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Coronaviruses are ring-shaped, enveloped RNA viruses of the family Coronaviridae. In addition to four human-pathogenic coronaviruses, which cause minor respiratory infections, three zoonotic pathogens have been identified that have been transmitted from animals to humans. These can cause severe pneumonia in patients. In late 2019 / early 2020, several patients in Wuhan, China were found to be infected with the latest zoonotic coronavirus (SARS-CoV-2 and initially called 2019-nCoV). Since then, the number of patients has been increasing in China, Italy, Germany and worldwide. The current case numbers are available on the website of the World Health Organisation (WHO).
Two previous outbreaks of coronavirus attracted worldwide attention as well. A characteristic feature of the SARS-CoV outbreak (trigger of the Severe Acute Respiratory Syndrome) of spring 2003 was the high proportion of medical personnel among people infected. However, SARS-CoV has not been detected in humans since 2004. MERS-CoV (trigger of Middle East Respiratory Syndrome) has been circulating mainly on the Arabian Peninsula since 2012. All three variants, SARS-CoV-2, SARS and MERS, belong to the group of ß-coronaviruses.
The novel coronavirus (SARS-CoV-2) can be transmitted from person to person. According to the Robert Koch Institute, the information available to date on the epidemiology of SARS-CoV-2 shows that transmission is possible through close contact (in homes or during care, for example) between people.
Based on what is currently known about the virus, infection can occur via droplets and contact, such as through bodily secretions and excretions. It can be assumed that – as with other coronaviruses – transmission occurs primarily via excretions or secretions of the respiratory tract (droplet infection). These arise, for example, when speaking, coughing or sneezing, but also during medical interventions (for example, endotracheal intubation, suction from the respiratory tract). Cases have also been reported of people who have contracted the disease from people who had only shown non-specific symptoms.
Transmission of the SARS pathogen to other people usually occurred during the second week of illness. Transmission from person to person is also possible with MERS. The morbidity or infection rate in household contacts of primary cases is described as low. In hospitals, however, several outbreaks have already occurred, some of them large.
As with other respiratory pathogens, infection with SARS-CoV-2 can lead to symptoms including coughing, rhinitis, scratchy throat and fever. Some patients also suffer from diarrhoea.
However, in patients with a weakened immune system, the virus appears to be associated with a more severe course, leading to respiratory problems and pneumonia. Deaths have so far occurred mainly in patients of advanced age and/or who are already living with underlying chronic diseases. SARS and MERS are also coronaviruses that can cause severe respiratory diseases and lead to pneumonia in people who are infected.
The incubation time in SARS-CoV-2 is not known for sure so far, but is estimated to be up to 14 days. In SARS, the incubation time was 1-2 weeks, and in MERS 2-10 days. Many properties of the novel coronavirus are currently not known. These include, for example, the period when infected people are most contagious (infectivity), the severity of the disease, and the period over which infected people excrete the virus is or are still infectious.
From the available data and experience gathered with other coronaviruses, hygiene measures in confirmed cases of infection with Covid-19 are based on the procedure for SARS and MERS, as outlined in the German commission for hospital hygiene and infection prevention (KRINKO) recommendation (in German only) "Infektionsprävention im Rahmen der Pflege und Behandlung von Patienten mit übertragbaren Krankheiten". Similar interim guidance is provided by the US Centers for Disease Control and Prevention. In addition, the data on virus aetiology and transmission routes known to date suggest that experience with influenza should be taken into account.
Germany’s KRINKO recommends additional measures including accommodating the patient in an isolation room with their own washroom/lavatory. The number of people the patient comes in contact with should be limited and kept as small as possible. When entering the patient’s room, hospital staff should wear personal protective equipment consisting of a protective gown, disposable gloves and a fine particle mask with multi-layer mouth/nose protection (protection level FFP2; FFP3 or respirator. This is particularly important where there is significant exposure, such as during bronchoscopy or other activities where large amounts of particles could be expelled and present in the atmosphere. In addition, protective goggles and long-sleeved, waterproof disposable apron should be worn during the corresponding nursing, diagnostic or therapeutic activities on the patient.
In addition, Germany’s technical rules for biological agents in healthcare (TRBA 250) require that the patient should also wear a mouth and nose protector when medical staff has direct patient contact or is working in the near vicinity, in particular if the employees may be exposed to coughing fits of the patient.
If there is a ventilation and air-conditioning system in the patient rooms that could distribute the air other rooms, it must be switched off.
Hand disinfection should be carried out with a disinfectant with virucidal effectiveness. It should be carried out in compliance with the known indications, in accordance with WHO guidelines “My 5 Moments for Hand Hygiene”, which also cover frequency of glove changing. Hand hygiene should be performed before leaving the airlock of the patient’s room.
Surfaces near the patient (hand contact)such as bedside table, lavatories, door handles must be disinfected daily using a surface disinfectant with proven, at least limited virucidal effectiveness. If necessary, the disinfection measures must be extended to contaminated surfaces or other surfaces that are at risk of contamination. Final disinfection is carried out with at least limited virucidal products.
In addition, all medical devices and instruments that directly touch or are connected to patients (such as ECG electrodes, stethoscopes) should be used on one individual only then disinfected after each use. If transported in a closed, externally disinfected container, central reprocessing is possible. Whenever possible thermal disinfection procedures are preferred. If this is not possible, disinfectants certified limited virucidal effectiveness should be used.
Covers for wipe disinfection should be used on the patient’s bed and mattress. Dishes used by the patient can be transported to the dishwasher in a closed container and cleaned at a temperature > 60°C.
Laundry or textiles should be cleaned in a laundry disinfection process. In addition, contaminated and highly infectious waste should be disposed of in accordance with federal/state infectious and hazardous medical waste guidelines.
According to a study by the universities of Greifswald and Bochum, the novel coronavirus can survive for up to nine days on inanimate surfaces such as metal, glass or plastic.
Other coronaviruses show a survival time of three hours SARS between 72 and 96 hours.
The required spectrum of efficacy against coronaviruses is: limited virucidal. Agents with an extended effectiveness range against viruses such as "limited virucidal PLUS" or "virucidal" can also be used.
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