Why get vaccinated?
Influenza (“flu”) is a contagious disease. It is caused by the influenza virus, which can be spread by coughing, sneezing, or nasal secretions.
Anyone can get influenza, but rates of infection are highest among children. For most people, symptoms last only a few days. They include:
- fever/chills
- sore throat
- fatigue
- muscle aches
- cough
- headache
- runny or stuffy nose
- weakness
Young children, people aged 65 and older, pregnant women, and people with certain health conditions – such as heart, lung, liver, kidney, disease or a weakened immune system – can get much sicker. Flu can cause high fever and pneumonia, and make existing medical conditions worse. It can cause diarrhea and seizures in children.
By getting vaccinated you can protect yourself from influenza and may also avoid spreading influenza to others.
Inactivated influenza vaccine
There are 2 different types of inactivated Influenza vaccines, trivalent and quadrivalent containing 3 and 4 influenza viruses, respectively. Influenza viruses are always changing, so annual vaccination is recommended. Each year, scientists try to match the viruses in the vaccine to those most likely to cause flu that year. The flu vaccine will not prevent illness caused by other viruses, including flu viruses not contained in the vaccine.
It takes up to 2 weeks for immunization to develop after being vaccinated. Immunization lasts about a year.
Who should get inactivated influenza vaccine and when?
All people 6 months of age and older should get the flu vaccine.
Vaccination is especially important for people at higher risk of severe influenza:
- Elderly (aged 50 or above).
- Children (6-59 months of age).
- Healthcare personnel.
- Household contacts and caregivers of persons with medical conditions.
- People who have chronic lung diseases (asthma, chronic obstructive pulmonary disease, etc.), chronic heart diseases, liver disease, chronic renal disease, neurologic, hematologic, or metabolic disorders (including diabetes mellitus or people who receive long-term aspirin therapy).
- Patients who are immunosuppressed (those with human immunodeficiency viruses (HIV) or who are receiving drugs to suppress the immune system such as chemotherapy and long-term steroids).
- Women who are or will be pregnant during the influenza season.
- Morbidly obese (body mass index or BMI equal to or greater than 40).
Get an influenza vaccine annually as soon as it is available. This should provide protection if the flu season comes early. In Thailand, influenza can occur at any time, but most influenza occurs from June through September and January through February. Getting a vaccination in December, or even later, will still be beneficial in most years.
| Age |
Dosage |
Number of shot |
| Children from 6 months to 9 years of age |
0.5 milliliter |
1-2* (4 week apart) |
| Children from 9 years of age and adults |
0.5 milliliter |
1 |
*Children who get vaccinated for the first time
What if people cannot get inactivated influenza vaccine on time?
Contact your doctor to organize vaccination if miss a dose. Generally, those who miss the second shot can resume the schedule without repeat doses. The body still responds to the vaccine and makes antibodies protect against flu.
Special precautions
- Tell your doctor if you have any severe (life-threatening) allergies, including a severe allergy to eggs. A severe allergy to any vaccine component may be a reason not to get the vaccine.
- Tell your doctor if you ever had Guillain-Barre Syndrome (a severe paralytic illness, also called GBS).
- People who are moderately or severely ill should usually wait until they recover before getting flu vaccine. If you are ill, talk to your doctor about whether to reschedule the vaccination. People with a mild illness can usually get the vaccine.
What are undesirable effects of inactivated influenza vaccine?
| Mild problems |
Soreness, redness, or swelling where the shot was given, hoarseness, sore, red or itchy eyes, cough, fever, aches, headache, itching, fatigue. If these problems occur, they usually begin soon after the shot and last 1-2 days. |
| Severe problems |
Life-threatening allergic reactions from vaccines are very rare. If they do occur, it is usually within a few minutes to a few hours after the shot. Signs of a severe allergic reaction can include difficulty breathing, hoarseness or wheezing, hives, paleness, weakness, a fast heart beat or dizziness. |
If there is a severe reaction, get the person to a doctor right away and tell him what happened, the date and time it happened, and when the vaccination was given.
Drug Interactions
ยาบางชนิดอาจส่งผลต่อการออกฤทธิ์ของวัคซีนได้ เช่น Belimumab, Fingolimod และยากดภูมิบางชนิด
วัคซีนป้องกันไข้หวัดใหญ่สามารถให้พร้อมกับวัคซีนชนิดอื่นได้รวมถึงวัคซีนป้องกันโรคติดเชื้อนิวโมคอคคัส
References
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Last modify: January 13, 2025