Introduction

The outbreak of a new coronovirus disease in the central Chinese province of Hubei in December 2019 marks the beginning of a new pandemic called Coronavirus Disease 2019 (COVID-19). COVID-19 is caused by infection with SARS-CoV-2.

Coronaviruses are encapsulated single-stranded RNA viruses. SARS-CoV-2 belongs to the beta subgroup of corona viruses, which can cause severe respiratory diseases and can be transmitted respiratory, faecal-oral and vertical from mother to unborn child [1].

Among the initial 425 patients with COVI-19 pneumonia, the mean age was 59 years. The mean incubation period was 5.2 days. The 95th percentile was 12.5 days. The calculated basal reproductive index R0 was 2.2: One infected person caused on average two further infections [2]. By February 26, 2020, more than 78,000 laboratory-confirmed COVID-19 patients had been registered in China [3].

The pandemic has added other hotspots, such as the USA, Korea, Iran, Italy and Spain. The number of detected infections worldwide has risen to more than 500,000 by the end of March [4].

Prevention

Triage of patients with suspected COVID-19 disease is an important step. The diagnosis is initially based on clinical symptoms such as fever, fatigue, dry cough, headache, diarrhoea, haemoptysis, dyspnoea, rhinorrhoea, pneumonia. X-rays and CT are also performed. Laboratory tests can confirm the suspicion [5].

Doctors and nurses must be protected. Protective masks and glasses reduce the transmission of the virus. This is all the more important as “social distancing” from the patient is only possible to a limited extent. Clinical dermatology with gaze diagnostics from a distance of more than 20 cm bears the danger of misdiagnosis. Dermatoscopy brings patient and doctor into even closer contact.

Regular hand washing and disinfection with alcoholic solutions is a daily routine for the medical practice. In times of a pandemic these protective measures are intensified [6].

However, structural and organisational aspects are also important. In the clinics, this concerns tumour boards, consoles, emergency rooms, etc. Telemedical methods, if available, can help to reduce contact to the absolute minimum [6,7].

However, personal protective equipment (PPE) can itself lead to the triggering or aggravation of pre-existing dermatoses. Inflammatory papules of the facial skin have been observed for example after wearing protective goggles for a long time. But acne and rosacea can also flourish under PPE [6,8].

Intensified hand hygiene can put a great deal of strain on the epidermal protective barrier and lead to irritant contact eczema. The rule is that disinfecting alone is better tolerated than a combination of washing and disinfecting. Skin protection creams and foams before work and moisturizers during the day help to regenerate and protect the epidermal barrier function. Avoid putting on protective gloves with wet hands [6,7].

An excellent Cochrane review on occupational hand eczema showed that moisturisers, either on their own or in combination with protective creams, help to support the epidermal barrier function in the short and long term [9].

Generalized exanthema with fever

COVID-19 patients could react to antibiotics and antiviral substances with an exanthema. The dermatologist has an important function in the differential diagnosis of febrile exanthema caused by infections and drug-induced febrile exanthema. DRESS syndrome (Drug related eosinophilia with systemic symptoms) is such a significant differential diagnosis [10]. Important infection-associated febrile exanthema is found in classical viral infectious diseases such as measles, rubella or dengue fever.

Among Chinese COVID-19 patients, lymphopenia (75.4%) and a reduction of circulating eosinophils (52.9%) were frequently observed. Drug exanthema (11.4%) and urticaria (1.4%) were the most common cutaneous symptoms in COVID-19 patients [11]. An Italian study in 88 CIVID-19 patients observed exanthema (n=14), urticaria (n=3) and varicella-like vesicles (n=1) [12].

However, COVID-19-specific skin manifestations have not yet been identified.

System therapy in COVID 19 times

Especially in the treatment of severe inflammatory dermatoses the system therapy with Biologica and Small Molecules has gained great importance in the last 10 years, for example in psoriasis, acne inversa, therapy-resistant urticaria or neurodermatitis. Should the treatment be interrupted? Should patients be readjusted to these drugs?

The data situation is still thin at present. The professional associations in Germany, such as the DDG (German Society of Dermatology), the German Society of Rheumatology and PsoNet, have pleaded in a consensus process for the continuation of systemic therapy in asymptomatic patients with regard to COVID-19. This is done against the background of avoiding severe relapses that could weaken the immune system. Of course, there should be a reliable indication for systemic therapy [13,15].

What is the procedure for planned systemic therapy? Here, the preparations must be considered individually. As a general rule, systemic glucocorticoids are not recommended for acute COVID-19 disease, as they may prolong viral excretion [16].

Tumour necrosis factor-alfa inhibitors are generally not recommended for acute infections. Within this group, Infliximab, including its biosimilars, appears to have an increased risk of infection with COVID-19 [17]. Ustekinumab, risankizumab, ixekizumab and brodalumab have not shown an increased risk of respiratory infections in studies, but are contraindicated in symptomatic patients [19]. Nevertheless, the data should be interpreted with caution, as they were collected before the COVID 19 pandemic. Interleukin-17 is important in protecting the mucosa from bacterial and fungal infections. Disturbed expression of interleukin-17 has been linked to pulmonary hypersensitivity, asthma and pulmonary fibrosis [20].

In summary, the indication for systemic therapies, especially immunomodulating drugs, should be viewed critically at present [21].