2. COVID-19

COVID-19 is a type of infectious pneumonia caused by SARS-CoV-2 and was first reported in early December 2019 in Wuhan City, Hubei Province, China. It is a potentially fatal disease with high infectivity. The earliest cluster of COVID-19 identified as “pneumonia of unknown etiology” or “atypical pneumonia” were defined as evidence of pneumonia on X-Ray or Computer Tomography scans, fever of 38 degrees or higher, normal or low white blood cell count, and no clinical improvement despite standard antibiotics treatment for 3 to 5 days. According to the studies from China and European countries, symptoms of COVID-19 include fever, olfactory dysfunction, gustatory dysfunction, cough and shortness of breath etc.

Main symptoms of COVID-19


2.1a What Are the Ocular Manifestations of COVID-19 and Their Significance

What are the ocular manifestations of COVID-19 and their significance?

Kelvin H. Wan, Raymond Lai Man Wong, Kenny Ho Wa Lai, Suber S. Huang, Dennis Shun Chiu Lam

 Conjunctivitis has been reported in isolated case reports and case series as one of the manifestations in COVID-19 patients.  The proportion of COVID-19 patients with conjunctivitis ranges from 0.8% to 31.6%.1-5  It is indistinguishable from the common viral conjunctivitis that brings patients to clinics or hospitals to see general practitioners or eye doctors.  Can tears or eye secretion act as a source of infection and any special precautions needed when facing individuals with red eyes?

In a large retrospective study of 1099 patients with laboratory-confirmed COVID-19 from 552 hospitals across 30 provinces in China, conjunctival congestion was reported in 9 (0.8%) patients.1  At a single hospital center in Hubei province China, the authors identified 12 of 38 (31.6%) patients had ocular manifestations that they attributed to conjunctivitis, including conjunctival hyperemia, chemosis, epiphora, or increased secretions.2  Of these 12 patients with conjunctivitis, RT-PCR from conjunctival swab was positive in 2 (16.7%) cases. Compared to patients without ocular symptoms, the authors reported that those with ocular symptoms had higher white blood cell and neutrophil counts and higher levels of procalcitonin, C-reactive protein, and lactate dehydrogenase.  The American Academy of Ophthalmology disagreed with this characterization and commented that “chemosis in a critically ill patient most likely represents third-spacing or fluid overload, not conjunctivitis”.6 

A prospective study from the First Affiliated Hospital of Zhejiang University collected tear and conjunctival secretions from 30 patients twice over a span of 2-3 days.  2 conjunctival samples from 1 (3.3%) patient who had conjunctivitis yielded positive RT-PCR results, whereas the other 58 samples from 29 patients were negative.3 In a prospective study conducted in Singapore of 17 patients, 64 tear samples were obtained throughout the first 3 weeks since the onset of presentation.  1 (5.9%) patient developed conjunctival injection and chemosis during the hospital stay.  All samples tested negative for SARS-CoV-2 on viral isolation and RT-PCR even though nasopharyngeal swab samples remain positive.4    Of the 121 patients managed at Renmin Hospital of Wuhan University, 8 (6.6%) patients had ocular symptoms (details of symptoms not specified). Only one was tested positive for SARS-CoV-2 in the conjunctiva, whereas 2 (1.7%) ophthalmologically asymptomatic patients were tested positive for conjunctival SARS-CoV-2.  The presence of ocular symptoms or a positive result of conjunctival SARS-CoV-2 was not significantly correlated with the duration of disease.5  Further studies are needed to elucidate the implications of the virus detected on the conjunctiva in a minority of the patients.

Tears or eye secretion could be a potential source of infection, even if concurrent conjunctivitis is absent. Ophthalmologists could be the first point of contact for COVID-19 patients, in particular for those who may present as conjunctivitis.  In the midst of the COVID-19 epidemics, wearing surgical masks in medical settings for personal protection and reducing environmental contamination is advisable, whereas full personal protection equipment including N95 respirators, glove, protective clothes, cap, and etc. would be needed in handling suspected or confirmed cases.  During the current pandemic, patients presenting with red eye (commonest cause is conjunctivitis) must be managed with a high degree of caution and appropriate protective measures to mitigate the spread of COVID-19.  



1. Guan W-j, Ni Z-y, Hu Y, et al. Clinical Characteristics of Coronavirus Disease 2019 in China. New England Journal of Medicine. 2020. In Press

2. Wu P, Duan F, Luo C, et al. Characteristics of Ocular Findings of Patients With Coronavirus Disease 2019 (COVID-19) in Hubei Province, China. JAMA Ophthalmol. 2020. In Press
3. Xia J, Tong J, Liu M, et al. Evaluation of coronavirus in tears and conjunctival secretions of patients with SARS-CoV-2 infection. Journal of Medical Virology. 2020;92:589-94.
4. Seah IYJ, Anderson DE, Kang AEZ, et al. Assessing Viral Shedding and Infectivity of Tears in Coronavirus Disease 2019 (COVID-19) Patients. Ophthalmology. 2020. In Press
5. Zhou Y, Duan C, Zeng Y, et al. Ocular Findings and Proportion with Conjunctival SARS-COV-2 in COVID-19 Patients. Ophthalmology. 2020. In Press6. AAO. Important coronavirus updates for ophthalmologists. https://www.aao.org/headline/alert-important-coronavirus-context. Accessed April 22, 2020.  


2.1b Main Symptoms of COVID-19


2.1c High infectivity (Why is COVID-19 so infectious?)

1. Molecular Level: SARS-CoV-2 utilizes the same cellular receptors as SARS-CoV, the human Angiotensin Converting Enzyme 2 (hACE2). Therefore, it is expected that this new virus would behave similar to SARS-CoV in terms of transmission properties, such as causing lower instead of upper respiratory tract symptoms. However, unlike SARS-CoV or MERS-CoV, epithelial cells in human airway are more suitable than standard tissue culture medium for the growth of SARS-CoV-2. 

2. Long Incubation Period & Asymptomatic Transmission: The incubation period of SARS-CoV-2 is up to 24 days and the virus is capable of human-to-human transmission among asymptomatic individuals or those displaying only mild symptoms. Unlike SARS in which most patients developed fever, a very large study involving 1,099 COVID-19 patients showed only 43.8% of them had fever at the time of admission. This renders comprehensive early identification of cases via temperature screening extremely difficult. 

3. Viral shedding is the highest early in the illness course, when patients are in the community before hospitalization.

4. Low CFR: People would be more complacent and less compliant to preventive measures.

2.1d Case fatality rate (CFR) & risk factors

CFR of male is 39.0% higher
than that of female  




CFR increases with age
Elderly (aged >70) should have higher level of awareness



CFR increases with pre-existing medical conditions
People with cardiovascular disease should have higher level of awareness

For details, please visit here (https://www.worldometers.info/coronavirus/coronavirus-age-sex-demographics/)



1. Guan W, Ni Z, Hu Y, et al. (2020): Clinical Characteristics of Coronavirus Disease 2019 in China. New England Journal of Medicine. In press

2. Habibzadeh P & Stoneman EK (2020): The Novel Coronavirus: A Bird’s Eye View. The International Journal of Occupational and Environmental Medcine 11: 65-71.

3. Rothe C, Schunk M, Sothmann P, et al. (2020): Transmission of 2019-nCoV Infection from an Asymptomatic Contact in Germany. New England Journal of Medicine 382: 970-971.

4. Wölfel R, Corman VM, Guggemos W et al. (2020): Virological assessment of hospitalized patients with COVID-2019. Nature. In press

5. Erin KM and Jason MP (2020): COVID-19 Treatment: A Review of Early and Emerging Options. Open Forum Infectious Diseases. In press

6. Jerome R. Lechien, Carlos M. Chiesa-Estomba, Daniele R. De Siati, et al. Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease (COVID-19): a multicenter European study.

2.2 COVID-19 Animation: What Happens If You Get Coronavirus?

2.3 People Need To Take This Seriously’: Video Shows Lung Damage In Coronavirus Patient


2.4 Skin Rash Should Be Considered Fourth Key Symptom of Covid

Skin rash should be considered fourth key symptom of COVID

2.5 Why Do Asymptomatic COVID-19 Cases Even Happen?

2.26 Why Do Asymptomatic COVID-19 Cases Even Happen

2.6 What Could Happen When Covid-19 Collides With Flu Season

2.7 Age-Related Differences in Nasopharyngeal Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Levels in Patients With Mild to Moderate Coronavirus Disease 2019 (COVID-19)

Age-Related Differences in Nasopharyngeal Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Levels in Patients With Mild to Moderate Coronavirus Disease 2019 (COVID-19)

2.8 Coronavirus: Could Cells That Fight Common Cold Help People Beat Covid-19

Coronavirus could cells that fight common cold help people beat Covid-19

2.9 Covid-19: Immune System Derails

Immune System Derails

2.10 Chronic Fatigue Syndrome a Possible Long-term Effect of Covid-19, Experts Say

Chronic Fatigue Syndrome a Possible Long-term Effect of Covid-19, Experts Say

2.11 Adults May Not Be the Only Covid ‘long Haulers.’ Some Kids Still Have Symptoms, Months After Falling Ill

Adults may not be the only Covid 'long haulers.' Some kids still have symptoms, months after falling ill

2.12 Covid-19 Symptoms Often Appear in This Order, According to a New Study

COVID-19 symptoms often appear in this order, according to a new study

2.13 Effects of a Major Deletion in the Sars-cov-2 Genome on the Severity of Infection and the Inflammatory Response: an Observational Cohort Study

Effects of a major deletion in the SARS-CoV-2 genome on the severity of infection and the inflammatory response

2.14 From ‘happy Hypoxia’ to Purpuric Rashes — Here Are All the Perilous Ways the Coronavirus Attacks the Body

From ‘happy hypoxia’ to purpuric rashes — here are all the perilous ways the coronavirus attacks the body

2.15 Projecting the Transmission Dynamics of Sars-cov-2 Through the Postpandemic Period

Projecting the transmission dynamics of SARS-CoV-2 through the postpandemic period

2.16 A Supercomputer Analyzed Covid-19 — and an Interesting New Theory Has Emerged

A Supercomputer Analyzed Covid-19 — and an Interesting New Theory Has Emerged

2.17 Diarrhoea and Vomiting May Be Key Sign of Covid in Children – Study

Diarrhoea and vomiting may be key sign of Covid in children – study

2.18 Covid-19 Patients May Have Prolonged Gut Infection, Study Finds

2.19 As Evidence Builds That Covid-19 Can Damage the Heart, Doctors Are Racing to Understand It

2.20 More Long-term Damage Caused by COVID-19 Than Expected

2.21 US Reinfection Case Raises Question: How Long Does Covid Immunity Last?

2.22 Coronavirus: Constantly Surprising Virus Found to Be Heat Tolerant, Self-healing and Very Resilient in Lab Tests

2.23 Scientists Find An Avenue To Attack The Coronavirus, Aided By Cloud Imaging

2.24 How Do Children Fight Off the Coronavirus?

2.25 35 Years of Research Into Coronavirus Infections Show Long-Term Immunity Is Unlikely

2.26 Covid Virus ‘Survives for 28 days’ in Lab Conditions

2.27 Coronavirus Reinfections Are Real but Very, Very Rare

2.28 New Covid Strain: How Worried Should We Be?

2.29 Neanderthal Gene Found in Many People May Open Cells to Coronavirus and Increase COVID-19 Severity

2.30 Ohio Researchers Say They’ve Identified Two New Covid Strains Likely Originating in the U.S.

2.31 Post-COVID Lungs Worse Than the Worst Smokers’ Lungs, Surgeon Says

2.32 1 in 3 Discharged Coronavirus Patients Returned to Hospital Within 5 Months, Researchers Say

2.33 Fast-Spreading COVID Variant Can Elude Immune Responses