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The flu vaccine and coronavirus

This section provides important information about flu vaccination and how it helps with COVID-19.

The relationship between COVID-19 and the flu

It is not possible to tell the difference between COVID-19 and influenza (the flu) based on symptoms. The coronavirus SARS-CoV-2 has joined the ranks of the cold and flu viruses that circulate each year. Since these viruses all cause respiratory illnesses with similar symptoms, the only way to know for sure which one you have is through a lab test.

The following table provides an overview of common respiratory illnesses.

Legend: +++ often, ++ less often, + sometimes, / (rather) rare

Illness COVID-19 Influenza (flu) Common cold
Cause Coronavirus SARS-CoV-2 Influenza viruses >100 different viruses (and bacteria)
Onset of symptoms If symptomatic, tends to be less abrupt Abrupt Gradual, over days
Typical incubation period 4–6 days 1–2 days 2–10 days (depending on cause)
Immunity after infection or vaccination Not completely researched Partial Depends on type of causative agent and mmune status
Vaccine In testing phase Yes No
Medication Only non-specific Specific Only non-specific
Symptoms
Fever +++ +++ /
Cough +++ +++ ++
Shortness of breath + / /
Running nose/Sniff + + +++
Sneezing / / +++
Sore throat + + +++
Aches and pains + +++ +++
Headache + +++ +
Fatigue ++ +++ +
Diarrhea + + /
Itchy eyes / / /
Loss of smell + / /
Illness COVID-19 Influenza (flu) Common cold
Cause Coronavirus SARS-CoV-2 Influenza viruses >100 different viruses (and bacteria)
Onset of symptoms If symptomatic, tends to be less abrupt Abrupt Gradual, over days
Typical incubation period 4–6 days 1–2 days 2–10 days (depending on cause)
Immunity after infection or vaccination Not completely researched Partial Depends on type of causative agent and mmune status
Vaccine In testing phase Yes No
Medication Only non-specific Specific Only non-specific
Symptoms
Fever +++ +++ /
Cough +++ +++ ++
Shortness of breath + / /
Running nose/Sniff + + +++
Sneezing / / +++
Sore throat + + +++
Aches and pains + +++ +++
Headache + +++ +
Fatigue ++ +++ +
Diarrhea + + /
Itchy eyes / / /
Loss of smell + / /
Scroll left to view more of the table ⬅️

When should I see a doctor?

Respiratory infections are usually self-limiting, which means that they go away on their own within a few days or at most after two weeks. Nevertheless, a visit to the doctor or even a hospital admission may be necessary in some cases.

The Robert Koch Institute (RKI), Germany’s national public health institute, recommends a visit to the doctor for people with chronic illness, pregnant women, children younger than 2 years, people older than 60 years, and anyone who feels very unwell or has serious symptoms. Warning signs include increasing shortness of breath, persistent chest pain, tightness in the chest, uncontrollable fever, and confusion.

Chronically ill
Chronically ill
Pregnant
Pregnant
Older than 60
Older than 60
Younger than 2
Younger than 2
Breathing problems
Breathing problems
Chest Pain
Chest Pain
Fever
Fever
Confusion
Confusion
Flu vaccination and coronaviruses

For the flu – in contrast to COVID-19 – we already have a crucial preventive tool at our disposal in the form of the flu vaccine. The flu vaccine successfully prevents a significant number of influenza infections each year. From a medical point of view, there is currently nothing to indicate that the flu vaccine provides direct immunological protection against the coronavirus, SARS-CoV-2.

Nevertheless, it is possible to catch COVID-19 and the flu at the same time, which can be a life-threatening combination, especially for risk groups for whom the flu vaccine is already recommended.

The RKI therefore continues to recommend flu vaccination in fall and winter for all risk groups. The immunity provided by the vaccine can prevent influenza infections or at least reduce the severity so that the immune system can concentrate on defending itself against the coronavirus.

Side effects of the flu vaccine

Most people who receive vaccines have no side effects. For those that do, the side effects are usually very minor. They are sometimes referred to as an “immunization reaction” and are a manifestation of the normal reaction of the immune system to the virus. These minor side effects include redness or swelling at the injection site, muscle aches, transient tiredness or fatigue, and fever, which usually go away within a few days. No serious side effects have been described for the flu vaccine.

Flu vaccination in children

Children can also fall ill with the flu, although they are more frequently affected by common cold viruses. The symptoms of influenza are usually less severe in children than in adults and more like the symptoms of a common cold.

However, children with a serious chronic underlying disease should always be vaccinated against seasonal flu. Relatives who belong to a risk group should also be vaccinated to reduce both the child’s and their own risk of infection.

Parents getting vaccinated also has a positive impact on their child’s welfare. By getting vaccinated, they are more likely to avoid the flu and remain healthy so they can continue caring for their child.

Both COVID-19 and the flu at the same time

We know that it is possible to have the flu and COVID-19 at the same time. If you are exposed to a different virus when your body is already weakened by one respiratory infection, you are more likely to develop the other infection as well.

As a result of social distancing measures and the use of masks, the probability of contracting a respiratory infection has reduced by more than 50% in comparison to the previous year.

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