What Does a 95% Effective Vaccine Really Mean?

TL;DR

COVID-19 vaccines have different efficacy rates due to varying trial criteria, but all three authorized vaccines are highly effective at preventing death.

Transcript

Thanks to Brilliant for supporting this episode of SciShow. You can check out Brilliant.org/SciShow to learn more and get 20% off an annual premium subscription. This episode was filmed on March 19th, 2021. For up-to-date information on the COVID-19 pandemic, check out our playlist linked in the description. [♪ INTRO] If I offered you a choice betw... Read More

Key Insights

• ☠️ Efficacy rates for COVID-19 vaccines are based on clinical trials' primary endpoints and vary due to different trial criteria.
• ☠️ Comparing efficacy rates between different vaccines is not valid since trials were conducted at different times, locations, and with different virus strains.
• ❓ All authorized COVID-19 vaccines are highly effective at preventing death, which is a crucial outcome.
• ☠️ Real-world effectiveness of vaccines can be influenced by factors like vaccination rates, emergence of new variants, and social and racial inequities.
• 🦺 COVID-19 vaccines have undergone extensive testing and have been deemed safe and effective by regulatory bodies.
• 🌍 It is important to understand the difference between efficacy (in trials) and effectiveness (in the real world) when evaluating vaccine performance.
• 🔨 Vaccination remains a vital tool in reducing illness, hospitalization, and death from COVID-19.

Questions & Answers

Q: Why do COVID-19 vaccines have different efficacy rates?

Efficacy rates vary due to differences in trial criteria, such as counting symptomatic cases or moderate to severe cases, and when a case is counted after vaccination.

Q: Do higher efficacy rates mean better protection?

Efficacy rates do not directly translate to better protection. All three authorized vaccines are highly effective at preventing death, which is a primary goal.

Q: Can the efficacy rates change in the real world?

Efficacy rates measured in trials may differ from real-world effectiveness due to factors like vaccination rates, the emergence of new variants, and inequities in vaccination distribution.

Q: Are there concerns about the safety or efficacy of COVID-19 vaccines?

COVID-19 vaccines have undergone rigorous testing and have been authorized for use by regulatory bodies. They have proven to be safe and highly effective in preventing severe illness and death.

Summary & Key Takeaways

• COVID-19 vaccines have different efficacy rates, with the BioNTech-Pfizer vaccine at 95%, Moderna at 94%, and Janssen (Johnson & Johnson) at 66% (awaiting peer review).

• Efficacy numbers are calculated based on the number of cases in the placebo group compared to the vaccine group.

• Comparing efficacy numbers between different trials is not valid due to differences in trial criteria, locations, and timing.