H5N1 influenza pandemic: contingency plans

Nonetheless, the efficacy of neuraminidase inhibitors, even for non-H5N1 influenza A in healthy people and taken within 48 h of disease onset, is only slight (table).6-11 The use of oseltamivir in five of the ten cases reported in Vietnam did not show any obvious clinical efficacy, and the mortality was 80% in this cohort.12 The two neuraminidase inhibitors, oseltamivir and zanamivir, have not been directly compared in controlled trials. Their pharmacological properties are compared in the table.6-11 Although both have similar efficacy, zanamivir has fewer adverse reactions, and a favourable resistance profile. The resistance factor would be an important consideration in a pandemic situation. The reasons for zanamivir not being chosen for stockpiling might include concern that young children and patients with intellectual or coordination impairments would not be able to inhale zanamivir properly, although there are novel ways of giving the drug to children.13 The occurrence of bronchospasm and reduced lung function is very rare, and patients with asthma and chronic obstructive pulmonary disease (COPD) seem to tolerate inhalation of zanamivir as well as the placebo.14 The inhaled flow rate needed to give the custom-designed inhaler for zanamivir (49-110 L/min) is similar to that for accuhaler (30-90 L/min), and turbohaler (60-90 L/min), which are popular dry-powder inhalation devices used by many asthmatic and COPD patients, even during exacerbations.15,16 Therefore governments should also consider stockpiling zanamivir as an anti-influenza agent in their pandemic plans. Actual logistics for giving out antivirals to patients and close contacts need to be efficient and completed within 48 h. It seems more appropriate for community-based health-care personnel or even pharmacists, rather than hospital-based health-care workers, to handle such procedures.