Persons who are in the high-risk category for influenza associated complications are strongly advised to be vaccinated for influenza prior to the winter season. The vaccine takes two weeks to be effective so it is important that the vaccine be given before the influenza season starts. South Africa has a well established national influenza monitoring system run by the National Institute for Communicable Diseases which provides information on the influenza season and circulating influenza virus strains.
The influenza season usually starts toward the end of May, reaches a peak towards the end of June and the number of cases start to decrease towards the end of July. While the majority of people will not develop complications of influenza, those at risk for severe disease should definitely be vaccinated to reduce the occurrence of complications which can be very serious and even result in death. These complications include viral or bacterial pneumonias, infection of the heart muscle, and a worsening of underlying conditions, for example asthma, diabetes and heart disease.
Risk groups for influenza-related complications include:
- Pregnant women – irrespective of stage of pregnancy
- Persons over the age of 6 months with underlying medical conditions predisposing them to complications of influenza including the following:
- chronic lung disease
- chronic cardiac disease
- mild to severe diabetes
- HIV-infected persons
- All individuals over the age of 65 years
Persons living in the same household or carers of high- risk individuals and healthcare personnel should also be vaccinated to protect the at- risk group from influenza .
There is always some uncertainty regarding the predominant influenza strains of the forthcoming season. However, information from the influenza season in the 2010 northern hemisphere winter did not show significant changes in the viruses from the previous season to suggest an increase in severity or a change in resistance to antiviral medication.
The 2011 trivalent influenza vaccine for the southern hemisphere contains three different influenza strains and includes the influenza A H1N1 (pandemic) strain. It is currently available in the private health sector at a fee, as well as free through the public sector influenza vaccination programme. The composition of the 2011 vaccine for South Africa is the same as that used for the 2010 season but people vaccinated for the 2010 season need to be revaccinated as the effect of the vaccine lasts only about 9 months.
The influenza vaccine is safe, does not contain live virus and side- effects are uncommon. The best prevention against influenza is to be vaccinated. The vaccine is only effective against the influenza virus and not the many other causes of respiratory illness.
The virus is airborne and can be spread through the air by coughing and sneezing. It can also be contracted by touching surfaces contaminated by saliva and secretions of infected people so it is important to practice good hand hygiene as well as coughing and sneezing etiquette. The symptoms of influenza include fever, sore throat, cough, muscle pain, general body weakness, nausea and vomiting. Most people ill with influenza will recover without complications. Persons who are at highest risk of influenza-related complications should be prioritized for early treatment with influenza antiviral drugs.
This advisory is issued by the National Institute for Communicable Diseases, a division of the National Health Laboratory Service.
(Press release, April 2011)