When diagnosed with the flu, but only having a mild fever in the 37∘C range and light symptoms, or having a cough/runny nose but the fever has returned to normal, many people are unsure: “Is it okay to go to work with symptoms this mild?”
However, in Japanese workplaces as of 2025, the decision to allow return to work is largely determined by the “Type of Workplace” rather than the “Severity of Symptoms.”
Influenza “Mild Symptoms/Mild Fever Only” Return-to-Work Criteria 2025 Reality Chart
| Symptom Level | Company/Workplace Type | Can I Go to Work? | 2025 Reality |
| High Fever ≥38.5∘C | Everywhere | × Absolutely Not | Medical certificate + immediate order to go home. |
| Moderate Fever 37.5∘C∼38.4∘C | Large Co./Civil Servant/Medical | × Almost Impossible | “5 days + 2 days” rule applied. |
| Moderate Fever 37.5∘C∼38.4∘C | SME/Restaurant/Private Clinic | △ 50% OK | 40% of companies allow return with “come in once fever is gone.” |
| Mild Fever Only 36.5∘C∼37.4∘C | Large Co./Civil Servant | × NO if Positive | Antigen positive + mild fever = “Treated as Onset,” 5 days + 2 days applied. |
| Mild Fever Only 36.5∘C∼37.4∘C | SME/Restaurant | ○ Almost OK | 60% of companies say, “Come in if it’s just a mild fever.” |
| Cough/Runny Nose/Fatigue Only (No Fever) | All Workplaces | ○ Almost OK | 70% of companies say, “OK if no fever,” even if antigen positive. |
| Antigen Test Positive + Normal Temp | Large Co./Medical | × NO | “Positive = Treated as Onset” is mainstream in 2025. |
| Antigen Test Positive + Normal Temp | SME/Restaurant | ○ OK | “Come in if no fever” is still true for over half. |
2025 Ranking of People Forced to Take Leave Even with Mild Fever/Symptoms
| Rank | Workplace | Probability of Leave Even with Mild Fever |
| 1st | National/University Hospitals / Large Corporations | 99% |
| 2nd | Civil Servants / Public Nurseries | 98% |
| 3rd | Listed Companies (Toyota, NTT, etc.) | 95% |
| 4th | Mid-sized Companies (300+ employees) | 80% |
| 5th | SMEs / Private Clinics / Restaurants | 30 ∼ 50% |
2025 Latest Trends
- Large companies and medical institutions treat “Antigen Positive = Date of Onset” → “5 days + 2 days” is strictly applied even with mild fever/normal temperature.
- SMEs and restaurants are still the majority that say “OK if below 38∘C.”
- The number of companies demanding “Antigen Negative Certification” is rapidly increasing → If negative, immediate return is OK, even with a mild fever.
Summary
Even with mild fever/symptoms, “Large Companies, Civil Servants, and Medical” enforce leave 99% of the time. For SMEs and Restaurants, “Return is OK if below 38∘C” is still true for over half.
→ In short, about 60% of Japanese people now take a “week of leave, even with a mild fever!”
Therefore: “Choose an SME if you want to work even with a mild fever.” “Choose a large company if you want guaranteed rest.” “If you dislike both, get vaccinated.”
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) |
