Influenza Updates
Influenza, also known as “flu” is an acute respiratory illness caused by an infection of the respiratory tract with the influenza virus. There are two types of influenza viruses that commonly infect humans namely A and B. The flu viruses are typically in circulation before the winter months in South Africa with an average start of the flu season over the years 2005 to 2019 in week 20 (mid-May), ranging from the end April to mid-June.
The virus is spread from person to person. It can be passed from infected people to other people through inhalation of infected respiratory droplets from sneezing, coughing or talking. A person can also be infected by touching contaminated objects or surfaces that the flu virus is on and then touching their mouth, eyes or nose. People who are infected with influenza can prevent spread by doing the following:
- Covering their mouth when coughing with a tissue or cough into the elbow
- Wearing a mask
- Washing their hands frequently with soap and water or cleaning hands using an alcohol-based
sanitiser - Staying at home and trying to keep a distance from others
The most common symptoms in infected patients are sudden onset of fever, muscle pains and body aches, dry cough, sore throat, runny nose, feeling tired or unwell and headache. The symptoms develop anywhere from 1 to 4 days after infection and last for 2 to 7 days. For the majority of people, the symptoms commonly resolve without treatment. Complicated influenza infections can cause serious illness and in some cases death. Severely ill patients with influenza should be admitted to the hospital. The commonest complication of influenza is pneumonia.
Since the start of the influenza season in week 17 (week starting 22 April 2024), there has been a steady increase in the number of influenza cases from the pneumonia (hospitalised cases) surveillance sentinel sites. Based on the circulation of influenza in 2016-2019 and 2022-2023, the 2024 flu season transmission and impact are at a moderate level.
Recent Updates
FAQ
Most frequent questions and answers about Influenza
The influenza virus has two main types in humans: A and B. Influenza A is classified into different subtypes influenza A(H1N1)pdm09 and A(H3N2). Influenza A(H1N1)pdm09, which has colloquially been called “swine flu”, is the human influenza strain that emerged globally in 2009. This strain behaves like any other strain of seasonal influenza and infected patients should be treated like any other seasonal influenza case.
There are no specific public health interventions required for patients or contacts of patients infected with influenza A (H1N1)pdm09. The term “swine flu” should not be used, because this term refers to influenza in pigs.
Influenza infection resulting in mild illness is most common in children of school-going age between 5 and 15 years. Influenza can also cause severe illness and the following groups of people are at the highest risk of severe illness: children aged <5 years, adults aged 65 years or older, pregnant women, those who are obese (BMI ≥40) and those with chronic health conditions such as chronic heart disease, chronic lung disease (e.g. TB), kidney, liver, blood or metabolic diseases (e.g. diabetes), or weakened immune systems (e.g. HIV infection).
Influenza is normally a clinical diagnosis and not all patients require testing for diagnosis. Testing for diagnosis can be done to assist in the treatment and when there are a higher number of cases than expected to identify outbreaks. When testing is needed respiratory samples can be collected and these include nasopharyngeal or nasal swab, nasal wash or aspirate, throat swab and sputum.
The majority of infected people will only need bed rest, adequate fluid intake and potentially paracetamol or similar medications to help with the fever or aches. The more severe cases may need antiviral drugs for influenza that can only be prescribed by a medical doctor. The drugs are ideally administered early (within 48 hours of the onset of symptoms) in the disease. Antiviral treatment may also be used for people at risk of severe influenza early in the infection. People at risk for severe influenza illness or complications should consult their doctor early in the illness.
Influenza vaccination is the best way to prevent influenza infection. The influenza virus is constantly changing and vaccination for influenza has to be administered every year. The vaccine is an inactivated virus that is not harmful and cannot cause flu infection. It only offers protection about 2 weeks after administration. So ideally the flu vaccine should be taken early (March/April each year) before the flu season so that it has sufficient time to protect a person. However, it is never too late to vaccinate as long as the flu virus is circulating in the community.
While influenza and COVID-19 are both contagious respiratory illnesses caused by viruses, the viruses that cause them are not the same. COVID-19 is caused by infection with a new coronavirus (called SARS-CoV-2), and flu is caused by infection with influenza viruses.
Both viruses can cause mild to severe illness and present with similar symptoms including fever, cough, sore throat, shortness of breath, runny or blocked nose, muscle pains/body aches and fatigue. COVID-19, on the other hand, seems to spread more easily than flu and can result in a more serious illness in certain people. Other signs and symptoms of COVID-19, different from flu, may include a change in or loss of taste or smell.
COVID-19 infected people can also take longer to show symptoms, and they can be contagious for longer periods. Since some flu and COVID-19 symptoms are similar, it may be difficult to differentiate between them based on symptoms alone, and laboratory testing may be needed to confirm a diagnosis.
