Coronavirus COVID-19 – An Evidence Based Visual Review

covidThe recent outbreak of coronavirus has heightened the emotions of the public, ranging from anger to fear. We are constantly flooded with new information on a daily basis, with evolving facts and data causing uncertainties and doubts, further escalating panic and fear.

I went through tons of scientific journals and publications, and news feed in an attempt to learn more about the disease. The truth is: Much still needs to be learned about this infection and we will certainly have a much clearer picture as more data becomes available.

Here is a summary of relevant information and its justification, largely based on information from reliable scientific journals. (see citations at the bottom of this article)


How Dangerous is Coronavirus?

The 2019 novel Coronavirus (2019 n-CoV/COVID-19) began in early December 2019 when a patient was diagnosed with unusual pneumonia in the city of Wuhan, China. According to a report from the Annals of Internal Medicine, COVID-19 has a basic reproduction number of 2.3, which means for every single old case there will be 2.3 new cases, assuming there is no intervention. With the current intervention in place and effort to curb the spread, we are hopeful that the number of new cases will decrease.


According to the Imperial College of London report, the estimated Case Fatality Ratio (CFR, a measure of severity as the proportion of cases which are fatal within a specified time) are illustrated in the graph below:-


The estimates of the overall CFR in all infections (including both with and without symptoms) are 1%. This is lesser than SARS CFR, which was 9.6%. However, during the SARS epidemic, World Health Organisation (WHO) has initially reported CFR of about 3%. Therefore, these estimates should be viewed cautiously.


What are the Symptoms and Incubation Period?

One study from The Lancet observe that most patients had fever or cough, and a third have shortness of breath, whilst other symptoms are relatively less common.

According to WHO, symptoms may appear between 2 – 14 days. According to another study, the mean incubation period ranges from 2.1 – 11.1 days, with an estimated mean incubation period to be 6.4 days.

However, a recent study led by Dr Zhong Nan Shan found that the incubation period of the virus was as long as 24 days. This new research is based on data gathered over 1000 coronavirus patients in China. This is certainly worrying, as it may imply that people who are quarantined may have their isolation period extended.

However, according to this study, the median incubation period is 3 days. This translate to half of people exhibit symptoms within 3 days of contact, and those that have incubation period of 24 days are a relatively much smaller proportion. Nonetheless, this new study will help us evaluate our responses and formulate more effective steps to contain the disease.


Source: The Lancet. DOI:

What are the Mode of Transmission and Preventative Measures?

According to a Lancet review article, Bats seems to be the speculated original host of this virus. The presence of an intermediate host facilitating the viral infection in human is still unknown. There are speculations that Pangolin may be the animal source for this viral outbreak, but researchers’ work on this is yet to be published in full.

Outside of Wuhan China, where animal-human transmission sparks the outbreak of the virus, the spread of the virus takes place predominantly with close human-human contact, via respiratory droplets when an infected individual cough/sneezes.

There are various articles suggesting possible fecal-oral route transmission (digestive tracts). However, there were no conclusive evidence at this point. Similarly, the deputy head of Shanghai Civil Affairs Bureau reveal the possibility of aerosol transmission (airborne), but more evidence is needed.


With a better understanding of the mode of transmission, measures can be taken to help protect yourselves and your loved one from the disease. Wearing mask does confer protection to some degree, but hand hygiene remains the crucial step to minimize risk of infection.


Final Thoughts

Above and beyond the spread of the virus, it is also now important to curb spread of racism, xenophobia, discrimination against health care workers who work tirelessly on the front line. We should all stand on the side of humanity, and stay united as one race (human race) to overcome this threat together.



Wang D, Hu B, Hu C, et al. Clinical Characteristics of 138 Hospitalized Patients With 2019 Novel Coronavirus–Infected Pneumonia in Wuhan, China. JAMA. Published online February 07, 2020. doi:10.1001/jama.2020.1585
Zhang  H, Kang  ZJ, Gong  HY,  et al.  The digestive system is a potential route of 2019 nCoV infection: a bioinformatics analysis based on single-cell transcriptomes.  Preprint. Posted online January 31, 2020. bioRxiv 927806. doi:10.1101/2020.01.30.927806
Guan WJ, Ni ZY, Hu Y, et al. Clinical characteristics of 2019 novel coronavirus infection in China. doi:
Chen N et al. Lancet. 2020 Jan 29. doi: 10.1016/S0140-6736(20)30211-7.
Centers for Disease Control and Prevention. Coronavirus. Accessed February 11, 2020.
Backer Jantien AKlinkenberg DonWallinga Jacco. Incubation period of 2019 novel coronavirus (2019-nCoV) infections among travellers from Wuhan, China, 20–28 January 2020. Euro Surveill. 2020;25(5):pii=2000062.


Dr Vincent Tan

Medical Director
Self Aesthetics Medical Clinic

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