[Influenza Incubation Period] “Type A vs. Type B” Thorough Comparison! Which One is the Real Threat? (Particular caution with Type B in children)

Every winter, we brace for the flu. Is it Type A this year? Or Type B? In fact, these two types have significant differences that you should know, ranging from the length of the incubation period to the onset of symptoms and even the risk of severe illness.

While the perception that “Type A is severe and sudden” and “Type B is milder” is partially correct, Type B should not be underestimated, especially in households with small children. This article thoroughly compares Type A (H1N1, H3N2) and Type B from four perspectives: “Incubation Period Difference,” “Symptom Onset,” “Severity in Children,” and “Timing of Outbreaks.”

Differences Between Influenza Type A vs. Type B (Focusing on Incubation Period)

Actual Difference in Incubation Period (Feeling Level)

• Type A: Infected today → Sudden 40∘C fever + full-body pain tomorrow night or the morning after.
• Type B: Infected today → Presents with sluggishness and a fever around 38.5∘C the day after tomorrow or three days later.

→ This is why the impression is that “Type A comes suddenly” and “Type B comes with a slight delay.”

Current Situation in Japan (Practical Sense)

• This year, Type A (H1N1 and H3N2) began spreading first.
• Type B (Victoria lineage) is expected to increase from January to February.
• The pattern where “a person is knocked down by Type A → recovers → a family member contracts Type B” is very common every year.

✅ Summary

• The incubation period for Type A is slightly shorter and the onset is more abrupt.
• Symptoms for Type A are often more severe, but Type B is also dangerous for children.

→ Complacency is strictly forbidden for both!

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: