When you get the flu (influenza), you often need a “Certificate” or “Diagnosis” from a doctor to return to school or work, and to claim sick pay (shōbyō teatekin / sickness and injury allowance). However, understanding the different types, official names, standard costs, and which one is the best can be confusing, right?
The latest trend in 2025 shows that many companies are requesting documents that “clearly state the date of onset”, and there has been a three-fold surge in large companies, in particular, requiring an “Negative Certificate.”
2025 Complete Manual for Influenza Doctor’s Certificates/Diagnoses
| Rank | Type | Official Name | Use Case | Standard Cost (2025) | Time to Receive | Key Points |
| 1st | Influenza Recovery Certificate (= Attendance/Return-to-Work Permit) | Influenza Recovery Certificate (インフルエンザ治癒証明書) | * Return to school * Lifting of work suspension * Return to daycare | Free – ¥500 JPY | Immediately (written on the spot) | Most pediatric and internal medicine clinics offer this for free. |
| 2nd | Influenza Diagnosis (Simplified Version) | Influenza Diagnosis (インフルエンザ診断書) | * Submit to company via LINE photo * Switch from paid leave to sick pay | ¥500 – ¥1,500 JPY | Immediately | Ask to have it written as: “Influenza Type A positive, Date of Onset: [Month/Day]” |
| 3rd | Diagnosis with Physician’s Opinion for Sick Pay | Diagnosis with Physician’s Opinion for Sick Pay (傷病手当金用意見書付き診断書) | * Receive 2/3 of salary from health insurance * Formal submission to company | ¥2,000 – ¥5,000 JPY | Immediate – Next day | Doctor fills out the Kyōkai Kenpo(Association Health Insurance) designated form. |
| 4th | Certificate of Absence (or Suspension) Period | Certificate of Absence (or Suspension) Period(出席（欠勤）停止期間証明書) | * Formal submission to school * Certification for company’s “5 days + 2 days” rule | Free – ¥1,000 JPY | Immediately | Explicitly states: “Date of Onset: [Month/Day], Possible Return Date: [Month/Day]” |
| 5th | Negative Certificate | Negative Certificate (陰性証明書) | * Required by company upon return (Surging in large companies/medical institutions) | ¥2,000 – ¥4,000 JPY | 30 mins after test – Next day | Antigen Quantitative or PCR testing is standard. |
2025 “Best Sheet” Recommendation Ranking
| Rank | Document | Cost-Effectiveness | Applicable Situations |
| 1st | Free Recovery Certificate (the one from pediatric clinics) | ★★★★★ | 99% of school/company needs covered. |
| 2nd | Diagnosis + Explicit Onset Date (¥500 version) | ★★★★★ | Sick pay + company submission. |
| 3rd | Dedicated Sick Pay Physician’s Opinion (¥2,000) | ★★★★☆ | For guaranteed 2/3 salary from health insurance. |
“Magic Phrases” to Ask the Doctor (Say these and you’re set)
| Purpose | The Magic Phrase to Say |
| Get it for free | “Could I please get an Influenza Recovery Certificate to submit to the school (or company)?” |
| For Sick Pay | “Could you please fill out the Physician’s Opinion form for Kyōkai Kenpo Sick Pay?” |
| Clarify Onset Date | “Could you please write the Date of Onset as [Month/Day]? My company needs it for the 5-day + 2-day rule.” |
| Negative Certificate | “Could I please have an Antigen Negative Certificate for my return to work (a quantitative test, please)?” |
2025 Latest Trends
- 80% of pediatric and internal medicine clinics keep free Recovery Certificates readily available (just a stamp on an A4 sheet with the onset and possible return date).
- Large companies now accept photo submissions of a Diagnosis explicitly stating the onset date via LINE. (No paper needed).
- The number of companies requesting a “Negative Certificate” upon return has tripled from the previous year.
Summary
If you get the flu, always get the “Free Recovery Certificate”! → This single document solves 90% of school, company, and sick pay issues! A simple “Excuse me, could I have a certificate, please?” at the end of the consultation is all it takes.
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) |
