The National Advisory Committee on Immunization says there is now enough ``real-world evidence'' to show the Oxford-AstraZeneca COVID-19 vaccine is both safe and effective for seniors.

The decision reverses a recommendation made by the body on March 1, when the panel of vaccine experts said AstraZeneca hadn't included enough people over the age of 65 in its clinical trials.

NACI chair Dr. Caroline Quach said Tuesday that two studies of patients who received the vaccine in the United Kingdom have been released since then and show the AstraZeneca vaccine is both safe and effective for seniors, particularly against severe disease and hospitalization.

She says while the clinical trial data show the two mRNA vaccines from Pfizer-BioNTech and Moderna were more effective than AstraZeneca's, the data on the vaccines since they began being widely used shows similar levels of effectiveness.

Still NACI says if there is a choice, the mRNA vaccines should be prioritized for use on seniors, but they no longer recommend against using AstraZeneca for anyone over the age of 65.

Several European countries also reversed a recommendation against using it on seniors, including France, Germany and Italy.