The Vaccination Situation

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Phase I

Hey y’all! This week we’re getting into just exactly how vaccine trials work and the testing process required to get them approved. And in pretty straightforward nomenclature, each round is called a “phase”. According to the NIH, Phase I trials are for figuring out the safety of the vaccines. Additionally, side effects are observed and monitored to see if the vaccine can continue on to further stages of testing. It also provides the resources for researchers to discover the safe dosage range of the vaccine.

With each successive phase of vaccine trials, the amount of people increases. This means that phase I has the smallest amount of participants with about 20-80. This phase is essential because it is the first time that the vaccine is being tested on humans. This means that vaccine companies need to make sure there aren’t any unforeseen effects from the vaccine on humans. Making sure the vaccine is safe for humans is essential to advance to phase II.

Phase II

Okay, so the vaccine seems pretty safe now, right? Well… kinda. Phase II is necessary to make sure there weren’t any effects that were missed. This NIH article, discusses how the purpose of phase II is to expand the safety checks to double check nothing was missed and look for extreme cases that the small sample size of phase I couldn’t detect. Another major reason is to check the immune response and help dial in the dosage. Additionally, they are checking on timing and other various factors that influence efficacy.

By expanding to 100-300 participants, phase II trials have a more representative population than phase I. The researchers also sometimes introduce blinding and randomization at this point to help reduce bias. The data collection for this increased pool is typically a little more intense. Researchers collect immune response data such as antibody titers, T cell responses, and the duration of the immune response. All of these factors help set up for phase III by giving more information on dosage amounts and timing that will cause the greatest amount of benefit with the least amount of side effects.

Phase III

Finally, the long await phase III. Is it finally time to let the vaccine out to the public, and start saving lives? Not quite. Phase III is the final testing phase before public rollout. The participant pool for this phase is in the thousands, with some trials reaching the tens of thousands (we’ll discuss a case like this in a sec). They are randomly selected for which group they will be in to reduce bias from themselves and the researchers. This helps prevent systematic differences being created in the results and solidifies the authenticity of the results.

Now, let’s take a deep dive into a phase III study of the Moderna mRNA Covid vaccine. This study, published in the New England Journal of Medicine, outlines how these protocol were followed to test the efficacy of the Moderna vaccine. The study was double blind to prevent bias and ended up finding a 93.2% efficacy rate for the vaccine. And this efficacy was found for over 30,000 participants! Furthermore, it was 98% effective for severe disease. It’s crazy how this info relates to our personal lives! Hope you learned a little bit more about vaccines (I sure did) and can’t wait to get into some more micro things next week!