1892. Rise of COVID-19 Re-infections as Omicron Variant Prevailed: Implications on Monitoring the Course of the Pandemic

Background

The emergence of the highly infectious Omicron variant at the end of 2021 changed the pandemic dynamics, also causing an increase in COVID-19 re-infections. Our aim was to investigate suspected re-infections and the characteristics of individuals with multiple infections since the beginning of the pandemic until early April 2022.

Methods

Since the beginning of the pandemic, all COVID-19 positive tests (Rapid Antigen Tests - RAT and PCR) have been recorded in the COVID-19 National Electronic Registry. Cases were extracted and reported daily based on the first positive test for each individual (first episodes). Establishment of the Omicron variant, associated with a re-infection surge, triggered the decision for modifying case definition and applying a different methodology to include suspected re-infections in the number of daily reported cases after 3^rd of April. Suspected re-infections were defined as “positive PCR or RAT sample ≥90 days following a previous positive PCR or RAT”. The number of re-infections were estimated retrospectively on the Registry’s data.

Results

Overall, 6,348 suspected re-infections were recorded up to 15/12/2021 (0.6% of the laboratory confirmed tests), whereas until 3/4/22 the number was increased at 115.201, raising the percentage to 4%. Distribution of the number of reinfections per ISO week is depicted in Figure 1, along with the number of first episodes. Suspected re-infections stand for 3.7% of the total number of first episodes recorded up to 3/4/22 (3,077,711), with their integration having a noticeable effect on case counting. Among them, 99.3% represent a second episode of infection and 0.7% multiple re-infections. Median age of suspected re-infections was 29 years (IQR: 19-44) (Figure 2). The median length of the time interval between two subsequent infections was 8 months (IQR: 5-12) (Figure 3).

Conclusion

Up until mid-December 2021, COVID-19 re-infection was uncommon, changing to higher rates after the emergence of Omicron variant, thus documenting the immune escape capacity of this variant. Besides the improvement in surveillance, knowledge about the re-infections and their characteristics provides a proxy of the immune protection from previous exposure to COVID-19, against circulating variants over time.

Disclosures

All Authors: No reported disclosures.

The COVID-19 pandemic as inspiration to reconsider epidemic models: A novel approach to spatially homogeneous epidemic spread modeling

Epidemic spread models are useful tools to study the spread and the effectiveness of the interventions at a population level, to an epidemic. The workhorse of spatially homogeneous class models is the SIR-type ones comprising ordinary differential equations for the unknown state variables. The transition between different states is expressed through rate functions. Inspired by -but not restricted to- features of the COVID-19 pandemic, a new framework for modeling a disease spread is proposed. The main concept refers to the assignment of properties to each individual person as regards his response to the disease. A multidimensional distribution of these properties represents the whole population. The temporal evolution of this distribution is the only dependent variable of the problem. All other variables can be extracted by post-processing of this distribution. It is noteworthy that the new concept allows an improved consideration of vaccination modeling because it recognizes vaccination as a modifier of individuals response to the disease and not as a means for individuals to totally defeat the disease. At the heart of the new approach is an infection age model engaging a sharp cut-off. This model is analyzed in detail, and it is shown to admit self-similar solutions. A hierarchy of models based on the new approach, from a generalized one to a specific one with three dominant properties, is derived. The latter is implemented as an example and indicative results are presented and discussed. It appears that the new framework is general and versatile enough to simulate disease spread processes and to predict the evolution of several variables of the population during this spread.

Relating SARS-CoV-2 shedding rate in wastewater to daily positive tests data: A consistent model based approach

During the COVID-19 pandemic, wastewater-based epidemiology (WBE) has been engaged to complement medical surveillance and in some cases to also act as an early diagnosis indicator of viral spreading in the community. Most efforts worldwide by the scientific community and commercial companies focus on the formulation of protocols for SARS-CoV-2 analysis in wastewater and approaches addressing the quantitative relationship between WBE and medical surveillance are lacking. In the present study, a mathematical model is developed which uses as input the number of daily positive medical tests together with the highly non-linear shedding rate curve of individuals to estimate the evolution of global virus shedding rate in wastewater along calendar days. A comprehensive parametric study by the model using as input actual medical surveillance and WBE data for the city of Thessaloniki (~700,000 inhabitants, North Greece) during the outbreak of November 2020 reveals the conditions under which WBE can be used as an early warning tool for predicting pandemic outbreaks. It is shown that early warning capacity is different along the days of an outbreak and depends strongly on the number of days apart between the day of maximum shedding rate of infected individuals in their disease cycle and the day of their medical testing. The present data indicate for Thessaloniki an average early warning capacity of around 2 days. Moreover, the data imply that there exists a proportion between unreported cases (asymptomatic persons with mild symptoms that do not seek medical advice) and reported cases. The proportion increases with the number of reported cases. The early detection capacity of WBE improves substantially in the presence of an increasing number of unreported cases. For Thessaloniki at the peak of the pandemic in mid-November 2020, the number of unreported cases reached a maximum around 4 times the number of reported cases.

Comparative study of surgical wound closure with nylon interrupted sutures and running subcuticular vicryl rapide suture after open release of the carpal tunnel

BACKGROUND

Surgical decompression of the carpal tunnel is considered the method of choice for its treatment with satisfactory results documented. Various methods and suturing materials have been used for closure of the surgical wound. In the present study, we compared interrupted mattress closure by means of nylon suture to running subcuticular closure with vicryl rapide suture. As far as we know, there is no similar study in the literature.

METHODS

A total of twenty patients were included in the study. Ten of them had their surgical wound closed with 3.0 nylon suture in an interrupted fashion and for the rest, a running subcuticular 3.0 vicryl rapide was used. All patients filled in a questionnaire about VAS perceived pain and a Quick DASH score sheet, preoperatively, at two and six weeks postoperatively. The cosmesis of the scar was assessed using the POSAS v2.0 system at two and six weeks after surgery and overall incidence of infections was noted as well.

RESULTS

There was no statistically important difference between the two groups of patients in regards to postoperative VAS pain levels at two and six weeks. Likewise, no statistically significant difference was evident as far as Quick DASH score, POSAS score and infections were concerned.

CONCLUSIONS

Our results suggest that the use of running subcuticular vicryl rapide suture is an attractive alternative to interrupted nylon sutures for closure after open carpal tunnel decompression, lacking any significant drawbacks.

LAY SUMMARY

Surgery for carpal tunnel decompression is considered the method of choice for its treatment with documented satisfactory results. Various methods and suturing materials have been used for closure of the surgical wound. In the present study, we compared the use of a non-absorbable suture, placed intermittently to an absorbable continuous intradermal suture. A total of twenty patients were included in the study. Half of them had their wound closed with the absorbable suture and the other half with the non-absorbable suture, as described above. All patients were evaluated as far as pain, scar characteristics, functional outcomes of the operated hand and incidence of infection, at two and six weeks after surgery. After analysis of the data, no significant differences were found between the two groups, suggesting that both of these techniques are equally safe and efficacious.

Efficacy of fesoterodine fumarate (8 mg) in neurogenic detrusor overactivity due to spinal cord lesion or multiple sclerosis: A prospective study

AIMS

Antimuscarinic drugs are the first-line choice in the treatment of patients with neurogenic Detrusor Overactivity (nDO). Fesoterodine fumarate is the newest antimuscarinic drug. Limited data are published about the use of fesoterodine fumarate in patients suffering from neurogenic lower urinary tract dysfunction. Our study aims to determine the efficacy of fesoterodine fumarate on patients with nDO due to spinal cord lesion or multiple sclerosis (MS).

METHODS

This is an open-label prospective interventional study. Eligible patients were 18-80 years old with SCL or MS and nDO confirmed by a urodynamic study (UDS). At baseline, patients underwent a UDS to confirm nDO. Quality of life (QoL) was assessed by the Short-Form (SF) Qualiveen questionnaire. Patients received fesoterodine 8 mg/day for 3 months and were re-evaluated with UDS and SF-Qualiveen. The primary endpoint was the confirmation of the maximum detrusor pressure (P_detmax ) reduction after treatment. Secondary endpoints were: evaluation of maximum bladder capacity and compliance and QoL effect. Statistical analysis included Wilcoxon-test using SPSSv26.

RESULTS

One hundred and twenty-four patients completed the study. Ninety-five of them (76.6%) had SCL, while 29 (23.4%) had MS. P_detmax , maximum bladder capacity, and compliance had significant reduction after treatment (p < .001) in the whole group and each subgroup. SF-Qualiveen revealed a significant increase in QoL in each group (p < .001).

CONCLUSIONS

Fesoterodine fumarate (8 mg) is an efficacious drag in patients with SCL and MS, as it significantly decreases the detrusor pressure, increases the bladder capacity and compliance, and improves the QoL.

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.