What percent effective is Pfizer vaccine?

[Anna Linde]

I want to know about the effectiveness of the Pfizer vaccine. How can I calculate this?

 

[Dr.Peterson]

I want to know about the effectiveness of the Pfizer vaccine. How can I calculate this?

Well, first you need some data; and then you need to determine the definition of "effectiveness" of a vaccine. Is one of those what you are asking for?

Here is one source for the latter (the first one Google directs me to when I type in "define vaccine effectiveness"): https://www.scientificamerican.com/article/experts-answer-the-biggest-covid-vaccine-questions1/

Here are more details: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3798059/