Influenza Vaccine: Near-Zero Severe Illness with 2 Doses! Complete Guide and Side Effect Management Manual for “Children (6 Months – 15 Years Old)”
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Getting the influenza vaccine is an essential preventative measure for children (6 months to 12 years old) who are in group settings, as it helps contain the epidemic and prevents severe illness in the child themselves. For children under 13 years old, “2 doses” are mandatory to ensure proper immunity, and it is recommended to receive them 2 to 4 weeks apart.
As of 2025 data, children who complete the two-dose series have an illness prevention rate of 70% to 90%, and critically, the prevention of severe complications like encephalopathy and pneumonia is nearly 100%. Furthermore, good news: many municipalities offer robust subsidy programs, making the actual cost of vaccination virtually ¥0 to ¥4,000 (for both doses combined).
Influenza Vaccination “Children (6 Months – 15 Years Old)”
Item
2025 Rule and Recommendation
Target Age
6 months to 15 years old (Up to 9th grade)
Doses Required
6 months – 12 years old (Under 13):2 Doses Mandatory / 13 years and older: 1 Dose is OK
Recommended Interval
2 to 4 weeks apart (4 weeks is best) / Minimum interval of 13 days
Best Schedule
1st Dose: Mid-October to Early November / 2nd Dose: Mid-November to Early December
Effectiveness
2 doses prevent illness by 70–90%, and severe illness by nearly 100%.
Average Cost (No Subsidy)
¥3,000 – ¥4,500 per dose → ¥6,000 – ¥9,000 total for 2 doses
Actual Burden (With Subsidy)
¥0 – ¥4,000 (2 doses combined) / Completely free in many areas like Yokohama, Nagoya, Suginami, and Minato Wards.
Side Effects
Injection site pain/redness: 50–70% / Fever ≥38∘C: 5–8% (1 day only) → 90% of children have a milder reaction to the second dose.
Children Who Must Be Vaccinated
Nursery/Kindergarten/Elementary school students, and those with underlying conditions like asthma, allergies, or heart disease.
Ranking of Reasons Why Children Should Get the Shot
Rank
Reason
1st
Prevents class closures/school outbreaks (Unvaccinated classes often close every year).
2nd
Prevents transmission to family (Especially protecting the elderly and infants).
3rd
Prevents severe illness (encephalopathy/pneumonia) by nearly 100%.
4th
Very low cost due to subsidies (often virtually free).
Complete Manual for Managing Influenza Vaccine Side Effects in Children (6 Months – 15 Years Old)
Symptom
Incidence Rate
When Does It Appear?
Management (Solves 99% of cases)
Pain/Redness/Swelling at Injection Site
60–80%
Immediately – Next day
Apply a cold compress (towel-wrapped ice pack for 10 min x 3 times) / Gently move the arm (make a fist/open hand) / Empathizing(“It hurts, doesn’t it?”) often helps.
Fever ≥38∘C
5–10%
6–24 hours post-shot
Administer paracetamol suppositories or syrup immediately (10mgper 1kg of body weight) / Ensure high fluid intake (sports drinks, pediatric electrolyte solution) / Dress lightly + keep the room temperature below 24∘C.
Malaise/Lethargy
10–20%
Next day
Rest + unlimited watching of favorite TV shows/cartoons / Sweet treats (jelly/ice cream) to improve mood.
Headache/Muscle Pain
3–5%
Next day
Administer paracetamol / Gently massage the shoulders and legs.
Hives/Difficulty Breathing 30 min Post-Shot
Less than 1 in 1 million (Extremely Rare)
Immediate
→ Return to the clinic immediately (Anaphylaxis).
“Absolute Signs to Go to the Hospital”
A fever of ≥39.5∘C persists for over 6 hours.
The fever does not drop even after administering a suppository.
The arm remains severely swollen and stiff one week after the injection.
Wheezing or facial swelling occurs.
Summary
For nursery school and elementary school children, “2 doses are the standard.” → Subsidies are excellent in 2025, allowing for complete winter protection for virtually ¥0 to ¥3,000!
90% of a child’s side effects end with “sore arm + fever for only 1 day.” → Fear of side effects → Risk of 39−40∘C for 5 days + encephalopathy risk. → Endure 1 day of side effects → Zero class closures + protection for the whole family. → Getting the shot is overwhelmingly 100 times easier!
At-Home Testing Kit Ranking (Combined COVID-19 and Influenza)
Here is the English translation of the ranking table for at-home diagnostic kits that test for both COVID-19 and Influenza A/B:
