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 Many of these originated from “outdated manufacturing methods or fears of past infectious diseases” and have been successively withdrawn by the guidelines of the Ministry of Health, Labour and Welfare (MHLW), the Japan Pediatric Society, and the CDC.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.”
Vaccine Misconceptions
| Urban Legend (Myth) | Target Vaccine | Until When Was It Advised? | Reason Why It Was Born | The Truth (As of 2025) |
| “People with egg allergies cannot be vaccinated.” | MMR, Influenza, and others made with egg culture. | ∼ Early 2010s (still at some older hospitals) | Older vaccines had more residual egg protein, leading to rare cases of anaphylaxis. Myth spread that “if you can’t eat eggs, you can’t get the shot.” | 99.99% can be vaccinated! The trace protein is tolerable. Only severe allergies require caution (resolved with recombinant vaccines). Japan Pediatric Society: Mild allergies are OK. |
| “No strenuous exercise, alcohol, or bathing for 24 hours after vaccination.” | DPT, Japanese Encephalitis, Polio, etc. | ∼ 2000s (strong lingering effect from DPT) | The old DPT in the 1970s ∼80s often caused suppuration at the injection site, which bathing could worsen. Also, a misconception that alcohol weakens immunity. | Immediate OK! The needle hole closes in minutes. No restrictions on exercise, alcohol, or bathing. Side effects (fever/pain) are proof of immune activation. CDC:Antibody formation is 10 times faster than natural immunity, making it safe. |
| “Vaccines cause autism.” | MMR, Hib, Rotavirus, etc. | Popularized from 1998 Anderson paper (withdrawn) ∼ 2010s. | A fraudulent UK paper was globally disseminated. The timing (vaccination at age 1 coinciding with autism diagnosis) caused misunderstanding. | Completely False! Large-scale studies (over 1 million people) show zero association. WHO/CDC:Genetic/environmental factors cause autism. The paper’s author had his medical license revoked. |
| “Aluminum and formaldehyde accumulate in the brain and are toxic.” | Hib, Polio, DTaP/IPV, etc. | ∼ Early 2020s (resurfaced by anti-vaccine movements) | Exaggeration of trace component use as “poison.” Arousing anxiety despite quantities being less than in everyday foods (vegetables/dairy). | Safe quantities! Aluminum is an immune booster and less than what the body naturally produces. Formaldehyde is minimal. FDA: Less than 0.001% of lifetime exposure limit. Zero scientific evidence of brain accumulation. |
| “Cannot be vaccinated on days with a cold or fever.” | All routine immunizations (BCG, HPV, etc.) | ∼ 2010s (still circulating among mothers) | Concern about worsening infection with old live vaccines (BCG). Spread by extension of the flu vaccine rule. | Mild cold / Below 37.4∘C is OK!Inactivated vaccines have zero live viruses. Immune activation may even increase effectiveness. Japan Pediatric Society:Postponement only for 37.5∘C or higher. |
| “Natural infection provides stronger immunity.” | HPV, Rotavirus, etc. | ∼ Present (due to “naturalist” trends) | Romanticizing naturally acquired immunity as “natural and genuine.” Ignores the risk of severe illness. | The Reverse is True! Natural infection carries high risks of complications (infertility, cancer). Vaccines safely form antibodies. CDC: Vaccines reduce natural infection fatality rates by 99%. |
| “Simultaneous vaccination confuses the immune system.” | DTaP/IPV + Hib + PCV (Pneumococcal) | ∼ 2015 (popular in parenting books) | Misunderstanding that a baby’s immune system is “weak.” Urban legend of “overload” from multiple antigens. | Safe! Infants can handle tens of thousands of antigens at 2 months old. Simultaneous vaccination results in equal or higher antibody titers. MHLW: Shortens the schedule for increased efficiency. |
2025 Background of These Myths and Why They Still Persist
- Historical Reason: Vaccine manufacturing from the 1970s ∼ 90s had more impurities, leading to noticeable side effects (e.g., DPT suppuration). This created rules like “No Bathing” which spread as urban legends through word-of-mouth.
- Modern Dissemination: Resurgence via social media and anti-vaccine movements. COVID-19 created derivatives like the “microchip conspiracy theory” (featured on a popular Japanese mystery TV show, boosting viewership).
- Scientific Reality: All myths have been debunked by large-scale studies. While vaccines save millions of lives annually, these myths lowering vaccination rates are a unique Japanese problem (e.g., HPV vaccination rate remains in the 20% range).
Summary
These urban legends are “remnants of past fears.” → The risk of not getting vaccinated (e.g., measles epidemic, rise in cervical cancer) is 100 times greater! If you are anxious, please consult your primary care physician.
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) |
