HKUMed on COVID-19

Basic Information about the Disease


Information provided by the School of Public Health.
(Last updated: 27 April 2020)
What is COVID-19?
  • COVID-19 is an infectious disease caused by the novel coronavirus SARS-CoV-2.
  • SARS-CoV-2 originates from the same family of viruses with the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) and Middle East Respiratory Syndrome Coronavirus (MERS-CoV), but it is not the same virus.
  • This new virus, named SARS-CoV-2, has not been previously identified in humans before the ongoing outbreak that was first identified in Wuhan, China in December 2019.
  • COVID-19 causes illness ranging from mild respiratory symptoms to severe complications and death.
How does the virus spread?
  • While the SARS-CoV-2 virus originated in animals and the intial human cases were "zoonotic", the virus has been transmiting from person to person since December 2019.
  • Currently there is limited information on exactly how SARS-CoV-2 spreads from one person to another. The transmission modes of the virus at present are thought to be similar to other respiratory viruses:
    • Droplets
    • Direct contact
    • Indirect contact via contaminated surfaces
    • Aerosols
    • Possibly through fecal-oral route because coronaviruses can also infect the gastrointestinal tract
  • At present, we also do not know if there is one transmission mode that is more important than the others, and this is an important scientific question which we are trying to answer.
  • Usually, infected persons are most contagious when they are symptomatic, as in the case of other respiratory viruses. There is some evidence that infected persons can be infectious even without showing any symptoms or before their symptoms appear. It is still unclear how important asymptomatic or pre-symptomatic transmissions are for SARS-CoV-2.
What are the symptoms of COVID-19?
  • As with some other respiratory viruses, COVID-19 has a broad clinical spectrum. Some infected persons show no symptoms, others could range from mild respiratory illness to severe complications and life-threatening illness. A small fraction of illnesses have been fatal. Most of the identified cases have had fever, and many had respiratory symptoms such as dry cough and shortness of breath. Some identified cases have pneumonia.
  • At present, older adults and adults with underlying health conditions appear to be at the highest risk of severe disease.
What are some preventive measures?

Currently, there is no vaccine to prevent COVID-19, preventive measures are mostly non-pharmaceutical:

  • Personal protective measures
    • Maintain good hand hygiene
    • Practice good respiratory etiquette
    • Wear a surgical mask
    • Avoid touching eyes, nose and mouth
  • Environmental hygiene
    • Disinfect frequently touched objects and surfaces
    • Inspect drainage pipes regularly and make sure the drain outlets contain water by adding half a litre of water into each drainage trap (U-trap) about once a week
  • Social distancing measures
    • Isolation of infected persons at home or in hospitals
    • Quarantine of potentially infected persons (e.g. those who have been in prolonged close contact with known cases) either at home or in special quarantine facilities
    • Refrain from visiting crowded places
    • Maintain distance from other persons, especially those who are showing respiratory illness symptoms
    • Workplaces can consider measures such as working from home or working in staggered shifts
Are there any treatments?
  • There is not yet any specific antiviral treatment recommended for COVID-19 patients. The current treatment is mainly supportive, that is to relieve clinical symptoms.
  • There are ongoing investigations for some specific treatments for COVID-19, including antiviral remdesivir, combination of lopinavir and ritonavir, convalescent plasma, and chloroquine.
What is currently being done in research?
  • Researchers are trying to gain better understanding on the transmission dynamics and severity of COVID-19 from documentations of outbreaks and chains of transmission in China and elsewhere.
  • These information would affect how control and mitigation measures should be implemented, for example, the incubation period and viral shedding of infected persons would provide insights on the duration of quarantine and isolation respectively.
  • The latest research updates are available here and also the scientific research section of the School of Public Health site.