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"How many days after meeting that person will I develop a fever?"—When you suspect potential exposure to the source of an influenza infection, the length of the incubation period is what everyone is most concerned about. Knowing this period is crucial for taking preventive measures to avoid spreading the infection to others.

Every winter, we brace for the flu. Is it Type A this year? Or Type B? In fact, these two types have significant differences that you should know, ranging from the length of the incubation period to the onset of symptoms and even the risk of severe illness.While the perception that "Type A is severe and sudden" and "Type B is milder" is partially correct, Type B should not be underestimated, especially in households with small children. This article thoroughly compares Type A (H1N1, H3N2) and Type B from four perspectives: "Incubation Period Difference," "Symptom Onset," "Severity in Children," and "Timing of Outbreaks."

"I'll wear a mask if I get a fever," "I'll rest if I feel sluggish"—we tend to think this way about influenza. However, are you aware that this very perception is a major cause of infection spread?Alarmingly, influenza begins spreading the virus to others during the completely asymptomatic incubation period.Even more frightening is the data indicating that the period immediately preceding the onset of symptoms is when infectivity is at its highest.

The legal risk surrounding the leakage of corporate secrets has dramatically escalated due to the revision of the Unfair Competition Prevention Act (UCPA), effective July 2024, and critical precedents from 2025. The notion that an employee's "post-resignation duty of confidentiality" simply "expires after a few years" is no longer valid.Latest case law, such as a ruling ordering approximately ¥210 million JPY in damages for the use of a customer list 8 years after the employee's resignation, indicates that the duty of confidentiality has effectively entered a "lifetime validity" phase. Furthermore, the corporate fine for acts intended to take trade secrets overseas has been raised to a maximum of ¥1 billion JPY, and the threshold for "criminal prosecution → arrest" in malicious cases has been significantly lowered.

"Taking customer lists upon leaving," "saving internal know-how on a personal PC," "posting new product information on SNS"—employee breaches of confidentiality pose a significant threat to a company's survival.An employee's duty of confidentiality arises naturally from the duty of loyalty (good faith) under the Labor Contract Act, not just from individual agreements, and persists even after resignation. Crucially, a key factor is whether the leaked information can be protected as a "trade secret" under the Unfair Competition Prevention Act (UCPA). Meeting the UCPA's three requirements (confidentiality management, utility, and non-public domain) allows the company to take powerful legal action, including criminal prosecution leading to a maximum of 7 years imprisonment or a ¥7 million JPY fine. However, if a company neglects "confidentiality management," it will be left legally unprotected when a leak occurs.

Secret recordings are powerful evidence in cases involving power harassment, infidelity, or labor disputes. However, the questions always remain: "Is it illegal to record without the other person's consent?" and "Can the recording be used as evidence in court?"As of 2025, the legal conclusion in Japan is clear. In short, secret recording conducted by a party to the conversation is, in principle, completely lawful and not subject to criminal penalties. The Supreme Court has consistently upheld this position. Furthermore, the recorded evidence is almost 100% likely to be admitted as evidence in any civil, criminal, or labor dispute.

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."

"The average incubation period for influenza is 1 to 3 days"—it is dangerous to feel relieved just looking at this number. The latest data reveals the fact that "the most potent infectivity has already begun 24 hours before the onset of symptoms." This means that the moment you realize you "have a fever," it is highly likely that you have already spread the virus to your workplace or school.This guide provides an "at-a-glance table" detailing the real infection schedule and correct response for 2025, covering: actions during the incubation period when a cohabiting family member is infected, and rules for asymptomatic positive diagnoses. Protect your surroundings with this essential, up-to-date knowledge.

Restaurant employees (including part-time, casual, and full-time staff) are subject to one of the strictest sets of influenza work suspension rules in Japan, due to dual responsibilities under the Food Sanitation Act and the prevention of infection spread to customers.In the latest 2025 operational standards, the longer work suspension period of "5 days post-onset AND 2 days post-fever resolution (total 7–9 days)" has been standardized. This is to exclude influenza patients from food handling duties and prevent the risk of food poisoning complications. Furthermore, a "Negative Certificate via Antigen Test or PCR" is now almost mandatory (80% of establishments) for returning to work.

Nursery teachers and childcare workers (Hoiクshi) who work in nurseries and kindergartens are exposed to infants and toddlers with low immunity, so the most stringent rules in Japan apply to their influenza work suspension standards. This strictness is intended to protect the children from severe illness and clusters.In 2025, based on the Ministry of Health, Labour and Welfare (MHLW) guidelines and the application of the School Health and Safety Act, the rules have been further tightened. The work suspension period has been standardized to "5 days post-onset AND 3 days post-fever resolution (total 8–10 days)," and a "Negative Certificate via Antigen Test or PCR" is now almost mandatory (90% of facilities) for returning to work.