Pandemic (H1N1) 2009: epidemiological, clinical and prevention aspects

The influenza pandemic caused by the new H1N1 virus has by now affected all the continents of the world. However, the extent and likely impact are still uncertain. Like seasonal flu, the illness is mild and self-limiting in a great majority of cases, with only 1%-2% of patients requiring hospitalization. In a few cases, the clinical course can deteriorate in a matter of hours, leading to severe complications and eventually death. The risk of complications is higher among those who have preexisting diseases, such as asthma, heart disease and kidney disease, and among pregnant women. In such cases, antiviral treatment should not be delayed pending laboratory confirmation. The preferred antiviral drug is oseltamivir, and zanamivir is an alternative. Antiviral treatment is not necessary for those who are otherwise healthy, and have mild or uncomplicated illness. It is beneficial for patients with progressive lower respiratory tract disease or pneumonia, and those with underlying medical conditions and pregnant patients. As the supply of antivirals is limited, they should be used judiciously and where appropriate. There is a limited supply of pandemic influenza vaccine available in a few countries and efforts to produce it in India are presently underway. Effective personal preventive measures include shielding one's mouth and nose while coughing and sneezing, frequent washing of hands with soap, avoiding mass gatherings and voluntary isolation by symptomatic individuals. While at present the virus is causing a mild disease, the next wave may be more severe. Hence, enhanced surge capacity of health services is required for the clinical management of an increased patient load.