[Use of masks by children to prevent infection with SARS-CoV-2].

After initial reluctance masks have emerged as an important means of restricting the spread of SARS-CoV‑2, the new coronavirus causing COVID-19. Other simple measures are keeping a distance of at least 1 ½ m from other persons and observing hygiene recommendations, including washing or even disinfecting the hands, coughing into the crook of the arm and remaining at home when sick. Combining the initial letters of the German words for the three measures ( distance-hygiene-face mask) the acronym AHA was formed, a colloquial German word meaning that the speaker understood the information presented. This acronym was later extended by the letter "L", initial letter of "Lüften" meaning air ventilation for indoor rooms and arriving at AHA‑L, recommended by the federal German Health Institute the Robert Koch Institute. In fact, masks including surgical masks and face coverings can form an effective barrier against the spread of the virus: protecting other people from droplets expelled from the throat of the speaker wearing a mask and even in part protecting the wearer from inhaling droplets emanating from other peoples' throats. Studies to find out if wearing masks might impose risks did not find essential problems: alterations of respiratory parameters due to an increased airway resistance remained within normal limits in healthy adults and even in asthmatics whose disease was well controlled; however, many adults expressed their unease with masks describing them as cumbersome and inconvenient. Emotional resistance against masks made it increasingly more difficult for them to use a mask. Efficient application of masks requires, in addition to a logical explanation of its effect, the evocation of empathy for vulnerable people who can be protected from catching a possibly deadly disease. In children there are very few data on adverse effects of wearing a mask although there is ample experience in children with serious diseases compromising defense against infectious agents acquired via respiratory mucus membranes; however, when using masks appropriately in children relevant adverse effects have not been reported and are not to be expected. Masks should only be used in children when they are healthy and awake and can remove the masks themselves anytime they like. Children 10 years or older can use masks efficiently when they have been informed beforehand appropriate to their age. Under these conditions they can also be obliged to wear masks in certain situations, for example while walking through the school building to their desk in class. To limit the period of wearing a mask normally they will be allowed to remove the mask when sitting in class and keeping their distance. Children in primary schools may use masks, but they should not be obliged to wear them and children in kindergartens should not use masks. This exemption of younger children does not expose school and kindergarten teachers to additional risks since the infectivity with SARS-CoV‑2 is age-dependent and increases with age reaching adult values only after 12 years of age.