This Evidence Review summarizes strategies used in Canada and internationally to distribute antivirals to vulnerable groups in a timely manner, both as a prophylactic measure and as treatment. Evidence exists for the efficacy of antivirals to reduce complications of and mortality from influenza. Clinical trials in healthy adults have suggested that antivirals can prevent the onset of influenza in 70%-90% of cases, when taken as prescribed. Prior to 2009, however, practitioners in North America had relatively little experience using antivirals in the primary care setting. Antivirals had been used primarily to control seasonal influenza outbreaks in health-care and long-term care institutions. This review also identifies challenges to using antivirals, and how some of these challenges could be overcome. Finally, it summarizes lessons learned through nation- or region-wide evaluations of the response to the 2009 pandemic.
Key Points:
Antivirals (e.g. oseltamivir and zanamivir) were the only medical intervention available during the initial phases of the 2009 influenza A (H1N1) pandemic before vaccines could be developed.
Stockpiling of antivirals for prophylactic and therapeutic use was an integral component of the pandemic preparedness plan in many countries.
While pre-exposure prophylaxis was generally not recommended, prophylactic use of antivirals for individuals who were pregnant or had serious underlying conditions, and who had been in close contact with an infectious case may have been warranted and required clinical judgement.
Optimal use of the antiviral stockpiles requires clear objectives, eligibility and triggers, protocols, and an administration and delivery system. The possibility of the emergence of resistant influenza strains should also be considered.
A number of countries found innovative solutions to dispensing antivirals during the 2009 pandemic. For example, the National Pandemic Flu Service in the U.K. implemented a telephone-based self-assessment and antiviral prescription system which was linked to antiviral collection points in pharmacies and other establishments in local communities.
