COVID-19 pandemic

On 31 December 2019, health authorities in China reported to the World Health Organization (WHO) a cluster of viral pneumonia cases of unknown cause in Wuhan, Hubei Province, and an investigation was launched in early January 2020. On 30 January, the WHO declared the outbreak a Public Health Emergency of International Concern (PHEIC); at that date there were 7,818 cases confirmed globally, affecting 19 countries in five WHO regions.

The early cases mostly had links to the Huanan Seafood Wholesale Market and so the virus is thought to have a zoonotic origin. The virus that caused the outbreak is known as SARS‑CoV‑2, a newly discovered virus closely related to bat coronaviruses, pangolin coronaviruses, and SARS-CoV. The scientific consensus is that COVID-19 has a natural origin.

The earliest known person with symptoms was later discovered to have fallen ill on 1 December 2019, and that person did not have visible connections with the later wet market cluster. Of the early cluster of cases reported that month, two-thirds were found to have a link with the market. On 13 March 2020, an unverified report from the South China Morning Post suggested a case traced back to 17 November 2019 (a 55-year-old from Hubei) may have been the first person infected.

The WHO recognized the spread of COVID-19 as a pandemic on 11 March 2020. Europe, Iran, US, South Korea, and Japan reported surging cases and their total numbers quickly passed China’s.

Signs and symptoms

Symptoms of COVID-19

Symptoms of COVID-19 can be relatively non-specific and infected people may be asymptomatic. The two most common symptoms are fever (88 per cent) and dry cough (68 per cent). Less common symptoms include fatigue, respiratory sputum production (phlegm), loss of the sense of smell, loss of taste, shortness of breath, muscle and joint pain, sore throat, headache, chills, vomiting, hemoptysis, and diarrhea.

Approximately one person in five becomes seriously ill and has difficulty breathing. Emergency symptoms include difficulty breathing, persistent chest pain or pressure, sudden confusion, difficulty waking, and bluish face or lips; immediate medical attention is advised if these symptoms are present.

Further development of the disease can lead to potentially fatal complications including pneumonia, acute respiratory distress syndrome, sepsis, septic shock, and kidney failure.

Some of those infected may be asymptomatic, with no clinical symptoms but test results that confirm infection, so researchers have issued advice that those with close contact to confirmed infected people should be closely monitored. Chinese estimates of the asymptomatic ratio range from few to 44 per cent. The usual incubation period (the time between infection and symptom onset) ranges from one to 14 days; it is most commonly five days.

Diagnosis

Demonstration of a swab for COVID-19 testing

COVID-19 can be provisionally diagnosed on the basis of symptoms and confirmed using reverse transcription polymerase chain reaction (rRT-PCR) testing of infected secretions or CT imaging of the chest.

Viral testing

The standard test for current infection with SARS-CoV-2 uses RNA testing of respiratory secretions collected using a nasopharyngeal swab, though it is possible to test other samples. This test uses real-time rRT-PCR which detects presence of viral RNA fragments.

A number of laboratories and companies are developing serological tests, which detect antibodies produced by the body in response to infection.  As of 6 April 2020, none of these has been proved sufficiently accurate to be approved for widespread use.

Imaging

A CT scan of the chest of a person with COVID‑19. It shows light patches in the lungs.

Characteristic imaging features on chest radiographs and computed tomography (CT) of people who are symptomatic include asymmetric peripheral ground-glass opacities without effusions. The Italian Radiological Society is compiling an international online database of imaging findings for confirmed cases. Due to overlap with other infections such as adenovirus, imaging without confirmation by rRT-PCR is of limited specificity in identifying COVID-19. A large study in China compared chest CT results to PCR and demonstrated that though imaging is less specific for the infection, it is faster and more sensitive.

Prevention

Strategies for preventing transmission of the disease include maintaining overall good personal hygiene, washing hands, avoiding touching the eyes, nose, or mouth with unwashed hands, and coughing or sneezing into a tissue and putting the tissue directly into a waste container. Those who may already have the infection have been advised to wear a surgical mask in public. Physical distancing measures are also recommended to prevent transmission. Health care providers taking care of someone who may be infected are recommended to use standard precautions, contact precautions, and eye protection.

Many governments have restricted or advised against all non-essential travel to and from countries and areas affected by the outbreak. The virus has already spread within communities in large parts of the world, with many not knowing where or how they were infected.

Misconceptions are circulating about how to prevent infection; for example, rinsing the nose and gargling with mouthwash are not effective. There is no COVID-19 vaccine, though many organizations are working to develop one.

Hand washing

Hand washing is recommended to prevent the spread of the disease. The CDC recommends that people wash hands often with soap and water for at least twenty seconds, especially after going to the toilet or when hands are visibly dirty; before eating; and after blowing one’s nose, coughing, or sneezing. This is because outside the human body, the virus is killed by household soap, which bursts its protective bubble. CDC further recommended using an alcohol-based hand sanitizer with at least 60 per cent alcohol by volume when soap and water are not readily available. The WHO advises people to avoid touching the eyes, nose, or mouth with unwashed hands. It is not clear if washing hands with ash if soap is not available is effective at reducing the spread of viral infections.

Surface cleaning

Surfaces may be decontaminated with a number of solutions (within one minute of exposure to the disinfectant for a stainless steel surface), including 62–71 per cent ethanol, 50–100 per cent isopropanol, 0.1 per cent sodium hypochlorite, 0.5 per cent hydrogen peroxide, and 0.2–7.5 per cent povidone-iodine. Other solutions, such as benzalkonium chloride and chlorhexidine gluconate, are less effective. The CDC recommends that if a COVID-19 case is suspected or confirmed at a facility such as an office or day care, all areas such as offices, bathrooms, common areas, shared electronic equipment like tablets, touch screens, keyboards, remote controls, and ATM machines used by the ill persons, should be disinfected.

Face masks and respiratory hygiene

Recommendations for wearing masks have been a subject of debate. The WHO has recommended healthy people wear masks only if they are at high risk, such as those who are caring for a person with COVID-19. China and the United States, among other countries, have encouraged the use of face masks or cloth face coverings more generally by members of the public to limit the spread of the virus by asymptomatic individuals as a precautionary principle. Several national and local governments have made wearing masks mandatory.

Surgical masks are recommended for those who may be infected, as wearing this type of mask can limit the volume and travel distance of expiratory droplets dispersed when talking, sneezing, and coughing.

Social distancing

Social distancing (also known as physical distancing) includes infection control actions intended to slow the spread of disease by minimizing close contact between individuals. Methods include quarantines; travel restrictions; and the closing of schools, workplaces, stadiums, theatres, or shopping centers. Individuals may apply social distancing methods by staying at home, limiting travel, avoiding crowded areas, using no-contact greetings, and physically distancing themselves from others. Many governments are now mandating or recommending social distancing in regions affected by the outbreak. Non-cooperation with distancing measures in some areas has contributed to the further spread of the pandemic.

The maximum gathering size recommended by U.S. government bodies and health organizations was swiftly reduced from 250 people (if there was no known COVID-19 spread in a region) to 50 people, and later to 10. On 22 March 2020, Germany banned public gatherings of more than two people.  A Cochrane review found that early quarantine with other public health measures are effective in limiting the pandemic, but the best manner of adopting and relaxing policies are uncertain, as local conditions vary.

Older adults and those with underlying medical conditions such as diabetes, heart disease, respiratory disease, hypertension, and compromised immune systems face increased risk of serious illness and complications and have been advised by the CDC to stay home as much as possible in areas of community outbreak.

In late March 2020, the WHO and other health bodies began to replace the use of the term “social distancing” with “physical distancing”, to clarify that the aim is to reduce physical contact while maintaining social connections, either virtually or at a distance. The use of the term “social distancing” had led to implications that people should engage in complete social isolation, rather than encouraging them to stay in contact with others through alternative means.

Some authorities have issued sexual health guidelines for use during the pandemic. These include recommendations to have sex only with someone you live with, and who does not have the virus or symptoms of the virus.

Self-isolation

Self-isolation at home has been recommended for those diagnosed with COVID-19 and those who suspect they have been infected. Health agencies have issued detailed instructions for proper self-isolation.

Many governments have mandated or recommended self-quarantine for entire populations living in affected areas. The strongest self-quarantine instructions have been issued to those in high risk groups. Those who may have been exposed to someone with COVID-19 and those who have recently travelled to a country or region with widespread transmission have been advised to self-quarantine for 14 days from the time of last possible exposure.