Are influenza flu vaccines safe

The flu is through Influenza-A- and Influenza-B viruses.

The first symptoms of flu are malaise, fatigue, rapidly rising fever, chills, headache, muscle and joint pain, followed by loss of appetite and dizziness. Eye complaints, especially when looking to the side, photophobia as well as tearing and burning eyes are also frequently reported.

American soldiers during the 1918 Spanish flu.
Photo: National Museum of Health and Medicine, License Creative Commons

Symptoms such as dry cough, sore throat, hoarseness, and runny nose may also become more severe as the flu progresses. Especially in children, gastrointestinal signs such as nausea, vomiting, abdominal pain and diarrhea are often in the foreground.

Fever, the easiest symptom to recognize, rises rapidly to values ​​above 38 ° C in the first 12 hours, with peaks of up to 41 ° C. The fever phase usually lasts 3 days, but can last up to 8 days. Sometimes there are subsiding and recurring attacks of the fever, especially if fever-lowering drugs (antipyretics) are taken.

The recovery phase lasts an average of 1 to 2 weeks, but it can also extend over several weeks.

In Switzerland, 100,000 to over 300,000 people see a doctor every winter because of a flu-like illness.

Source: BAG - Bulletin 29 (July 15, 2019)


The risk of an influenza-related complication exists in any case, but it is significantly higher in certain risk groups.

Primary, viral and secondary, bacterial frontal sinus infections, otitis media, bronchitis, pneumonia and pseudo croup occur most frequently. But pleurisy, myositis, myocarditis and pericarditis with subsequent dilated cardiomyopathy, myocardial infarction and toxic shock can also occur and be life-threatening. Meningitis, encephalitis, myelitis, and Guillain-Barré syndrome are also possible.

In Switzerland, the seasonal flu causes 1,000 to 5,000 hospitalizations every year.

additional Information:

Analysis of influenza in Switzerland

Seasonal flu - situation report Switzerland

PDF report on the 2019-2020 flu season

PDF - Seasonal Influenza: Answers to Frequently Asked Questions from Professionals (2018)

PDF - FAQ Seasonal Influenza (2018)

Review Article AIM: "Clinical Diagnosis Can Be Difficult"


Flu shot

Influenza vaccines contain the surface proteins of 3 or 4 virus strains that are expected to circulate in Switzerland in winter. They do not contain aluminum salts.

To remain effective, vaccination must be repeated between September and December each year, even if the circulating viruses and vaccines do not change.


Recommendations for everyone

The vaccination remains the simplest, most effective and most economical preventive measure to protect yourself and those around you from the flu and its complications. During the current Covid-19 pandemic, our inpatient health care could be stressed if the number of cases increases. Simple preventive measures, good hygiene and the flu vaccination help to reduce the burden of disease in winter. The recommendations for flu vaccination (as of 2013) are unchanged. The vaccination is recommended for all people with an increased risk of complications and their regular contact persons (including close relatives) as well as all health professionals. In 2020, more vaccine doses will be available than in previous years to cover the expected increased demand. However, some of the cans will only arrive in Switzerland towards the end of the year. That is why the recommended time span for vaccination is “from mid-October and until the start of the flu epidemic”. In most winters, we get the flu outbreak in January.


Recommendations for people with an increased risk of complications

  • People over 65 years of age.
  • People (from the age of 6 months) with any of the following chronic diseases:
    o heart disease;
    o lung disease (e.g. bronchial asthma);
    o Metabolic disorders that affect the function of the heart, lungs or kidneys (e.g. diabetes or morbid obesity, BMI> = 40);
    o neurological (e.g. Parkinson's, cerebrovascular disease) or musculoskeletal disease that affects the function of the heart, lungs or kidneys;
    o hepatopathy; Renal failure;
    o Asplenia or dysfunction of the spleen (including hemoglobinopathies);
    o Immunodeficiency (e.g. HIV infection, cancer, immunosuppressive therapy).
  • Pregnant women from the 2nd trimester of pregnancy and women who gave birth in the last 4 weeks.
  • Premature babies (born before the 33rd week or with a birth weight below 1500 g) from the age of 6 months for the first two winters after birth.
  • Patients in nursing homes and facilities for people with chronic diseases.


Recommendations for people with an increased risk of contact and / or transmission

  • The medical and nursing staff and all other people who have direct contact with patients, be it in hospitals, clinics or doctor's offices, in home care, in old people's and nursing homes or in spa facilities.
  • Adults and children who are in close contact with people at risk or who live in the same household with them.


Degree of protection of vaccination against influenza

The antigens in the vaccine correspond to the viruses in circulation. Studies estimate the effectiveness depending on the season and vaccinated people at 20 to 80%. The flu vaccine is less effective in certain people who belong to a risk group, and especially in the elderly. However, it can reduce the incidence of flu and flu mortality.


Known side effects of the flu vaccine

The flu shot is very safe. Its effects are well known. Billions of vaccine doses have been administered around the world since 1945. All flu vaccines currently used in Switzerland are inactivated. So they do not contain any infectious viruses that can cause flu, but only the antigens of three flu virus strains currently in circulation (one each of the viruses A / H1N1, A / H3N2 and Influenza B).

The most common side effect is a slight local reaction at the injection site. It occurs in 10 to 40% of vaccinated people and subsides after a few hours or a maximum of two days. General mild symptoms such as fever, nausea, muscle pain, joint pain, headache and other flu symptoms occur in 5 to 10% of people vaccinated.

Serious allergic reactions such as angioedema, asthma or anaphylaxis are very rare (less than 1 in 10,000 vaccinated people). They can generally be explained by hypersensitivity to the proteins in the chicken egg. Undesired neurological phenomena, e.g. B. Guillain-Barré syndrome are also very rare.

additional Information:

Vaccinate against the flu

PDF - Facts Vaccination Seasonal Influenza (2013)

PDF - Flu protection during pregnancy: Vaccination makes sense (2017)

PDF - Factsheet: Influenza Vaccination (2017)

PDF - Recommendations against Influenza - 2020-21

PDF - COVID 19 and the influenza vaccination strategy for influenza season 2020 2021 (National COVID-19 Science Task Force, 26.9.2020)

PDF - Flu: Recommendations for Influenza Vaccination (2011)

PDF - Flu vaccination recommendation - short version (2017)

PDF - flu? Vaccination makes sense. A brochure for healthcare professionals (2017)