There is a world of difference between “Seasonal Influenza,” which circulates every winter, and “Novel Influenza,” which causes global pandemics, in terms of their nature, infectivity, and social impact, despite both carrying the name “influenza.”
Influenza “Seasonal vs. Novel” Complete Difference Summary (2025 Latest)
| Item | Seasonal Influenza (Every Winter) | Novel Influenza (Pandemic Level) |
| Classification (Infectious Diseases Act) | Category V (Weakest) | New Influenza or Highly Pathogenic Infectious Disease (Equivalent to Category II – Strongest) |
| Viral Type | Type A (H1N1, H3N2), Type B (Mutates slightly every year = Antigenic Drift) | A completely new antigen type (e.g., Avian Flu H5N1 transmitted human-to-human) |
| Global Circulation | Every December–March (Approx. 10 million people in Japan) | Once every few decades to 100 years (e.g., 1918 Spanish Flu, 2009 H1N1) |
| Immunity Status | Adults and children have partial immunity (Vaccines from last year offer some protection) | Almost the entire population has no immunity →Severity/Mortality rate is 10 to 100 times higher |
| Severe Illness Rate | 0.1–0.5% (Higher in the elderly and those with underlying conditions) | 2–40% (In 1918, 500 million infected globally, 50 million died) |
| Mortality Rate | Approx. 3,000 to 10,000 deaths annually in Japan (direct + pneumonia complications) | Past examples: 0.5–4% (2009 was milder at 0.02%) |
| Infectious Disease Act Response | Reporting mandatory but no Article 18 notification (No compulsory measures) | Article 18 notification by prefectural governor + legal force (Restriction of movement, mandatory hospitalization possible) |
| Work/School Suspension | Company/school self-rule (5 days + 2 days) | Legal enforcement (Fines or compulsory hospitalization are possible for refusal) |
| Vaccine | Annual predictive vaccine (Trivalent or Quadrivalent) in October–December | None in the first year → Emergency production 6 months to 1 year later |
| Treatment Drugs | Tamiflu, Xofluza, etc., are effective | High possibility of drug resistance (Tamiflu was effective in 2009) |
| Current Situation in 2025 | Peak expected in December, as usual | None has emerged yet (High alert for Avian Flu H5N1 transmitting human-to-human) |
🚨 2025 “Which is Worse?” One-Line Comparison
| Seasonal Influenza | Novel Influenza |
| “An intense version of the annual cold.” | “A virus humanity is encountering for the first time.” |
| Vaccine available → mostly mild cases when infected. | No vaccine → severe illness and death across all age groups. |
| Time off work lasts 7 days. | Suspension of social functions (School closures, movement restrictions/lockdowns). |
| Kills 10,000 people annually in Japan. | Worst case historically: Killed 50 million people worldwide. |
✅ Summary
Seasonal Influenza = “A strong enemy that comes every year” → 90% preventable with a vaccine.
Novel Influenza = “The once-in-a-century demon” → No vaccine and brings society to a standstill.
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:
| Rank | Product Name (Manufacturer) | Targets Detected | Sensitivity (Detection Rate) (Estimate: 12-48h Post-Onset) | Result Time | Approximate Price (Per Test) | Suitability for Pregnant Women / Children | Key Features & Availability |
| 1 | Panbio COVID-19/Flu A&B | COVID + Flu A/B | COVID: Approx. 90% | Flu: Approx. 85% | 15 mins | ¥1,980 – ¥2,480 | ◎ (Shallow Nasal Swab) |
| 2 | クイックナビ-Flu+COVID | Same (COVID + Flu A/B) | COVID: 88% | Flu: 80–85% | 15–20 mins | ¥1,780 – ¥2,200 | ◎ (Designed for children’s use) |
| 3 | KBMラインチェック nCoV/Flu | Same (COVID + Flu A/B) | COVID: 85% | Flu: Approx. 80% | 15 mins | ¥1,480 – ¥1,980 | ◎ |
| 4 | イージードック Flu＆COVID-19 | Same (COVID + Flu A/B) | COVID: 87% | Flu: 82% | 15 mins | ¥2,200 – ¥2,600 | ◎ (Many cases of use by pregnant women) |
