key: cord-290598-wquwtovs authors: li, s.; qiu, y.; tang, l.; wang, z.; cao, w.; xu, g.; sun, x. title: Seroprevalence of immunoglobulin M and G antibodies against SARS-CoV-2 in ophthalmic patients date: 2020-09-23 journal: nan DOI: 10.1101/2020.09.22.20198465 sha: doc_id: 290598 cord_uid: wquwtovs Using serological test to estimate the prevalence and infection potential of coronavirus disease 2019 in ocular diseases patients help understand the relationship between ocular diseases and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We conducted a cross-sectional study assaying the IgG and IgM antibodies in 1331 individuals with ocular diseases by using a magnetic chemiluminescence enzyme immunoassay kit, during the period from February 2020 to May 2020. In our study, the seroposivity in total ocular disease patients was 0.83% (11/1331). The patients with different ocular diseases including xerophthalmia, keratitis, conjunctival cyst, cataract, glaucoma, refractive error, strabismus and others had seroposivity of 2.94%, 12.5%, 25%, 4.41%, 2.63%, 1.6%, 2.22% and 0%, respectively. Among that, two ocular surface disease groups (keratitis and conjunctival cyst) had higher seroprevalence compared with others. All the participants were reverse transcription polymerase chain reaction negative for SARS-CoV-2 from throat swabs. Our study evaluated the seroprevalence in patients with different ocular diseases, which will help us understand the relationship between ocular disease and SARS-CoV-2 infection. Furthermore, the serological test for the presence of IgM and/or IgG antibodies against SARS-CoV-2 might provide accurate estimate of the prevalence of SARS-CoV-2 infection in patients with ocular diseases. Coronavirus disease 2019 (COVID-19), a novel respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in December 2019. Moreover, COVID-19 is highly contagious and quickly expanded into a pandemic, which put enormous strain on the public health system worldwide. As we know, the symptoms of the patients infected with SARS-CoV-2 vary from person to person, including asymptomatic infection, respiratory symptom, and acute respiratory distress syndrome [1] . Noteworthy, some patients had ocular manifestations including conjunctival hyperemia, chemosis, epiphora, or increased secretions [2] . A recent study reported that SARS-CoV-2 receptor angiotensin-converting enzyme 2 and entry protease TMPRSS2 was strongly detected in human conjunctival, limbal and corneal epithelium, indicating that human ocular surface might provides a potential entry portal for SARS-CoV-2 [3] . In order to understanding the relationship between SARS-CoV-2 infection and ocular diseases, estimating the prevalence of the COVID-19 in ocular disease patients is urgently needed. The prevalence of COVID-19 in ocular disease patients is difficult to estimate. Firstly, the diagnosis of COVID-19 depends on viral RNA detection that tested by reverse transcription polymerase chain reaction (RT-PCR) usually in symptomatic individuals [4] , and the viral RNA detections in asymptomatic individuals are limited. A research in Spain showed that approximately one third patients infected with SARS-CoV-2 were asymptomatic [5] , which reminded us that there still many asymptomatic patients have been undetected and undiagnosed. Secondly, it is difficult that detecting SARS-CoV-2 RNA in tears sample of patients whose throat swabs showed positive result, even at the patients of COVID-19 with ocular manifestations [6] . Therefore, it is necessary to consider about utilizing serological assay to detect SARS-CoV-2 infection in the subclinical patients with ocular disease [7] . The serological test, a validated assay for antibodies (IgG and IgM) against the SARS-CoV-2 viral, have advantage of easy serum sample collection and high throughput. Most patients with COVID-19 can detect antibodies between 7 and 14 days after diagnosis [8, 9] , and the antibodies still remain at high level at 4 month after diagnosis [10] . In this study, we assay the IgG and IgM antibodies in ocular disease patients undiagnosed COVID-19 (people have no symptom of COVID-19 and negative result for viral RNA testing) to estimate the seropositivity rate in different type of ocular disease. We enrolled 1331 individuals with different ocular diseases but negative to SARS-CoV-2 RNA testing in Eye and ENT Hospital of Fudan University from February 2020 to May 2020. A total of 1331 individuals, including 34 xerophthalmia patients, 8 keratitis patients, 4 conjunctival cyst patients, 454 cataract patients, 38 glaucoma patients, 188 refractive error patients, 90 strabismus patients and 515 other ocular diseases patients, were enrolled. Demographic data, including age, gender and the diagnosis of ocular diseases of each participant, were collected. The participants were screened for SARS-CoV-2 . CC-BY-NC-ND 4.0 International license It is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 23, 2020. . infection by a serological test for IgG and IgM antibodies against a recombinant antigen of the virus. For all study individuals, RT-PCR tests for viral RNA from throat swabs were conducted. The Medical Ethics Committees of Eye and ENT Hospital of Fudan University approved this study, and the study adhered to the principles of the Declaration of Helsinki. Informed consent was obtained from all participants. Throat swabs were collected and tested for SARS-CoV-2 RNA in a designated virology laboratory (KingMed Diagnostics, Shanghai, China) using the RT-PCR assay. Serum samples were collected in clinical laboratory in Eye and ENT Hospital of Fudan University. The IgG and IgM antibodies against SARS-CoV-2 spike protein and nucleoprotein were measured using a commercially available magnetic chemiluminescence enzyme immunoassay kit (Bioscience, Chongqing, China) according to the manufacturer's instructions. Antibody levels were expressed as the ratio of the chemiluminescence signal over the cutoff (S/CO) value. An S/CO value higher than 1.0 for either IgG or IgM was regarded as positive. If S/CO value higher than 0.7 but lower than 1.1, the serum sample will be retested. Previous study has been validated serological assay with serum samples [13] . We conducted a serological survey testing the IgG and IgM antibodies against SARS-CoV-2 antigens in each participant of different ocular disease. The level of IgM and IgG antibodies are presented in Fig 1. We found the seroprevalence was 0.83% in total 1331 individuals with ocular diseases. Furthermore, seroprevalence in different type of ocular disease vary from 0% to 25%. Conjunctival cyst group had the highest seroprevalence up to 25%, the following is the keratitis group with the seroprevalence of 12.5%. We estimated a seroprevalence of 4.41% in cataract group, 2.94% in xerophthalmia group, 2.63% in glaucoma group, 2.22% in strabismus group, 1.60% in refractive error group, and 0% in other ocular diseases group (table 1) . Then, we divided the all patients into three groups: ocular surface diseases group, no-ocular surface diseases group and visual optics diseases group and the seropositive rate were 1.91%, 0.36% and 1.45%, respectively (table 2). Assessing the prevalence of COVID-19 in patients with ocular diseases will help us understand the relationship between ocular disease and SARS-CoV-2 infection. Our study evaluated the seroprevalence in patients with different ocular diseases, including xerophthalmia, keratitis, conjunctival cyst, cataract, glaucoma, refractive error, strabismus and others. We assessed the performance of the IgG and IgM from 1331 outpatients of SARS-CoV-2 RNA testing negative. In this study, the IgG and IgM antibodys we assayed are targeted to the nucleoprotein and a peptide from the spike protein of SARS-CoV-2 [11] . The result of our study showed that total positive rate of IgM or IgG (0.83%) was . CC-BY-NC-ND 4.0 International license It is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 23, 2020. . close to the seropositive rate (0.8%) of community setting from several cities in china which reported by another serological study [12] . However, the seroprevalence was significantly high in specific groups contain keratitis group and conjunctival cyst group. Some clinical and scientific evidences indicated that human ocular surface is susceptible to SARS-CoV-2 [13, 14] . A recent case reported that a clinician wearing N95 mask but not protecting eyes was infected with SARS-CoV-2 [13] . An animal study showed that SARS-CoV-2 can infect patients via the conjunctival route in rhesus macaques [14] . Therefore, it is possible that patients with ocular diseases, especially ocular surface diseases such as keratitis and conjunctival cyst, manifest the SARS-CoV-2 receptor angiotensin-converting enzyme 2 up-regulation in ocular surface and more sensitive to SARS-CoV-2 infection [15] . Nonetheless, the infection mechanism of conjunctical route needs further researched. Our study has some limitations. First of all, this was a single-center study. All of the individuals involved in our study were from Eye and ENT Hospital of Fudan University and the number of participant was not large enough, which might influenced presentation of the seroprevalence we estimated. Next, if samples were collected before infected individuals had serological response, the result of serological assay could produce false negative. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 23, 2020. . is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 23, 2020. . is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 23, 2020. . https://doi.org/10.1101/2020.09.22.20198465 doi: medRxiv preprint Clinical features of patients infected with 2019 novel coronavirus in Wuhan Characteristics of Ocular Findings of Patients With Coronavirus Disease 2019 (COVID-19) in Hubei Province Co-expression of SARS-CoV-2 entry genes in the superficial adult human conjunctival, limbal and corneal epithelium suggests an additional route of entry via the ocular surface Evaluating the accuracy of different respiratory specimens in the laboratory diagnosis and monitoring the viral shedding of 2019-nCoV infections Prevalence of SARS-CoV-2 in Spain (ENE-COVID): a nationwide, population-based seroepidemiological study Assessing Viral Shedding and Infectivity of Tears in Coronavirus Disease 2019 (COVID-19) Patients Testing for SARS-CoV-2 antibodies Antibody responses to SARS-CoV-2 in patients of novel coronavirus disease Humoral Immune Response to SARS-CoV-2 in Iceland Antibody responses to SARS-CoV-2 in patients with COVID-19 Seroprevalence of immunoglobulin M and G antibodies against SARS-CoV-2 in China 2019-nCoV transmission through the ocular surface must not be ignored Ocular conjunctival inoculation of SARS-CoV-2 can cause mild COVID-19 in rhesus macaques COVID-19 receptor ACE2 is expressed in human conjunctival tissue The authors declare no competing interests.