On the impact of mass screening for SARS-CoV-2 through self-testing in Greece.

Background: Screening programs that pre-emptively and routinely test population groups for disease at a massive scale were first implemented during the COVID-19 pandemic in a handful of countries. One of these countries was Greece, which implemented a mass self-testing program during 2021. In contrast to most other non-pharmaceutical interventions (NPIs), mass self-testing programs are particularly attractive for their relatively small financial and social burden, and it is therefore important to understand their effectiveness to inform policy makers and public health officials responding to future pandemics. This study aimed to estimate the number of deaths and hospitalizations averted by the program implemented in Greece and evaluate the impact of several operational decisions. Methods: Granular data from the mass self-testing program deployed by the Greek government between April and December 2021 were obtained. The data were used to fit a novel compartmental model that was developed to describe the dynamics of the COVID-19 pandemic in Greece in the presence of self-testing. The fitted model provided estimates on the effectiveness of the program in averting deaths and hospitalizations. Sensitivity analyses were used to evaluate the impact of operational decisions, including the scale of the program, targeting of sub-populations, and sensitivity (i.e., true positive rate) of tests. Results: Conservative estimates show that the program reduced the reproduction number by 4%, hospitalizations by 25%, and deaths by 20%, translating into approximately 20,000 averted hospitalizations and 2,000 averted deaths in Greece between April and December 2021. Conclusion: Mass self-testing programs are efficient NPIs with minimal social and financial burden; therefore, they are invaluable tools to be considered in pandemic preparedness and response.

Non-Healing Corneal Ulcer and Uveitis Following Monkeypox Disease: Diagnostic and Therapeutic Challenges.

PURPOSE: The ocular manifestations of Monkeypox virus (Mpox) infection remain incompletely characterized. Our goal is to present a case series of non-healing corneal ulcers with associated uveitis caused by Mpox infection as well as management recommendations for Mpox-related ophthalmic disease (MPXROD). METHODS: Retrospective case series. RESULTS: Two male patients with recent hospitalization for systemic Mpox infection presented with non-healing corneal ulcer associated with anterior uveitis and severe IOP elevation. Despite initiation of conservative medical treatment including corticosteroid treatment for uveitis, in both cases, there was clinical progression with enlarging cornea lesions. Both cases received oral tecovirimat with complete healing of the corneal lesion. CONCLUSIONS: Corneal ulcer and anterior uveitis are rare complications of Mpox infection. Although Mpox disease is generally anticipated to be self-limited, tecovirimat may be an effective intervention in poorly healing Mpox keratitis. Corticosteroids should be used with caution in Mpox uveitis, as they might lead to worsening infection.

Influenza transmission during COVID-19 measures downscaling in Greece, August 2022: evidence for the need of continuous integrated surveillance of respiratory viruses.

After the near absence of influenza and other respiratory viruses during the first 2 years of the COVID-19 pandemic, an increased activity of mainly influenza A(H3N2) was detected at the beginning of August 2022 in Greece on three islands. Of 33 cases with respiratory symptoms testing negative for SARS-CoV-2 with rapid antigen tests, 24 were positive for influenza: 20 as A(H3N2) subtype and four as A(H1N1)pdm09 subtype. Phylogenetic analysis of selected samples from both subtypes was performed and they fell into clusters within subclades that included the 2022/23 vaccine strains. Our data suggest that influenza can be transmitted even in the presence of another highly infectious pathogen, such as SARS-CoV-2, with a similar transmission mode. We highlight the need for implementing changes in the current influenza surveillance and suggest a move from seasonal to continuous surveillance, especially in areas with a high number of tourists. Year-round surveillance would allow for a timelier start of vaccination campaigns and antiviral drugs procurement processes.

Overview of Mpox Outbreak in Greece in 2022-2023: Is It Over?

In May 2022, for the first time, multiple cases of mpox were reported in several non-endemic countries. The first ever case of the disease in Greece was confirmed on 8 June 2022, and a total of 88 cases were reported in the country until the end of April 2023. A multidisciplinary response team was established by the Greek National Public Health Organization (EODY) to monitor and manage the situation. EODY's emergency response focused on enhanced surveillance, laboratory testing, contact tracing, medical countermeasures, and the education of health care providers and the public. Even though management of cases was considered successful and the risk from the disease was downgraded, sporadic cases continue to occur. Here, we provide epidemiological and laboratory features of the reported cases to depict the course of the disease notification rate. Our results suggest that measures for raising awareness as well as vaccination of high-risk groups of the population should be continued.

Time Lag between COVID-19 Diagnosis and Symptoms Onset for Different Population Groups: Evidence That Self-Testing in Schools Was Associated with Timely Diagnosis among Children.

Early identification of COVID-19 cases has been vital for reducing transmission and enabling treatment. In Greece, in autumn 2021 when Delta was the predominant circulating variant, unvaccinated citizens had to be tested before attending activities, and self-testing was required twice a week for students (5−17 years). Here, we describe the time of diagnosis by age group and possible exposure to assess testing strategies (September to November 2021). Information on the presence of symptoms at the time of diagnosis was available for 69,298 cases; 24,855 (36%) were asymptomatic or tested the same day as onset (early diagnosis), 21,310 (31%) reported testing one day after, and 23,133 (33%) did so two or more days after the onset of symptoms. The median lag was 2 days (1−14). Early diagnosis significantly differed among age groups (p-value < 0.001) and was higher among children. For every one-year increase of age, the odds of an early diagnosis were reduced by 1%. Cases exposed during training activities or in settings such as accommodation centers and hospitals were more frequently diagnosed early. The percentage of persons having a positive self-test before a rapid test/PCR diagnosis ranged from 7% in the age group of 60 years and above to 86% in the age group of 5−17 years. The provision of self-tests in schools and increased testing in closed settings led to an earlier diagnosis and probably to a decreased transmission of the virus in the period during which Delta was the predominant variant in Greece. However, more effort is needed for early diagnosis of adults in the community, especially after the onset of symptoms.

Development and Analytical Validation of a One-Step Five-Plex RT-ddPCR Assay for the Quantification of SARS-CoV-2 Transcripts in Clinical Samples.

Highly sensitive methodologies for SARS-CoV-2 detection are essential for the control of COVID-19 pandemic. We developed and analytically validated a highly sensitive and specific five-plex one-step RT-ddPCR assay for SARS-CoV-2. We first designed in-silico novel primers and probes for the simultaneous absolute quantification of three different regions of the nucleoprotein (N) gene of SARS-CoV-2 (N1, N2, N3), a synthetic RNA as an external control (RNA-EC), and Beta-2-Microglobulin (B2M) as an endogenous RNA internal control (RNA-IC). The developed assay was analytically validated using synthetic DNA and RNA calibrator standards and then was applied to 100 clinical specimens previously analyzed with a commercially available CE-IVD RT-qPCR assay. The analytical validation of the developed assay resulted in very good performance characteristics in terms of analytical sensitivity, linearity, analytical specificity, and reproducibility and recovery rates even at very low viral concentrations. The simultaneous absolute quantification of the RNA-EC and RNA-IC provides the necessary metrics for quality control assessment. Direct comparison of the developed one-step five-plex RT-ddPCR assay with a CE-IVD RT-qPCR kit revealed a very high concordance and a higher sensitivity [concordance: 99/100 (99.0%, Spearman's correlation coefficient: -0.850, p < 0.001)]. The developed assay is highly sensitive, specific, and reproducible and has a broad linear dynamic range, providing absolute quantification of SARS-COV-2 transcripts. The inclusion of two RNA quality controls, an external and an internal, is highly important for standardization of SARS-COV-2 molecular testing in clinical and wastewater samples.

Cold-Season Epidemic Dynamics of COVID-19 in Two Major Metropolitan Areas in Greece: Hypotheses and Implications for Public Health Interventions.

Many respiratory viruses, including coronaviruses, follow seasonal transmission dynamics. Analyzing the social and environmental mechanics of the emergence of SARS-CoV-2 over the first cold season provides insight into designing targeted interventions. We analyzed all fully anonymized SARS-CoV-2 case data in two metropolitan areas, Attika and Thessaloniki, diagnosed between September 1st and December 31st, 2020. The emergence of the second wave in Greece occurred in October-November. SARS-CoV-2 diagnoses in Thessaloniki increased quasi-exponentially in mid-October, coinciding with the increase in the proportion of diagnoses in young people aged 18-39. The same pattern was observed in Attika with an almost 2-week delay, even though Attika had a higher prevalence of cases throughout summer until the second wave. Crucially, the nighttime temperature in Thessaloniki dropped below 18°C 3 weeks earlier than that in Attika. Epidemic growth was independently associated with the proportion of cases attributed to the 18-39 age group as well as with the drop in nighttime temperature below 18°C in both metropolitan areas but with a time difference. This pattern can be explained by a shift of nighttime entertainment activities from open-air to closed spaces, which occurs as nighttime temperature drops. Vaccination of young individuals can be crucial in decelerating the cold-season dynamics of SARS-CoV-2.

Low circulation of respiratory syncytial and influenza viruses during autumn-winter 2021 in the industrial workplace and long-term healthcare facilities in Athens, Greece.

The emergence of SARS-CoV-2 has pinpointed the importance of non-pharmaceutical interventions (NPIs), which have been traditionally used for the prevention of the spread of respiratory viruses among individuals. The aim of our study was to capture the level of circulation of respiratory syncytial and influenza viruses during a period of medium severity NPIs due to SARS-CoV-2 pandemics in Greece. A total of 2,225 nasopharyngeal samples were received during the year 2021 as a part of the routine diagnostic service and were divided into two study groups: (a) January to September 2021 and (b) October to the end of December 2021. The latter is the time of the year when there is a peak of infections from most respiratory viruses, and thus, most of the samples were tested in that period. The samples were taken from three different sites, i.e., (a) industrial workers in a factory, (b) elderly homecare facilities, and c) people who actively asked to be tested for SARS-CoV-2. All the samples were tested simultaneously for SARS-CoV2, RSV, and influenza virus. A total of 2,110 samples were negative for either of the three viruses, 106 were SARS-CoV-2-positive, and 9 were RSV-positive from which 7 were found in the workers' group. None of the samples was found to be positive for the influenza virus, and no sample had co-infection. Our study shows the low-level circulation of RSV and influenza viruses during autumn-winter 2021 and will provide a reference for future studies of RSV and influenza in Greece.

Upregulation of Human Endogenous Retroviruses in Bronchoalveolar Lavage Fluid of COVID-19 Patients.

Severe COVID-19 pneumonia has been associated with the development of intense inflammatory responses during the course of infections with SARS-CoV-2. Given that human endogenous retroviruses (HERVs) are known to be activated during and participate in inflammatory processes, we examined whether HERV dysregulation signatures are present in COVID-19 patients. By comparing transcriptomes of bronchoalveolar lavage fluid (BALF) of COVID-19 patients and healthy controls, and peripheral blood monocytes (PBMCs) from patients and controls, we have shown that HERVs are intensely dysregulated in BALF of COVID-19 patients compared to those in BALF of healthy control patients but not in PBMCs. In particular, upregulation in the expression of specific HERV families was detected in BALF samples of COVID-19 patients, with HERV-FRD being the most highly upregulated family among the families analyzed. In addition, we compared the expression of HERVs in human bronchial epithelial cells (HBECs) without and after senescence induction in an oncogene-induced senescence model in order to quantitatively measure changes in the expression of HERVs in bronchial cells during the process of cellular senescence. This apparent difference of HERV dysregulation between PBMCs and BALF warrants further studies in the involvement of HERVs in inflammatory pathogenetic mechanisms as well as exploration of HERVs as potential biomarkers for disease progression. Furthermore, the increase in the expression of HERVs in senescent HBECs in comparison to that in noninduced HBECs provides a potential link for increased COVID-19 severity and mortality in aged populations. IMPORTANCE SARS-CoV-2 emerged in late 2019 in China, causing a global pandemic. Severe COVID-19 is characterized by intensive inflammatory responses, and older age is an important risk factor for unfavorable outcomes. HERVs are remnants of ancient infections whose expression is upregulated in multiple conditions, including cancer and inflammation, and their expression is increased with increasing age. The significance of this work is that we were able to recognize dysregulated expression of endogenous retroviral elements in BALF samples but not in PBMCs of COVID-19 patients. At the same time, we were able to identify upregulated expression of multiple HERV families in senescence-induced HBECs in comparison to that in noninduced HBECs, a fact that could possibly explain the differences in disease severity among age groups. These results indicate that HERV expression might play a pathophysiological role in local inflammatory pathways in lungs afflicted by SARS-CoV-2 and their expression could be a potential therapeutic target.

Molecular Epidemiology of SARS-CoV-2 in Greece Reveals Low Rates of Onward Virus Transmission after Lifting of Travel Restrictions Based on Risk Assessment during Summer 2020.

The novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread rapidly during the first months of 2020 and continues to expand in multiple areas across the globe. Molecular epidemiology has provided an added value to traditional public health tools by identifying SARS-CoV-2 clusters or providing evidence that clusters based on virus sequences and contact tracing are highly concordant. Our aim was to infer the levels of virus importation and to estimate the impact of public health measures related to travel restrictions to local transmission in Greece. Our phylogenetic and phylogeographic analyses included 389 full-genome SARS-CoV-2 sequences collected during the first 7 months of the pandemic in Greece and a random collection in five replicates of 3,000 sequences sampled globally, as well as the best hits to our data set identified by BLAST. Phylogenetic trees were reconstructed by the maximum likelihood method, and the putative source of SARS-CoV-2 infections was inferred by phylogeographic analysis. Phylogenetic analyses revealed the presence of 89 genetically distinct viruses identified as independent introductions into Greece. The proportion of imported strains was 41%, 11.5%, and 8.8% during the three periods of sampling, namely, March (no travel restrictions), April to June (strict travel restrictions), and July to September (lifting of travel restrictions based on thorough risk assessment), respectively. The results of phylogeographic analysis were confirmed by a Bayesian approach. Our findings reveal low levels of onward transmission from imported cases during summer and underscore the importance of targeted public health measures that can increase the safety of international travel during a pandemic. IMPORTANCE Our study based on current state-of-the-art molecular epidemiology methods suggests that virus screening and public health measures after the lifting of travel restrictions prevented SARS-CoV-2 onward transmission from imported cases during summer 2020 in Greece. These findings provide important data on the efficacy of targeted public health measures and have important implications regarding the safety of international travel during a pandemic. Our results can provide a roadmap about prevention policy in the future regarding the reopening of borders in the presence of differences in vaccination coverage, the circulation of the virus, and the presence of newly emergent variants across the globe.

COVID-19 Outbreak on a Passenger Ship and Assessment of Response Measures, Greece, 2020.

We describe response measures to an outbreak involving 128 (33.4%) coronavirus disease cases (46.1% asymptomatic) among 383 persons onboard a passenger ship. Multivariate analysis indicated that dining in certain rooms and bar areas, nationality, working department (for crew members), and quarantining onboard the ship were significantly associated with infection.

In-flight transmission of COVID-19 on flights to Greece: An epidemiological analysis.

BACKGROUND: The emergence in China in late 2019 and subsequent progression of a pandemic of a respiratory disease named coronavirus disease 2019 (COVID-19) was highly facilitated by international travel. We present 5 cases of probable in-flight transmission in Greece. METHODS: We studied international passengers arriving to or departing from Greece from February 26 through March 9, 2020. Contact tracing extended up to 4 days before the onset of symptoms and focused on close contacts. Close contacts were defined as persons sitting within a distance of <2 m for >15 min, including passengers seated two seats around the index case and all crew members and persons who had close contact with the index case. RESULTS: We investigated 18 international flights with 2224 passengers and 110 crew members. Main countries of departure included Northern Italy, Israel and the United Kingdom. In accordance with the national surveillance investigation, in these flights there were 21 index cases and 891 contact traced cases. Six index cases were symptomatic during the flight. Of the 891 contact traced cases, 4 passengers and 1 crew member developed laboratory-confirmed infection (3 with COVID-19 and 2 with asymptomatic infection); they travelled on the same flight with two COVID-19 cases. CONCLUSIONS: Air travel has played a central role in the progression of the COVID-19 pandemic. However, there are scarce data about in-flight transmission. Our extensive investigation showed five cases of probable in-flight transmission. Efforts should be placed in order to ensure the prompt implementation of appropriate infection control measures on board.

Environmental contamination of SARS-CoV-2 on surfaces, air-conditioner and ventilation systems.

BACKGROUND: COVID-19 can be transmitted directly through respiratory droplets or indirectly through fomites. SARS-CoV-2 has been detected on various environmental surfaces, air samples and sewage in hospital and community settings. METHODS: Environmental samples were collected from a ferryboat during a COVID-19 ongoing outbreak investigation and a nursing home and from three COVID-19 isolation hospital wards and a long-term care facility where asymptomatic COVID-19 cases were isolated. Samples were tested by real-time reverse transcriptase-polymerase chain reaction. RESULTS: SARS-CoV-2 was detected on swab samples taken from surfaces of food preparation and service areas, hospital isolation wards, an air exhaust duct screen, air-conditioning filter, sewage treatment unit and air sample during investigations conducted in response to COVID-19 outbreaks on a ferryboat, nursing home, isolation facility and COVID-19 hospital wards. DISCUSSION: Food preparation areas and utensils can be contaminated during COVID-19 outbreaks. Respiratory droplets/nuclei from infected persons can be displaced by the air flow and deposited on surfaces. It can be assumed that in the same manner, air flow could transfer and deposit infected respiratory droplets/nuclei from infected persons to the mucous membranes of persons standing against the air flow direction.