Benefits of the Influenza Vaccine for Adults: More Than Just Preventing the Flu

By: dr. Darren Gosal, Sp.PD, AIFO-K - Internal Medicine Specialist, certified in adult vaccinology and holding an International Certificate of Vaccination (ICV) accredited by the Ministry of Health of the Republic of Indonesia.

Influenza, or the flu, is often regarded as a mild illness that resolves on its own. However, for some individuals, influenza infection can cause more severe symptoms and even increase the risk of complications.
This risk warrants particular attention, especially among the elderly and individuals with chronic conditions such as diabetes, heart disease, chronic lung disease, kidney disorders, liver disease, or conditions affecting the immune system.
One measure that can help provide protection against influenza is regular vaccination.

When is the best time to get an influenza vaccine?

The WHO recommends administration every February and September. In Indonesia, vaccination can be carried out year-round using the influenza vaccines available at the time.

Why Should We Be Concerned About Influenza?

Influenza is a respiratory tract infection caused by the influenza virus. Transmission can occur through respiratory droplets or contact with contaminated surfaces.
Symptoms may include fever, cough, sore throat, runny nose, muscle pain, headache, and fatigue.
In healthy individuals, influenza generally resolves on its own. However, in certain groups, it can progress to a more serious condition, leading to complications such as pneumonia or the exacerbation of pre-existing chronic illnesses.
The WHO classifies the elderly and individuals with chronic diseases as groups at higher risk of severe illness or complications from influenza.

What Are the Benefits of the Influenza Vaccine?

The influenza vaccine helps the immune system recognize the influenza virus so that the body can mount a response when exposed to it.
Some benefits of the influenza vaccine include:

1. Helps Lower the Risk of Contracting Influenza
   Vaccination can help reduce the likelihood of contracting influenza. Although the vaccine does not provide 100 percent protection, it remains a key measure in preventing the disease.
2. Helps Reduce the Risk of Severe Illness and Complications
   If a person contracts influenza despite being vaccinated, the vaccine can help lower the risk of the illness becoming severe. This is particularly important for individuals with certain risk factors, as influenza can exacerbate pre-existing health conditions.
3. Important for People with Chronic Diseases
   Individuals with diabetes, heart disease, chronic lung disease, kidney disease, liver disease, and other medical conditions face a higher risk of complications if they contract influenza.
   Therefore, the influenza vaccine is a preventive measure worth considering as part of comprehensive health management.
   The WHO prioritizes individuals with chronic medical conditions in influenza vaccination programs because this group is at higher risk of complications resulting from the virus.
4. Helps Protect Vulnerable Groups
   Vaccination also offers broader benefits by helping to reduce the risk of influenza transmission within the community—especially when interacting with the elderly or individuals with specific health conditions.

However, vaccination still needs to be accompanied by other preventive habits, such as washing hands, practicing proper cough and sneeze etiquette, and avoiding close contact with others when experiencing influenza symptoms.

Why Does the Influenza Vaccine Need to be Done Periodically?

Influenza viruses are constantly changing. Consequently, the composition of influenza vaccines is periodically evaluated and updated to match the influenza viruses expected to circulate.

Vaccines can provide up to 90% protection in healthy individuals under the age of 65, provided the vaccine strain matches the circulating virus.
Furthermore, protection conferred by influenza vaccines can wane over time. Immunity acquired through inactivated influenza vaccination lasts less than one year due to "antigenic drift" in the influenza viruses circulating within the population. Vaccine effectiveness depends on the degree of match between the vaccine strain and the circulating virus, as well as the age and health status of the individual being immunized.

For these reasons, annual influenza vaccination is generally recommended. The PAPDI guidelines for adult immunization also recommend the administration of a single dose of influenza vaccine each year.

Who Should Consider the Influenza Vaccine?

Influenza vaccination may be considered for adults, particularly those at higher risk of influenza complications, such as:

• Elderly individuals
• People with diabetes
• People with heart disease
• People with chronic lung disease
• People with chronic kidney or liver disease
• Individuals with conditions affecting the immune system
• Healthcare workers or those who frequently interact with vulnerable groups
• Pregnant women, as some studies indicate that influenza infection is associated with premature birth and fetal death.

The American College of Obstetricians and Gynecologists recommends that women who are pregnant, might be pregnant, or are within two weeks postpartum receive the inactivated influenza vaccine during flu season.
Individual health conditions vary; therefore, consulting a doctor is advisable to determine the appropriate vaccine type and timing, and to ensure the vaccination is suitable for the patient's health status.

Types of Influenza Vaccination

There are 3 types of formulations:

1. Live attenuated influenza vaccine (LAIV).
2. Inactivated influenza vaccine (IIV).
3. Recombinant influenza vaccine (RIV).

In Indonesia, the available influenza vaccine is the inactivated influenza vaccine (IIV). Based on the type of strain, there are 2 types of influenza vaccine:

1. Trivalent inactivated influenza vaccine: protects against two influenza A strains (A/H1N1 and A/H3N2) and one influenza B strain (B/Victoria)
2. Quadrivalent inactivated influenza vaccine: protects against two influenza A strains (A/H1N1 and A/H3N2) and two influenza B strains (B/Victoria and B/Yamagata)

Side Effect

• Local reactions are the most common (15–20%) and include pain, redness, and induration at the injection site; these are temporary and generally resolve within 1–2 days.
• Systemic symptoms—such as fever, chills, and muscle aches—are nonspecific and occur in less than 1% of cases. These symptoms appear 6–12 hours after vaccination and resolve within 1–2 days.
• Allergic reactions or systemic anaphylaxis are extremely rare and may occur only due to hypersensitivity to vaccine components, particularly egg protein.

Who Should Not Be Vaccinated?

Contraindications include a history of anaphylaxis following the administration of the influenza vaccine or reactions to vaccine components, such as egg protein.
Individuals with moderate to severe acute illness should not be vaccinated until their symptoms have subsided.
Pregnancy and breastfeeding are not contraindications for the inactivated influenza vaccine; however, live vaccines are contraindicated during pregnancy.

Can It Be Administered Alongside Other Vaccines?

Recommendations indicate that the influenza vaccine can be administered concurrently with other vaccines, such as the COVID-19 vaccine, respiratory syncytial virus (RSV) vaccine, and pneumococcal vaccines (PCV15, PCV20, or PPSV23).

Vaccination as Part of Maintaining Health

Maintaining health involves more than just addressing illness after it appears; preventive measures play a crucial role, especially for individuals with risk factors or chronic conditions.

The influenza vaccine is a preventive measure that can help reduce the risk of influenza and its complications.
If you have a chronic condition, are undergoing specific medical treatments, have a history of severe allergies, or wish to know if the influenza vaccine is suitable for your health status, please consult a doctor first.

RS Premier Jatinegara offers consultation services with Internists certified to issue the International Certificate of Vaccination (ICV) to help determine the preventive measures and care best suited to your health needs.

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