Protecting Children & Adults from Seasonal Flu (Influenza) Through Vaccination

Seasonal flu, or influenza, is a contagious respiratory illness affecting billions of people worldwide each year ¹. It can lead to mild or severe illness and, in some cases, can be fatal ¹. While anyone can contract the flu, certain groups - including young children, the elderly, and individuals with preexisting health conditions or weakened immune systems - are at higher risk ^1,2. In fact, most hospitalisations and deaths related to the flu disease occur within these high-risk populations ¹.

Vaccination is an effective way to protect both adults and children from the flu ^1,3. In this blog, we will cover important information about the flu disease, including its symptoms, complications, preventive measures, and the critical role vaccination plays in reducing the spread and severity of the illness.

Overview of Seasonal Flu (Influenza)

Influenza is an acute viral infection that attacks the respiratory system, including the nose, throat, and lungs. It is caused by influenza viruses that spread through droplets released into the air when an infected person coughs, sneezes, or talks. These respiratory droplets can infect people nearby. Additionally, the virus can spread through hands contaminated with influenza viruses ^1,4.

Transmission occurs rapidly in crowded environments such as schools and nursing homes ¹.

There are four types of influenza viruses ^1,5:

• Influenza A viruses are classified into subtypes based on the hemagglutinin (H) and neuraminidase (N) proteins found on their surface. Currently, the subtypes commonly circulating among people include A(H1N1) and A(H3N2). Influenza A viruses are the only influenza viruses that cause flu pandemics.
• Influenza B viruses are classified into lineages rather than subtypes, with the two main lineages being B/Yamagata and B/Victoria.
• Influenza C is less common and usually leads to mild infections, presenting minimal public health concerns. It is not considered as a cause of human epidemics.
• Influenza D viruses primarily affect cattle and can spread to other animals, but they are not known to infect humans or cause illness in people.

Among the four types of influenza viruses, only types A and B are responsible for seasonal epidemics ^1,5.

Flu disease is prevalent worldwide, causing around one billion cases annually, including 3-5 million severe instances ¹. The virus causes between 290,000 and 650,000 respiratory deaths annually, especially among high-risk groups ^1,4.

While flu can affect anyone, certain groups are more at risk ^1,4:

1. Pregnant women
2. Children under 5 years old, particularly those younger than 2 years old
3. Older adults
4. People with chronic medical conditions (e.g., heart, lung, kidney, metabolic, neurodevelopmental, liver, or blood disorders)
5. Individuals with immunosuppressive conditions or treatments (e.g., HIV, chemotherapy, steroids, or cancer)
6. Health and care workers face higher risks of infection and spreading the virus due to frequent patient contact.

An effective way to lower the risk of flu disease and its serious complications is by getting a flu vaccination each year ^1,3,4.

Identifying Flu Symptoms in Children and Adults

The incubation period for influenza, which is the time from exposure to the virus until symptoms begin, is usually about 2 days but can range from 1 to 4 days. This means flu symptoms generally appear around 2 days after exposure to an infected person ¹.

Flu symptoms are similar across all age groups and can vary from mild to severe ^1,4. Mild symptoms typically appear suddenly and may include ^1,2:

1. Sudden fever
2. Dry cough
3. Sore throat
4. Headache
5. Runny or stuffy nose
6. Muscle and joint aches
7. Severe malaise (a general feeling of being unwell)
8. Chills
9. Fatigue or tiredness
10. Vomiting and diarrhoea (more common in children than adults)

It's important to note that not everyone with the flu will have a fever ², and the cough can be quite severe, sometimes lasting 2 weeks or longer ¹.

Recognising Severe Flu Symptoms

Most people recover from fever and flu symptoms within a week, but some individuals may develop severe symptoms that require immediate medical attention ¹.

Severe flu symptoms to watch for include -

In children ²:

1. Rapid or difficult breathing
2. Bluish colour of the lips or face
3. Indented ribs with each breath
4. Chest discomfort
5. Intense muscle pain (child refusing to walk)
6. Dehydration (no urine for 8 hours, dry mouth, lack of tears when crying)
7. Unresponsiveness or lack of engagement while awake
8. Seizures
9. Fever over 104^o F that isn't reduced with medication
10. Any fever in infants younger than 12 weeks old
11. Fever or cough that initially improves but then returns or gets worse
12. Deterioration of pre-existing medical conditions

In adults ²:

1. Trouble breathing or feeling short of breath
2. Ongoing pain or pressure in the chest or abdomen
3. Persistent dizziness, confusion, or difficulty waking up
4. Seizures
5. Lack of urination
6. Intense muscle pain
7. Extreme weakness or unsteadiness
8. Fever or cough that initially improves but later returns or worsens
9. Aggravation of chronic medical conditions

If any of these symptoms appear, seek medical care immediately, especially for children, the elderly, or those with pre-existing conditions.

Complications of Flu Disease

Along with severe symptoms, some individuals may be at risk of serious complications that can be life-threatening and even fatal ². These complications are more likely to occur in high-risk individuals and may include ^2,1:

1. Sinus infections
2. Ear infections
3. Pneumonia.
4. Extreme inflammation in the body, leading to sepsis (a life-threatening response to infection).
5. Inflammation of the heart (myocarditis)
6. Inflammation of the brain (encephalitis)
7. Inflammation of muscles (myositis, rhabdomyolysis)
8. Multi-organ failure (e.g., respiratory or kidney failure)
9. Asthma attacks in people with asthma
10. Worsening heart disease in people with chronic heart conditions.

Death due to flu disease primarily affects high-risk groups. In industrialised countries, most flu-related deaths occur in people aged 65 and older. Research shows that in developing countries, 99% of flu-related deaths in children under five are associated with lower respiratory infections ¹.

Importance of Flu Vaccination

Flu vaccination is a safe and effective way to protect adults and children from influenza ³. It works by stimulating the body's immune response to the virus without causing the illness ⁶.

Here’s why getting the flu vaccination is important ⁷:

1. Prevents flu-related illnesses.
2. Reduces the need for doctor visits and decreases flu-related health issues.
3. Lowers the risk of severe flu symptoms.
4. Decreases the likelihood of requiring ICU care and reduces flu-related fatalities.
5. Cuts down on hospitalisations due to the flu.
6. Is crucial for individuals with chronic health conditions, helping manage chronic lung conditions and lowering the incidence of cardiac events.
7. Protects expectant parents and their babies from the flu during pregnancy.
8. Can be life-saving for children by reducing severe flu cases and hospital visits.

For parents, consider the 7-Star Protection Programme, which includes the flu vaccination along with other vital vaccinations such as Hepatitis A, Chickenpox, Rubella, and more. Consult a paediatrician to learn about the 7-Star Vaccination schedule and ensure your child is fully protected against these potentially serious illnesses.

Additional measures to reduce the spread of influenza viruses ^1,3:

1. Wash hands regularly with soap and water.
2. Cover your coughs and sneezes with your elbow or a tissue, and make sure to dispose of tissues properly.
3. Avoid close contact with sick individuals.
4. Avoid touching your eyes, nose, or mouth.
5. Keep surfaces and objects clean and disinfected.
6. Practice good hygiene in public places, such as wearing masks.

Conclusion

Seasonal flu is a contagious respiratory illness that can affect anyone ², but there are effective ways to protect yourself and your family ³.

Flu vaccination is a safe and effective way to protect adults and children from the virus and its potential complications ^1,3. By getting vaccinated each year, you can protect yourself and help prevent the spread of the flu within the community ⁷.

Stay proactive this flu season - get vaccinated and encourage those around you, especially those in high-risk groups, to do the same.

References

1. Influenza (seasonal). (n.d.). Who.int. Retrieved September 11, 2024, from https://www.who.int/news-room/fact-sheets/detail/influenza-(seasonal)
2. (2024i, July 29). Flu symptoms & complications. Centers for Disease Control and Prevention. https://www.cdc.gov/flu/symptoms/symptoms.htm
3. CDC. (2025b, January 14). Preventing seasonal flu. Influenza (Flu). https://www.cdc.gov/flu/prevention/?CDC_AAref_Val=https://www.cdc.gov/flu/prevent/prevention.htm
4. CDC. (2024c, June 5). About flu. Centers for Disease Control and Prevention. https://www.cdc.gov/flu/about/index.html
5. CDC. (2024a, September 27). Types of influenza viruses. Influenza (Flu). https://www.cdc.gov/flu/about/viruses-types.html?CDC_AAref_Val=https://www.cdc.gov/flu/about/viruses/types.htm
6. CDC. (2023, August 7). Explaining how vaccines work. Centers for Disease Control and Prevention. https://www.cdc.gov/vaccines/hcp/conversations/understanding-vacc-work.html
7. CDC. (2025a, January 14). Benefits of the flu vaccine. Flu Vaccines Work. https://www.cdc.gov/flu-vaccines-work/benefits/index.html