Making the most of masks


Making the most of masks

from the Public Health Expert blog
 Mask - Adam Nieścioruk on Unsplash
Updating the evidence on mask effectiveness [Image: Adam Nieścioruk on Unsplash]

Masks and vaccination have a central role in minimising the health and economic impact of COVID-19, regardless of the long-term strategy we use against the pandemic. These interventions depend on both good performance and high population coverage. Here we update evidence on mask effectiveness and make the case that mask use needs to be universal in all indoor environments at Alert Level 2, including workplaces, schools, and high risk settings such as gyms.

Dr Nitasha Rimar, Dr Lucy Telfar Barnard, Dr Amanda Kvalsvig, Lesley Gray, Prof Michael Baker*

The Public Health Expert is published by the University of Otago

As New Zealand’s outbreak of the COVID-19 Delta variant continues, and the public becomes eager to move out of lockdown, the need to prevent new outbr
  1. Johansson, M.A., et al., SARS-CoV-2 transmission from people without COVID-19 symptoms. JAMA Network Open, 2021. 4(1): p. e2035057-e2035057.
  2. Howard, J., et al., An evidence review of face masks against COVID-19. Proceedings of the National Academy of Sciences, 2021. 118(4).
  3. Organization, W.H., Mask use in the context of COVID-19: interim guidance, 1 December 2020. 2020, World Health Organization.
  4. Taminato, M., et al., Homemade cloth face masks as a barrier against respiratory droplets-systematic review. Acta Paulista de Enfermagem, 2020. 33.
  5. Wang, D., et al., Selection of homemade mask materials for preventing transmission of COVID-19: A laboratory study. PLoS ONE, 2020. 15(10): p. e0240285.
  6. Hendrix, M.J., et al., Absence of Apparent Transmission of SARS-CoV-2 from Two Stylists After Exposure at a Hair Salon with a Universal Face Covering Policy – Springfield, Missouri, May 2020. MMWR Morb Mortal Wkly Rep, 2020. 69(28): p. 930-932.
  7. Payne, D.C., et al., SARS-CoV-2 infections and serologic responses from a sample of US Navy service members—USS Theodore Roosevelt, April 2020. Morbidity and Mortality Weekly Report, 2020. 69(23): p. 714.
  8. Lyu, W. and G.L. Wehby, Community Use Of Face Masks And COVID-19: Evidence From A Natural Experiment Of State Mandates In The US: Study examines impact on COVID-19 growth rates associated with state government mandates requiring face mask use in public. Health Affairs, 2020. 39(8): p. 1419-1425.
  9. Rader, B., et al., Mask-wearing and control of SARS-CoV-2 transmission in the USA: a cross-sectional study. The Lancet Digital Health, 2021. 3(3): p. e148-e157.
  10. J Abaluck, L.K., A Styczynski et al. The Impact of Community Masking on COVID-19: A Cluster-Randomized Trial in Bangladesh. 2021; Available from:
  11. Liang, M., et al., Efficacy of face mask in preventing respiratory virus transmission: A systematic review and meta-analysis. Travel Medicine and Infectious Disease, 2020. 36: p. 101751.
  12. Coclite, D., et al., Face mask use in the community for reducing the spread of COVID-19: a systematic review. Frontiers in Medicine, 2020. 7.
  13. Liao, M., et al., A technical review of face mask wearing in preventing respiratory COVID-19 transmission. Current Opinion in Colloid & Interface Science, 2021: p. 101417.
  14. Ju, J.T., L. Boisvert, and Y.Y. Zuo, Face masks against COVID-19: Standards, efficacy, testing and decontamination methods. Advances in Colloid and Interface Science, 2021: p. 102435.
  15. World Health Organization. Coronavirus disease (COVID-19) advice for the public: When and how to use masks. 2021; Available from:
  16. Centers for Disease Control and Prevention. Science Brief: Community Use of Cloth Masks to Control the Spread of SARS-CoV-2. 2021; Available from:
  17. European Centre for Disease Prevention and Control. Using face masks in the community: first update – Effectiveness in reducing transmission of COVID-19. 2021; Available from:
  18. Bourouiba, L., Turbulent gas clouds and respiratory pathogen emissions: potential implications for reducing transmission of COVID-19. JAMA, 2020. 323(18): p. 1837-1838.
  19. Verma, S., M. Dhanak, and J. Frankenfield, Visualizing the effectiveness of face masks in obstructing respiratory jets. Physics of Fluids, 2020. 32(6): p. 061708.
  20. Hamner, L., High SARS-CoV-2 attack rate following exposure at a choir practice—Skagit County, Washington, March 2020. MMWR. Morbidity and Mortality Weekly Report, 2020. 69.
  21. Samannan, R., et al., Effect of face masks on gas exchange in healthy persons and patients with chronic obstructive pulmonary disease. Annals of the American Thoracic Society, 2021. 18(3): p. 541-544.
  22. Shaw, K., et al., Wearing of cloth or disposable surgical face masks has no effect on vigorous exercise performance in healthy individuals. International Journal of Environmental Research and Public Health, 2020. 17(21): p. 8110.
  23. Gandhi, M., et al., Masks Do More Than Protect Others During COVID-19: Reducing the Inoculum of SARS-CoV-2 to Protect the Wearer. Journal of General Internal Medicine, 2020. 35(10): p. 3063-3066.
  24. Gandhi, M. and G.W. Rutherford, Facial masking for Covid-19—potential for “variolation” as we await a vaccine. New England Journal of Medicine, 2020. 383(18): p. e101.
  25. Li, Y., et al., Probable airborne transmission of SARS-CoV-2 in a poorly ventilated restaurant. Building and Environment, 2021. 196: p. 107788.
  26. Heald-Sargent, T., et al., Age-Related Differences in Nasopharyngeal Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Levels in Patients With Mild to Moderate Coronavirus Disease 2019 (COVID-19). JAMA Pediatrics, 2020. 174(9): p. 902-903.
  27. Yonker, L.M., et al., Pediatric severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2): clinical presentation, infectivity, and immune responses. The Journal of Pediatrics, 2020. 227: p. 45-52. e5.
  28. American Academy of Pediatrics. Children and COVID-19: State-Level Data Report. 2021; Available from:
  29. Radia, T., et al., Multi-system inflammatory syndrome in children & adolescents (MIS-C): A systematic review of clinical features and presentation. Paediatric Respiratory Reviews, 2021. 38: p. 51-57.
  30. Swartz, M.K., Post-COVID Conditions in Children. Journal of Pediatric Health Care, 2021. 35(5): p. 457-458.
  31. Fischer, E.P., et al., Low-cost measurement of face mask efficacy for filtering expelled droplets during speech. Science Advances, 2020. 6(36).
  32. Pan, J., et al., Inward and outward effectiveness of cloth masks, a surgical mask, and a face shield. Aerosol Science and Technology, 2021. 55(6): p. 718-733.
  33. Brown, C.M., et al., Outbreak of SARS-CoV-2 infections, including COVID-19 vaccine breakthrough infections, associated with large public gatherings—Barnstable County, Massachusetts, July 2021. Morbidity and Mortality Weekly Report, 2021. 70(31): p. 1059.
  34. Keehner, J., et al., Resurgence of SARS-CoV-2 infection in a highly vaccinated health system workforce. New England Journal of Medicine, 2021.
  35. Goldberg, Y., et al., Waning immunity of the BNT162b2 vaccine: A nationwide study from Israel. medRxiv, 2021.
  36. Thomas, S.J., et al., Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine through 6 Months. New England Journal of Medicine, 2021.