Influenza also called flu is an acute viral respiratory infection, transmitted by the influenza virus.
What is influenza?
Influenza also called flu 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.
How do you get flu?
The flu virus spread mainly by droplets made when people with flu cough, sneeze or talk. These droplets can
land in the mouths or noses of people who are close by. You can also catch flu by touching a surface or an object that has flu virus on it and then touching your mouth, eyes or nose.
How long is a person with influenza contagious?
People with flu maybe able to pass on the flu to someone else before they know that they are sick, as well as while they are sick. A person with flu may be contagious 1 day before symptoms appear and for 3-7 days after the onset of symptoms. Some people, especially young children and people with weakened immune systems, maybe be able to infect others for an even longer time
How soon will I get sick if I am exposed to the flu?
The time from when a person is exposed to flu virus to when symptoms begin is about 1 to 4 days, with an average of about 2 days.
What are the signs and symptoms of influenza?
- Sudden onset of fever
- Acute upper respiratory symptoms: dry cough, sore throat
- General symptoms: malaise, headache, fatigue, muscle pain and body aches , cold shivers and hot sweats
- Some people may have vomiting and diarrhoea, though this is more common in children than adults.
What are the possible complications?
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 X-Ray features of pneumonia and myocarditis.
- Complications involving other organs: ear infections, sinus infections, encephalitis, severe dehydration, renal failure and multiple organ failure.
- Worsening of underlying conditions such as: asthma, Chronic Obstructive Pulmonary Disease (COPD), diabetes, hypertension, renal or liver insufficiency, Congestive Cardiac Failure (CCF) and other cardiovascular diseases.
Who is at risk of developing complications?
- Pregnant women, and including the 2 week period after delivery
- Young children (<2 years old)
- Elderly people (>65 years of age)
- People with existing chronic diseases (heart, lung, kidney, endocrine) for example diabetes or asthma, persons who are immunosuppressed
- Morbidly obese people (BMI ≥40 or BMI≥35 with obesity related health conditions).
- People ≤18 years of age receiving chronic aspirin therapy
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. However, getting vaccinated even later can be protective, as long as flu viruses are still circulating. The flu vaccine is recommended for the following groups:
- Pregnant women at any stage of pregnancy (including 2 weeks after delivery)
- Persons over 6 months with medical conditions such as chronic respiratory (asthma, tuberculosis), cardiac diseases, chronic renal diseases, diabetes mellitus, individuals who are immunosuppressed (e.g HIV) or obese
- Healthcare workers
- Residents of old-age homes and chronic care and rehabilitation institutions
- Persons over the age of 65 years
- Persons aged 6 months to ≤18 years on long-term aspirin therapy
- Children aged 6 months to 59 months
- Adults and children who are family contacts of high-risk cases
- Any persons wishing to minimise the risk of influenza acquisition.
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
- Cover nose and mouth with a tissue when coughing or sneezing and throw away used tissue in bin.
- Wash hands often with soap or use an alcohol based hand rub, especially after coughing, sneezing, or blowing the nose.
- 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:
- Bed rest
- Drink plenty of water and other clear fluids
- Symptomatic treatment for cough, fever, nasal congestion, etc
Antiviral agents such as Tamiflu are recommended for persons at risk of complications. Antiviral agents are not generally prescribed for contacts of persons with influenza as a preventative measure.
Routine laboratory testing of patients with influenza illness is not required.
Where can I get flu vaccine?
Flu vaccines are offered at local clinics, hospitals and private providers (pharmacies and private practitioners)