Public Health Interventions: lessons learned Mark Loeb MD, MSc McMaster University

Public Health Interventions Influenza (H1N1) 2009 Non-pharmacologic interventions - school closure, quarantine - PPE Pharmacologic interventions - targeted use of anti-virals - uptake and effectiveness of vaccination

MMWR July 30, 2010

Context 2009 H1N1 pandemic less virulent than expected, plans based on previous assumptions had to be rethought Interventions previously planned had to be reassessed Tension between the urgent need to collect and understand information and the need to take immediate action Because implementation takes place at the local level, it had to be adapted to local capabilities and existing systems.

Pandemic influenza as 21th century urban public health crisis Mexico CityNYCShared Elements Initial appearance National surveillance School introduction Core activities: Intensive, multi- faceted media Campaign Novel syndromic surveillance developed pre-pandemic were activated Coordination of government at different levels; collaboration of public health and emergency response Promotion of personal hygiene Extensive public communications campaign via pre-existing program Surveillance a function of organization and provision of health services Extensive social distancing, wide spread school closures Selective school closureCriteria for re-opening schools were unclear Bell DM et al. Emerg Infect Dis 2009; 15:

School Closure and Mitigation of Pandemic (H1N1) 2009, Hong Kong Wu JT et al. Emerg Infect Dis 2010; 3:

Quarantine Methods and Prevention of Secondary Outbreak of Pandemic (H1N1) 2009 Chu CY et al, Emerg Infect Dis 2010; August

N95 respirators vs Surgical Masks pH1N1 Considerable uncertainty about the effectiveness of personal respiratory devices against pH1N1 In the inter-pandemic setting, surgical masks, which filter large droplet particles, are recommended for HCWs For H1N1, recommendations vary from uniform use of N95 (CDC) to N95 use restricted to aerosol generating procedures (WHO)

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Surgical Masks to protect HCWs against pH1N1 Figure 1. Weekly number of confirmed cases of pandemic novel swine ‐ origin influenza A (H1N1)–2009 among patients and health care workers (HCWs) at Tan Tock Seng Hospital, Singapore, 26 April–31 August 2009.

Summary of the Four Outbreaks of 2009 H1N1 Influenza and Efficacy Prophylaxis and Other Interventions Lee VJ et al. N Engl J Med 2010;362: Oseltamivir Ring Prophylaxis for Containment of 2009 H1N1 Influenza Outbreaks Lee VJ et al, NEJM 2010: 362;

Phylogenetic Relationships among the Viruses Identified during the Four Outbreaks with the Use of Whole-Genome Sequencing Lee VJ e Lee VJ et al, NEJM 2010: 362; t al. N Oseltamivir Ring Prophylaxis for Containment of 2009 H1N1 Influenza Outbreaks

Uptake of Influenza A (H1N1) 2009 Monovalent Vaccine: MMWR 2010 Apr 9(13)397 Median 37% (21% to 85%) children aged 6 months to 17 yrs 33% (19% to 56%) for ACIP target groups by state Median 25% (10% to 47%) for adults 25 to 64 years at high risk

Public’s Response to 2009 H1N1 influenza Pandemic Steelfisher GK et al. NEJM 2010; 362: e65

Interim Results: Influenza A (H1N1) 2009 Monovalent and Seasonal Influenza Vaccination Coverage Among Health-Care Personnel — United States, August 2009–January 2010 MMWR 2010 Apr 9;59 (13)397

Copyright restrictions may apply. Nolan, T. et al. JAMA 2010;303: Immune Responses After the First and Second Vaccinations With 2009 Influenza A(H1N1) Vaccine as Measured by the Hemagglutination Inhibition (HI) Assay

Pandemic Influenza Breakthrough infections and estimates of vaccine effectiveness in Germany Wichmann et al, Euro Surveill 2010; 15 (18); 19561

Vaccine effectiveness in pandemic influenza – primary care reporting (VIPER): an observational study to assess the effectiveness of the pandemic influenza A (H1N1)vaccine Study from Scotland, retrospective cohort design Network of 41 general practises (250,000 patients), n=59, 712 Linked medical records data with laboratory testing H1N1 (October to December 2009) 1,492 swabs (only 1 vaccinated was positive) Report 95% effectiveness (95%CI 76% to 100%) of H1N1 vaccine in high priority groups Simpson et al, Health Tech Assess 2010; 14:

Hutterite Cluster RCT

Copyright restrictions may apply. Loeb, M. et al. JAMA 2010;303: Flow Diagram of Trial

RCT – Year 2 Data Follow up from November 2009 to May 2010 N= day post vaccine analysis 1077/3840 (28%) = H1N1 vaccine 54 cases of H1N1 (PCR confirmed) - 1/1072 or 0.1%(H1N1 vaccine) - 53/2768 or 2% (No H1N1 vaccine)

Vaccination and H1N1 (2009) Infection Monovalent vaccine n=1071 No monovalent vaccine n=2715 P Value Protective Effectiveness Participants with H1N1 (2009) influenza detected by RT-PCR– no.(%)* 1 (0.1%)53(2%)95% (65% to 99%) Seasonal Vaccine n=994 No seasonal Vaccine n=2846 HR (95% CI) Participants with H1N1 (2009) Detected by RT-PCR – no. (%)17 (1.7%)37 (1.3%)1.36 ( )0.35

Summary Selected nonpharmacological interventions appear to be have had an effect Ring prophylaxis (military setting) highly effective Early data support effectiveness of the monovalent vaccine Need improvement on vaccine uptake in both community and healthcare settings