Overview / History

Influenza B is a type of flu viruses which is capable of circulating widely among humans. Globally, there are seasonal variations in transmission of the virus, but are not known to have pandemic potential. The virus can affect people in all age groups and usually causes mild illness. It is included in seasonal influenza vaccines and annual vaccination with this vaccine helps in preventing infection.

Mode of spread

Coughing / Sneezing

Transmission

Influenza B causes fever, cough, headache, bodyache, malaise, sore throat and runny nose. Most cases are mild and patients recover on their own within a week. However cough may be prolonged. Some people may need treatment with antiviral medications. Severe cases occur among people in the high-risk groups who may require hopsitalisation.

Symptoms

Influenza B causes fever, cough, headache, bodyache, malaise, sore throat and runny nose. Most cases are mild and patients recover on their own within a week. However cough may be prolonged. Some people may need treatment with antiviral medications. Severe cases occur among people in the high-risk groups who may require hopsitalisation.

Diagnosis

Flu is diagnosed on the basis of signs and symptoms. The virus type can be confirmed through specialised lab tests.

Treatment

Because it is a viral illness, influenza B does not respond to antibiotics. Flu can generally be treated with antiviral medications, which are most effective when given very soon after symptoms begin. Antiviral treatment is not needed in all cases. Treatment decisions are made on an individual assessment by a person's doctor or other medical provider. Many choose to alleviate their symptoms with over-the-counter (non-prescription) medications.

Vaccination

Influenza type B is included in the seasonal influenza vaccine. Annual vaccination is required.

Prevention

The most efficient way to prevent influenza B is to be vaccinated against it. Vaccination needs to be repeated annually, as flu viruses change rapidly. One year's vaccine is not effective against the viruses that will circulate widely the next year. Flu vaccines usually contain two or three strains of influenza virus that are expected to be most prevalent in the upcoming flu season. Vaccination is recommended for:

• International travellers.
• Anyone over 6 months of age who wants to avoid getting the flu.
• People at high risk for severe infections
• Women who will be in the second or third trimester of pregnancy during the influenza season. Vaccination is considered safe throughout pregnancy, but most medical providers usually avoid vaccinating women during the first trimester.

The vaccine is 70 to 90 percent effective in preventing influenza among healthy adults. The vaccine may be less effective in very old and very young people, but it can still help avoid serious complications from the flu.

• Maintain good personal hygiene.
• Wash your hands frequently. Carry a hand sanitizer for use when soap and water are not readily available.
• Avoid touching your face.
• Avoid people who are obviously sick.
• Ensure all routine vaccinations are up to date. This includes pneumococcal vaccination for some groups of people.

Risk to travellers

Influenza is one of the most common vaccine-preventable diseases among travellers. To reduce the chances of developing influenza B, all travellers should be vaccinated annually. The risk of exposure to influenza depends on the time of year and destination.

• In the Northern Hemisphere, the flu season generally ranges from November through March.
• In the Southern Hemisphere, most activity occurs from April through September.
• In the tropics, the risk of exposure exists throughout the year.

Further Reading