In the video clip shared online, the Pfizer executive accurately states that studies of the vaccine’s effect on virus transmission from person to person were not performed during the original clinical trials of the company’s vaccine.
At the time governments were negotiating advance purchases of vaccine in 2020, the European Medicines Agency had already laid out requirements for an application for conditional marketing authorization of a COVID-19 vaccine, clinical trials were underway, and tests to show the vaccine prevented onward transmission were not required of any vaccine maker.
In a presentation later that year (here), the EMA listed vaccine benefits that clinical trials were intended to demonstrate (slide 8), which included only safety and at least 50% efficacy against “symptomatic disease” (here).
The same presentation slide describes “Other benefits likely uncertain at approval and only clearer after the vaccine is used” to include the vaccine’s “long term protection,” “prevention of infection (asymptomatic cases),” and “prevention of virus transmission in the community - needs specific studies post-approval necessary to show.”
The U.S. Food and Drug Administration laid out similar expectations for vaccine trials in June of 2020, and did not require data regarding the effect on virus transmission. (here)