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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.

When you contract the flu, the most pressing concerns are"Exactly how many days will I have to take off?"and"What happen...

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.

When diagnosed with the flu, the question of "How many days should a student stay home?" and "When can an office worker return to work?" needs to be answered immediately. The rest period is crucial not just for recovery, but also for preventing the spread of infection to others.Under the 2025 guidelines, the required rest period for influenza has two strict conditions: "5 days must pass since onset" and "2 days must pass since fever subsides (3 days for infants/preschoolers)." Based on this calculation, the total rest period is generally a minimum of about 7 days.

The Quadrivalent (DPT-IPV) vaccine is mandatory for children, but do you assume "adults no longer need a booster shot"? If so, this is a major mistake. Especially, immunity against Tetanus wanes after about 10 years, and an infection from soil or a wound can be life-threatening for adults, with a mortality rate of 10%∼50%.However, the question of whether you need to be boosted for "all components" is usually "overkill."

When your child receives the Quadrivalent (DPT-IPV) vaccine, have you heard alarming stories from parents or grandparents about the old DPT (Triple) vaccine? Tales like "The side effects were terrible, I got a fever close to 40∘C," or "The injection site swelled hugely, and bathing was strictly forbidden."In fact, this perception is the true root of modern vaccination myths, such as "No bathing after the flu shot." The old DPT vaccine from the 1970s ∼ 80s was indeed a "vaccine of terror" with a high risk of severe reactions due to its manufacturing method.However, the current Quadrivalent (DPT-IPV) vaccine has evolved to a completely different level of safety. This article thoroughly explains the entire scope of this dramatic evolution—with the fever rate dropping from 50% to 1% and severe swelling becoming nearly zero—using a complete comparison chart with the old DPT.

Myths like "No bathing for 6 hours after the influenza vaccine" are deeply rooted for other vaccines as well. Many of these originated from "outdated manufacturing methods or fears of past infectious diseases" and have been successively withdrawn by the guidelines of the Ministry of Health, Labour and Welfare (MHLW), the Japan Pediatric Society, and the CDC. Below are the most common myths heard in Japan, explained with scientific evidence, detailing "why they were born" and "the truth."

After getting the influenza vaccine, have you ever been told by a nurse or doctor, "Please take only a shower today and wait 6 hours before taking a bath"? Although many hospitals now say, "You can go right away," this "6-hour post-vaccination waiting rule" stubbornly persisted as a long-standing custom in Japan.

After receiving the influenza vaccine, many people feel uncertain and have questions about daily life: "Should I avoid exercise today?" "Is it okay to take a bath?" "Can I drink alcohol?" In particular, the outdated information that "bathing is prohibited for 6 hours after vaccination" still persists, leading people to unnecessarily restrict their daily activities.However, based on the latest clinical knowledge in 2025, the conclusion is very simple: "If you adhere only to the 30-minute waiting rule, you can resume 100% of your normal life starting on the day of vaccination."

"My child developed a runny nose and a mild fever (37.2∘C) on the day of the appointment. Should I cancel?" — This is one of the most frequently asked questions every flu vaccination season. Many people hesitate, fearing that "side effects will be worse if vaccinated with cold symptoms" or "the vaccine will be ineffective because the immune system is weakened by illness."However, the latest scientific and clinical data in 2025 completely overturn this common concern.