Pfizer
A Pfizer executive said on Monday that neither she nor other Pfizer officials knew whether its COVID-19 vaccine would stop transmission before entering the market in late 2020.

Member of the European Parliament, Rob Roos, asked during a session:
"Was the Pfizer COVID vaccine tested on stopping the transmission of the virus before it entered the market? Did we know about stopping immunization before it entered the market?"
Pfizer's Janine Small, president of international developed markets, said in response:
"No ... You know, we had to ... really move at the speed of science to know what is taking place in the market."
Roos, of the Netherlands, argued in a Twitter video Monday that following Small's comments to him, millions of people around the world were duped by pharmaceutical companies and governments.
"Millions of people worldwide felt forced to get vaccinated because of the myth that 'you do it for others.'" Now, this turned out to be a cheap lie" and "should be exposed."
The Epoch Times notes that in late 2020 the Food and Drug Administration wrote that there were no data available to determine whether the vaccine would prevent transmission and for how long.

Around the same time, Pfizer CEO Albert Bourla said his firm was "not certain" if those who receive its vaccine will be able to transmit COVID-19 to other people.

However, during spring 2021 a number of people, including President Joe Biden and his Chief Medical Adviser Anthony Fauci, claimed vaccinated people are "dead ends" for the virus. Fauci said:
"When you get vaccinated, you not only protect your own health and that of the family but also you contribute to the community health by preventing the spread of the virus throughout the community."
Fauci later rowed back on these claims, saying that the vaccine prevents severe disease, hospitalisation and death from COVID-19. However, U.S. vaccination policy has remained wedded to the notion that it stops transmission, with mandates and coercion routinely imposed by public authorities and employers citing federal Government advice. Many of these policies, including the ban on unvaccinated visitors entering the United States, remain in force.