" typically means that the data themselves in some ...
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4 votes
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How do I read this graph about pneumonia death rates in the elderly?

I agree the presentation is confusing. There are 4 categories, two are the same category except separated by age. The other two categories are not separated by age. There are two gray colors; the ...
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4 votes

Do experimenters in clinical trials refuse to give a placebo to a patient depending on his condition?

Two facts you need: first, clinical trials have very strict rules for who can be in them. Second, some trials are "drug A vs placebo" while others are "Drug A vs Drug B" or "...
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4 votes
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Did covid vaccine studies use an active placebo (with side effects)?

Of the three vaccine products that have been approved or had emergency use authorization in the United States, all used saline placebo in the clinical trial. From the Pfizer Polack et al paper: With ...
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  • 2,328
3 votes
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What is the purpose of the "observation cohort" in a clinical trial?

This entire study was observational; they refer to the entire group as the "observation cohort" but they selected a subset of cases who received a certain treatment to complete their further analyses. ...
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3 votes
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What would it be like to participate in a (coronavirus) challenge trial, in the US?

You would want to talk to the staff who are recruiting patients; I'm not aware of any such trials that have started anywhere yet. I would expect you would have access to most of those things depending ...
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3 votes
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Is this study stating red algae reduces cold virus by 92% believable?

Looking at this from the perspective of an infectious disease epidemiologist, the kind of person who often reads (and occasionally runs) studies of this type, I'm skeptical. A number of reasons why: ...
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  • 2,423
3 votes

When would a placebo/control group *not* be used in medical research?

I'll point out some possible situations; these are certainly not exhaustive and some can overlap, but will probably give you a better idea. Some of the terminology I'll use might be a bit US-centric, ...
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2 votes

Are these studies about red algae reducing cold virus by 92% believable?

One might wonder why they gave an ambiguous and questionably relevant figure like "reduces virus by 92%" rather than saying "people recovered more quickly" or something like that. The answer is that ...
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  • 295
2 votes
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What is the meaning of "group-by-region interaction effects" (PET scan study of brains affected by schizophrenia)?

The authors did an experiment with two independent variables: group and region. The groups are "schizophrenia" and "no schizophrenia" (controls). The a priori regions were the frontal cortex, anterior ...
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2 votes

Can COVID-19 be damaging lung without showing fever?

The range of symptoms for people infected with SARS-CoV-2 are extreme. There are reports of asymptomatic children with CT scans showing viral pneumonia. Among the paediatric patients in our study, ...
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2 votes
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Meaning of "D1 q3w" in a poster to a clinical trial

D1 means on day one of the three weekly cycles. DI is a typo. https://oncologypro.esmo.org/meeting-resources/esmo-2016/Lurbinectedin-PM01183-administered-once-D1-every-3-weeks-q3w-in-combination-with-...
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2 votes

what is the difference between clinical trial study and clinical study?

From https://clinicaltrials.gov/ct2/about-studies/learn#WhatIs: A clinical study involves research using human volunteers (also called participants) that is intended to add to medical knowledge. ...
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2 votes
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If placebo controls work even when the patient is aware that the treatment is a placebo. Why are deceptive placebo controls used?

The entire point of having a placebo control from a statistics perspective is that the only thing different between the groups is the treatment. You cannot say this is true if you also tell people ...
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2 votes
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The process of drug approval; The flow from R&D, planning a clinical trial to drug approval, or other additional process

I'm afraid it would be frowned you all if I answered it by myself and took my response as a solution, but... As I mentioned in the comments section above, I found a very summarized resource on the FDA'...
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2 votes
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Relationship between FDA Agencies and the Advisory Committee

In the final stage of FDA's approval process, what is the 'agency'? What is the role of them? The agency is the Food and Drug Administration (FDA). They are an agency within the Department of Health ...
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  • 5,872
2 votes

Were thrombocyte counts or bleeding events monitored at all during ChAdOx1 (AZD1222) clinical trials?

Apparently some testing was conducted; it's mentioned on p. 49 in the MHRA assessment report, albeit not in a lot of detail: Laboratory testing was only conducted in a subgroup of subjects up to 28 ...
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  • 5,803
2 votes
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Meaning of "There was no assessment of the types or effectiveness of risk factor controls over time in reducing stroke odds"

Full Background The full-text of the study that Dr. Goldstein discusses is available online at: https://www.ahajournals.org/doi/10.1161/STROKEAHA.120.032995 Chen MH, Tsai SJ, Su TP, Li CT, Lin WC, ...
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2 votes

Do experimenters in clinical trials refuse to give a placebo to a patient depending on his condition?

Two things: Clinical trials are generally double-blinded, meaning that neither the subjects nor the researchers know what the subject is receiving, and Potential ethical issues are considered ahead ...
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  • 21
1 vote
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Meaning of "(ref)" in a table describing the characteristics of patients taking part in a cancer study

The authors are fitting a regression model. It is common in regression with factors as predictors to consider one level of the factor as a "reference" level. Every other variable in the ...
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