08 April 2010
The influenza season in South Africa generally starts towards the end of May and peaks in June with transmission continuing generally but tailing off to the end of July and August. South Africa has well established national influenza monitoring system run by the National Institute for Communicable Diseases that provides information on influenza, and circulating influenza virus strains. Currently no cases with influenza have been identified through this surveillance.
There is some uncertainty regarding the influenza strains of the forthcoming season but it is likely that the pandemic influenza A (H1N1) strain also known as ‘swine flu’ will in all probability reappear as the dominant influenza strain this winter.
This is based on what was experienced during the northern hemisphere winter season. In the United States and the UK between 70-99% of the viruses identified were the pandemic influenza A (H1N1) strain. What is often seen is that a new pandemic strain goes on to replace the previous seasonal influenza strains and then it circulates in the following seasons with minor changes each year. No significant changes in the virus to suggest an increase in severity or a change in drug resistance were identified during the northern Hemisphere influenza season.
The 2010 trivalent influenza vaccine contains three different influenza strains and includes the influenza A H1N1 (pandemic) strain. It is currently available in the private health sector as well as the first phase of the public sector influenza vaccination programme.
There is however a shortage of the vaccine in the private sector for a number of reasons, including production problems because one of the strains in the vaccine did not grow well; some manufacturers switched to producing the monovalent (swine flu) vaccine last year in response to the pandemic; an increased demand due to people’s fears following the pandemic last year as well as a large purchase of vaccines for the public programme.
Generally, in South Africa the uptake of the influenza vaccine in previous years has been low and lots of vaccine doses went unused and vaccine supplies are to some extent based on previous usage.
While the majority of persons will not develop complications of influenza, those at risk for severe disease should be vaccinated. These include pregnant women irrespective of the stage of pregnancy, persons over the age of 6 months with underlying medical conditions– chronic lung disease, chronic cardiac disease, diabetes, HIV infected persons and other who are immunosuppressed, and those over 65 years of age.
The National Department of Health has embarked on an immunization campaign in the public sector which will be rolled out in two stages. The first phase which started this week will initially target front -line workers at ports of entry and in health care institutions and children 15 years and younger on antiretroviral therapy for HIV. The second phase which will be in May will target amongst others persons with chronic diseases and pregnant women.
The best prevention against influenza is to be vaccinated. You can also protect yourself and others by practicing good hand hygiene, cough and sneezing etiquette. Most people ill with influenza will recover without complications. Persons that are at highest risk of influenza-related complications should be prioritized for early treatment with influenza antiviral drugs.
Issued by the National Institute for Communicable Diseases, a division of the National Laboratory Service
For more information please contact Nombuso Shabalala on 011 555 0545 or 082 886 4238