When you contract the flu, the “home isolation (suspension from work/school) period” varies strictly depending on your occupation and position. For schools, civil servants, and medical/caregiving sectors, there are clear legal/institutional rules of “5 days since onset + 2 days since fever subsides.” However, for general company employees, especially those in Small and Medium-sized Enterprises (SMEs), these rules tend to be ambiguous.
Influenza “How Many Days of Home Isolation?” 2025 Latest At-a-Glance Chart
| Target Group | Legal/Rule-Based Home Isolation Period | Effective Guideline (2025) |
| Nursery/Kindergarten/Elementary/Junior/High School | 5 days since onset + 2 days since fever subsided (3 days for preschoolers) | Total 6 ∼ 9 days (Average 7-8 days off) |
| University/Vocational School | Varies by institution (Treated as attendance suspension) | Mostly the same 5 days + 2 days is mainstream. |
| Civil Servants (National/Local) | 5 days since onset + 2 days since fever subsided (Personnel Authority Rules/Local Ordinances) | Total around 7 days (100% salary paid) |
| Nursery Staff / Caregivers / Medical Personnel | 5 days since onset + 3 days since fever subsided (Facility Standard) | Total 8 ∼ 10 days |
| General Employee (Large Companies) | 5 days + 2 days is almost standard in work regulations. | Total around 7 days (Special leave or paid annual leave) |
| General Employee (SMEs / No explicit rules) | No legal requirement. | Effectively, the most common is return 2-3 days after fever subsides (Total 5-6 days). |
Specific Example (Assuming Onset is January 1st, 2025)
| Target Group | Day Fever Subsides | Earliest Possible Return Date | Days Off |
| Elementary School Student | January 3rd | January 6th (Mon) | 6 Days |
| Company Employee (Large Co.) | January 4th | January 7th (Tue) | 7 Days |
| Nursery Staff | January 4th | January 8th (Wed) | 8 Days |
| SME (No Rule) | January 3rd | January 5th (Sun) | 5 Days |
2025 Realistic Threshold for Those Who Want to Return as Soon as Possible
- A full 2 days (48 hours) have passed since the fever completely subsided.
- Cough/runny nose is at a level that is “not likely to infect others.”
- Negative result on the antigen test (if required by the company).
→ The number of people who return in a total of 5-6 days after meeting these criteria is rapidly increasing (especially at companies that allow telework).
Summary
Approximately 70% of Japanese people adhere to “5 days since onset + 2 days since fever subsided = Minimum 7 days” of home isolation. (Civil servants, nursery staff, school-related personnel, and large company employees)
The remaining 30% (SMEs, freelancers) can effectively return in 5-6 days.
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) |
