A new rapid evidence brief, Improving mask use to stop COVID-19 transmission, from Koi Tū: The Centre for Informed Futures at the University of Auckland, synthesises the most up-to-date international research on the three main types of face masks – medical, cloth and N95 respirators. It provides suggestions for border workers, essential workers, and everyday New Zealanders (NZ).

The authors say N95 masks should be mandatory for managed isolation and quarantine (MIQ) workers, people staying in MIQ and all other personnel connected to border.

Ministry of Health guidelines on mask use for managed isolation and quarantine facility staff were updated in November 2020  and significantly strengthened in August 2021  after the emergence of the Delta variant. That update significantly extended the use of N95 respirators in MIQ although they did not make their use universal at the border.

Various laboratory tests suggest medical masks typically filter 50-75 percent of various test particles. Gaps around the face allow leakage of air, which significantly reduces mask effectiveness.

The effectiveness of medical masks can be greatly improved – filtering up to 60-90 percent of particles when modified to improve the seal against the face.

According to the experts, one simple way to make medical masks more effective is to “knot and tuck”, knotting the sides of the ear loops near the mask and tucking the pleats of the mask inwards.