"Scientists and vaccine developers initially thought those first two shots would reduce transmission of the COVID-19 virus" Dr. Tam said.

Patently false.

Both Pfizer and Moderna's FDA briefs unequivocally made it clear they gave no assurances wrt transmissibility. Read sections 8.2 - 8.4.

Further, the CMO of Moderna, Tal Zaks in the BMJ, Oct 14, 2020 “Our trial will not demonstrate prevention of transmission, because in order to do that you have to swab people twice a week for very long periods, and that becomes operationally untenable.”

https://www.cbc.ca/news/politics/tam-federal-vaccine-mandates-under-review-1.6389844