Thread by @realscientists

So I decided not to talk about vaccines today. Instead, I will be talking about clinical trials more broadly. I know quite a bit about vaccines but not enough to call myself an expert. And expert opinion is needed right now. So imma stay in my lane.

I worked doing project management for clinical trials during my gap year between undergrad and grad school. It was boring but I learned a lot

A clinical trial is seen as the best was to find a causal link between two variables

Say we wanted to look at if medication AX lowers blood pressure

The investigator assigns the exposure level (AX or placebo) to participants in a random manner, hence why clinical trials are also called randomized controlled trials (RCTs)

A "double-blind" study is seen as the best-case scenario where both the participants and researcher have no idea who got AX and who got a placebo

I feel like the term "double-blind" is ableist. Let me know if it is, please

The primary benefit of randomization is that it will eliminate both conscious bias and unconscious bias associated with the selection of a treatment for a given patient

Causal effects can be estimated without assumptions
and without prior knowledge of common
causes of blood pressure levels

Now since we are trying to eliminate the influence of outside factors other than AX and the placebo, that means the results are not generalizable to the public

Efficacy can be defined as the performance of an intervention/treatment under ideal and controlled circumstances, whereas effectiveness refers to its performance under 'real-world' conditions

So while the efficacy of AX may be high in this controlled study, but until we add social and cultural contexts, we don't know the effectiveness of AX

But we do know that AX is directly connected to blood pressure

Clinical trials that support FDA approvals of new drugs have a median cost of $19 million

There are four phases of clinical trials:

Preclinical research is not done on humans

Phase 0 tries to understand how the drug impacts the body. There is a small sample size of about 10 people who are given small doses of the drug

Phase 1 tries to find the best dose of a new drug with the fewest side effects. A sample size of about 20 is used. This is to test the safety of the drug.

Phase 2 assesses safety as well as if a drug works. Phase II trials are done in a larger sample size. Often, new combinations of drugs are tested and patients are closely monitored

Phase 3 is normally where randomization comes in. In this phase, we compare a new drug to the standard treatment that patients usually get. Phase 3 trials enroll 100+ patients

The study will be stopped early if the side effects of the new drug are too severe or if one group has better results

Phase 4 trials test the new drugs approved by the FDA. The drug can be tested in several hundreds or thousands of patients