Influenza (Flu) in Children: Symptoms, Treatment and Prevention

What Is Influenza (Flu)?

Influenza is an acute respiratory infection caused by influenza viruses and is especially common in children. Influenza viruses fall into three main groups: influenza A, influenza B and, rarely, influenza C. In children, the illness is most often caused by influenza A and influenza B. Influenza A is popularly known as “swine flu”.

In children, influenza causes high fever, tiredness and respiratory symptoms. The risk of complications may be higher, especially in young children. Worldwide, influenza is one of the main reasons for hospital admissions and healthcare visits in children.

Children play an important role in spreading the influenza virus in the community, because they may shed the virus for longer than adults and may be more contagious.

How Does Influenza Spread in Children?

The influenza virus is highly contagious and usually spreads:

• Through droplets from coughing and sneezing
• Through close contact
• Via contaminated surfaces
• Via dirty hands

The virus can spread quickly in closed, crowded spaces, which is why the risk of transmission is higher in schools and nurseries.

In children, the contagious period is usually reported as:

• 1 day before symptoms start
• 5–7 days after symptoms start

In young children this period may be longer.

Symptoms of Influenza in Children

Flu symptoms in children usually start suddenly and progress quickly. The most common symptoms are:

• High fever
• Cough
• Sore throat
• Runny nose
• Muscle aches
• Headache
• Tiredness
• Loss of appetite

Some children may also have gastrointestinal symptoms such as:

• Vomiting
• Diarrhoea
• Abdominal pain

These are more common in young children.

With influenza A, high fever is the most prominent feature. The fever stays just as high and recurs just as often, and usually does not settle until about 5 days have passed. Effective fever monitoring and management are important at this stage. Care must be taken to avoid overusing fever reducers and medication poisoning.

With influenza B, tiredness, exhaustion and loss of appetite – in short, feeling completely wretched – are more prominent than fever. Bone pain is very noticeable. The child wants to sleep all the time and may not even have the energy to play. If the child cannot eat or drink enough, hospital admission and intravenous fluids may be needed. Blood tests are not essential, but if they are done, they may show reduced white blood cell, red blood cell and platelet counts. Blood counts return to normal after the illness.

Symptoms of Influenza in Babies

In babies, flu symptoms may be different:

• High fever
• Feeding difficulties
• Irritability
• Drowsiness
• Rapid breathing

Influenza can be more serious in babies and they should be monitored closely.

How Long Does Influenza Last in Children?

Influenza usually follows this course:

• High fever for the first 3 days
• Marked symptoms for 5–7 days
• Tiredness for 1–2 weeks

In some children the cough may last longer.

When Is Influenza Dangerous in Children?

See a healthcare professional if your child has:

• A high fever lasting more than 3 days
• Difficulty breathing
• Rapid breathing
• Bluish skin or lips
• Inability to eat
• Extreme tiredness
• Vomiting and inability to keep fluids down

These signs may indicate that complications are developing.

Complications of Influenza in Children

Influenza can cause serious complications in some children:

• Pneumonia
• Bronchiolitis
• Middle ear infection
• Sinusitis
• Enlarged adenoids
• Asthma flare-ups

The risk of complications is higher in children under 5.

In children with enlarged adenoids that had been stable until then, recurrent ear infections, chronic night-time cough, fluid in the ears and temporary hearing loss may follow an episode of influenza, and adenoid surgery may even become necessary. It is therefore especially important for children being followed up for enlarged adenoids to take precautions against influenza.

Treatment of Influenza in Children

Treatment of influenza is usually supportive:

• Rest
• Plenty of fluids
• Fever control
• Nose cleaning

In some cases antiviral medicines may be used, particularly for children in risk groups. It is important to know that antivirals are effective when started within the first 48 hours of illness; if started later, they cannot prevent the illness from running its course. Because of side effects such as nausea and vomiting, not everyone tolerates antivirals easily.

How Can Children Be Protected from Influenza?

To protect against influenza, the following are recommended:

• Washing hands frequently
• Avoiding crowded places
• Avoiding contact with sick people
• Cleaning toys
• The flu vaccine

The flu vaccine plays an important role in reducing the risk of influenza in children. It can be given to all children over 6 months of age. The vaccine given to children is the same as the one given to adults. Half doses are not used: children receive the full dose regardless of age. Children under 9 who are being vaccinated against flu for the first time need two doses one month apart; in the following years a single dose is enough. Having had influenza earlier in the same season does not remove the need for vaccination – the vaccine protects against both types.

Conclusion

Influenza is a common infection in children that can sometimes lead to serious complications. Recognising early symptoms, appropriate follow-up and seeking medical advice when needed are important. Influenza should be monitored more carefully in children in risk groups.

References

1. Krammer, F., Smith, G. J., Fouchier, R. A., Peiris, M., Kedzierska, K., Doherty, P. C., … & García-Sastre, A. (2018). Influenza. Nature Reviews Disease Primers, 4(1), 3. https://pubmed.ncbi.nlm.nih.gov/29955068/
2. Nair, H., Brooks, W. A., Katz, M., Roca, A., Berkley, J. A., Madhi, S. A., … & Campbell, H. (2011). Global burden of respiratory infections due to seasonal influenza in young children. The Lancet, 378(9807), 1917–1930. https://pubmed.ncbi.nlm.nih.gov/22078723/
3. Heikkinen, T., & Järvinen, A. (2003). The common cold and influenza in children. The Lancet, 361(9351), 51–59. https://pubmed.ncbi.nlm.nih.gov/12517470/
4. Uyeki, T. M., Bernstein, H. H., Bradley, J. S., Englund, J. A., File, T. M., Fry, A. M., … & Pavia, A. T. (2019). Clinical practice guidelines by the Infectious Diseases Society of America. Clinical Infectious Diseases, 68(6), e1–e47. https://pubmed.ncbi.nlm.nih.gov/30566567/