When you hear the word “influenza” in the winter, most people probably imagine high fever and severe body aches. However, there are three main types of influenza—Type A, Type B, and Type C—and they differ completely in the severity of symptoms, frequency of outbreaks, and the level of vigilance we should maintain.
Which type causes the “Novel Influenza” that makes the news every year? Is it true that “Type B is better than Type A”? And what exactly are the symptoms of “Type C,” which is barely known to exist?
Influenza Type A, Type B, and Type C Differences (Super Simple Summary)
| Item | Type A | Type B | Type C |
| Annual Outbreak? | Major outbreak every year | Moderate outbreak every year | Rarely circulates |
| Symptom Severity | Severe to extremely severe | Moderate to slightly severe | Mild (Level of a common cold) |
| Typical Symptoms | 39–40∘C + severe body aches | 38–39∘C range + fatigue | Runny nose and light cough |
| Severity in Children | High risk of severe illness, common acute encephalopathy | Can be severe, but less common | Almost never causes severe illness |
| Causes Novel Flu? | All Novel/Pandemics are Type A | Never causes novel flu | Never causes novel flu |
| Speed of Mutation | Extremely fast | Slow | Almost non-existent |
| Included in Vaccine? | Yes (2 subtypes) | Yes (1–2 lineages) | No (Not necessary) |
| Infects Animals? | Yes (Birds, pigs, etc.) | Rarely infects animals | No |
| Impression in Japan | The image of “Influenza = Type A” | “Slightly better than Type A” | “Wait, was that even the flu?” level |
| As of 2025 | Currently a major outbreak | Expected to increase from Jan–Mar | Almost zero |
✅ Summary
- Type A → The genuinely frightening one (the main culprit every year).
- Type B → Slightly better, but caution is essential (especially for children).
- Type C → Practically just a common cold (nobody worries about it).
In Japan, when someone says they “caught the flu,” it is 99.9% Type A or Type B. Type C is so rare that hospitals barely even test for it.
