COVID-19

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by SARS-CoV-2, a virus closely related to the SARS virus.

It is primarily spread through human-to-human transmission, via respiratory droplets from infected individuals when they cough or sneeze. It's incubation period is generally between 2 and 14 days. Advice to limit transmission includes wearing surgical face masks and maintaining good hygiene (such as washing hands regularly).

Infected individuals may be asymptomatic, but infection can also develop into symptoms such as fever, coughing, myalgia, tiredness and breathing difficulties. Further development can result in severe pneumonia, acute respiratory distress syndrome, sepsis and septic shock and eventually death.

There are no vaccines nor antiviral medicines designated for treatment, with clinical measures generally confined to relieving symptoms and providing supportive care, but research is currently underway to develop new drugs and re-purpose existing medications.

The disease was initially presented to health authorities during December 2019 in Wuhan, Hubei, China, as a cluster of people with pneumonia of no clear cause, from whom a strain of a novel coronavirus was first isolated and identified in early 2020 as 2019-nCoV (now labelled SARS-CoV-2).

The World Health Organization (WHO) and U.S. Centers for Disease Control (CDC) recommend that persons who suspect that they are carrying the virus wear a surgical face mask and seek medical advice by calling a doctor rather than directly visiting a clinic in person. The WHO has declared the 2019–20 coronavirus outbreak to be a Public Health Emergency of International Concern (PHEIC). As of 19 February 2020, only Mainland China was listed as an area with known ongoing community spread of the disease.The disease is the cause of the 2019–20 coronavirus outbreak.

Signs and symptoms

Those infected may either be asymptomatic or develop symptoms, including fever, cough or shortness of breath. Diarrhea or upper respiratory symptoms (e.g. sneezing, runny nose, sore throat) are less frequent. Cases can progress to pneumonia, multi-organ failure, and death.

The length of the incubation period is estimated to be between two and ten days by the World Health Organization and between two and 14 days by the United States Centers for Disease Control and Prevention (CDC). A study had found rare cases where the incubation period was as long as 24 days.

Cause

The disease is caused by the virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), previously referred to as the 2019 novel coronavirus (2019-nCoV). The virus is thought to have an animal origin.

It is primarily spread between people via respiratory droplets from the coughs and sneezes. Officials in Shanghai confirmed several transmission modes, including direct transmission, contact transmission and aerosol transmission, the latter two involving transmission when someone touches a surface contaminated with tainted respiratory droplets and inhalation of air contaminated with tainted respiratory droplets.

An epidemiological study of the first 72,314 cases suggested that there may have been a "continuous common source" of the outbreak in December 2019, which would imply that several animal to human zoonotic events occurred at the Huanan Seafood Wholesale Market. According to this theory, the primary source of infection became human-to-human transmission in early January 2020.

Diagnosis

The WHO has published several testing protocols for the disease. Testing uses real time reverse transcription-polymerase chain reaction (rRT-PCR). The test can be done on respiratory or blood samples. Results are generally available within a few hours to days. Chinese scientists were able to isolate a strain of the coronavirus and publish the genetic sequence so that laboratories across the world could independently develop PCR tests to detect infection by the virus.

Diagnostic guidelines released by Zhongnan Hospital of Wuhan University suggested methods for detecting infections based upon clinical features and epidemiological risk. These involved identifying patients who had at least two of the following symptoms in addition to a history of travel to Wuhan or contact with other infected patients: fever, imaging features of pneumonia, normal or reduced white blood cell count, or reduced lymphocyte count.

Prevention

No vaccine currently exists against SARS-CoV-2.

The Ministry of Health in Singapore advises people that "those who are unwell should wear a mask and see a doctor immediately but there is no need to wear a mask if you are well" (The use of masks by healthy members of the public is not recommended outside of China.). It has advised against all non-essential travel to Mainland China. In addition, it lists several precautions under its health advisory:

• Do not eat raw or undercooked meats;
• Stay clear of crowded places and avoid close contact with people who are sick (something known as social distancing);
• Maintain good hygiene and frequently wash hands when appropriate;
• Cough or sneeze into a tissue and directly dispose of the tissue into a garbage can;
• Wear a surgical face mask if you are coughing, sneezing or have other respiratory symptoms;
• Seek prompt medical attention if you are feeling unwell.

If a person is suspected to be infected, to prevent transmission, the U.S. CDC recommends that the infected individual stay at home except to get medical care; call ahead before visiting a healthcare provider; wear a surgical face mask (especially in public); cover coughs and sneezes with a tissue; regularly wash hands with soap and water; and avoid sharing personal household items.

Management

There are no specific antiviral medications approved for this disease. Symptoms are managed with supportive care. The WHO has published detailed treatment recommendations for hospitalized patients with severe acute respiratory infection (SARI) when a SARS-CoV-2 infection is suspected. The WHO also recommended volunteers take part in randomized controlled trials for testing the effectiveness and safety of potential treatments.

The Beijing branch of China's National Health Commission suggested the use of lopinavir/ritonavir as part of treatment plans in the absence of an approved drug for this indication. The lopinavir/ritonavir combination and interferon can now be claimed for via health insurance in some countries.

Psychological

Infected individuals may experience distress from quarantine, travel restrictions, side effects of treatment, or fear of the infection itself. To address these concerns, the National Health Commission of China published a national guideline for psychological crisis intervention on 27 January 2020.

Alternative medicine

Chinese health authorities recommend the use of traditional Chinese medicine (TCM) in addition to standard medical supportive care to prevent or treat the disease. On 22 January, National Health Commission put TCM into the third issue of the COVID diagnostic and treatment plan. On 2 February, Wuhan officials ordered all patients to be put on a specific TCM treatment. On 14 February, Wuhan opened a TCM-oriented temporary hospital. The efficacy and safety of TCM has not been established in coronavirus infections.

Prognosis

According to WHO, based on analysis of 44,000 cases of COVID-19 in Hubei province, around 80% of patients only have a mild form of the disease, 14% developed more severe disease such as pneumonia, 5% have critical disease, and 2% of cases are fatal.^[58] Among those who died initially, many had preexisting conditions, including hypertension, diabetes, or cardiovascular disease, and the median time of disease was found to be 14 days (range 6-41 days).

Epidemiology

Overall mortality and morbidity rates due to infection are not well established; while the case fatality rate changes over time in the current outbreak, the proportion of infections that progress to diagnosable disease remains unclear. However, preliminary research has yielded case fatality rate numbers between 2% and 3%; in January 2020 the WHO suggested that the case fatality rate was approximately 3%, and 2% in February 2020 in Hubei. An unreviewed preprint study by Imperial College London among 55 fatal cases noted that early estimates of mortality may be too high as asymptomatic infections are missed. They estimated a mean infection fatality ratio (the mortality among infected) ranging from 0.8% when including asymptomatic carriers to 18% when including only symptomatic cases from Hubei province.