According to the media outlet, citing CDC officer Sara Oliver, there is "no known or expected causal relationship between the vaccine and Bell's palsy".
"Post authorisation safety and effectiveness studies will be critical as well. Specifically, surveillance for Bell’s palsy could help determine any possible causal relationship", Oliver said, as quoted by the broadcaster.
On Friday, the four reported cases of facial paralysis were confirmed by the CDC's Advisory Committee on Immunisation Practices.
One of the trial participants experienced the Bell's palsy three days after getting the shot, another — 48 days after the vaccination.
All four incidents, according to the Food and Drug Administration (FDA), were "consistent with the expected background rate in the general population" and "there is no clear basis upon which to conclude a causal relationship at this time".
Pfizer's COVID-19 vaccine, developed under a joint-venture with Germany's BioNTech, was given an FDA authorisation for emergency use on Friday.
The United States remains the worst-hit nation, with more than 15.8 million confirmed cases and over 295,000 fatalities.