The university's Department of Public Health participated in what claims to be the most extensive international review of masks ever published.
Led by the University of Oxford, researchers examined more than 400 previous studies on the efficacy of masks.
"The benefits of wearing a mask have been hotly debated over the past few years," University of Otago associate professor Amanda Kvalsvig said.
"The findings of this rigorous review and reanalysis put an end to that uncertainty. We now have a clear pathway to action, including reducing the number of respiratory infections in winter 2024."
Professor Michael Baker said New Zealanders needed better access to effective masks.
Typical cloth face coverings were proven to have a positive impact, but the most effective were N95 and FFP2 respirators.
He said New Zealand should update its policy to protect at-risk groups, protect people at work and in healthcare, and to respond to pandemics.
"Updating our policies will allow all New Zealanders to benefit from the effective and versatile protection that masks provide against seasonal, epidemic and pandemic infections," he said.
The study also identified sore points for mask use, including discomfort and inconvenience as well as difficulties in communication for deaf and hearing-impaired people.
"We need to see these challenges as a call to action," Kvalsvig, herself deaf and a lip-reader, said.
"By investing in better design, more inclusive policies, and clearer communication, we can optimise masks for real-world use and ensure that everyone can benefit from this valuable public health protection."
