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Studies showed it decreased infection and transmission against the original strain of Covid.[0]

It lost effectiveness against delta and then became nearly ineffective against Omicron (although still helping with reduction of hospitalizations and deaths).

Non-mRNA vaccine is available now (Novavax) and the effectiveness, or lack thereof, seems similar.

[0] https://med.stanford.edu/news/all-news/2021/07/vaccination-a...