Detection of SARS-CoV-2 in ophthalmic secretions

Dear Editor,

We read with great interest the article entitled “COVID-19 and the eye” recently published in this journal.¹ The authors comprehensively evaluated the transmission of SARS-CoV-2 through ocular surfaces and here we present the preliminary data regarding the detection of SARS CoV-2 from the eye swabs.

The epidemic of COVID-19 emerged in Wuhan city, China in December 2019, has now been declared as pandemic of novel SARS-CoV-2 by World Health Organization (WHO) on March 11,2020.² As of August 11, 2020 over 20 million laboratory confirmed cases and over 0.7 million deaths were reported across the globe.³ Pakistan reported its first case of COVID-19 on February 26, 2020, now the number of total confirmed cases rose to 285,191 including 6112 deaths as of August 11, 2020.³ It is mainly considered that SARS-CoV-2 is transmitted through the respiratory droplet or via direct contact. The other transmission routes such as fecal-oral route or transmission through the ocular secretions have not been determined in detail. The identification of other route of transmission is an important measures in the control and prevention of COVID-19 pandemic. Limited data is available regarding the detection and transmission of SARS-CoV-2 through the ocular secretions. It is indicated that the detection of COVID-19 from the ocular secretions may be the source of infection in hospital settings especially for the clinicians dealing with Eye, ear and nose infection.

From June 6 through June 28, 2020, a total of 35 suspected COVID-19 patients were enrolled for the study and both conjunctival and oropharyngeal swabs samples were collected from all patients admitted in the isolation ward of a tertiary care hospital, Pakistan Institute of Medical Sciences-(PIMS) Islamabad. Written consent was obtained from all patients before the sample collection. Collected samples were transported to the Department of Virology National Institute of Health (NIH) Islamabad for the laboratory confirmation. Study was approved by the internal review board of NIH and PIMS.

Out of total 35 patients, 25(71.4%) were male and 10(28.5%) were female. Age of the patients enrolled for this study was ranging from 20 to 65 years. Symptoms associated with suspected COVID-19 patients, 35(100%) had fever, 21(60%) had dry cough, and 17(48.6%) had difficulty in breathing. Low lymphocytes and platelet count was noted in both group. There was no any significant difference was observed in the hematological and biochemical markers between the both groups. All demographic, clinical and laboratory characteristics of patients are given in the Table 1 .

Table 1.

Demographic, clinical and laboratory characteristics of COVID-19 patients.

Demographic Data
Age (Years)	30
Locality	Abbottabad, KPK
Gestational Weeks	10
Covid-19 (rRT-PCR positive date	04-Jun-20
Medical history	None
Delivery Mode	Miscarriage;18-Jun-20
Ultrasound findings	Placental inflammation
Clinical Features
Fever	99.8 0F
Cough	+
Sore throat	+
Loss of smell and taste	+
Shortness of breath	+
Chest pain	+
Headache	+
Myalgia/Fatigue	+
Nausea/Vomiting	+
Abdominal pain	+
Diarrhea	+
Laboratory Findings
Hb (g/dL: 11.5 to 16.5)	9.7
WBCs count (4-10 × 109/L)	11.7 × 109
Neutrophils (2-7 × 109/L)	9.96 × 109
Lymphocytes (1-3 × 109/L)	1.26 × 109
Platelet count (150-400 × 103/µL)	130 × 103
Total Bilirubin (0.2-1.0mg/dl)	0.9
ALT (<50 U/L)	67
ALP (65-306 U/L)	383
Urea (10-52mg/dl)	32
Creatinine (upto 1.0 mg/dl)	0.8
CRP (0-6 mg/L)	37
Hepatitis B,C	Negative
Toxoplasma gondi (IgM/IgG)	Negative
Salmonella (IgM/IgG)	Negative
Rubella (IgM/IgG)	Negative
CMV (IgM/IgG)	Negative
HSV (IgM/IgG)	Negative
Outcomes
Covid-19 (rRT-PCR negative date)	29-Jun-20
Maternal Outcome	Survived

Hb = Hemoglobin, WBC= White blood cells, ALT= Alanine amino transferase, ALP= Alkaline phosphatase, CRP= C- Reactive protein, Hb= Hemoglobin, CMV= Cytomegalovirus, HSV= Herpes simplex virus, rRT-PCR= Real-time reverse transcription polymerase chain reaction,

Nucleic acid (RNA) was extracted from all samples including oropharyngeal and conjunctival swabs and were tested by using real-time RT- PCR.

All 35 oropharyngeal swab samples were detected positive for SARS CoV-2, however out of total 35 conjunctival swab samples, 3(8.5%) were detected positive by using real-time RT-PCR. 2(66%) out of 3 conjunctival SARS-Cov-2 positive patients were having dry cough, whereas 3(100%) patients were suffering from fever and difficulties in breathing. There was no ocular manifestation observed among patients with positive conjunctival specimens and similar information has already been reported by the previous study.⁴ Results of the present study support the evidence that ophthalmic secretions may not be the main source of transmission for the novel SARS-CoV-2, but the role of eye in the transmission of this highly contagious virus must not be ignored. Our results are consistent with other reports, although the percentage of positivity is low from ophthalmic secretions as compared to respiratory secretions; this route of transmission cannot be ruled out and needs for further detail investigations.

Previously, coronaviruses are reported as less infectious, causing common cold like symptoms by infecting upper respiratory tract. Because of the previous investigations on coronaviruses it is known that its transmission occurs through infectious respiratory droplets and contaminated fomites. Therefore, the primary source of sampling is the throat/nasal swab, and samples from the lower respiratory tract.⁵ In the current pandemic situation, additional knowledge is required to understand the transmission patterns of SARS-CoV-2 in order to overcome the spread of this newly emerged virus. Tears can be a potential body fluid to harbor coronaviruses, as human eye conjunctiva usually remains exposed to respiratory droplets in air and if rubbed with contaminated hands. In 2004, SARS-coronavirus was detected from tear samples in 37.5% positive cases and in another study, positivity of SARS-CoV-2 from conjunctival swabs was 16.6% which contributed to the evidence of eye as a carrier.^{6 , 7} It is already reported that many health care workers have been infected by COVID-19 and three ophthalmologists died of COVID-19 in Wuhan China.⁸ Presence of SARS-CoV-2 in the eyes up to 27 days after the onset of infection reported previously⁹ is a matter of great concern. High infection rate and rapid spread of SARS-CoV-2 intrigued the need to investigate the possible role of eyes as shedding route or portal of entry of this SARS CoV-2. However, our study is limited by its small number of cases. Another limitation of our study is lack of long term follow up of patients and unable to collect the sample at multiple time period to check the duration of virus presence in the eyes. The potential for conjunctival transmission of COVID-19 is worth further detail investigations.

Recognizing the risk for viral exposure, all front line medical health care workers including physicians, ophthalmologists and dentists should adopt proper personal protective measures (such as mask PPE and face sheet) to reduce the risk of further transmission of COVID-19 while caring for patients.

Authors contributions

YA, NM, AI, SSZZ, SS, MS and MSR conceived and designed the study. MQA, NA, RA, MU, MH were responsible for data collection, lab testing, data analysis. YA, NM, MU wrote the manuscript draft.

Declaration of Competing Interest

We declared that there is no conflict of interest.