Corona virus ( covid 19)
Corona virus (Covid 19)
The World Health Organisation (WHO) originally called this illness "novel coronavirus-infected pneumonia (NCIP)", and the virus itself had been provisionally named "2019 novel coronavirus (2019-nCoV)" 1.
The COVID-19 outbreak has affected all COVID-19 (coronavirus disease 2019) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), previously known as 2019 novel coronavirus (2019-nCoV), a strain of coronavirus. The first cases were seen in Wuhan, China, in late December 2019 before spreading globally 1,2,10. The current outbreak was officially recognised as a pandemic on 11 March 2020 44.
Terminology
On 11 February 2020, the WHO officially renamed the clinical condition COVID-19 (a shortening of COronaVIrus Disease-19) 15. Coincidentally, on the same day, the Coronavirus Study Group of the International Committee on Taxonomy of Viruses renamed the virus "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2) 16,22,46. The names of both the disease and the virus should be fully capitalised, except for the 'o' in the viral name, which is in lowercase 16,22,41.
The official virus name is similar to SARS-CoV, the virus strain that caused epidemic severe acute respiratory syndrome (SARS) in 2002-2004, potentially causing confusion 38. The WHO has stated it will use "COVID-19 virus" or the "virus that causes COVID-19" instead of its official name, SARS-CoV-2, when communicating with the public 45.
Epidemiology
On 22 April 2020, the number of cases of confirmed COVID-19 globally is over 2.5 million 5. COVID-19 has now been diagnosed in 185 territories, in six continents according to an online virus tracker created by the medical journal, The Lancet, and hosted by Johns Hopkins University 5,13. As of 19 April 2020, there are 6 countries with >100,000 cases, 21 countries with 1,000 to 10,000 confirmed cases and 53 countries with between 1000 and 10,000 confirmed cases 5.
NB: Surveillance methods and capacity vary dramatically between countries. Presymptomatic carriers may be present in many communities and presymptomatic transmission has been documented; asymptomatic carriers have been uncommonly reported and no asymptomatic transmission has been documented (2 Apr 2020) 113.
The R0 (basic reproduction number) of SARS-CoV-2 has been estimated between 2.2 and 3.28 12,33, that is each infected individual, on average, causes between 2-3 new infections.
The incubation period for COVID-19 was initially calculated to be ~5 days, which was based on 10 patients only 12. An American group performed an epidemiological analysis of 181 cases, for which days of exposure and symptom onset could be estimated accurately. They calculated a median incubation period of 5.1 days, that 97.5% became symptomatic within 11.5 days (CI, 8.2 to 15.6 days) of being infected, and that extending the cohort to the 99th percentile results in almost all cases developing symptoms in 14 days after exposure to SARS-CoV-2 92.
The number of deaths from COVID-19 exceeded 170,000 globally on 21 April 2020 5. The case fatality rate is ~2-3% 5,93. It is speculated that the true case fatality rate is lower than this because many mild cases are not being tested, which thus skews the apparent death rate upwards 93.
A paper published by the Chinese Centre for Disease Control and Prevention (CCDC) analysed all 44,672 cases diagnosed up to 11 February 2020. Of these, ~1% were asymptomatic, and ~80% were classed as "mild" 25.
Another study looked at clinical characteristics in COVID-19 positively tested close contacts of COVID-19 patients 81. Approximately 30% of those COVID-19 positive close contacts never developed any symptoms or changes on chest CT scans. The remainder showed changes on CT, but ~20% reportedly developed symptoms during their hospital course, none of them developed severe disease 81. This suggests that a high percentage of COVID-19 carriers are asymptomatic.
In the Chinese population, 55-60%% of COVID-19 patients were male; the median age has been reported between 47 and 59 years 12,93.
Symptoms of COVID-19
Symptoms vary from person-to-person with COVID-19. It may produce few or no symptoms. However, it can also lead to severe illness and may be fatal. Common symptoms include:
- fever
- breathlessness
- cough
- potential loss of taste or smell
It may take 2–14 days for a person to notice symptoms after infection.
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