Medically reviewed by Dr Lam Jing Kai, Jackie, M.B.B.S. (Singapore)
What is Influenza?
Influenza, commonly known as “the flu”, is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue.
Influenza may sometimes progress to serious diseases such as pneumonia, which can be caused by the virus or by a subsequent bacterial infection. Other complications of infection include acute respiratory distress syndrome, meningitis, encephalitis, and worsening of pre-existing health problems such as asthma and cardiovascular disease.
In a typical year, 5–15% of the population contracts influenza.
Influenza can cause severe illnesses, especially in the young, elderly, or patients with underlying chronic medical conditions. There is an average of 3–5 million severe cases annually in the world, with up to 650,000 Influenza related deaths each year.
There are 4 subtypes of Influenza Virus, A, B, C, D. Influenza A is known to be the most serious variant as it can cause serious illnesses and it spreads rapidly. Thus, it wields the potential to cause pandemics. It is therefore seen by most countries to be of high risk and a priority in their healthcare strategies.
How does it spread?
Influenza is spread predominantly by coming into contact with the droplets an infected person discharges. This means that it is highly transmissible within a 2-meter radius of the infected person coughing, sneezing, or talking.
The time between exposure to the virus and development of symptoms, called the incubation period, is 1–4 days, though the incubation period most commonly requires just 1–2 days. People with flu are most contagious in the first three to four days after their illness begins.
How does it affect our children?
Influenza, especially Influenza A, is known to cause a high fever, body aches, a cough, and other symptoms. Young children can have prolonged duration of high fevers, and can develop other symptoms such as vomiting, poor oral intake and display low activity levels. The fever duration in young children can range from 5 to 7 days and complications such as pneumonia, meningo-encephalitis, and dehydration can occur.
How do we reduce the spread of Influenza?
- Avoid close contact with infected individuals.
- Stay at home and isolate when infected with Influenza to prevent transmission to others.
- Cover your mouth and nose when sneezing, and wear a mask if contact is necessary.
- Clean your hands thoroughly before and after contact with an infected individual.
- Clean your hands thoroughly before and after contact with an infected individual.
How do we prevent Influenza?
There is a vaccination against Influenza that has shown to be effective in preventing Influenza, as well as reducing the severity and duration of illness. It is commonly known as a ‘Flu Jab’. As the Influenza virus mutates rapidly, it is recommended to get up to date with the latest vaccine and get an Influenza vaccination annually.
The vaccine is recommended for everyone, especially for people who are at high risk of developing influenza complications such as:
- Elderly aged 65 years and older
- Pregnant women in any trimester
- Persons with chronic medical conditions such as diabetes or heart, lung, liver and kidney disease
- Persons with lower body resistance to infections due to:
- Conditions such as leukaemia, HIV, spleen removal, or organ transplant
- Using medications or receiving treatment such as taking long-term steroids, certain cancer drugs or radiation therapy
- Residents staying in intermediate or long-term care facilities.
- Persons aged 18 years or younger and receiving long-term aspirin therapy.
- Children aged 6 months to 5 years old also have lower body resistance to Influenza infections and are highly recommended to stay up to date with the Influenza vaccine.
How do we diagnose and treat Influenza?
Influenza is diagnosed via a nasopharyngeal swab which is available at all Keystone Clinic & Surgery branches. It is done like a COVID-19 PCR swab, whereby a soft brush will be inserted into a patient’s nose to obtain samples from the nasopharynx. The test kit will show results usually within the next minute and will show whether a patient is infected with Influenza A or B.
The mainstay of treatment for Influenza infections is symptomatic treatment. This includes medications for fever and other symptoms that the infected individual may display, as well as adequate rest and hydration.
What medication should be used to treat Influenza?
In many studies, Oseltamivir, also known as Tamiflu, has shown to reduce the duration of illness by 1 to 2 days and the severity of illness for affected individuals. Hence using Tamiflu can reduce the likelihood of hospitalisations.
In Singapore hospitals, Tamiflu is also routinely offered to affected individuals who are hospitalised and used for most patients with severe illnesses in the Intensive Care Unit (ICU).
There may be some benefit in taking antivirals even outside of that 48-hour window. A study done in 2015 found that children given Tamiflu within five days of falling sick experienced an improvement in symptoms. They also had significantly less virus shedding, which means they were much less likely to spread the illness to others. Tamiflu has been shown to be effective for Influenza prevention after having close contact with an infected individual.
Lastly, children that were given post-exposure prophylaxis for 10 days achieved a protective effect of 55-80%.
Therefore, it is highly recommended that you bring an infected person to see the doctor as soon as possible for early assessment and clinical review.