Influenza(Flu) prevention tips and "flu shot "


English セルフケア・対処 インフルエンザ

Type of Influenza

There are 3 types of influenza virus (Type-A, B and C). Among these, types which are seasonal are Type-A and B. Type-A strains being the more severe and causes a pandemic, occurring once in several decades.Type-C occurs sporadically, not causing any seasonal epidemics. With the combination of 2 proteins (H) and (N) on the surface of the virus, there are 144 different influenza A subtypes. While influenza B viruses are further classified into two lineages.

Flu symptoms

When you have typical influenza, besides symptoms of upper airways such as runny nose, sore throat, you have systemic symptoms such as fever higher than 38 degrees Celsius, malaise and joint pains.
However, recent flu studies confirmed that there are flus with only mild symptoms such as runny nose and sore throat without any fever. Furthermore, there are more people who have asymptomatic infections than those who have mild symptoms.

If people with low immunity such as elderly persons and infants have influenza, symptoms can be severe and some heavy complications like pneumonia and influenza encephalitis can occur. People with chronic diseases, pregnant persons, obese persons with a BMI over 40 and people in long-term care medical facilities have to be careful as they have a higher risk to present severe symptoms.

Prevention of Influenza! Flu shot(Flu vaccine) effectiveness

Flu vaccine is important in order to prevent having influenza. Its effectiveness can vary depending on the person's age, however it reduces about 50 to 60 % the appearance of symptoms, its severeness. Some studies show that flu vaccine reduced the flu-associated hospitalizations among adults by about 70 %.

Flu shot as a prevention

Flu vaccine is renewed each year. The new vaccine is made till the summer of the new season. It is made based on virus strain of world's flu epidemics and by trying to predict what could be the Japanese epidemic of the season.

Previously, flu shot was a 3 types virus mixed vaccine (Type-A 2 subtypes + Type-B 1 subtype). Since 2015, 1 subtype was added to Type-B, which became 4 types of virus mixed vaccine, making it more effective with an effectiveness and prevention against severe symptoms.

It takes about two weeks after vaccination for antibodies to develop in the body and provide protection against flu. Its maximum effectiveness is about 1 to 2 months after the inoculation.

Make plans to get vaccinated early in fall, before the flu season begins.

In case of children, as the basic immune system is low, it is recommended to have 2 inoculations. About 4 weeks interval is needed between the first and the second inoculation.

How flu spreads?

There are mainly two ways to become infected by the flu viruses. The first way is by droplet infection, and the second is by contact infection.
A cough contains about 900,000 droplets, sneezing contains 2 million droplets and a 5 minutes talk generates as many droplets as a cough.

In recent years, a third way which is "Aerosol infection" is attracting expert's attention. Aerosol is a situation when particles in the air are stabilized, such as clouds, cigarette smoke and frozen breath. It is thought that Aerosolized flu virus particles are in the air, and by breathing it could transmit its virus.

Flu home remedies

Practice correct hand washing

What is important to avoid flu infection is "hand washing". It's an efficient way to remove flu viruses physically. You can improve the efficiency by practicing "correct hand washing". We recommend you to wash hands when you have been out.

Wearing a mask is also efficient

Wearing a mask is also efficient for avoiding flu. Masks prevent particles including flu viruses to spread for a while. It is recommended to wear masks when you go out or when you cough to prevent passing your infection to others.

Preventing flu by regulating indoor temperature , humidity and by staying healthy

Regulating the right room temperature and humidity will also prevent from infection. Keeping 50~70% humidity and 20~25 C° temperature will lessen the virus propagation. Staying healthy by having a correct lifestyle such as regular exercise, have enough sleep, maintain a healthy diet to keep your resistance are important.

Influenza treatment

You need to see a doctor if you think having flu symptoms. Especially, for people having a high risk to develop complications, we recommend them to consult rapidly. If you are diagnosed having a flu, the intake of antiviral treatment within 2 days will make your symptoms less severe and shorting fever with 1~2 days.

The current main antiviral treatment is "neuraminidase inhibitor". It consists of confining the virus in the infected cell, to avoid the contamination to other cells. For adult treatment, you have "Oseltamivir (ex:Tamiflu)" an oral preparation which you have to take twice a day for 5 days. An inhaler type medication "Zanamivir (ex: Relenza)" to take twice a day for 5 days. An inhaler type medication "Laninamivir (ex: Inavir)" in a single administration.
For children below 9 years old, a dry syrup type Oseltamivir (ex:Tamiflu) is recommended.
For people having difficulties in oral and inhaler type medication, "Peramivir (ex: Rapivab)" a drip infusion type medication is possible.

Furthermore, since 2018, "endonuclease inhibitor" a new antiviral treatment was approved and is available. It consists of blocking the enzyme which flu virus needs to multiplicate. "Baloxavir (ex: Xofluza)" an oral preparation in a single administration will avoid from forgetting the intake of medication. On the other hand, there are some studies saying that there is a high probability that "Baloxavir" could develop virus resistance. In October 2019, the Japanese association for infection diseases stated that "Due to lack of data, Baloxavir is not recommended for children over 12 years old and young adults for the moment."

Yet, regardless of taking or not of antiviral treatment, flu infection in children generates strange reactions such as running suddenly or a bursting out of a room. It's therefore important to keep an eye on them and to be vigilant.