International Day of Immunology April 29th - Strengthening the immune system and defences in children

29 April 2022

Appearance/clinical picture

In the first period after birth, maternal antibodies protect the babies from pathogens. This so-called nest protection fades after about three months. During this time, however, the child's organism works on its own immune defence: with each contact with a pathogen, the child's defence system gets to know a new germ and finds a way to render it harmless. Upon renewed contact with the pathogen, lymphocytes (a subgroup of the white blood cells) remember the pathogen, and the immune system can fight it off faster and in a more targeted manner.
An infection therefore always occurs when the pathogen is (still) unknown to the body's defences. The child's immune system therefore needs coughs, colds and sore throats. Only in this way can the body's defences develop. An immune system cannot learn anything in an environment where perfect hygiene is constantly observed.

Symptoms/complaints of increased susceptibility to infection

When children get one cold after another, parents often worry a lot. However, the increased occurrence of simple viral infections that heal again without complications are not an indication of immune deficiency, especially if the child has frequent contact with other children (e.g., in a day care centre). An increased susceptibility to colds, which is indicative of an immune deficiency, only exists when

  • a toddler or pre-school child has more than eight to twelve infections per year
  • the infection does not heal despite adequate therapy
  • there are frequent relapses with the same pathogen
  • the course of the disease is more severe than usual
  • the child regularly suffers from complications, such as middle ear or lung inflammations, encephalitis or meningitis
  • the infectious disease is caused by unusual pathogens
  • there are persistent fungal deposits on the skin, nails or in the mouth
  • deep-seated skin or organ abscesses occur regularly
  • permanent damage occurs
  • immune deficiency diseases have already been diagnosed in the family.


The term 'immunity' refers to the insensitivity (resistance) of an organism to external attacks such as those by viruses, bacteria or fungi. Immunity therefore means protection against infectious diseases. It is composed of innate and acquired (adaptive) resistance:

  • Innate immunity is based on special protein molecules (antibodies) that can recognise pathogens. These are transferred from the mother to the foetus via the placenta and protect it from infectious diseases after birth. Innate immunity reacts in the same way to all microorganisms, which is why it is also called the 'non-specific immune system'.
  • Acquired immunity is the result of pathogen contact in which the defence system had to actively deal with the causative agents of the disease. In such a case, doctors speak of 'immunisation'. A 'hidden immunisation' occurs when the body silently deals with bacteria or viruses. In both cases, the defence reaction sets in more quickly upon renewed contact with the now-known pathogen. Acquired resistance is therefore only against the pathogen that caused the disease, which is why it is also called the 'specific immune system'.

This defence memory is also the reason why people contract some diseases, such as measles, only once in their lifetime. However, resilience is not necessarily linked to these specific mechanisms: the canine distemper virus, for example, which is closely related to the measles virus, does not cause disease in humans at any time. This immunity is based on innate, non-specific resistance. In this process, the pathogen is recognised as foreign on the basis of certain surface structures, and rendered harmless. Humans are therefore immune to some pathogens from the beginning, and can acquire immunity to others.

Medical treatment

In cases of increased susceptibility to infections due to a congenital or acquired immune deficiency, the paediatrician will initiate a well-reviewed treatment procedure. In normal development, medicinal measures to strengthen the immune system are not necessary, as the child's immune system - just like other organs - grows and matures. The immune system is trained and strengthened for later.

Naturopathic treatment/tips and home remedies for self-help

Immune-boosting agents can strengthen the defences of adults, but can be dangerous for children. For example, garlic is taboo for children younger than 10 months. Honey must not be given to children under one year of age. The use of food supplements should also be discussed with a paediatrician before the first dose.
In addition to microbiological therapy, which is intended to rebuild damaged intestinal flora, phytotherapy and certain methods such as traditional Chinese medicine (TCM), Schüssler's biochemistry, or nutritional therapy approaches can be used to strengthen the immune system. In addition to the complaints, homoeopathy also takes into account the specific mental and constitutional conditions (concerning the physical disposition and mental structure).
Before using phytotherapeutics, i.e., (fresh) plant extracts, the paediatrician should be consulted. Remedies that may be appropriate include:

  • Ribwort plantain for the relief of dry coughs
  • Marshmallow against irritated mucous membranes
  • Fresh red coneflower (Echinacea purpurea) in special preparations for children (from the age of four)

Furthermore, child health can be supported by the following simple measures:

  • Sufficient fluid intake prevents the mucous membranes from drying out and thus reduces susceptibility to infections. Still water or herbal teas are recommended.
  • Avoid dry air, e.g., by ventilating or placing inhalers in rooms.

Complication: immunodeficiency

Congenital (primary) immunodeficiencies are very rare - about one child in 10,000 is affected. In these cases, the body's own defence system does not function adequately, which is why it cannot ward off pathogens such as bacteria, viruses, fungi or parasites. Typical signs are:

  • frequent infections with bacteria and viruses
  • recurrent (relapsing) and deep-seated skin or organ abscesses
  • stubborn fungal coatings on the skin or nails
  • inadequate weight gain and impaired growth
  • increased incidence of serious diseases such as pneumonia or meningitis, blood poisoning

The cause of a congenital immunodeficiency is a genetic defect - the immune deficiency is therefore inherited. Such a defect can occur immediately after birth, but also later in life. In contrast, acquired (secondary) immune deficiencies are caused, for example, by infectious diseases (e.g., measles), tumour diseases (e.g., leukaemia) or drugs (e.g., immunosuppressants that suppress the immune system).

When to see a doctor

In the case of a cold, a visit to the doctor is advisable if

  • the temperature of a baby younger than three months rises to 38 °C or higher, or the baby coughs
  • a child's body temperature is 39 °C or more (high fever) or it does not return to normal after two days at the latest
  • the baby or child refuses to drink for a long period of time
  • the baby or child seems apathetic
  • the general condition is poor or the child appears very ill
  • the cough or cold lasts longer than a week or gets worse
  • breathing difficulties, hoarseness or faster breathing occur
  • the child is in pain
  • earache occurs (in children under two years of age) or lasts for more than two days
  • the cough is painful or sounds barking
  • the mucus turns yellowish or becomes reddish in colour due to blood being mixed in
  • symptoms such as diarrhoea or vomiting develop
  • a skin rash appears
  • the parents feel worried
  • there is a suspicion of increased susceptibility (see under symptoms/complaints of increased susceptibility to infection).

Risk factors for the increased occurrence of diseases

During the cold season in autumn and winter, viruses and bacteria are very apparent. They feel particularly comfortable in the low temperatures and multiply quickly. In addition, wet and cold weather and fluctuating temperatures put a great strain on the child's immune system. Heating in living rooms further irritates the mucous membranes in the respiratory tract and dries them out. The consequence is a poorer removal of pathogens - the children are more susceptible to infection. Psychological and physical stress, lack of sleep or a lack of nutrients further weaken the immune system and lead to one inflammation chasing the next.


Child health can be supported by simple measures:

  • Breastfeeding
  • Varied diet. The vitamins, minerals and dietary fibres strengthen the immune system.
  • Avoid excessive hygiene, as this promotes the development of e.g., allergies
  • 30- to 60-minutes spent in nature per day
  • No smoking in the home or in the car
  • Regular ventilation of the living area
  • Watch out for mould infestation
  • Sufficient sleep, as the immune system can recover during sleep
  • Maintaining a room temperature of 18 °C in the bedroom
  • Avoiding stress, as stress hormones weaken the body's defences
  • Zest for life, exercise, fresh air - because immune function and the psyche are closely related

Especially during pregnancy

Already during pregnancy, expectant mothers can do a few things to strengthen the immune system of their unborn child by

  • avoiding stress
  • eating a healthy and balanced diet
  • not smoking
  • not drinking alcohol
  • planning for a vaginal birth where possible

Which vitamins strengthen the immune system?

The basis for a well-functioning immune system is a varied, balanced diet with plenty of fruit and vegetables, according to the food pyramid. Only with the right mix of nutrients can the child's immune system optimally ward off pathogens. The following vitamins and minerals are particularly important for a strong defence:

  • Vitamin A supports the innate as well as the acquired immune system. It is involved in maintaining the skin and mucous membranes, the external barriers against pathogens. Vitamin A is found in animal foods such as liver, and its precursor, beta-carotene, is found in coloured fruits and vegetables such as carrots, spinach, tomatoes and apricots.
  • Vitamin D supports, among other things, the macrophages (scavenger cells) of the non-specific as well as the lymphocytes (subgroup of white blood cells) of the specific defence system. It is formed in the skin by sunlight. It is mainly found in fatty fish, such as herring or salmon, as well as porcini mushrooms and chicken eggs.
  • Vitamin C protects, among other things, the cells of the immune system by scavenging free radicals (antioxidant effect). It activates the macrophages (scavenger cells) and is found, for example, in citrus fruits, peppers and cabbage vegetables.
  • Zinc improves, among other things, the maturation of certain immune defence cells. Meat, milk, cheese, legumes and whole grain products in particular are rich in the trace element.
  • Selenium is important for both the innate and acquired immune system. Good sources of selenium include nuts, such as peanuts and Brazil nuts, and certain types of fish, such as herring and tuna.
  • Iron improves the activity of macrophages (scavenger cells) and increases the number of lymphocytes, among others, which belong to the white blood cells. It is contained in meat and meat products.

However, the largest part of the immune system is located in the intestine. The function of these defence cells depends, among other things, on the intestinal bacteria. For this reason, children benefit from a well-nourished intestinal flora. Fibre from whole grain products or vegetables, so-called prebiotics, serve as food for these microbes and should therefore not be missing from the diet. Likewise, dairy products with live bacteria (probiotics) and fermented foods such as sauerkraut support a strong immune system by providing a positive intestinal environment.


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Deutsche Gesellschaft für Kinder- und Jugendmedizin: Mein Kind hat ständig Infekte... (2018),
Liese: Das infektanfällige Kind, Z. Allg. Med. 2003; 79:483 – 489.

Kayser, Bienz, Eckert, Zinkernagel: Medizinische Mikrobiologie, Thieme, 10. Auflage (2001)
Naturmedizin für Kinder, Zabert Sandmann, 1. Auflage (2005)
Mayatepek: Pädiatrie, Urben & Fischer, 1, Auflage (2007)


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