Coronavirus (COVID-19) outbreak 2020
What is it?
Prior to this outbreak, there were six known coronaviruses that infect humans, and many more that are only known to infect animals. It is likely that this novel coronavirus outbreak originated in an animal population before crossing over to infect humans. The original source of this cross-over has not been definitively identified.
Some coronaviruses are associated with outbreaks of serious disease, such as Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS), but others cause common and generally mild upper respiratory tract infections. Coronaviruses are believed to cause a significant percentage of all common colds in children and adults.
Not all people experiencing a coronavirus infection will have symptoms or serious illness. There is no vaccine to prevent coronavirus infection. Supportive care is recommended for people who are infected and experience symptoms; antiviral treatments are not available to treat patients who have contracted the virus.
A laboratory test is available to confirm whether someone has been infected with nCoV.
How is COVID-19 spread?
Human transmission of COVID-19 has now been confirmed, which means the animal host is no longer necessary for the disease to spread, and the virus can pass from person to person.
Last updated: 22 Jan 2020. Information will be updated as evidence emerges.
The exact mode of transmission of nCoV is not known. Other coronaviruses that can be transmitted from person to person are typically spread through contact with people experiencing a coronavirus infection, or through contact with droplets of their saliva or other bodily fluids, which can contain the virus. Previous outbreaks of coronavirus, including SARS and MERS, the two most dangerous outbreaks to date, have spread primarily through contact and droplets.
Typically, coronaviruses spread through:
- Contact with droplets created when an ill person coughs or sneezes, as droplets of saliva or other fluids carrying the virus are projected onto other people or objects;
- Close personal contact, such as touching, shaking hands, or sexual contact;
- Touching an object or surface where the virus has been deposited, such as doorknobs or personal belongings, and then touching your mouth, nose, or eyes without first washing your hands;
- Some coronaviruses, such as SARS-CoV, could be found in the faeces and urine of people infected with the virus and may be spread through contact with those fluids.
It is currently unknown whether all the above conditions allow for transmission of this newly discovered coronavirus, or whether it can be transmitted in new ways.
Some coronaviruses can live for several days on surfaces or in faeces. They are easily and quickly killed by common disinfectants, including bleach and alcohol. Evidence from other coronavirus outbreaks, including outbreaks of serious coronaviruses such as MERS-CoV and SARS-CoV, point to the need for direct contact with an ill person, or infected personal belongings or surfaces, for the virus to be transmitted. In these previous serious coronavirus outbreaks, simply being in the same room, office or train as someone suffering from a coronavirus infection has not put people at high risk of infection. Most documented cases of transmission of previous serious outbreaks of coronaviruses have been between ill people and caregivers (at home or in a health facility) and between people in other intimate relationships, such as between family members living with someone who has fallen ill with a coronavirus infection.
The incubation and transmission period is currently estimated at 1-12.5 days with the 5-6 days average. Based on the previous cases with SARS and MERS it can be assumed that the incubation period is up to 14 days. As for whether people can transmit the infection before they are symptomatic, this can not currently be excluded as a possibility but the majority of the confirmed infections come from persons with symptoms.
What are the symptoms?
Most people experience a coronavirus infection at some point in their lives, with time-limited and non-severe symptoms such as respiratory symptoms, fever, cough, and shortness of breath. Human coronaviruses can sometimes cause lower-respiratory tract illnesses, such as pneumonia or bronchitis. This is more common in people with cardiopulmonary disease, people with weak immune systems, infants, and older adults. In addition to pneumonia and severe acute respiratory infections, severe cases of infection can result in kidney failure and death.
People with underlying illness, compromised immune systems, or with other respiratory infections at the same time may be at heightened risk of suffering serious illness as a result of coronavirus infection. People with compromised immune systems may also experience different or fewer symptoms than other people with the same illness.
The estimated incubation period is believed to be between 0 and 14 days, with symptoms lasting between 1-15 days, with a median of 12 days. Patients who have experienced severe illness or have died seem to begin with milder illness, and deteriorate 5-7 days after first showing symptoms.
Initial information about this COVID-19 outbreak point to it causing much higher rates of severe illness than the more common coronaviruses. Among the first 278 lab-confirmed cases, 2% died, 4% were in critical condition, and 18% became severely ill. While these percentages may decline in coming days as less severe cases are confirmed, there remains potential for significant morbidity and mortality as this spreads to a greater population.
How to prevent the spread of coronavirus?
Similar to preventing infection with other viruses likely to be spread through contact or droplets, all people should be encouraged to regularly and properly wash their hands. World Health Organization recommends frequent handwashing with hot water and soap or, if they are not available, using the alcohol disinfectant gel, especially after being in contact with ill persons or spending time in a potentially risky environment.
Anyone coughing or sneezing should cover their mouth and nose, and maintain hand hygiene. Avoid close contact with people showing symptoms of respiratory illness, with symptoms like coughing or sneezing. WHO recommends keeping a distance of 1 to 3 meters from persons coughing, sneezing or having a high temperature. Avoiding touching one’s mouth, nose and eyes with one’s hands also decreases the infection risk if there are droplets of fluid of an infected person on one’s hands.
For people caring for loved ones with mild respiratory illnesses at home, home use of surgical masks early and consistently along with correct and consistent handwashing may reduce the chance that they become infected. It is not clear how long the virus can survive on surfaces outside of a human body (furniture, clothes) and preliminary estimates put it at a couple of hours. Applying usual household disinfectants to these surfaces is sufficient to destroy the virus.
WHO recommends wearing a face mask only if you yourself have a respiratory infection, thus preventing infecting others through saliva droplets, if you suspect that you are infected or if you are providing care to a person who may be infected. It must be stressed that wearing a mask is not a guarantee that the infection will be prevented and it must be combined with the aforementioned measures; keeping distance from infected persons and rigorous handwashing.
In previous serious outbreaks of coronavirus-related illness, such as the 2003 SARS outbreak, consistent application of contact and droplet protection have been enough to prevent spread of the disease from patients to caregivers during most care-giving activities.
What is the global risk?
Early modelling of the outbreak4 indicates that it is likely that many early cases were not detected, either because symptoms were not severe enough for people to seek care, or because people with severe respiratory illness were not tested for the virus. Given this modelling and other information about the likely existence of people with mild or asymptomatic cases, it is possible that there are many more cases, both serious and mild, than what has been reported. The threat of pandemic caused by novel respiratory viruses like nCoV cannot be discounted, given the ability of the virus to spread from person to person and the global population’s lack of immunity to this new virus.
The potential spread of this novel virus is likely to be facilitated by upcoming events, such as lunar new year celebrations and related gatherings and travel, while global transportation networks have already facilitated international spread of the virus. However, there is no evidence that the six previously known coronaviruses can spread without direct contact with infected people or surfaces contaminated with droplets, which may limit the potential for more rapid spread as is seen with airborne pathogens such as measles.