6 groups of underlying diseases that can easily become severe and cause high complications if you get the flu

So what are the underlying diseases associated with flu? 

1. People with chronic lung disease​​ ​

Influenza virus is a virus that mainly attacks the respiratory tract. Therefore, it is not surprising that people with chronic lung disease are considered to be at high risk of contracting influenza and developing dangerous complications for the body in the lungs, kidneys, liver.

Includes pre-existing respiratory conditions such as: Asthma; Bronchiectasis; Chronic obstructive pulmonary disease (COPD), chronic bronchitis and emphysema; Pulmonary fibrosis and other interstitial lung diseases.

The risk may vary depending on the type of respiratory disease involved: COPD and interstitial lung disease are characterized by fibrosis and loss of elasticity in the lungs. This can reduce a person's ability to breathe on their own if they get the flu; Asthma does not cause fibrosis, but the infection can cause a severe and potentially life-threatening attack, especially in people with poorly controlled asthma; Bronchiectasis is associated with excess mucus production. If pneumonia develops as a complication of the flu, the airway obstruction can be life-threatening.

Chronic medical conditions may increase the risk of severe illness in people with influenza.

2. People with immune deficiency ​​

People with immunodeficiency have weakened immune systems, making them less able to fight off bacterial and viral infections. Loss of immunity not only increases the risk of catching the flu, but also increases the likelihood of developing complications after getting the flu.

Immunodeficiency typically affects the following groups of people: People with HIV infection; People undergoing chemotherapy and radiation therapy for cancer; Organ transplant recipients, who are taking long-term immunosuppressive drugs to prevent organ rejection; People with primary immunodeficiency, often related to a genetic defect.

3. People with cardiovascular disease

The respiratory and cardiovascular systems are closely linked. Oxygen received from the lungs is distributed throughout the body by the heart and circulatory system. When infected with the respiratory virus, the lungs' gas exchange is limited, and the heart has to work harder to ensure the oxygen supply to the body's vital organs such as the brain, kidneys, heart, etc.

In people with pre-existing cardiovascular disease such as high blood pressure, myocardial infarction, coronary artery disease, arrhythmia. it increases the burden on the heart, not only increasing the severity of high blood pressure but also potentially triggering a heart attack or stroke.

4. People with diabetes ​ ​

Both type 1 and type 2 diabetes cause abnormally high blood sugar levels if left uncontrolled. Poor blood sugar control is the main reason why some people with diabetes are more likely to get the flu and experience a more severe illness.

Chronic hyperglycemia can lead to a condition called acidosis, in which acids called ketones reduce the production of immune cells, including T lymphocytes and neutrophils. This results in an increased susceptibility to influenza infection and subsequent complications from influenza.

5. People with liver disease

Influenza infection can complicate pre-existing liver disease, as evidenced by elevated liver enzymes and worsening of liver disease, including viral liver disease.

Some experts believe that many drugs used to treat severe respiratory infections, including antibiotics, antivirals, and steroids, may damage liver cells.

6. People with chronic kidney disease ​

Chronic kidney disease (CKD) and influenza can increase the risk of worsening the disease. The risk increases with the severity of the disease, with people on dialysis at highest risk.

People with advanced chronic kidney disease often have compromised immune systems, which can contribute to an increased risk of influenza. Because the lungs, heart, and kidneys function together, any impairment of one organ will invariably affect the others. If pneumonia develops after influenza, the kidneys may also be more severely damaged.

In summary: People with underlying diseases and risk factors must strictly follow the flu prevention measures according to the Ministry of Health and good management of existing underlying diseases are the best ways to minimize the risk of complications after influenza infection.

If there are no contraindications, people with underlying medical conditions should be vaccinated against influenza annually. Immunity to influenza is formed approximately 2 weeks after vaccination.

Marvin Fry

Update 10 February 2025