GSK is conducting a global retrospective chart review of patients treated with zanamivir as part of the Compassionate Use Program (CUP), in an effort to collect as much information as possible on the use of this investigational drug. The retrospective chart review is intended to gain a better understanding of the safety profile of investigational zanamivir and of clinical outcomes in the large number of patients treated outside of a clinical trial setting.

This is an observational, retrospective, multi-centre, cohort data collection study.

The CUP retrospective review study has been designed to collect safety and clinical outcome data from pediatric and pregnant patients (collectively referred to as the "Tier 1" cohort) treated globally within the CUP during the 2009/2010 pandemic (from May 2009) through 31 January 2011. The study will also attempt to collect data from other adult patients (referred to as the "Tier 2" cohort) who were treated at sites identified as having Tier 1 patients.

The treating physician at each site will receive a letter from the GSK medical director inviting him/her to participate in the retrospective chart review study. Physicians (or their delegates) who agree to participate will receive study-related documentation [including the protocol and case report form (CRF)] to orient the site to the study details and CRF. For the purposes of this study, the term "site" generally refers to a hospital where in-patient treatment was provided.

The retrospective chart review will be monitored via remote visits by telephone. The interviewer will be a Kendle associate assigned to the study who will not have direct access to the patient's source documents or medical records during conduct of the study. The physician/delegate will review the patient's chart and record data on a paper CRF. The CRF will be in the English language. Site personnel will mail completed CRFs to Kendle. Kendle will review the CRF for data quality, and conduct a remote monitoring visit via telephone to address any data queries, if required. No visits to participating sites are planned.

Inclusion Criteria:

1. Pediatric or pregnant patients that received zanamivir aqueous solution as part of the Compassionate Use Program from May 2009 through 31 January 2011 (Tier 1 cohort).
2. Adult patients (Tier 2 cohort) that received zanamivir aqueous solution as part of the Compassionate Use Program from May 2009 through 31 January 2011, treated at the same site as a Tier 1 patient.

Exclusion Criteria:

1. Adult patients that received zanamivir aqueous solution at non-Tier 1 sites.
2. Pediatric or pregnant patients that received zanamivir aqueous solution as part of the Compassionate Use Program after 31 January 2011.

350 patients previously treated with zanamivir aqueous solution as part of the CUP, at an estimated 100 sites in over 15 countries are targeted for participation. Medical information on safety and clinical outcomes from Tier 1 and Tier 2 patients will be collected within this retrospective chart review study.

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.