PREPAREDNESS, PREVENTION AND CONTROL OF COVID-19 IN PRISONS AND OTHER PLACES OF DETENTION 10 7. COVID-19 VIRUS: PATHOGEN CHARACTERISTICS, SIGNS AND SYMPTOMS, TRANSMISSION 7.1 Pathogen characteristics Coronaviruses are a large family of viruses found in both animals and humans. Some infect people and are known to cause illnesses ranging from the common cold to more severe diseases, such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). A novel coronavirus is a new strain of coronavirus that has not previously been identified in humans. The latest novel coronavirus, now called COVID-19 virus, had not been detected before the outbreak reported in Wuhan, China, in December 2019. So far, the main clinical signs and symptoms reported in people during this outbreak include fever, coughing, difficulty in breathing, and chest radiographs showing bilateral lung infiltrates. Although the current outbreak of COVID-19 is still evolving, infection may present with mild, moderate or severe illness and can be passed from human to human, primarily (as in other respiratory viruses) by droplet spread. While about 80% of cases manifest as a mild illness (i.e. non-pneumonia or mild pneumonia), approximately 20% progress to a more severe illness, with 6% requiring specialist medical care, including mechanical ventilation. Situation reports on the outbreak, updated daily, are available on the WHO website.20 Most estimates of the incubation period of COVID-19 range from 1 to 14 days, with a median of 5–6 days.21 This means that if a person remains well 14 days after exposure (i.e. contact with an infected person), they may not have been infected. However, these estimates may be updated as more data become available. 7.2 Signs and symptoms of COVID-19 The most common symptoms of COVID-19 are fever, tiredness and dry cough. Some patients may have aches and pains, nasal congestion, runny nose, sore throat or diarrhoea. These symptoms are usually mild and begin gradually. Some people become infected but do not develop any symptoms and do not feel unwell. Most people (about 80%) recover from the disease without needing special treatment. Around one out of every five people who are infected with COVID-19 becomes seriously ill and develops difficulty breathing. Older people, and those with underlying medical problems such as high blood pressure, heart problems or diabetes, are more likely to develop serious illness. Based on the latest data, about 3–4% of reported cases globally have died, but mortality varies according to location, age and existence of underlying conditions.22 People with fever, cough and difficulty breathing should seek medical attention.23 7.3 Transmission of COVID-19 Respiratory secretions, formed as droplets and produced when an infected person coughs, sneezes or talks, contain the virus and are the main means of transmission. 20 Coronavirus disease (COVID-19) situation reports. Geneva: World Health Organization; 2020 (https://www.who.int/emergencies/diseases/novel-coronavirus-2019/situation-reports). 21 Coronavirus disease 2019 (COVID-19): situation report 30. 19 February 2020. Geneva: World Health Organization; 2020 (https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200219-sitrep-30-covid-19.pdf?sfvrsn=3346b04f_2). 22 WHO Director-General’s opening remarks at the media briefing on COVID-19. 3 March 2020. Geneva: World Health Organization; 2020 (https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19---3-march-2020). 23 Q&A on coronaviruses (COVID-19). 23 February 2020. Geneva: World Health Organization; 2020 (https://www.who.int/news-room/q-a-detail/q-a-coronaviruses).