[How Long is the Influenza Incubation Period?] Detailed Analysis of the Most Common Onset Timing by Type and Age

“How many days after meeting that person will I develop a fever?”—When you suspect potential exposure to the source of an influenza infection, the length of the incubation period is what everyone is most concerned about. Knowing this period is crucial for taking preventive measures to avoid spreading the infection to others.

Length of Influenza Incubation Period (As of 2025)

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Actual Distribution (Most Common Pattern)

• Onset within 24 hours → Approx. 10%
• 24–48 hours → Approx. 60% (This is the most common)
• 48–72 hours → Approx. 25%
• 72 hours or more → Approx. 5% or less

✅ Summary

“Onset occurs 1 to 2 full days after infection.” This is the most common pattern.

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: