A lecture given at the BOHS Conference in Harrogate in 2010.

1. What did we learn from the influenza pandemic of 2009/10? John Cherrie

4. The pandemic… http://www.who.int/

5. Fatalities in the EU… Total 2876 UK 457 http://ecdc.europa.eu/en/healthtopics/Pages/Pandemic_Influenza.aspx

9. Exposure models… Nicas and Jones. Relative contributions of four exposure pathways to influenza infection risk. Risk Analysis (2009) vol. 29 (9) pp. 1292-1303 Nicas and Jones. Relative contributions of four exposure pathways to influenza infection risk. Risk Analysis (2009) vol. 29 (9) pp. 1292-1303

10. Relative contribution of different pathways Nicas and Jones. Relative contributions of four exposure pathways to influenza infection risk. Risk Analysis (2009) vol. 29 (9) pp. 1292-1303

12. 1918

13. Effectiveness of masks in lab tests… Study Design Conclusions Gawn et al Challenge test on test subject - Spray aerosol (<1μm to >200μm with approximately 50% of the particle number distribution <20μm) Surgical masks provide around a 6-fold reduction in exposure. Properly fitted respirators could provide at least a 100-fold reduction. Eninger et al Challenge test on dummy head - Aerosol only Penetration of aerosol about 3.5% (PF=30)

14. Respiratory protection… Study Design Conclusions Aiello et al 1437 young adults living in university residence halls during the 2006–2007 influenza season was designed. Residence halls were randomly assigned to 1 of 3 groups— face mask use, face masks with hand hygiene, or control— for 6 weeks. Neither face mask use and hand hygiene nor face mask use alone was associated with a significant reduction in the rate Cowling et al Systematic review There is some evidence to support the wearing of masks or respirators during illness to protect others, and public health emphasis on mask wearing during illness may help to reduce influenza virus transmission. There are fewer data to support the use of masks or respirators to prevent becoming infected. Loeb et al A randomized control trial to compare the surgical mask with the N95 respirator in protecting health care workers against influenza. Among nurses in Ontario tertiary care hospitals, use of a surgical mask compared with an N95 respirator resulted in non inferior rates of laboratory- confirmed influenza. Maclntyre et al Prospective cluster-randomized trial comparing surgical masks, non–fit- tested P2 masks, and no masks in prevention of influenza- like illness (ILI) in households. Concluded that household use of face masks is associated with low adherence and is ineffective for controlling seasonal respiratory disease. However, during a severe pandemic when use of face masks might be greater, pandemic transmission in households could be reduced. Jacobs et al Health care workers in a tertiary care hospital in Japan were randomized into 2 groups: 1 that wore face masks and 1 that did not. No difference in flu symptoms but statistically significant increase in “feeling bad” and headaches amongst those wearing masks. Jefferson et al Review systematically the evidence of effectiveness of physical interventions to interrupt or reduce the spread of respiratory viruses. Hand washing more than 10 times daily (odds ratio 0.45) Wearing masks (0.32), Wearing N95 masks (0.09), Wearing gloves (0.43), Wearing gowns (0.23), and Hand washing, masks, gloves, and gowns combined (0.09). Cowling et al Cluster randomized, controlled trial. 07 people presenting to outpatient clinics with influenza- like illness who were positive for influenza A or B virus by rapid testing (index patients) and 794 household members (contacts) in 259 households. Interventions implemented within 36 hours of symptom onset in the index patient, transmission of RT-PCR–confirmed infection seemed reduced, an effect attributable to fewer infections among participants using facemasks plus hand hygiene (adjusted odds ratio, 0.33 [95% CI, 0.13 to 0.87]) Study Design Conclusions Aiello et al 1437 young adults living in university residence halls during the 2006–2007 influenza season was designed. Residence halls were randomly assigned to 1 of 3 groups— face mask use, face masks with hand hygiene, or control— for 6 weeks. Neither face mask use and hand hygiene nor face mask use alone was associated with a significant reduction in the rate Cowling et al Systematic review There is some evidence to support the wearing of masks or respirators during illness to protect others, and public health emphasis on mask wearing during illness may help to reduce influenza virus transmission. There are fewer data to support the use of masks or respirators to prevent becoming infected. Loeb et al A randomized control trial to compare the surgical mask with the N95 respirator in protecting health care workers. Use of a surgical mask compared with an N95 respirator resulted in non inferior rates of laboratory- confirmed influenza. Maclntyre et al Prospective cluster-randomized trial comparing surgical masks, non–fit- tested P2 masks, and no masks in prevention of influenza- like illness (ILI) in households. Concluded that household use of face masks is associated with low adherence and is ineffective for controlling seasonal respiratory disease. However, during a severe pandemic when use of face masks might be greater, pandemic transmission in households could be reduced. Jacobs et al Health care workers in a tertiary care hospital in Japan were randomized into 2 groups: 1 that wore face masks and 1 that did not. No difference in flu symptoms but statistically significant increase in “feeling bad” and headaches amongst those wearing masks. Jefferson et al Review systematically the evidence of effectiveness of physical interventions to interrupt or reduce the spread of respiratory viruses. Hand washing more than 10 times daily (odds ratio 0.45) Wearing masks (0.32), Wearing N95 masks (0.09), Wearing gloves (0.43), Wearing gowns (0.23), and Hand washing, masks, gloves, and gowns combined (0.09). Cowling et al Cluster randomized, controlled trial. 07 people presenting to outpatient clinics with influenza- like illness who were positive for influenza A or B virus by rapid testing (index patients) and 794 household members (contacts) in 259 households. Interventions implemented within 36 hours of symptom onset in the index patient, transmission of RT-PCR–confirmed infection seemed reduced, an effect attributable to fewer infections among participants using facemasks plus hand hygiene (adjusted odds ratio, 0.33 [95% CI, 0.13 to 0.87])

16. Slide presentation on OH-world.org You can download this and other presentations from OH-world.org Follow my blog on Twitter.com/JohnCherrie