Influenza Prophylaxis: What to Do When a Family Member or Travel Companion Has the Flu | Preventive Anti-Influenza Medication (Tamiflu®, Inavir®, Xofluza®)

■When Someone You Are Traveling With Gets the Flu

Influenza (the flu) can turn a long-awaited trip upside down. If a family member or travel companion develops the flu while you are in Japan, the rest of the group is at high risk of catching it within days — sharing the same hotel room, meals, and transportation makes close contact almost unavoidable.

The good news is that there are preventive medications that can significantly lower your chance of becoming ill after such exposure. This is called “post-exposure prophylaxis.” Our clinic can prescribe these medications for travelers.

■ Why Influenza Spreads So Easily

Influenza is one of the most contagious respiratory infections. It spreads through droplets produced when an infected person coughs, sneezes, or talks, and through hands and surfaces contaminated with the virus.

A person with influenza can spread the virus from about one day before symptoms start until roughly five to seven days after. Because the virus is contagious even before the first symptoms appear, other members of a travel group are often already exposed by the time the diagnosis is made. Within households, it is common for several people to fall ill one after another.

■ What Influenza Feels Like

Unlike the common cold, influenza typically begins abruptly. Within hours, a person may develop:

• High fever, often 38–40°C (100–104°F), with chills
• Severe muscle and joint aches
• Intense fatigue and weakness
• Headache
• Sore throat, cough, and nasal symptoms

The fever and body aches are usually severe enough to keep a person in bed for several days. For travelers, this often means cancelled plans, missed flights, and days spent in a hotel room.

■ Who Is at Risk of Severe Illness

For most healthy adults, influenza is a miserable but self-limiting illness. However, some people are at higher risk of complications such as pneumonia, worsening of an existing illness, and hospitalization. These include:

• Adults aged 65 years or older
• People with chronic lung disease (asthma, COPD)
• People with heart disease
• People with diabetes
• People with chronic kidney disease
• People with weakened immune systems (cancer treatment, immunosuppressive medication)
• Pregnant women
• Young children

If you or a member of your group falls into one of these categories and has been in close contact with someone who has influenza, preventive medication is particularly worth considering.

■ Preventive Anti-Influenza Medication (Post-Exposure Prophylaxis)

The same antiviral medications used to treat influenza can also be used, at a different dose, to prevent illness after exposure. In clinical studies, starting prophylaxis promptly after close contact reduced the risk of developing symptomatic influenza by roughly 70–90%.

Three medications are available at our clinic for this purpose.

【Tamiflu® (oseltamivir) — oral capsule】

• Taken once daily for 7–10 days
• Available for adults and children (pediatric dosing is weight-based; dry syrup is available for young children)
• The most widely used option worldwide

【Inavir® (laninamivir) — inhaled powder】

• A single inhalation completes the course (an alternative two-day schedule is also available)
• Available for adults and children
• Convenient for travelers who do not want to carry medication for the rest of their trip
• Not suitable for people who have difficulty inhaling the powder properly (e.g., some young children or people with severe asthma)

【Xofluza® (baloxavir marboxil) — oral tablet】

• A single oral dose completes the course (the dose is adjusted by body weight)
• Available for adults and children (granules are available for younger children)
• The most convenient option for travelers who prefer not to use an inhaler or take medication for several days
• Approved in Japan for post-exposure prophylaxis since 2020

【Timing is essential】

Both medications should be started as soon as possible and within 48 hours of the last close contact with the person who has influenza. The sooner prophylaxis begins, the more effective it is. If you have been exposed, please do not wait for symptoms to appear.

■ Important Points to Know

• Preventive medication greatly reduces the risk of illness, but it does not provide 100% protection. If you develop a fever or other symptoms despite taking it, please seek medical care so that you can be tested and treated.
• Prophylaxis does not replace influenza vaccination. It is a short-term measure after a specific exposure.
• Anti-influenza medication used for prevention is also generally not covered by overseas travel insurance, because preventive treatment for a person who is not ill falls outside the scope of most policies. Prophylaxis is therefore provided on a self-pay basis. We will explain the cost before prescribing.
• Basic precautions still matter: hand washing, wearing a mask around the person who is ill, ventilating the room, and, where possible, avoiding sharing a bed or room.

■ What We Can Do at Our Clinic

We provide:

• English-speaking medical care
• Rapid influenza testing for the person with symptoms
• Assessment of exposure and individual risk factors by a physician
• Prescription of preventive anti-influenza medication (Tamiflu®, Inavir®, Xofluza®) for family members and travel companions
• Treatment for those who have already developed influenza, including antiviral medication, fever reducers, and intravenous (IV) fluid therapy when needed
• Medical certificates for airlines, hotels, or travel insurance when required
• Referral to specialist medical facilities if needed

■ Appointment

At our clinic in Shinsaibashi, Osaka, international travelers can receive medical care with confidence. Same-day appointments and English-language support are available.

If a member of your family or travel group has been diagnosed with influenza and you would like to discuss preventive medication, please contact us as soon as possible — ideally within 48 hours of contact.

International Clinic Osaka Shinsaibashi (ICOS) provides same-day English-speaking medical care, including influenza testing, treatment, and preventive medication. International visitors are welcome.

Address:
SURE Nishishinsaibashi 4F, 1-13-25 Nishishinsaibashi, Chuo-ku, Osaka, Japan

Phone:
+81-6-6484-6392

Email:
c.icos@international-clinic-osaka.com