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SARS-CoV-2 RNA detection in tears and conjunctival secretions of COVID-19 patients with conjunctivitis

  • Noemi Güemes-Villahoz
    Correspondence
    Corresponding author: Barbara Burgos-Blasco, Hospital Clinico San Carlos. Ophthalmology Department, Calle del Prof Martín Lagos, s/n, 28040 Madrid.
    Affiliations
    Servicio de Oftalmología, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
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  • Barbara Burgos-Blasco
    Correspondence
    Corresponding author: Barbara Burgos-Blasco, Hospital Clinico San Carlos. Ophthalmology Department, Calle del Prof Martín Lagos, s/n, 28040 Madrid.
    Affiliations
    Servicio de Oftalmología, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
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  • Ana Arribi-Vilela
    Affiliations
    Microbiology Department. Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC). Madrid, Spain
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  • Pedro Arriola-Villalobos
    Affiliations
    Servicio de Oftalmología, Hospital Clínico San Carlos, Departamento de Inmunología, Oftalmología y ORL, Facultad de Medicina, Universidad Complutense de Madrid, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
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  • Beatriz Vidal-Villegas
    Affiliations
    Servicio de Oftalmología, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
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  • Rosalia Mendez-Fernandez
    Affiliations
    Servicio de Oftalmología, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
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  • Alberto Delgado-Iribarren
    Affiliations
    Microbiology Department. Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC). Madrid, Spain
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  • Julian Garcia-Feijoo
    Affiliations
    Servicio de Oftalmología, Hospital Clínico San Carlos, Departamento de Inmunología, Oftalmología y ORL, Facultad de Medicina, Universidad Complutense de Madrid, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
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      Dear Editor,
      We read with great interest the recent study of Azzi et al.
      • Azzi L.
      • Carcano G.
      • Gianfagna F.
      • et al.
      Saliva is a reliable tool to detect SARS-CoV-2.
      regarding the possible role of saliva in the detection of SARS-CoV-2. We congratulate the authors for their excellent study and their results highlighting that saliva represents a promising tool in COVID-19 diagnosis.
      Similarly to saliva, there is evidence regarding the presence of SARS-CoV-2 RNA in tears and conjunctival secretions in patients with COVID-19.
      • Xia J.
      • Tong J.
      • Liu M.
      • Shen Y.
      • Guo D.
      Evaluation of coronavirus in tears and conjunctival secretions of patients with SARS-CoV-2 infection.
      ,
      • Chen L.
      • Liu M.
      • Zhang Z.
      • et al.
      Ocular manifestations of a hospitalised patient with confirmed 2019 novel coronavirus disease.
      However, collecting ocular fluids or secretions for SARS-CoV-2 detection appears to have limited diagnostic value.
      • Ulhaq Z.S.
      • Soraya G.V.
      The prevalence of ophthalmic manifestations in COVID-19 and the diagnostic value of ocular tissue/fluid.
      Conjunctivitis has been also described as an ocular manifestation related to SARS-CoV-2 infection, with prevalence of conjunctivitis ranging from 0.8% to 31.6%.
      • Guan W.
      • Ni Z.
      • Hu Y.
      • et al.
      Clinical Characteristics of Coronavirus Disease 2019 in China.
      ,
      • Wu P.
      • Duan F.
      • Luo C.
      • et al.
      Characteristics of Ocular Findings of Patients With Coronavirus Disease 2019 (COVID-19) in Hubei Province, China.
      Some studies suggest that SARS-CoV-2 detection rate in conjunctival secretions could be higher in patients with conjunctivitis.
      The main purpose of our study was to evaluate the presence of viral RNA of SARS-CoV-2 in conjunctival swab specimen of COVID-19 patients with conjunctivitis and its identification value. To the best of our knowledge, this is the first study of its kind that evaluates a large patient series with conjunctivitis related to COVID-19.
      This cross-sectional study was conducted at the Hospital Clinico San Carlos (HCSC) of Madrid, Spain. The study was approved by the Clinical Research Ethics Committee of this institution and was conducted in accordance with the tenets of the Declaration of Helsinki. Informed consent was obtained from all patients.
      From April 15 to May 15, 2020 hospitalized patients for COVID-19 with conjunctivitis were consecutively recruited. The inclusion criteria were: over 18 years of age; patient with positive reverse transcriptase–polymerase chain reaction (RT-PCR) test from nasopharyngeal swab for SARS-CoV-2, hospitalized due to COVID-19, conjunctivitis diagnosis and ability to give verbal consent. Those patients admitted to the intensive care unit, unable or unwilling to give consent were excluded.
      Upon notification of a possible conjunctivitis case, 2 ophthalmologists examined the patients and if a diagnosis of conjunctivitis was confirmed, a conjunctival swab was collected. The conjunctival samples were obtained from both eyes in patients with bilateral conjunctivitis and from the affected eye in patients with unilateral conjunctivitis.
      Conjunctival swab was collected with a sterile synthetic fiber swab (Flexible minitip size Nylon® flocked swab) into the lower fornix without topical anesthesia. We used the same swab to obtain a specimen from both eyes in cases of bilateral conjunctivitis. The swab was immersed into a viral transport medium (Universal transport Media-UTM®, Copan, Italy), and stored at 4°C before being tested for SARS-CoV-2. RT‐PCR assays were performed at Microbiology Department of HCSC with cuantitative GeneXpert Xpert Xpress® SARS-CoV-2 (Cepheid, USA). Viral loads are inversely correlated with cycle threshold (Ct) values, Ct value of 40 indicates negative results.
      Of the 543 hospitalized patients, 28 patients were notified as possible conjunctivitis and 21 of them had positive RT-PCR test from nasopharyngeal swab for SARS-CoV-2. Of those, 14 patients were finally diagnosed with conjunctivitis and conjunctival swab was collected. The mean age of the patients was 72.6 years (range 33-92 years) and the male-to-female ratio was 0,36 (5:9). Six patients (43%) had mild, 5 patients (36%) had moderate disease and 3 patients (21%) had severe disease.
      SARS-CoV-2 RNA was detected in conjunctival swab of one patient (7%) among the 14 patients with conjunctivitis and laboratory-confirmed COVID-19. In this patient, the PCR Ct was 25, which means an elevated viral load.
      Despite the main modes of transmission of SARS-CoV-2 are through respiratory droplets and direct contact with contaminated objects or surfaces, other routes such as ocular transmission should not be ignored.
      SARS-CoV-2 RNA has been detected in tears and conjunctival secretions of patients both with and without conjunctivitis.
      • Zhou Y.
      • Duan C.
      • Zeng Y.
      • et al.
      Ocular Findings and Proportion with Conjunctival SARS-COV-2 in COVID-19 Patients.
      Zhou et al. found a proportion with positive results for conjunctival SARS-CoV-2 detection of 2.5% (3 patients out of 121 patients). Of the 8 patients with conjunctivitis included in the latter study, only one tested positive for SARS-CoV-2 in conjunctival swab. Another study carried out in China analyzed tear and conjunctival samples of 30 patients with COVID-19. The only one patient with conjunctivitis yielded positive real-time polymerase chain reaction (RT-PCR) results.
      • Xia J.
      • Tong J.
      • Liu M.
      • Shen Y.
      • Guo D.
      Evaluation of coronavirus in tears and conjunctival secretions of patients with SARS-CoV-2 infection.
      Our study was conducted on patients with conjunctivitis, finding a proportion of 7.14% (1/14) with positive RT-PCR for conjunctival specimen, higher than most other studies in COVID-19 patients without conjunctivitis. Therefor, RT-PCR could be of more value in conjunctivitis patients.
      The low positive rate of SARS-CoV-2 RNA test by RT-PCR in tears and conjunctival secretions exhibits a relatively low likelihood of detecting the virus in ocular samples of COVID-19 patients. Therefore, the development of conjunctivitis could be a consequence of an inflammatory response, rather than due to viral replication. Also, time of sampling could explain negative tests for SARS-CoV-2 RNA. In the current study, most samples were taken on the second day of conjunctivitis symptoms. It would be interesting to know the amount of time that the virus is detectable in ocular secretions.
      The presence of SARS-CoV-2 RNA in ocular secretions may be explained by hand-eye inoculation. Transmission may occur through accidental inoculation of viral particles from the patient's hands or by direct eye contact with infected upper respiratory droplets or contaminated fomites, as it happens in other types of viral conjunctivitis such as adenoviral conjunctivitis.
      • Labib B.A.
      • Minhas B.K.
      • Chigbu D.I.
      Management of Adenoviral Keratoconjunctivitis: Challenges and Solutions.
      Although a high COVID-19 cohort was followed, a small percentage developed conjunctivitis during the hospital admission. Also, RT-PCR does not have 100% sensitivity, so negative test results may be false negative and do not exclude the presence of the virus. Sensitivity may be increased if multiple specimens are collected. However, due to the limited RT-PCR reagents and kits during the pandemic situation, we were only able to collect one sample for both eyes.
      The detection of SARS-CoV-2 RNA in tears and conjunctival swabs highlights the role of the eye as a possible route of transmission of the disease, since the ocular surface might represent both a potential site of virus replication and a transmission route of the infection. Further large sample and more comprehensive studies are warranted to evaluate the presence of SARS-CoV-2 in tears and conjunctival swabs and its diagnostic value, especially in patients with conjunctivitis.

      Declaration of Competing Interest

      None.

      References

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        Saliva is a reliable tool to detect SARS-CoV-2.
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