Influenza Transmission, Cause, Treatment and Risk Factors

Everybody, without exception, is at risk of contracting and spreading the flu. When you are sick with the flu, you are likely going to stay at home to ride out the infection and get the proper rest and treatments. 

It is also likely that you will have to endure symptoms that will make you feel miserable for at least a week. If you happen to have respiratory diseases, you are highly likely to develop complications.

Influenza Symptoms

Once you are infected with the flu, symptoms are likely to appear quickly. People who are likely to suffer from complications, such as individuals who have chronic lung disease, should immediately seek medical attention. 

A physician may prescribe antiviral medications to fight off the infection and alleviate symptoms. Once the medication works, the symptoms should subside within a few days. 

Some of the most common influenza symptoms include:

  • High fever
  • Headache, joint pain, and muscle aches
  • Dry cough (may sometimes be productive)
  • Chills
  • Sore throat
  • Fatigue or general body malaise
  • Runny nose and nasal congestion

Children may also experience nausea, diarrhea, vomiting, and other stomach-related conditions. Some adults may also experience these symptoms, but they are far more common among younger individuals. For most people, recovery from influenza is usually fast. 

Often, symptoms disappear in just a week or two. However, the speed of recovery will depend on the age and health condition of the individual. Older people, for example, often experience weakness for an extended period of time after other symptoms are gone.

Influenza Causes

The virus that causes influenza often enters the body through the nose, when it is inhaled. The virus then goes down the throat and to the lungs. Influenza transmission often occurs when a person sick with flu sneezes, coughs, or even talks. 

These actions generate fluid droplets from the nose or mouth. These droplets become airborne and could become inhaled by other people within proximity. Another means of transmission is through the hands or skin. If a person comes in contact with mucus secretions by touch and happens to put his/her hands to the eyes, nose, and mouth, the virus could enter that person’s body. 

It is also possible to transmit the influenza virus even before a sick person experiences any symptoms. This transmission can happen up to seven days after a person has become sick. People who are immuno-compromised or those who are young can even remain infectious for a long time.

Different Routes of Influenza Transmission

  • There are different ways the influenza virus can be transmitted. These include:
  • direct contact with sick individuals
  • contact by touching contaminated objects, also called fomites. These include toys, doorknobs, solid surfaces, drinking glasses, etc.
  • inhalation of aerosols/droplets that contain the influenza virus

How effective each mode is in influenza transmission is not fully known.

Risk Factors

For people who are considered high risk, influenza is considered very serious. Certain types of diseases put certain people at higher risk of influenza. These include:

  • asthma, bronchiectasis, cystic fibrosis, and COPD. 
  • heart disease
  • diabetes and other chronic metabolic disorder
  • chronic kidney disease
  • morbid obesity
  • immunity-related diseases such as HIV and AIDS
  • liver disorders
  • severe anemia

People who are undergoing treatments that suppress immunity are also considered high-risk, as well as young children and teens who are on long-term aspirin therapy. 

When to Seek Medical Advice

If you are not sick, go to your doctor for your annual flu shot. The influenza vaccine should be given to a child who is at least 6 months old and to older individuals. The vaccine is usually made available during the fall season, so schedule an appointment to get your flu vaccine. 

If you experience any influenza symptoms, make sure to get in touch with your physician right away. He/She will likely give you antivirals. Receiving influenza treatment as early as possible is important to avoid complications. Antivirals will help reduce the severity of influenza symptoms and the duration of the illness.

If you are experiencing complications associated with the flu such as pneumonia, take note of your symptoms carefully. Pneumonia is caused by the influenza virus or bacteria that enter the lungs due to a weakened immune system as a result of the flu. If you find it difficult to breathe, see a doctor right away.

Seek medical assistance if you experience chest pain due to coughing or if you produce phlegm that is yellow, green, or has blood.

You may also experience other infections that are related to the flu, such as sinusitis, ear infections, and bronchitis.

If your coughing does not resolve after other flu symptoms have disappeared, it is also important to seek professional medical advice. Some people experience coughing for several weeks and months after a bout with the flu. Oftentimes, this is similar to the symptoms associated with asthma and will be treated using asthma medications. If this is the type of cough you have, consult a doctor.

How Does the Influenza Vaccine Work?

Influenza vaccines can provide excellent protection from seasonal illness and its severe consequences. But to work well, vaccines must be given yearly because influenza viruses tend to change. About two weeks after the influenza vaccine is administered, the body begins to create antibodies that will help protect against diseases associated with the flu. The antibodies will help target the type of viruses from which the vaccine was created. One flu vaccine can protect against four types of flu viruses that current research shows to be the most common in the coming season.

Influenza Vaccine Benefits

Vaccination can help reduce the risk of hospitalisation due to flu among young children, adults, and the elderly. It can prevent thousands of hospital admissions annually. In 2019 alone, over 310,000 flu notifications confirmed by laboratories resulted in over 800 deaths associated with influenza between the period of December until October 6th.

Who Should Have Flu Vaccinations?

As a preventive tool, flu vaccinations can offer protection for people who are at high risk of complications due to medical conditions and for pregnant or breastfeeding women. Flu vaccination is also important for certain groups of people, such as:

  • infants and children who are 5 years old or older
  • adults who are 65 years old or older
  • Aboriginal people
  • Torres Strait Islanders
  • people who work in certain occupations
  • travellers

Many employers provide their workers with flu vaccinations in the workplace because this has proven to be an effective way to increase productivity and reduce absenteeism.


The yearly flu vaccination is recommended for babies who are 6 months of age or older. According to a 2017 study performed by the US CDC (Centers for Disease Control and Prevention), influenza vaccines for babies have shown high efficacy in reducing the risk of death from the disease.

Pregnant Women

Women who receive flu vaccines during their pregnancy are at a lower risk of developing flu-associated acute infections of the respiratory system by 50%. In fact, a 2018 study showed that pregnant women who received a flu vaccine had a 40% reduced risk of hospitalisation.

Flu vaccines also help protect the unborn child. According to several studies, babies born to mothers who received the flu vaccine while pregnant were protected from the disease for several months post-birth. 

Seniors and the Elderly

Senior individuals who are 65 years of age or older should receive their annual influenza vaccine. For this age group, doctors recommend the adjuvanted flu vaccine (Fluad Quad) because it offers enhanced protection against flu strains that cause serious illness in older people. 

Mortality rates associated with influenza among older adults are high, but seniors who have received flu vaccines have a reduced risk of hospitalisation due to flu and pneumonia. They also have a reduced incidence of all-cause mortality.