Influenza : Frequently Asked QuestionsWhat is Influenza (flu)?
It is an acute viral respiratory infection, transmitted by the influenza virus. This virus has three main types A, B and C. Influenza A is classified into different subtypes. The currently circulating seasonal viruses are A (H1N1), influenza A (H3N2) and influenza B viruses. The flu viruses are typically in circulation in the winter months in South Africa with an average start of the first week of June, although this varies.
2013 influenza season
The 2013 annual influenza season is well underway having started at the beginning of May. To date, the dominant influenza strain in South Africa for the 2013 season is influenza A(H1N1) pdm09 (previously commonly known as ‘swine flu’); this strain first appeared in 2009 and in subsequent years has become one of the influenza strains that circulate every year during the flu season. The clinical presentation, severity and management of influenza A(H1N1) pdm09 is the same as for seasonal flu. The 2013 Influenza vaccine will be protective against is Influenza A(H1N1) pdm09 .
The NICD has a national influenza surveillance programme in all nine South African provinces, whiconitors the timing of the flu season and circulating strains.
What are the signs and symptoms of influenza?
While most influenza illness is mild, complications (particularly pneumonia) are always a concern in persons with underlying conditions or certain risk factors. Complications within the chest are usually characterised by: shortness of breath at rest or during usually tolerated activity, chest pain, low blood pressure, clinical or XR features of pneumonia and myocarditis.
Who is at risk of developing complications?
How does flu spread?
The flu virus spreads via droplets when infected people talk, cough or sneeze, which could be inhaled by people who are in close contact. Occasionally drops that have landed on surfaces get transmitted through the individual touching the surface then also their mouths, noses or eyes.
When is a person contagious?
This varies with younger children or immuno-compromised people having longer periods of being contagious but generally a healthy adult is contagious for 1 day prior to the start of symptoms and 5 to 7 days after developing symptoms.
Who should be vaccinated?
The flu vaccine is developed each year according to the prediction of strains that will be in circulation for that season and should therefore be administered every year as the strains evolve continuously. For the South Africa influenza season, the optimal time for vaccination is around March/April each year. The vaccine is effective after 10-14 days and the flu season typically starts around May so it’s important that the vaccine is administered in time for the flu season. The flu vaccine is recommended for the following groups:
How effective is the vaccine
The vaccine offers some level of protection to all groups that have an indication to be vaccinated but those individuals who are <2 years and >65 years of age or are immuno-compromised have a lower protective immune response than others. However the vaccine does offer these high risk groups some protection. The influenza vaccine will not protect against the many other viruses that circulate during the winter season and cause respiratory infections.
How safe is the vaccine?
The vaccine cannot result in influenza infection as there is no live virus contained within the vaccine. Some persons experience mild fever and local pain at the injection site. Overall the vaccine has an excellent safety record.
Can the vaccine still be given once the flu season has started?
Persons who fall into the ‘risk groups’ should still be vaccinated even if they did not receive the vaccine before the flu season started. The season typically continues until August/September each year. Since the vaccine takes 10-14 days to be effective, that person will not be protected if they are infected with flu in the interim.
How do you prevent the spread of flu?
Infected people should stay at home and try to limit contact with other people, they should also cover their noses and mouths with a tissue when coughing or sneezing and discard the tissue accordingly (cough etiquette). They should also wash their hands with soap and water or use an alcohol based hand rub. Linen and eating utensils should be washed thoroughly with soap prior to sharing with non infected persons. Surfaces that are commonly touched should be cleaned and disinfected.
How do you treat flu?
Most of the treatment is generic and involves symptom relief unless the individual is very sick or is at risk of developing complications (see ‘Who is at risk of developing complications?’). If you fall onto this category then you need to see a doctor as you may need to take antiviral medication.
For uncomplicated cases at low risk then the prevention of further spread and the following measures are advised:
Routine laboratory testing of patients with influenza illness is not required.