Who Does the Flu Affect Most? — Risks, Symptoms, Prevention (2025)

 The Flu: Who is Most at Risk?

Risks/Complications/Symptoms and Prevention (2025 Guide)

Disclaimer!

The content provided on this website/blog is for educational and informational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment. Always seek the guidance of your qualified healthcare provider regarding any medical condition, symptoms, or treatment.

Author!

This article was written by Dr. Humaira Latif, MBBS, KMU Peshawar, a Gynae/Obs specialist with over 14 years of experience in women’s health and ultrasound diagnostics. As a medical and health content creator, Dr. Latif is committed to providing accurate, up-to-date, and evidence-based information to educate and empower readers while maintaining professional and ethical standards.

Last Updated: 20/2/2026.

1. The Flu: Who is Most at Risk?

Every year millions are affected with the Influenza (Flu) virus worldwide but are not taken seriously and therefore, millions of cases become serious leading to hundreds of thousands of hospitalizations every year throughout the world. Many people will recover in 1 to 2 weeks, however, some will have a much higher risk of complications.

Knowing who is at a higher risk will allow families, caregivers, and healthcare professionals to take measures to prevent the Influenza virus quickly.

2. What is the Influenza Virus?

Influenza is a contagious respiratory illness caused by infection from the Influenza virus, that occurs through droplets of air from an infected person coughing, sneezing, or talking and can also spread through the act of touching a contaminated surface and then touching their face.

3. Signs of the Flu

The following are common signs of the flu when someone has contracted the influenza virus:

• Sudden high temperature
• Dry cough
• Sore throat
• Runny/blocked nose
• Headaches
• Muscle and joint aches
• Extreme tiredness
• Chills
• Vomiting/diarrhea (especially seen in children)

Within 1-4 days of contracting the virus, someone would start to see the symptoms and they would last up to 2 weeks.

4. Who is Most at Risk of Getting the Flu?

The Influenza virus can infect everyone from all age groups however, there are certain groups of people who are significantly more at risk of developing severe illness and/or complications because of the Influenza virus.

1. Older Adults (65 years and older)

• With age, the immunity systems to fight infections become less efficient.
• Impaired immune functioning
• Chronic illnesses present
• Lung capacity reduced
• Increased chances of acquiring pneumonia

Most flu-related hospitalizations and deaths each year are in older adults. In addition, the symptoms from a mild infection may quickly escalate to more serious breathing problems.

2. Children under 5 years (children younger than two at higher risk).

Children have an immature immune system that may compromise their bodies' ability to fight off a viral infection (flu).

Risks to children:

• Increased risk of dehydration
• Increased numbers of febrile seizures
• Increased risk of needing to be hospitalized due to the flu
• Increased chance of acquiring a secondary bacterial infection
• Children younger than 6 months are particularly susceptible to the flu as they do not qualify for receiving the flu vaccine.

3. Pregnant Women:

During pregnancy, a woman's immune system, heart, and lung function undergo changes.

Risk factors associated with pregnancy include:

• Due to the presence of an elongated uterus, the lungs cannot expand properly leading to diminished capacity of the lungs to bring in oxygen
• Changes in how the body responds to an infection
• Throughout pregnancy, a woman's need for oxygen will increase each day
• If a woman becomes infected with the flu while pregnant, it may result in serious complications, such as pneumonia, a need for hospitalization, or complications related to the pregnancy.

4. Individuals Diagnosed with Any Chronic Health Condition

Individuals diagnosed with an underlying health condition are at significantly greater risk to contract an illness severely or develop a severe complication from an illness.

Chronic diagnoses may include, but are not limited to:

• Asthma
• COPD
• Diabetes
• Heart disease
• Kidney disease
• Hepatic disease
• Neurologic disease
• Obesity (BMI ≥30)

For individuals with these chronic diseases, the influenza virus can exacerbate existing seven diseases and increase the likelihood of mortality.

5. People with Weakened Immune Systems

Weakened immune systems greatly diminish a person's ability to resist viral infections.

Examples of people that have immune suppression include:

• Cancer patients receiving chemotherapy
• Organ transplant recipients
• People taking long-term steroid medications
• People with HIV

The flu will last longer and generally be more serious illnesses for any of these populations.

6.  Healthcare Workers/Caregivers

Healthcare workers/caregivers are among those at the highest risk of contracting the flu due to frequent exposure to other people that have it.

Reasons for Being at Risk:

• Constant exposure to respiratory droplets
• Exposed to patients with the highest risk
• Possibility of spreading the flu to the “at-risk” population
• All healthcare providers are recommended to be vaccinated against the flu to protect themselves and their patients from infection.
• Potential Complications from the Flu

Most people recover from the flu without difficulties, but complications can arise from the flu; this risk is more common in the higher risk groups.

5. complications from the flu are:

• Pneumonia (both viral and bacterial)
• Bronchitis
• Cumulative sinusitis
• Ear infections
• Severe complications include:
• Acute respiratory distress syndrome (ARDS)
• Myocarditis (inflammation of the heart)
• Encephalitis (inflammation of the brain)
• Sepsis
• Multi-organ failure

Having prompt access to medical care significantly reduces the likelihood of experiencing a serious complication from the flu.

6. Warning Signs Indicating a Need for Medical Care

Request for Medical Care at Once for Adults (If Any of the Following Exist):

• Trouble breathing
• Chest pressure/pain
• Constantly being dizzy
• Confused
• Very weak and lethargic
• Flu-like symptoms improve for two days and then suddenly return with renewed vigour

Request for Medical Care at Once for Children (If Any of the Following Exist):

• Fast laboured breathing
• Blue colouration of lips/face
• Will not drink anything
• Repeated vomiting
• Unresponsive

7. Preventing the Flu:

Resisting the Flu is best accomplished through prevention.

1. A Yearly Vaccination for the Flu

Getting vaccinated against the flu will be the best way to reduce the risk of infection as well as the severity of the flu should you become infected.

Benefits of Flu Vaccination:

• ↓ Risk of becoming infected
• ↓ Rate of hospitalizations
• ↓ Risk of developing severe complications

Protects those family members who are at higher risk

2. Practice Good Hygiene

• Washing your hands often with soap and water
• Using alcohol-based hand sanitizer when needed
• Not touching your face
• Covering your mouth and nose with a tissue or coughing/sneezing into your arm

3. Stay Home When Sick

• If you become sick, you should limit your exposure to others.
• Not working or going to school
• Limiting contact with those at higher risk for severe illness
• Making sure to rest your body so it can heal.

4. Maintain a Strong Immune System

Keeping your immune system healthy through:

• Adequate nutrition
• Sufficient amount of sleep each night
• Regular exercise
• Drinking plenty of water
• Controlling chronic diseases effectively

8. Overview of Treatment.

With most cases of flu, you only need to treat the symptoms and provide supportive care.

Home Care:

• Take the time to rest
• Drink plenty of fluids
• Take any fever-reducing medication if prescribed by your healthcare provider

Antiviral Medication:

Antivirals may be given to high-risk patients or patients with severe cases

• Work best when started as soon as symptoms begin
• Should be prescribed under the direction of a physician
• Highlights of Information

Everyone is at risk for influenza; however, certain groups should be monitored closely

Senior adults, children, pregnant women, and those with chronic conditions are considered at higher risk and should be monitored closely

Complications can occur but with proper timely care it is possible to prevent

Vaccination and hygiene are still the #1 defenses

9. Questions and Queries.

Q1.Is influenza dangerous for healthy adults?

Most healthy adults do not develop complications related to influenza but some may develop severe illness as a result of influenza.

Q2. Can Pregnant women get the inactivated flu vaccine?

Yes, there has been no evidence that inactivated flu vaccine causes harm to the baby or the mother; however, it provides the following benefits both to mother & baby: protection against influenza.

Q3. When can I expect to be contagious with influenza?

Generally, a person can expect to start being contagious approximately 1 day before their first symptoms and continue to be contagious up through day 5-7 after their initial symptoms have started.

11. Summary.

Influenza is more than just a seasonal illness; for individuals at high risk, influenza can result in serious health issues. It is critical to understand who is at risk so that families can develop prevention, early detection and timely treatment strategies.

Keeping up to date on immunization and adequate hygiene practices will help protect you and your family.

12. Related Articles.

1.  For a detailed comparison between respiratory illnesses, refer to the difference between common cold and flu:

https://dryasirhumaira342.blogspot.com/2025/09/difference-between-cold-and-flu.html

2.  To learn how your immune system defends against pathogens, see:

https://dryasirhumaira342.blogspot.com/2025/11/how-immune-system-protects-body.html

3.   Learn proven strategies to strengthen immunity in:

https://dryasirhumaira342.blogspot.com/2025/08/how-to-strengthen-your-immune-system.html

4.  For vaccination safety during pregnancy:

https://dryasirhumaira342.blogspot.com/2025/07/pregnancy-vaccination-safety-guide.html

13. Official Health Organization References

1.  World Health Organization — Seasonal Influenza Fact Sheet

Provides global seasonal flu facts, symptoms, severity, and high-risk groups.

 Published: 28 February 2025

https://www.who.int/news-room/fact-sheets/detail/influenza-%28seasonal%29

Reference: World Health Organization. Seasonal Influenza (Fact Sheet). Published 28 February 2025.

2. World Health Organization — Clinical Practice Guidelines for Influenza

Official WHO guideline on influenza management and antivirals.

Published: 12 September 2024

https://www.who.int/publications/i/item/9789240097759

Reference: World Health Organization. Clinical Practice Guidelines for Influenza. Published 12 September 2024.

3. U.S. Centers for Disease Control and Prevention (CDC) — 2025–2026 Flu Season Resource

 CDC 2025–26 seasonal flu guidance including vaccine updates and recommendations.

Published: 7 January 2026

 https://www.cdc.gov/flu/season/2025-2026.html

Reference: Centers for Disease Control and Prevention (CDC). 2025–2026 Flu Season. Published 7 January 2026.

4. CDC Yellow Book — Influenza Information for Travelers and Clinicians

 Detailed CDC flu chapter used for clinical and travel guidance.

Published: 23 April 2025

https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/influenza.html