After recovering from the flu, the most pressing concern is determining “When can I return to work?” While there is a desire to return quickly, rules to prevent the spread of infection are strictly defined based on occupation and company size.
As of 2025, the rule that approximately 75% of workers in Japan follow—“5 days must pass since onset AND a full 2 days (48 hours) must pass since fever subsided”—has become the de facto national standard.
Influenza “Return-to-Work Criteria” 2025 Japan National Reality Summary (At-a-Glance Chart)
| Workplace Type | Criteria for Return to Work OK (2025) | Medical Certificate / Negative Test? | Effective Days Off |
| Civil Servants (National/Local) | 5 days since onset AND 2 days since fever subsided (Personnel Authority Rules/Local Ordinances) | Not required (Self-declaration) | 7 ∼ 8 Days |
| Public School Teachers | Same as above | Not required | 7 ∼ 8 Days |
| Nursery Staff / Kindergarten Teachers | 5 days since onset AND 3 days since fever subsided (Minimum Standards for Child Welfare Facilities) | Almost Mandatory | 8 ∼ 10 Days |
| Healthcare Workers (Hospitals) | 5 days since onset AND 2 days since fever subsided + Negative Antigen Test (Nearly 100% at National/University Hospitals) | Negative testmandatory | 7 ∼ 9 Days |
| Large Corporations (Toyota, NTT, etc.) | “5 days + 2 days” in 99% of internal rules. | Medical certificate or Photo Submission | Around 7 Days |
| Mid-sized Companies (300+ employees) | 80% follow “5 days + 2 days,” otherwise “OK once fever is gone and feeling well.” | Half require medical certificate | 6 ∼ 7 Days |
| SMEs / Private Clinics / Restaurants | A full 1-2 days (within 48 hours) since fever completely subsided + Mild cough level. | Mostly not required | 4 ∼ 6 Days |
| Telework-Permitting Companies | Immediate remote return OK once fever subsides (Return to office is 5 days + 2 days) | Not required | Effectively 3 ∼ 4 Days |
2025 “Return-to-Work OK” Fastest Checklist
- Note the Date of Onset (The day the fever first appeared).
- Have 5 days passed since the onset? (e.g., Onset Monday → 5 days passed on Saturday).
- Has a full 2 days (48 hours) of normal temperature continued without fever reducers?
- Is the cough/runny nose at a level that can be “mostly prevented by a mask”?
- Have you prepared the documents required by the company (Medical certificate or photo of negative test)?
→ If all are YES, you are OK to return to work!
Summary
The national average of “5 days since onset + a full 2 days (48 hours) since fever subsided” has become the return-to-work standard for approximately 75% of working people in Japan.
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) |
