The eye as the discrete but defensible portal of coronavirus infection

[Lacrimal duct infections]

In addition to being a drainage system, the lacrimal ducts actively defend the eye through the action of the lacrimal pump, the presence of resident flora (lacriome) and the mucosa-associated immune tissue. Infection occurs when mucosal immune functions are overwhelmed. Lacrimal infection is a vicious circle, in which infection leads to inflammation and post-inflammatory sequelae, themselves a source of occlusion and stagnation, which in turn encourages infection. Whatever the initial trigger - post-traumatic occlusion, inflammation (e.g. allergic) or infestation by a virulent germ, the management of lacrimal duct infection must take account of this vicious circle. When infection sets in, changes in the mucosa can range from submucosal inflammatory infiltrates to pseudocysts, and in the most severe cases to metaplasia, dysplasia and squamous cell carcinoma. Histological sampling is therefore imperative in the case of surgery on a chronically infected mucosa. Clinical assessment, aided if necessary by a dacryoscan, must be able to detect differential diagnoses (lacrimal sac carcinoma, dacryocystocele in children) and serious forms (gonococcal ophthalmia neonatorum, peridacryocystitis), look for signs of dacryoliths, and differentiate between acute and chronic infection. Antibiotic treatment should be adapted to the identified or presumed organism involved or used sparingly in cases of chronic infection. Dacryoliths can be removed by curettage in the case of canaliculitis with concretions, but surgery is required for larger dacryoliths (canaliculotomy, or dacryocystorhinostomy in the case of lacrimal sac dacryoliths). Antibiotic prophylaxis for lacrimal surgery is recommended only in cases with associated rhinosinusitis, inflammation of the lacrimal sac, or a history of infected mucocele or dacryocystitis.

Detection of SARS-CoV-2 binding receptors and miscellaneous targets as well as mucosal surface area of the human lacrimal drainage system

PURPOSE

Our aim was to evaluate a potential role for the lacrimal drainage system (LDS) as a portal of entry and conduit for SARS-CoV-2 in human infection. We also investigate the mucosal surface area. The relatively long tear contact time in a closed system raises the possibility that this pathway may contribute to the initiation of systemic infection. We looked for expression of ACE2, the main receptor for SARS-CoV-2, as well as cofactors such as TMPRSS2 and other enzymes such as cathepsinB, CD147, elastase1, furin, neuropilin1, neuropilin2, TMPRSS11D and trypsin which also play a role in SARS-CoV-2 infection, in this system.

METHODS

Human tissue samples of the draining tear ducts from body donors were analyzed by RT-PCR, Western blot and immunohistochemistry. It is not known whether the respective body donors were Sars-Cov-2 positive at any time; they were negative when they entered the institute. Besides, the draining LDS of body donors were measured to determine the mucosal surface in the lacrimal system.

RESULTS

The expression of the main receptor studied, ACE2, cofactors such as TMPRSS2 and other enzymes such as cathepsinB, CD147, elastase1, furin, neuropilin1, neuropilin2, TMPRSS11D and trypsin were all detected at the gene and protein level. The average mucosal surface area of the lacrimal sac and nasolacrimal duct was calculated to be 110 mm2.

CONCLUSION

The results show the presence of all analyzed receptors in the efferent LDS. With an average tear passage time of 3 min and a relatively large mucosal surface area, the LDS could therefore be considered as a portal of entry and conduit for SARS-CoV-2. In addition, it represents a surface that should be taken into consideration in the administration of topically applied medication to the ocular surface.

COVID-19 and Alzheimer's Disease Share Common Neurological and Ophthalmological Manifestations: A Bidirectional Risk in the Post-Pandemic Future

A growing body of evidence indicates that a neuropathological cross-talk takes place between the coronavirus disease 2019 (COVID-19) -the pandemic severe pneumonia that has had a tremendous impact on the global economy and health since three years after its outbreak in December 2019- and Alzheimer's Disease (AD), the leading cause of dementia among human beings, reaching 139 million by the year 2050. Even though COVID-19 is a primary respiratory disease, its causative agent, the so-called Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), is also endowed with high neuro-invasive potential (Neurocovid). The neurological complications of COVID-19, resulting from the direct viral entry into the Central Nervous System (CNS) and/or indirect systemic inflammation and dysregulated activation of immune response, encompass memory decline and anosmia which are typically associated with AD symptomatology. In addition, patients diagnosed with AD are more vulnerable to SARS-CoV-2 infection and are inclined to more severe clinical outcomes. In the present review, we better elucidate the intimate connection between COVID-19 and AD by summarizing the involved risk factors/targets and the underlying biological mechanisms shared by these two disorders with a particular focus on the Angiotensin-Converting Enzyme 2 (ACE2) receptor, APOlipoprotein E (APOE), aging, neuroinflammation and cellular pathways associated with the Amyloid Precursor Protein (APP)/Amyloid beta (Aβ) and tau neuropathologies. Finally, the involvement of ophthalmological manifestations, including vitreo-retinal abnormalities and visual deficits, in both COVID-19 and AD are also discussed. Understanding the common physiopathological aspects linking COVID-19 and AD will pave the way to novel management and diagnostic/therapeutic approaches to cope with them in the post-pandemic future.

[Influence of the COVID-19 pandemia on the ophthalmologic emergency department in the Toulouse University Hospital during the first lockdown from March the 17th to May the 10th of 2020]

INTRODUCTION

We conducted this study to assess the impact of the COVID-19 pandemic and the lockdown in France from March 17, 2020 to May 10, 2020, on the ophthalmic emergency department at Toulouse University Hospital, compared to the period from March 2 to March 16, 2020.

MATERIALS AND METHODS

This was a retrospective observational study, conducted in the ophthalmic emergency department of Toulouse University Hospital. We included the patients presenting to the emergency department from March 2 to May 10, 2020. We recorded age, sex, day of visit, time until care was received, past ocular history, outpatient or inpatient status, final diagnosis and its severity, outpatient or inpatient disposition, and medical or surgical treatment after the emergency department visit.

RESULTS

We found a substantial decrease in the number of patients per day, mostly during the first month of the lockdown: 44 patients per day before the lockdown compared to 23 patients per day during the first month, followed by 38 patients per day for the second month of lockdown; more patients visiting promptly; and elderly patients represented a higher proportion of patients.

CONCLUSION

The first lockdown in France due to the COVID-19 pandemic had an impact on the Toulouse ophthalmic emergency department, especially concerning the number of patients per day; this study helps to assess individual behavior in this context of a public health crisis.

Detection of Airborne Influenza A and SARS-CoV-2 Virus Shedding following Ocular Inoculation of Ferrets

Despite reports of confirmed human infection following ocular exposure with both influenza A virus (IAV) and SARS-CoV-2, the dynamics of virus spread throughout oculonasal tissues and the relative capacity of virus transmission following ocular inoculation remain poorly understood. Furthermore, the impact of exposure route on subsequent release of airborne viral particles into the air has not been examined previously. To assess this, ferrets were inoculated by the ocular route with A(H1N1)pdm09 and A(H7N9) IAVs and two SARS-CoV-2 (early pandemic Washington/1 and Delta variant) viruses. Virus replication was assessed in both respiratory and ocular specimens, and transmission was evaluated in direct contact or respiratory droplet settings. Viral RNA in aerosols shed by inoculated ferrets was quantified with a two-stage cyclone aerosol sampler (National Institute for Occupational Safety and Health [NIOSH]). All IAV and SARS-CoV-2 viruses mounted a productive and transmissible infection in ferrets following ocular inoculation, with peak viral titers and release of virus-laden aerosols from ferrets indistinguishable from those from ferrets inoculated by previously characterized intranasal inoculation methods. Viral RNA was detected in ferret conjunctival washes from all viruses examined, though infectious virus in this specimen was recovered only following IAV inoculation. Low-dose ocular-only aerosol exposure or inhalation aerosol exposure of ferrets to IAV similarly led to productive infection of ferrets and shedding of aerosolized virus. Viral evolution during infection was comparable between all inoculation routes examined. These data support that both IAV and SARS-CoV-2 can establish a high-titer mammalian infection following ocular exposure that is associated with rapid detection of virus-laden aerosols shed by inoculated animals. IMPORTANCE Documented human infection with influenza viruses and SARS-CoV-2 has been reported among individuals wearing respiratory protection in the absence of eye protection, highlighting the capacity of these respiratory tract-tropic viruses to exploit nonrespiratory routes of exposure to initiate productive infection. However, comprehensive evaluations of how ocular exposure may modulate virus pathogenicity and transmissibility in mammals relative to respiratory exposure are limited and have not investigated multiple virus families side by side. Using the ferret model, we show that ocular exposure with multiple strains of either coronaviruses or influenza A viruses leads to an infection that results in shedding of detectable aerosolized virus from inoculated animals, contributing toward onward transmission of both viruses to susceptible contacts. Collectively, these studies support that the ocular surface represents a susceptible mucosal surface that, if exposed to a sufficient quantity of either virus, permits establishment of an infection which is similarly transmissible as that following respiratory exposure.

Association of COVID-19 Infection With Wearing Glasses in a High-Prevalence Area in Denmark and Sweden

Importance

Observational studies have indicated that glasses might protect against contracting COVID-19 through reduced airborne and contact transmission.

Objective

To investigate the association between wearing one's own glasses with contracting COVID-19 when adjusting for relevant confounders.

Design, Setting, and Participants

This cohort study was conducted during the first wave of the COVID-19 pandemic (June to August 2020) in Denmark and Sweden, where personal protective equipment was not recommended for the general population at the time. Employees at Falck, an international rescue corps with different job functions (ambulance, health care, office, and field staff, firefighters, and roadside assistance) participated in the study.

Exposures

The main exposure was wearing glasses (also including contact lenses and reading glasses), which was assessed in a questionnaire. Persons wearing glasses were compared with those who did not wear glasses (ie, nonusers). To adjust for potential confounders, information on age, sex, job function, and number of workday contacts were included.

Main Outcomes and Measures

The outcome was COVID-19 infection before (positive polymerase chain reaction test) or during the study period (biweekly voluntary tests with a rapid test). The investigated hypothesis was formulated after collecting the data.

Results

A total of 1279 employees in Denmark and 841 in Sweden were included (839 [39.6%] female and 1281 [60.4%] male; 20.5% were aged <40 years; 57.0%, 40-60 years, and 22.5%, >60 years). Of these, 829 individuals (64.8%) in Denmark and 619 (73.6%) in Sweden wore glasses. Wearing glasses was inversely associated with COVID-19 infection in the Swedish cohort (odds ratio [OR], 0.61 [95% CI, 0.37-0.99]; P = .047; seroprevalence, 9.3%) but not in the Danish cohort (OR, 1.14 [95% CI, 0.53-2.45]; P = .73; seroprevalence, 2.4%). Adjusting for age, sex, job function, and number of workday contacts in Sweden, wearing glasses no longer was associated with COVID-19 infection (OR, 0.64 [95% CI, 0.37-1.11]; P = .11). When stratifying by job function, a large difference was observed among office staff (OR, 0.20 [95% CI, 0.06-0.70]; P = .01) but not ambulance staff (OR, 0.83 [95% CI, 0.41-1.67]; P = .60) nor health care staff (OR, 0.89 [95% CI, 0.35-2.30]; P = .81).

Conclusions and Relevance

While wearing one's glasses was inversely associated with COVID-19 in Sweden in an unadjusted analysis, an association no longer was identified when adjusting for confounders. These results provide inconclusive findings regarding whether wearing one's own glasses is associated with a decreased risk of COVID-19 infections.

Conjunctival Swab Findings in 484 COVID-19 Patients in Four Hospital Centers in Slovakia

Since 2020, the COVID-19 (Coronavirus Disease 2019) has quickly become a worldwide health problem. Ophthalmologists must deal with symptoms as well. For the positive detection in the conjunctival sac swab in COVID-19 patients hospitalized in Slovakia during March 2021 in four hospital centers, we used a test based on a polymerase chain reaction (PCR). In a group of 484 patients, 264 males (55%) and 220 females (45%) with clinical symptoms were identified with COVID-19 as a clinical diagnosis. The PCR test swab results from the conjunctival sac taken on the same day were positive in 58 patients (12%), 31 males (with a mean age of 74.6 ± 13.59 years) and 27 females (with a mean age of 70.63 ± 14.17 years); negative in 417 patients (86%); and 9 patients (2%) had an unclear result. The cycle threshold values comparing the nasopharynx and conjunctiva were also different in the group of all patients divided by age and gender. In COVID-19 patients the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was detectable using PCR test in the nasopharynx but also in the conjunctival sac swab, where the positivity rate was only 12%.

A Systematic Literature Review and Bibliometric Analysis of Ophthalmology and COVID-19 Research

This review is proposed to summarize the updates on COVID-19 and ophthalmology along with the bibliometric features of articles that have been published since the beginning of the COVID-19 outbreak. The databases, including PubMed, Scopus, and Web of Science, were searched using "Coronavirus," "COVID-19," "SARS-CoV-2," "pandemic," "ophthalmology," "ophthalmic," and "eye" keywords. All published articles except commentaries, errata, and corrigenda up to April 2021 were included. Titles and abstracts were screened, and ophthalmology-focused articles were collected. The bibliographic information of the articles, such as the name and country of the first author, type of study, date of publication, language, and journal name, were extracted. Included studies were assessed using the Joanna Briggs Institute (JBI) critical appraisal checklist. After systematic searching, 2,669 distinct articles were screened by title/abstract, and 1,174 ophthalmology-focused articles were selected to be reviewed. Ophthalmology-focused publications accounted for less than 0.5 percent of the total COVID-19-related articles. Most of the articles were published in the Indian Journal of Ophthalmology, and the main publication type was "original article." Almost 88% of the publications were in English. There was a decline in the publication rate during the initial months of 2021 compared with the middle and last months of 2020. Most of the publications were affiliated with the United States of America. However, Singapore and the United Kingdom were the countries with the highest number of publications after population adjustment. Furthermore, a comprehensive review on major topics including SARS-CoV-2 ocular tropism, ophthalmic manifestations, ocular complications due to COVID-19 treatment strategies, the pandemic effect on ophthalmology care and operations, myopia progression during the pandemic, and telemedicine was conducted.

Surgical helmets can be converted into efficient disinfectable powered air-purifying respirators

BACKGROUND

Filtering facepiece respirators often fail to provide sufficient protection due to a poor fit. Powered air-purifying respirators (PAPRs) are not designed for healthcare personnel, and are challenging to disinfect. Surgical helmets (SH) are available in many United States hospitals but do not provide respiratory protection. Several modifications to SH have been suggested, but none are sufficiently compliant with safety and efficiency standards. The purpose of this investigation was the development of a filter adaptor, which converts SHs into efficient, safe, and disinfectable PAPRs.

METHODS

Four critical features were investigated close to regulatory requirements: total inward leakage of particles, CO₂ concentrations, intra-helmet differential pressure, and automated disinfection.

RESULTS

The average total inward leakage in the 2 independent tests were 0.005% and 0.01%. CO₂ concentrations were lower than in the original SH. The modification generates a positive differential pressure. The filter's performance was not compromised after 50 cycles in a sterilization machine.

DISCUSSION

The modified SH provides several hundred times better protection than FFP-3 masks.

CONCLUSIONS

Surgical helmets can be modified into safe, efficient, and disinfectable PAPRs, suitable for HCP and the operating room in particular. They can play a role in the preparedness for upcoming events requiring efficient respiratory protection.

Long-Acting Protective Ocular Surface by Instilling Adhesive Dual-Antiviral Nanoparticles

The eye is susceptible to viral infections, causing severe ocular symptoms or even respiratory diseases. Methods capable of protecting the eye from external viral invasion in a long-term and highly effective way are urgently needed but have been proved to be extremely challenging. Here, a strategy of forming a long-acting protective ocular surface is described by instilling adhesive dual-antiviral nanoparticles. Taking pseudotyped severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as a model virus, antiviral agent-loaded nanoparticles are coated with a "double-lock" hybrid cell membrane abundant with integrin-β1 and angiotensin converting enzyme II (ACE2). After instillation, the presence of integrin-β1 endows coated nanoparticles with steady adhesion via specific binding to Arg-Gly-Asp sequence on the fibronectin of ocular epithelium, achieving durable retention on the ocular surface. In addition to loaded inhibitors, the exposure of ACE2 can trap SARS-CoV-2 and subsequently neutralize the associated spike protein, playing a dual antiviral effect of the resulting nanoparticles. Adhesive dual-antiviral nanoparticles enabled by coating with a "double-lock" hybrid cell membrane could be a versatile platform for topical long-acting protection against viral infection of the eye.

Neuropathological Aspects of SARS-CoV-2 Infection: Significance for Both Alzheimer's and Parkinson's Disease

Evidence suggests that SARS-CoV-2 entry into the central nervous system can result in neurological and/or neurodegenerative diseases. In this review, routes of SARS-Cov-2 entry into the brain via neuroinvasive pathways such as transcribrial, ocular surface or hematogenous system are discussed. It is argued that SARS-Cov-2-induced cytokine storm, neuroinflammation and oxidative stress increase the risk of developing neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Further studies on the effects of SARS-CoV-2 and its variants on protein aggregation, glia or microglia activation, and blood-brain barrier are warranted.

COVID-19-Related Chronic Bilateral Dacryoadenitis: A Clinicopathological Study

IMPORTANCE

Pathological features of ophthalmic aftereffects of COVID-19 are important for new insight in treating patients.

OBJECTIVE

To examine the expression of SARS-CoV-2 nucleocapsid protein and angiotensin-converting enzyme 2 (ACE2) in lacrimal gland tissues of a patient with COVID-19 and a patient without COVID-19.

DESIGN, SETTING, AND PARTICIPANTS

In this retrospective case-control study, the case of a 35-year-old woman with positive test results for SARS-CoV-2 who had had lacrimal gland enlargements for 6 months was analyzed. A 43-year-old woman without COVID-19 who had idiopathic chronic bilateral dacryoadenitis served as a negative control.

MAIN OUTCOMES AND MEASURES

Histopathology and immunohistochemistry with anti-SARS-CoV-2 nucleocapsid protein and ACE2 in the lacrimal glands.

RESULTS

Both patients were Japanese women aged 35 years (case) and 43 years (control). Histopathologic findings in the patient with COVID-19 demonstrated marked inflammatory cell infiltration, lymphoid follicles, and germinal center formation in the lacrimal gland. The inflammation was mainly made up of lymphocytes and plasma cells with several polymorphonuclear leukocytes, where the lacrimal glands were atrophic. Of note, a number of lacrimal gland ducts markedly contained eosinophilic materials in the lumens, which indicated glandular damage. Immunoreactivity for SARS-CoV-2 nucleocapsid protein was noted in the inflammatory cells around the lacrimal gland ductal epithelia. In addition, strong ACE2 expression was noted in the lacrimal gland. In the patient without COVID-19, marked inflammation was noted in the lacrimal gland; however, there were no eosinophilic material deposits in the ductal lumens. SARS-CoV-2 nucleocapsid protein immunoreactivity was not observed, whereas ACE2 was expressed in the lacrimal glands.

CONCLUSIONS AND RELEVANCE

In this case-control study, expression of ACE2 indicated that the lacrimal gland could be a target organ for SARS-CoV-2 to adhere to. Chronic bilateral dacryoadenitis in the patient with COVID-19 showed SARS-CoV-2-positive inflammatory cells with glandular damage, which might be a COVID-19-associated ophthalmic aftereffect.

Coronavirus disease (COVID-19) and conjunctival sac swab findings

Background

The purpose of this article is to evaluate the positivity of conjunctival sac swab by PCR (Polymerase chain reaction) test in COronaVIrus Disease 19 (COVID-19) patients.

Methods

Inclusion criteria of our study were COVID-19 patients hospitalized during March 2021 in inpatient wards at University Hospitals in towns Bratislava and Zilina, Slovakia. The conjunctival sac swabs collected by four ophthalmologists were stored for 24 h, then analyzed in the laboratory of the Department of Microbiology and Immunology, Jessenius Faculty of Medicine in Martin, Comenius University, Slovakia. The sampling apparatus, used for conjunctival sac swab, was the Dacron polyester swab.

Results

We examined one group of 302 COVID-19 patients, 168 Male (56%) and 134 Female (44%). The patients’ mean age was 66.3 ± 13.66 years, ranging from 25 to 96 years, and the mean length of hospital stay in our patients with a nasopharyngeal positive PCR test was 7.33 ± 4.76, from 2 to 24 days.

The PCR tests from the conjunctival sac swabs were positive in 33 patients (11%), negative in 259 patients (86%), and ten patients (3%) were with the unclear result. In the group of 33 positive patients were 17 males with a mean age of 74.6 ± 13.59 years and 16 females with a mean age of 70.63 ± 14.17 years.

The cycle threshold (C_T) values differed significantly between conjunctival sac swabs from the nasopharynx and the conjunctiva. Medians of the values were 25.1 (14.1, 32.1) and 31.5 (22.6, 36.6) (P <  0.001), respectively.

Conclusion

This study affirmed that in COVID-19 patients the SARS-CoV-2 was detectable with PCR test in conjunctival sac swab, but the positivity rate was only about one to ten cases (11%).

Ocular Distribution of the Renin-Angiotensin-Aldosterone System in the Context of the SARS-CoV-2 Pandemic

The COVID-19 pandemic has resulted in an unprecedented impact on global health, economy, and way of life. SARS-CoV-2, the virus responsible for the disease, utilizes the ACE2 receptor found on host cells to mediate entry, replication, and infection. Numerous studies have elucidated the presence of many components of the renin-angiotensin-aldosterone system (RAAS) in the eye, including the ACE2 receptor. Considering this, and the anatomical vulnerability that the exposed ocular surface offers with its interconnectedness to the respiratory system, there is a theoretical risk of pathogen entry from the ocular route as well as the development of COVID-19-associated eye disease. Despite this, the actual epidemiological data demonstrates low ocular symptoms, possibly due to differing ACE2 receptor expression across age, ethnicity, and sex coupled with the protective properties of tears. We summarize the current literature on ocular RAAS with specific focus on the ACE2 receptor and its interplay with the SARS-CoV-2 virus.

Impact of COVID-19 pandemic on ophthalmic presentations to an Australian outer metropolitan and rural emergency department: a retrospective comparative study

Background

To analyse ophthalmic presentations to an outer metropolitan and a rural emergency department (ED) during the first wave of the COVID-19 pandemic in New South Wales (NSW), Australia.

Methods

A retrospective comparative study of ophthalmic emergency presentations to Campbelltown Hospital (fifth busiest NSW metropolitan ED; population 310,000) and Bowral and District Hospital (rural ED; population 48,000) before and during COVID-19 was conducted. Patient demographics, triage category, referral source, diagnosis, length of stay, departure status, and follow-up location were assessed from coding data between March 1st to May 31st in 2019 and 2020, corresponding to the peak case numbers and restrictions during the first wave of the COVID-19 pandemic in NSW. Differences before and during COVID-19 were analysed using chi-squared tests or independent sample t-tests.

Results

There was no change in ophthalmic presentations at Campbelltown (n = 228 in 2019 vs. n = 232 in 2020; + 1.75%, p = 0.12) and an increase at Bowral (n = 100 in 2019 vs. n = 111 in 2020; + 11%, p < 0.01) during COVID-19. Urgent ophthalmic presentations (Triage Category 3) decreased at Bowral (p = 0.0075), while non-urgent ophthalmic presentations (Triage Category 5) increased at both hospitals (Campbelltown p < 0.05, Bowral p < 0.01).

Conclusions

There was no change in the total number of ophthalmic presentations to an outer metropolitan and an increase to a rural ED during the first wave of the COVID-19 pandemic in New South Wales, Australia. A change in the type of ophthalmic presentations at these peripheral EDs suggest that a high demand for ophthalmic services remained despite the pandemic and its associated gathering and movement restrictions. A flexible healthcare delivery strategy, such as tele-ophthalmology, may optimise patient care during and after COVID-19.

Ocular transmissibility of COVID-19: possibilities and perspectives

Since the initial outbreak of coronavirus disease 2019 (COVID-19), extensive research has emerged from across the globe to understand the pathophysiology of this novel coronavirus. Transmission of this virus is a subject of particular interest as researchers work to understand which protective and preventative measures are most effective. Despite the well understood model of aerosol-respiratory mediated transmission, the exact mechanism underlying the inoculation, infection and spread of COVID-19 is currently unknown. Given anatomical positioning and near constant exposure to aerosolized pathogens, the eye may be a possible gateway for COVID-19 infection. This critical review explores the possibility of an ocular-systemic or ocular-nasal-pulmonic pathway of COVID-19 infection and includes novel insights into the possible immunological mechanisms leading to cytokine surge.

SARS-CoV-2 and its beta variant of concern infect human conjunctival epithelial cells and induce differential antiviral innate immune response

PURPOSE

SARS-CoV-2 RNA has been detected in ocular tissues, but their susceptibility to SARS-CoV-2 infection is unclear. Here, we tested whether SARS-CoV-2 can infect human conjunctival epithelial cells (hCECs) and induce innate immune response.

METHODS

Conjunctival tissue from COVID-19 donors was used to detect SARS-CoV-2 spike and envelope proteins. Primary hCECs isolated from cadaver eyes were infected with the parental SARS-CoV-2 and its beta variant of concern (VOC). Viral genome copy number, and expression of viral entry receptors, TLRs, interferons, and innate immune response genes were determined by qPCR. Viral entry receptors were examined in hCECs and tissue sections by immunostaining. Spike protein was detected in the cell culture supernatant by dot blot.

RESULTS

Spike and envelope proteins were found in conjunctiva from COVID-19 patients. SARS-CoV-2 infected hCECs showed high viral copy numbers at 24-72h post-infection; spike protein levels were the highest at 24hpi. Viral entry receptors ACE2, TMPRSS2, CD147, Axl, and NRP1 were detected in conjunctival tissue and hCECs. SARS-CoV-2 infection-induced receptor gene expression peaked at early time points post-infection, but gene expression of most TLRs peaked at 48 or 72hpi. SARS-CoV-2 infected hCECs showed higher expression of genes regulating antiviral response, RIG-I, interferons (α, β, & λ), ISG15 & OAS2, cytokines (IL6, IL1β, TNFα), and chemokines (CXCL10, CCL5). Compared to the parental strain, beta VOC induced increased viral copy number and innate response in hCECs.

CONCLUSIONS

Conjunctival epithelial cells are susceptible to SARS-CoV-2 infection. Beta VOC is more infectious than the parental strain and evokes a higher antiviral and inflammatory response.

Prevalence of SARS-CoV-2 amongst ophthalmologists throughout the first and second waves of the pandemic

The study aims to investigate the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among ophthalmology unit staff throughout the first and second waves of the outbreak, in order to verify the effectiveness of the measures adopted in containing the contagion.A retrospective observational study was conducted involving staff members, who received a naso/oropharyngeal swab when complaining of SARS-CoV-2 symptoms and once a month as a screening measure. They were tested for SARS-CoV-2 antibodies as a screening measure during the first and the second wave. Clinical activities performed during the outbreak were compared with those performed during the same period in 2019 and correlated with the number of coronavirus disease-2019 eye care workers.Analysis included 25 workers. Clinical infection was 0% and 12% whereas the prevalence of SARS-CoV-2 antibodies ranged from 4% to 8% in the first and second wave, respectively. The increase in the prevalence of SARS-CoV-2 infection between the first and the second wave was not significant (1/25 vs 3/25, P = .6092). Clinical activities significantly decreased during the first wave compared with the same period in 2019 (3256 vs 10,075, P < .0001, -68% to 2019), but increased during the second wave (8208 vs 3256, P < .0001, +152% to the first wave).Despite the increase in routine activities during the second wave, we did not observe a significant increase in SARS-CoV-2 prevalence. Strict protection measures seemed to contain the rate of contagion among the ophthalmology unit members even in a high-volume clinical setting in one of the most affected area by the coronavirus disease-2019 outbreak.

Characteristics of Chlamydia suis Ocular Infection in Pigs

Chlamydia (C.) suis can often be isolated from conjunctival swab specimens from pigs with conjunctivitis or keratoconjunctivitis. In the field, it is assumed to be a multifactorial disease triggered by immunosuppressing factors. This is the first experimental study to provoke clinical signs of conjunctivitis in pigs after C. suis primary mono-infection. Five six-week-old male piglets, free of ocular chlamydia shedding and seronegative for Chlamydia, were conjunctivally infected with the C. suis-type strain S45 (1 × 10⁹ inclusion forming units), while four piglets served as negative controls. The infection group developed clinical signs of conjunctivitis with a peak in the first week post-infection. Immunohistochemical evaluation revealed the presence of Chlamydia not only in the conjunctival epithelium, but also in the enlarged lacrimal glands, lungs, and intestine. No circulating antibodies could be detected during the whole study period of three weeks, although three different test systems were applied as follows: the complement fixation test, MOMP-based Chlamydiaceae ELISA, and PmpC-based C. suis ELISA. Meanwhile, high numbers of IFN-γ-producing lymphocytes within PBMC were seen after C. suis re-stimulation 14 days post-infection. Hence, these data suggest that entry via the eye may not elicit immunological responses comparable to other routes of chlamydial infections.

COVID-19 Ocular Prophylaxis: The Potential Role of Ozonated-Oils in Liposome Eyedrop Gel

Purpose

To assess whether ozonated-oil in liposome eyedrop gel (OED) could be used to prevent the severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection in an in vitro infection model.

Methods

First, we tested the efficacy of OED on in vitro cell regeneration and dry eye resolution in human corneal epithelial cells (hCE-2). Second, we assessed the in vitro anti-SARS-CoV-2 infection efficacy of OED using Vero E6 cells. Tissues were examined to assess different parameters: morphology, histology, and mRNA expression at 24 hours after treatment.

Results

OED could restore 50% of the scratch in the monolayer of hCE-2 cells in vitro compared with the 25% obtained with phosphate-buffered saline solution (PBS). At 24 hours after treatment with OED, the number of microvilli and the mucin network were restored, as observed using scanning electron microscopy. In Vero E6 cells infected with a primary SARS-CoV-2 strain and treated with OED two times/day, viral replication was found to be inhibited, with a 70-fold reduction observed at 72 hours after infection compared with that under the untreated and PBS-treated conditions.

Conclusions

SARS-CoV-2 transmission through the ocular surface should not be ignored. Although the prevalence of coronavirus disease 2019 conjunctivitis infection is low, the need for a barrier to prevent possible viral infection is warranted. OED treatment may prevent the risk of SARS-CoV-2 infection after 72 hours of twice-daily applications.

Translational Relevance

Dry eye condition might be a risk factor for SARS-CoV-2 infection and OED treatment may have a preventive role.

Late Corneal Stromal Deposits After COVID-19

ABSTRACT

We present 2 cases of striking stromal corneal infiltrates months after COVID-19 infection. While we cannot prove that these infiltrates are caused by or directly related to COVID-19, we did not find any other plausible cause that could explain these ophthalmic signs. In these cases, the ongoing process was detected in relatively early stages due to scheduled visits with patients and responded positively to prednisolone acetate 1% ophthalmic suspension. However, we do not know the response to treatment in more advanced cases.

A Review on the Serum Electrolytes and Trace Elements Role in the Pathophysiology of COVID-19

All the world is involved in the COVID-19 disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Coronavirus is a positive-sense RNA and has an envelope. There is no specific drug for this disease and treatment methods are limited. Malnutrition and electrolyte imbalance can make dysfunction in the immune system and impairment of the immune system causes increasing the risk of infection. Understanding the aspects of biological features of the virus will help the development of diagnostic tests, pharmacological therapies, and vaccines. Here, we review and discuss increasing and decreasing some trace elements and imbalance of serum and plasma electrolytes involving in COVID-19.

Viral inhibitors derived from macroalgae, microalgae, and cyanobacteria: A review of antiviral potential throughout pathogenesis

Viruses are abiotic obligate parasites utilizing complex mechanisms to hijack cellular machinery and reproduce, causing multiple harmful effects in the process. Viruses represent a growing global health concern; at the time of writing, COVID-19 has killed at least two million people around the world and devastated global economies. Lingering concern regarding the virus' prevalence yet hampers return to normalcy. While catastrophic in and of itself, COVID-19 further heralds in a new era of human-disease interaction characterized by the emergence of novel viruses from natural sources with heretofore unseen frequency. Due to deforestation, population growth, and climate change, we are encountering more viruses that can infect larger groups of people with greater ease and increasingly severe outcomes. The devastation of COVID-19 and forecasts of future human/disease interactions call for a creative reconsideration of global response to infectious disease. There is an urgent need for accessible, cost-effective antiviral (AV) drugs that can be mass-produced and widely distributed to large populations. Development of AV drugs should be informed by a thorough understanding of viral structure and function as well as human biology. To maximize efficacy, minimize cost, and reduce development of drug-resistance, these drugs would ideally operate through a varied set of mechanisms at multiple stages throughout the course of infection. Due to their abundance and diversity, natural compounds are ideal for such comprehensive therapeutic interventions. Promising sources of such drugs are found throughout nature; especially remarkable are the algae, a polyphyletic grouping of phototrophs that produce diverse bioactive compounds. While not much literature has been published on the subject, studies have shown that these compounds exert antiviral effects at different stages of viral pathogenesis. In this review, we follow the course of viral infection in the human body and evaluate the AV effects of algae-derived compounds at each stage. Specifically, we examine the AV activities of algae-derived compounds at the entry of viruses into the body, transport through the body via the lymph and blood, infection of target cells, and immune response. We discuss what is known about algae-derived compounds that may interfere with the infection pathways of SARS-CoV-2; and review which algae are promising sources for AV agents or AV precursors that, with further investigation, may yield life-saving drugs due to their diversity of mechanisms and exceptional pharmaceutical potential.

Spontaneous face- and eye-touching: Infection risk versus potential microbiome gain

The COVID-19 pandemic has piqued interest in spontaneous face-touch as a possible route of microbial infection, with eye-touch of particular importance since the ocular surface is a likely portal of human Coronavirus infection. Spontaneous face-touching is a poorly understood, ingrained habit for humans, who engage in this activity on average between 9 to 162 times per hour. Nearly half of spontaneous face-touches involve mucous membranes, and one third of those involve the eyes. The infective sequelae of self-touch are well documented in ophthalmological conditions such as infectious conjunctivitis, with risks for ocular surface disease beyond primary infection from pathogens such as human papillomavirus. Through tear film conveyance via the nasolacrimal duct, ocular surface pathogens may furthermore have access to the nasopharynx, oropharynx, and respiratory/gastrointestinal systems beyond. Ocular surface and face self-touch therefore represent a concerning possible method of not only local, but also systemic, self-inoculation. Conversely, microbial diversity in the mutualistic microbiome is being increasingly implicated as integral for developing immunity, and protecting against endocrinological and neurodegenerative disease, including those that affect the eye. Spontaneous face-touch brings the hands, the part of the body most in contact with the external world and with the highest temporal diversity, into direct contact with the body’s multiple microbiomes. The authors hypothesise that spontaneous self-touch may represent an important mechanism by which the skin, ocular surface, gastrointestinal, and respiratory tracts maintains microbial diversity and prevents dysbiosis. It may be that whilst the eyes are at risk of infection through self-touch, they may paradoxically benefit through the acquisition of a mutualistic microbiome, protective not only for the eyes, but for the body as a whole.

SARS-CoV-2 RNA and antibodies in tear fluid

Background/aims

SARS-CoV-2 is highly contagious. More evidence concerning extrapulmonary transmission routes such as the eyes is urgently needed. Although the humoral immune response is important in the viral containment, the local response in tears has not yet been studied. The aim of our study was twofold: to assess the prevalence of both SARS-CoV-2 RNA and antibodies in tear fluid.

Methods

In a first series, nasopharyngeal sampling and tear sampling by Schirmer test strips were performed in 26 acutely ill patients with COVID-19 to assess the presence of SARS-CoV-2 RNA by reverse transcription PCR. In a second series, IgG and IgA responses to SARS-CoV-2 spike protein in serum and tear fluid of convalescent individuals (n=22) were compared with control individuals (n=15) by ELISA.

Results

SARS-CoV-2 RNA was detected in tears of 7/26 (26.9%) patients with COVID-19. None of them had ocular symptoms. Convalescent individuals displayed a significant higher ratio of IgG (p<0.0001) and IgA (p=0.0068) in tears compared with control individuals. A sensitivity of 77.3% and specificity of 93.3% was observed for IgG, and 59.1% and 100% for IgA.

Conclusions

Our results demonstrate the presence of SARS-CoV-2 RNA and a local IgG and IgA immune response in tear fluid. These data confirm the possibility of SARS-CoV-2 transmission through tear fluid and the importance of the eye as a first defence against SARS-CoV-2, indicating the potential of tears as a non-invasive surrogate for serum in monitoring the host immune response.

The therapeutic potential of inorganic polyphosphate: A versatile physiological polymer to control coronavirus disease (COVID-19)

Rationale: The pandemic caused by the novel coronavirus SARS-CoV-2 is advancing rapidly. In particular, the number of severe courses of the disease is still dramatically high. An efficient drug therapy that helps to improve significantly the fatal combination of damages in the airway epithelia, in the extensive pulmonary microvascularization and finally multiorgan failure, is missing. The physiological, inorganic polymer, polyphosphate (polyP) is a molecule which could prevent the initial phase of the virus life cycle, the attachment of the virus to the target cells, and improve the epithelial integrity as well as the mucus barrier. Results: Surprisingly, polyP matches perfectly with the cationic groove on the RBD. Subsequent binding studies disclosed that polyP, with a physiological chain length of 40 phosphate residues, abolishes the binding propensity of the RBD to the ACE2 receptor. In addition to this first mode of action of polyP, this polymer causes in epithelial cells an increased gene expression of the major mucins in the airways, of MUC5AC and MUC1, as well as a subsequent glycoprotein production. MUC5AC forms a gel-like mucus layer trapping inhaled particles which are then transported out of the airways, while MUC1 constitutes the periciliary liquid layer and supports ciliary beating. As a third mode of action, polyP undergoes enzymatic hydrolysis of the anhydride bonds in the airway system by alkaline phosphatase, releasing metabolic energy. Conclusions: This review summarizes the state of the art of the biotherapeutic potential of the polymer polyP and the findings from basic research and outlines future biomedical applications.

The Transmission of SARS-CoV-2 Infection on the Ocular Surface and Prevention Strategies

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a global health problem. Although the respiratory system is the main impaired organ, conjunctivitis is one of its common findings. However, it is not yet understood if SARS-CoV-2 can infect the eye and if the ocular surface can be a potential route of SARS-CoV-2 transmissions. Our review focuses on the viral entry mechanisms to give a better understanding of the interaction between SARS-CoV-2 and the eye. We highlighted findings that give evidence for multiple potential receptors of SARS-CoV-2 on the ocular surface. Additionally, we focused on data concerning the detection of viral RNA and its spike protein in the various ocular tissues from patients. However, the expression level seemed to be relatively low compared to the respiratory tissues as a result of a unique environment surrounding the ocular surface and the innate immune response of SARS-CoV-2. Nevertheless, our review suggests the ocular surface as a potential route for SARS-CoV-2 transmission, and as a result of this study we strongly recommend the protection of the eyes for ophthalmologists and patients at risk.

In the eye of the storm: SARS-CoV-2 infection and replication at the ocular surface?

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) first emerged in December 2019 and spread quickly causing the coronavirus disease 2019 (COVID‐19) pandemic. Recent single cell RNA‐Seq analyses have shown the presence of SARS‐CoV‐2 entry factors in the human corneal, limbal, and conjunctival superficial epithelium, leading to suggestions that the human ocular surface may serve as an additional entry gateway and infection hub for SARS‐CoV‐2. In this article, we review the ocular clinical presentations of COVID‐19 and the features of the ocular surface that may underline the overall low ocular SARS‐CoV‐2 infection. We critically evaluate the studies performed in nonhuman primates, ex vivo organ culture ocular models, stem cell derived eye organoids and the differences in infection efficiency observed in different parts of human ocular surface epithelium. Finally, we highlight the additional work that needs to be carried out to understand the immune response of the ocular surface to SARS‐CoV‐2 infection, which can be translated into prophylactic treatments that may be applied to other organ systems.

Evidence of SARS-CoV-2 Transmission Through the Ocular Route

PURPOSE

Currently, the coronavirus disease 2019 (COVID-19) pandemic is raging around the world. However, the transmission of its pathogen, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is not fully clear. It is still controversial whether the ocular transmission of SARS-CoV-2 exists. This review aimed to summarize the evidence of SARS-CoV-2 ocular transmission.

METHODS

Online articles were searched till October 23, 2020 in Pubmed, Embase, and websites of World Health Organization, Centers for Disease Control and Prevention COVID-19, American Academy of Ophthalmology, and American Society of Cataract and Refractive Surgery under the search strategy of (((("COVID-19"[Mesh]) OR ("SARS-CoV-2"[Mesh])) OR (2019 novel coronavirus)) OR (2019-nCoV)) AND (((("Conjunctivitis"[Mesh]) OR (Ocular Surface)) OR ("Eye"[Mesh])) OR ("Ophthalmology"[Mesh])). The language was not restricted. After screening, 1445 records were excluded and 168 references original articles were finally included.

RESULTS

Cells of ocular surface express both the receptor of angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2), offering molecular bases for the ocular susceptibility to SARS-CoV-2. Accumulated COVID-19 patients presented conjunctivitis as the initial or the only symptom. Whether COVID-19 patients had ocular symptoms or not, SARS-CoV-2 was detectable on the ocular surface, and the isolated virus was infectious, proving that the ocular surface can not only be a reservoir but also a source of contagion. SARS-CoV-2 may reach the ocular surface by hand-eye contact and aerosols. Once SARS-CoV-2 reaches the ocular surface, it may transfer to other systems through the nasolacrimal system or hematogenous metastasis.

CONCLUSION

The ocular surface can serve as a reservoir and source of contagion for SARS-CoV-2. SARS-CoV-2 can be transmitted to the ocular surface through hand-eye contact and aerosols, and then transfer to other systems through nasolacrimal route and hematogenous metastasis. The possibility of ocular transmission of SARS-CoV-2 cannot be ignored.

SARS-COV-2 and Ocular Surface: From Physiology to Pathology, a Route to Understand Transmission and Disease

Coronaviruses gained public attention during the severe acute respiratory syndrome (SARS) outbreak in East Asia in 2003 and spread of Middle Eastern respiratory syndrome (MERS) in 2012. Direct human-to-human contact and droplet are the main methods of transmission. Viral stability in aerosols on different surfaces supports evidence on indirect viral acquisition from fomites through the mucous membranes of the mouth, nose, and eyes. Given the pandemic circumstances, the level of evidence in COVID-19 and ophthalmology regarding eye infection, conjunctival transmission, and viral shedding through tears is insufficient. Presently, conjunctival transmission of coronaviruses has not been confirmed and remains controversial. Considering the physiology of the lacrimal system and ocular surface, the eyes are considered an immunoprotective site, with several antiviral molecules and anti-inflammatory proteins. Nevertheless, they represent an interface with the exterior world and face daily putative aggressors. Understanding the host's ocular surface immunological and protective environment is crucial to clarify the potential of the conjunctiva as an entry route for SARS-CoV-2 and as part of this viral infection. We will discuss hypothetical ocular surface transmission mechanisms and related counterarguments addressed to both angiotensin-converting enzyme 2 receptors found on the conjunctival and corneal epithelia and lactoferrin, lysozyme, lipocalin and secretory IgA levels in the tear film. Hopefully, we will promote better understanding of this organ in COVID-19 infection and the potential transmission route that can be helpful in setting recommendations on best practices and protective guidelines to mitigate the disease spread.

Review of Clinical and Operative Recommendations for Ophthalmology Practices During the COVID-19 Pandemic

In response to climbing global case and fatality rates of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its associated disease, COVID-19, ophthalmology practices have modified their clinical and operative approach to patient care in an attempt to reduce spread of the virus. The presence of SARS-CoV-2 viral RNA in the preocular tear film raises speculation that the ocular surface can act as an initial site of infection as well as a potential source of person-to-person viral transmission. More recently, conjunctival specimens and immunohistochemical analyses have identified the presence of cellular surface factors necessary for SARS-CoV-2 infection on the ocular surface. Together, these results highlight the importance of safety measures in ophthalmology practices to prevent transmission of SARS-CoV-2. As ophthalmic exams typically require close proximity between a patient's respiratory tract and the provider, clinical and surgical recommendations are aimed at reducing unnecessary patient-provider interactions. Subspecialty professional guidelines can be used to instruct ophthalmologists on the necessity of various procedures and best practice measures. Ophthalmology practice during the COVID-19 pandemic has been dramatically curtailed in an effort to reduce the risk of transmission and converse valuable personal protective equipment (PPE), and the impacts of the ongoing pandemic on ophthalmology practices will be felt for the foreseeable future.

Smart polymeric eye gear: A possible preventive measure against ocular transmission of COVID-19

The angiotensin-converting enzyme 2(ACE-2) receptors with approx. 0.8% congestion in conjunctival surface, leads to increase susceptibility of Covid-19 transmission through ocular surface. It has been observed that prophylactic measures such as goggle or face shield are unable to offer complete protection against ocular transmission of SRS-CoV-2. Hence, it is hypothesized that topical ocular prophylaxis using biocompatible polymers with reported in-vitro and in-vivo evidence of ACE inhibition and antiviral activity appears to be a promising strategy for preventing ocular transmission of Covid-19 to healthcare workers. They are capable of binding to ACE-2 receptors which may provide highly potential trails to block virus entry to host cells. Further biopolymers imparting antiviral activities greatly improve their protective performance. They not only provide prolong protection but also are safe for long-term use. This article discusses the description of structural and functional attributes of ACE-2 to identify appropriate polymer with better binding affinity. Furthermore, potential polymers with appropriate concentration are suggested for evaluation through a hypothesis to consider them for Covid-19 implication.

Pharmacogenomics and Pharmacogenetics: In Silico Prediction of Drug Effects in Treatments for Novel Coronavirus SARS-CoV2 Disease

The latest developments in precision medicine allow the modulation of therapeutic approaches in different pathologies on the basis of the specific molecular characterization of the patient. This review of the literature coupled with in silico analysis was to provide a selected screening of interactions between single-nucleotide polymorphisms (SNPs) and drugs (repurposed, investigational, and biological agents) showing efficacy and toxicityin counteracting Covid-19 infection. In silico analysis of genetic variants related to each drug was performed on such databases as PharmGKB, Ensembl Genome Browser, www.drugs.com, and SNPedia, with an extensive literature review of papers (to May 10, 2020) on Covid-19 treatments using Medline, Embase, International Pharmaceutical Abstracts, PharmGKB, and Google Scholar. The clinical relevance of SNPs, known as both drug targets and markers, considering genetic variations with known drug responses, and the therapeutic consequences are discussed. In the context of clinical treatment of Covid-19, including infection prevention, control measures, and supportive care, this review highlights the importance of a personalized approach in the final selection of therapy, which is probably essential in the management of the Covid-19 pandemic.

The Outcome and Implications of Public Precautionary Measures in Taiwan-Declining Respiratory Disease Cases in the COVID-19 Pandemic

With the rapid development of the COVID-19 pandemic, countries are trying to cope with increasing medical demands, and, at the same time, to reduce the increase of infected numbers by implementing a number of public health measures, namely non-pharmaceutical interventions (NPIs). These public health measures can include social distancing, frequent handwashing, and personal protective equipment (PPE) at the personal level; at the community and the government level, these measures can range from canceling activities, avoiding mass gatherings, closing facilities, and, at the extreme, enacting national or provincial lockdowns. Rather than completely stopping the infectious disease, the major purpose of these NPIs in facing an emerging infectious disease is to reduce the contact rate within the population, and reduce the spread of the virus until the time a vaccine or reliable medications become available. The idea is to avoid a surge of patients with severe symptoms beyond the capacity of the hospitals’ medical resources, which would lead to more mortality and morbidity. While many countries have experienced steep curves in new cases, some, including Hong Kong, Vietnam, South Korea, New Zealand, and Taiwan, seem to have controlled or even eliminated the infection locally. From its first case of COVID-19 on the 21 January until the 12 May, Taiwan had 440 cases, including just 55 local infections, and seven deaths in total, representing 1.85 cases per 100,000 population and a 1.5% death rate (based on the Worldometer 2020 statistics of Taiwan’s population of 23.8 million). This paper presents evidence that spread prevention involving mass masking and universal hygiene at the early stage of the COVID-19 pandemic resulted in a 50% decline of infectious respiratory diseases, based on historical data during the influenza season in Taiwan. These outcomes provide potential support for the effectiveness of widely implementing public health precaution measures in controlling COVID-19 without a lockdown policy.