Participant shares experience with Pfizer COVID-19 vaccine trial A vaccine trial participant is sharing his experience so the public will feel confident in the process. and last updated 2020-12-18 21:29:00-05 NASHVILLE, Tenn. (WTVF) â One of the participants of Pfizer's COVID-19 vaccine trial is sharing his experience so the public will feel confident in the process. Clinical Research Associates is currently collecting data from multiple COVID-19 vaccine trials. Cornelius Henderson said he felt led by God to participate in the Pfizer one. "You certainly want to see more African Americans who received the vaccine to see what difference does it make since the infection in our community has been quite high and the death rate has been quite high," Henderson said.