Researchers urge delay in administering second dose of Pfizer's Covid-19 vaccine, cite strong data

In its response, Pfizer said that alternative dosing regimens of its
vaccine had not been evaluated yet and the decision to do that resided
with the health authorities. "We at Pfizer believe that it is critical
for health authorities to conduct surveillance on implemented
alternative dosing schedules to ensure that vaccines provide the
maximum possible protection," the company added.

https://economictimes.indiatimes.com/industry/healthcare/biotech/pharmaceuticals/researchers-urge-delay-in-administering-second-dose-of-pfizers-covid-19-vaccine-cite-strong-data/articleshow/81087842.cms