Reinfection risk of novel coronavirus (COVID-19): A systematic ‎review of current evidence

Role of viruses in periodontitis: An extensive review of herpesviruses, human immunodeficiency virus, coronavirus-19, papillomavirus and hepatitis viruses

Periodontitis is the inflammation of the supporting structures around the dentition. Several microbial agents, mostly bacteria, have been identified as causative factors for periodontal disease. On the other hand, oral cavity is a rich reservoir for viruses since it contains a wide variety of cell types that can be targeted by viruses. Traditionally, the focus of research about the oral flora has been on bacteria because the most widespread oral diseases, like periodontitis and dental caries, are outcomes of bacterial infection. However, recently and especially after the emergence of coronavirus disease 2019, there is a growing tendency toward including viruses also into the scope of oral microbiome investigations. The global high prevalence of periodontitis and viral infections may point out to a concomitant or synergistic effect between the two. Although the exact nature of the mechanism still is not clearly understood, this could be speculated through the manipulation of the immune system by viruses; hence facilitating the furthermore colonization of the oral tissues by bacteria. This review provides an extensive and detailed update on the role of the most common viruses including herpes family (herpes simplex, varicella-zoster, Epstein-Barr, cytomegalovirus), Human papillomaviruses, Human immunodeficiency virus and severe acute respiratory syndrome coronavirus 2 in the initiation, progression and prognosis of periodontitis.

Clinical characteristics and prediction model of re-positive nucleic acid tests among Omicron infections by machine learning: a real-world study of 35,488 cases

BACKGROUND

During the Omicron BA.2 variant outbreak in Shanghai, China, from April to May 2022, PCR nucleic acid test re-positivity (TR) occurred frequently, yet the risk factors and predictive models for TR remain unclear. This study aims to identify the factors influencing Omicron TR and to develop machine learning models to predict TR risk. Accurately predicting re-positive patients is crucial for identifying high-risk individuals, optimizing resource allocation, and developing personalized treatment and management plans, thereby effectively controlling the spread of the epidemic, reducing community burden, and ensuring public health.

METHODS

A retrospective study was conducted among individuals infected with Omicron BA.2 variant from April 12 to May 25, 2022, in the largest Shanghai Fangcang shelter hospital. Five machine learning models were compared, including k-nearest-neighbors (KNN), logistic regression (logistic), bootstrap aggregation (bagging), error back-propagation (BP) neural network, and support vector machines (SVM), to select the best prediction model for the TR risk factors.

RESULTS

A total of 35,488 cases were included in this real-world study. The TR and control groups comprised of 6,171 and 29,317 cases respectively, with a re-positive rate of 17.39%. Higher occurrence of TR was observed in young age, males, those with obvious symptoms, underlying diseases, and a low Ct value. The KNN model proved to be the best in predicting the prognosis in the overall evaluation (accuracy = 0.8198, recall = 0.8026, and AUC = 0.8110 in the test set).

INTERPRETATION

Higher TR risk was found in infected cases who were underage or with underlying diseases; vaccine brand and inoculation status were not significantly associated with TR. KNN was the most effective machine learning model to predict TR occurrence in isolation.

Intern nursing students' experiences in the COVID-19 vaccination unit and views on the COVID-19 vaccine: A phenomenological qualitative study

BACKGROUND

Improving acceptance of the COVID-19 vaccine among nursing students is an important strategy for both preventing infection and building public confidence in the vaccine.

OBJECTIVE

The aim of this study was to describe the views of intern nursing students on the COVID-19 vaccine and to evaluate their experiences in the COVID-19 vaccination unit.

METHODS

This was a phenomenological qualitative study with a descriptive design. The 46 intern nursing students included in this study were all trained in the COVID-19 vaccination unit. The data was collected at focus group interviews conducted during June 2021 and October 2021.

RESULTS

The mean age of intern nursing students was 22.78±0.91. From the focus group interviews, two themes were identified regarding the views of intern nursing students on the COVID-19 vaccine and their experiences in the COVID-19 vaccination unit: Theme 1. Positive views; Theme 2. Negative views. Intern nursing students described that they trust the COVID-19 vaccine and believe in its protection. Intern nursing students who performed their clinical practices in COVID-19 vaccination unit stated that they realized their responsibilities toward patients and the community.

CONCLUSIONS

From the INSs' point of view, confidence in the vaccine, responsibility towards patients, their families and the community, and VU practice experience, the health risk associated with COVID-19 positively affected their decision to be vaccinated against COVID-19. The participation of intern nursing students in clinical practice during the pandemic influenced both intern nursing students and population in terms of the uptake of COVID-19 vaccines.

Design, development and evaluation of a mobile-based self-care application for patients with COVID-19 not requiring hospitalization; a study of Northwest of Iran

BACKGROUND

Given the effective role of a mobile applications in disease management, disease monitoring, and self-care in patients with COVID-19 disease, we aimed to design, development and evaluation of a self-care Mobile app for COVID-19 patients not requiring hospitalization.

METHODS

The design, development and evaluation the usability of the self-care and education mobile app for patients with COVID-19 disease were conducted in two main phases at 2021 in Northwest of IRAN; (1) Determine the features and capabilities and (2) Design, development and evaluation of self-care mobile App. JAVA programming languages and Android Operating System were used and selected to design and development of a mobile app. There were 25 participants who conducted evaluations of the mobile app's usability and impact using the mobile health app usability a Questionnaire of User Interface Satisfaction was administered to assess the usability of the developed application. The results were analyzed via Excel 2013.

RESULTS

The model of developing a mobile app as an Information System was the Waterfall model. The smartphone application based on a set of capabilities and features was designed and consists of two main parts: the login screen for user registration, and the main home menu. The user interface includes three main pages or activities; (a) Main Menu for quick access to all of the pages, (b) Symptom management and monitoring to monitor the signs and symptoms during the illness, and (c) Set Reminders and Alarms to notify patients. The users' mean score of the application usability was calculated as 7.91 out of 9 indicating a good level of satisfaction.

CONCLUSION

This app can be a guideline and a useful tools for managing and monitoring symptoms, reminding medications, and implementing self-care instructions in outpatients. The authors suggest evaluating the efficacy and functionality test of mobile-based applications for COVID-19 in clinical trial studies.

Development of an instrument-free and low-cost ELISA dot-blot test to detect antibodies against SARS-CoV-2

Most laboratory tests to detect the presence of anti-SARS-CoV-2 antibodies use enzyme-linked immunosorbent assays (ELISA) or chemiluminescence immunoassays (CLIA); however, equipment for these immunoassays is unavailable in many areas of low- and middle-income countries. Rapid lateral flow immunoassay (LFIA) tests are an equipment-free option, but their high price may make them less suitable for conducting seroprevalence surveys. Here, we describe a simple dual antigen ELISA dot-blot test to detect anti-SARS-CoV-2 IgG antibodies with high sensitivity (94-98%) and specificity (92-100%), compared to commercially available ELISA and CLIA options. Additionally, this ELISA dot-blot test can be completed in one hour using minimal laboratory equipment. Importantly, this immunoassay is significantly more affordable than most LFIA tests available on the global market. The dot-blot strips may be stored for up to 7 days under freezing conditions. This ELISA dot-blot test is a cost-effective option for conducting seroprevalence screenings in areas lacking ELISA or CLIA facilities, compared to LFIA tests.

Evidence of SARS-CoV-2 reinfection: analysis of 35,000 subjects and overview of systematic reviews

BACKGROUND

Reinfection by SARS-CoV-2 is a rare but possible event. We evaluated the prevalence of reinfections in the Province of Modena and performed an overview of systematic reviews to summarize the current knowledge.

METHODS

We applied big data analysis and retrospectively analysed the results of oro- or naso-pharyngeal swab results tested for molecular research of viral RNA of SARS-CoV-2 between 1 January 2021 and 30 June 2021 at a single center. We selected individuals with samples sequence of positive, negative and then positive results. Between first and second positive result we considered a time interval of 90 days to be sure of a reinfection. We also performed a search for and evaluation of systematic reviews reporting SARS-CoV-2 reinfection rates. Main information was collected and the methodological quality of each review was assessed, according to A Measurement Tool to Assess systematic Reviews (AMSTAR).

RESULTS

Initial positive results were revealed in more than 35,000 (20%) subjects; most (28%) were aged 30-49 years old. Reinfection was reported in 1,258 (3.5%); most (33%) were aged 30-49 years old. Reinfection rates according to vaccinated or non-vaccinated subjects were 0.6% vs 1.1% (p < 0.0001). Nine systematic reviews were identified and confirmed that SARS-CoV-2 reinfection rate is a rare event. AMSTAR revealed very low-moderate levels of quality among selected systematic reviews.

CONCLUSIONS

There is a real, albeit rare risk of SARS-CoV-2 reinfection. Big data analysis enabled accurate estimates of the reinfection rates. Nevertheless, a standardized approach to identify and report reinfection cases should be developed.

Hindsight2020: Characterizing Uncertainty in the COVID-19 Scientific Literature

Following emerging, re-emerging, and endemic pathogen outbreaks, the rush to publish and the risk of data misrepresentation, misinterpretation, and even misinformation puts an even greater onus on methodological rigor, which includes revisiting initial assumptions as new evidence becomes available. This study sought to understand how and when early evidence emerges and evolves when addressing different types of recurring pathogen-related questions. By applying claim-matching by means of deep learning Natural Language Processing (NLP) of coronavirus disease 2019 (COVID-19) scientific literature against a set of expert-curated evidence, patterns in timing across different COVID-19 questions-and-answers were identified, to build a framework for characterizing uncertainty in emerging infectious disease (EID) research over time. COVID-19 was chosen as a use case for this framework given the large and accessible datasets curated for scientists during the beginning of the pandemic. Timing patterns in reliably answering broad COVID-19 questions often do not align with general publication patterns, but early expert-curated evidence was generally stable. Because instability in answers often occurred within the first 2 to 6 mo for specific COVID-19 topics, public health officials could apply more conservative policies at the start of future pandemics, to be revised as evidence stabilizes.

A systematic review of trials currently investigating therapeutic modalities for post-acute COVID-19 syndrome and registered on WHO International Clinical Trials Platform

BACKGROUND

Post-acute COVID-19 syndrome (PACS) is a well-recognized, complex, systemic disease which is associated with substantial morbidity. There is a paucity of established interventions for the treatment of patients with this syndrome.

OBJECTIVES

To systematically review registered trials currently investigating therapeutic modalities for PACS.

DATA SOURCES

A search was conducted up to the 16 September, 2022, using the COVID-19 section of the WHO Internal Clinical Trials Registry Platform.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, AND INTERVENTIONS

Interventional clinical trials of any sample size examining any therapeutic modality targeting persistent symptoms among individuals after diagnosis with COVID-19.

METHODS

Data on trial characteristics and intervention characteristics were collected and summarized.

RESULTS

After screening 17 125 trials, 388 trials, from 42 countries, were eligible. In total, we had 406 interventions, of which 368 were mono-therapeutic strategies, whereas 38 were intervention combinations. Among 824 primary outcomes identified, there were >300 different outcomes. Rehabilitation was the most employed class of intervention in 169 trials. We encountered 76 trials examining the pharmacological agents of various classes, with the most common agent being colchicine. Complementary and alternative medicine encompassed 64 trials exploring traditional Chinese medicine, Ayurveda, homeopathic medications, naturopathic medications, vitamins, dietary supplements, and botanicals. Psychotherapeutic and educational interventions were also employed in 12 and 4 trials, respectively. Other interventions, including transcranial direct current stimulation, transcutaneous auricular vagus nerve stimulation, general electrical stimulation, cranial electrotherapy stimulation, various stem cell interventions, and oxygen therapy interventions, were also employed.

CONCLUSION

We identified 388 registered trials, with a high degree of heterogeneity, exploring 144 unique mono-therapeutic interventions for PACS. Most studies target general alleviation of symptoms. There is a need for further high-quality and methodologically robust PACS treatment trials to be conducted with standardization of outcomes while following WHO's recommendation for uniform evaluation and treatment.

The impact of COVID-19 lockdown on cases and deaths of AIDS, gonorrhea, syphilis, hepatitis B, and hepatitis C in China: an interrupted time series analysis

BACKGROUND

China has implemented nationwide lockdown to contain COVID-19 from an early stage. Previous studies of the impact of COVID-19 on sexually transmitted diseases (STDs) and diseases caused by blood-borne viruses (BBVs) in China have yielded widely disparate results, and study on deaths attributable to STDs and BBVs are scarce.

OBJECTIVE

We aimed to elucidate the impact of COVID-19 lockdown on the cases, deaths, and case-fatality ratios of STDs and BBVs.

METHODS

We extracted the monthly cases and deaths data for AIDS, gonorrhea, syphilis, hepatitis B, and hepatitis C between January 2015 and December 2021 from the notifiable disease reporting database on the official website of the National Health Commission of China. We used descriptive statistics to summarize the number of cases and deaths, and calculated incidence and case-fatality ratios before and after implementing nationwide lockdown (January 2020). We used negative binominal segmented regression models to estimate the immediate and long-term impacts of lockdown on cases, deaths, and case-fatality ratios in January 2020 and December 2021, respectively.

RESULTS

A total of 14,800,330 cases and 127,030 deaths of AIDS, gonorrhea, syphilis, hepatitis B, and hepatitis C were reported from January 2015 to December 2021, with an incidence of 149.11/100,000 before lockdown and 151.41/100,000 after lockdown , and a case-fatality ratio of 8.21/1000 before lockdown and 9.50/1000 after lockdown . In the negative binominal model, AIDS cases (-23.4%; 0.766, 0.626-0.939) and deaths (-23.9%; 0.761, 0.647-0.896), gonorrhea cases (-34.3%; 0.657, 0.524-0.823), syphilis cases (-15.4%; 0.846, 0.763-0.937), hepatitis B cases (-17.5%; 0.825, 0.726-0.937) and hepatitis C cases (-19.6%; 0.804, 0.693-0.933) showed significant decreases in January 2020. Gonorrhea, syphilis and hepatitis C showed small increases in the number of deaths or case-fatality ratios in January 2020. By December 2021, the cases, deaths, and case-fatality ratios for each disease had either reached or remained below expected levels.

CONCLUSIONS

COVID-19 lockdown may have contributed to fewer reported cases of AIDS, gonorrhea, syphilis, hepatitis B, and hepatitis C, and more reported deaths or case-fatality ratios of gonorrhea, syphilis and hepatitis C in China.

CLINICALTRIAL

ABO blood group is involved in the quality of the specific immune response anti-SARS-CoV-2

Since December 2019, the coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread throughout the world. To eradicate it, it is crucial to acquire a strong and long-lasting anti-SARS-CoV-2 immunity, by either natural infection or vaccination. We collected blood samples 12-305 days after positive polymerase chain reactions (PCRs) from 35 recovered individuals infected by SARS-CoV-2. Peripheral blood mononuclear cells were stimulated with SARS-CoV-2-derived peptide pools, such as the spike (S), nucleocapsid (N) and membrane (M) proteins, and we quantified anti-S immunoglobulins in plasma. After 10 months post-infection, we observed a sustained SARS-CoV-2-specific CD4+ T-cell response directed against M-protein, but responses against S- or N-proteins were lost over time. Besides, we demonstrated that O-group individuals presented significantly lower frequencies of specific CD4+ T-cell responses against Pep-M than non O-group individuals. The non O-group subjects also needed longer to clear the virus, and they lost cellular immune responses over time, compared to the O-group individuals, who showed a persistent specific immune response against SARS-CoV-2. Therefore, the S-specific immune response was lost over time, and individual factors might determine the sustainability of the body's defenses, which must be considered in the future design of vaccines to achieve continuous anti-SARS-CoV-2 immunity.

Promoting Compliance to COVID-19 Vaccination in Military Units

BACKGROUND

On December 27th, 2020, the Israeli Defense Forces initiated a mass COVID-19 vaccination campaign aiming to vaccinate its personnel. This population upheld specific characteristics in terms of age and sex, lack of significant comorbidities, and a general scarcity of risk factors for sustaining a severe COVID-19 illness. We present the measures taken to increase vaccination compliance, and the vaccination rate that followed these actions. Our secondary goal was to compare between vaccination rates in frontline battalions and highly essential military units (group A) and rear administration and support military units (group B).

METHODS

This was a retrospective review that included 70 military units that were composed of 18,719 individuals of both sexes, mostly free of significant comorbidities. We divided the challenges of maximizing vaccination rates into two main categories: vaccine compliance (including communication and information) and logistical challenges. We compared the vaccination rates in groups A and B using a multivariable linear regression model. A P-value of .05 was considered significant.

RESULTS

The mean age in 70 military units was 22.77 ± 1.35 (range 18-50) years, 71.13% males. A total of 726 (3.88%) individuals have been found positive for SARS-CoV-2 between March 1st, 2020 and February 18th, 2021. On February 18th, 2021, 54 days after the vaccination campaign was launched, 15,871 (84.79%) of the study population have been vaccinated by the first dose of Pfizer COVID-19 vaccine, expressing an 88.21% compliance rate (excluding recovered COVID-19 cases who were not prioritized to be vaccinated at this stage). Vaccination compliance in military units from group A was found to be higher when compared to group B (P < .001), leading to a 90.02% of group A population being either previously SARS-CoV-2 positive or COVID-19 vaccinated.

CONCLUSIONS

A designated army campaign led by a multidisciplinary team could rapidly achieve a high COVID-19 vaccination rate. The information presented can serve organizations worldwide with similar characteristics that plan a mass COVID-19 vaccination campaign.

Quantitative electroencephalography interpretation of human brain activity after COVID-19 before and after Sudarshan Kriya Yoga

The COVID-19 pandemic has affected the entire world. The SARS-CoV-2 virus is wreaking havoc globally, leading to serious health problems and even death. The purpose of this study is to present the brainwave variability pattern using QEEG after exposure to COVID-19 and to introduce the subject of the Sudarshan Kriya Yoga (SKY)-based breathing technique. QEEG is one of the basic neurological examinations through which we can compare the changes in the nervous system after SARS-CoV-2 virus infection and observe the variation of brainwave frequencies with a breathing technique.

Cognitive dysfunction associated with COVID-19: Prognostic role of circulating biomarkers and microRNAs

COVID-19 is renowned as a multi-organ disease having subacute and long-term effects with a broad spectrum of clinical manifestations. The evolving scientific and clinical evidence demonstrates that the frequency of cognitive impairment after COVID-19 is high and it is crucial to explore more clinical research and implement proper diagnostic and treatment strategies. Several central nervous system complications have been reported as comorbidities of COVID-19. The changes in cognitive function associated with neurodegenerative diseases develop slowly over time and are only diagnosed at an already advanced stage of molecular pathology. Hence, understanding the common links between COVID-19 and neurodegenerative diseases will broaden our knowledge and help in strategizing prognostic and therapeutic approaches. The present review focuses on the diverse neurodegenerative changes associated with COVID-19 and will highlight the importance of major circulating biomarkers and microRNAs (miRNAs) associated with the disease progression and severity. The literature analysis showed that major proteins associated with central nervous system function, such as Glial fibrillary acidic protein, neurofilament light chain, p-tau 181, Ubiquitin C-terminal hydrolase L1, S100 calcium-binding protein B, Neuron-specific enolase and various inflammatory cytokines, were significantly altered in COVID-19 patients. Furthermore, among various miRNAs that are having pivotal roles in various neurodegenerative diseases, miR-146a, miR-155, Let-7b, miR-31, miR-16 and miR-21 have shown significant dysregulation in COVID-19 patients. Thus the review consolidates the important findings from the numerous studies to unravel the underlying mechanism of neurological sequelae in COVID-19 and the possible association of circulatory biomarkers, which may serve as prognostic predictors and therapeutic targets in future research.

Reinfection and reactivation of SARS-CoV-2

As the cases of SARS-CoV-2 infection escalates, the essence of in-depth knowledge around acquired immunity and emergence of reinfection and reactivation have to be captured. While being a rare phenomenon, reinfection occurs as the result of diminishing protection conferred by antibodies, especially IgG. Reactivation is more concerned with the role of various elements including shedding lingering viral RNA for a prolonged time and incomplete resolution of infection along with the insight of dormant viral exosomes’ role. The concept of testing positive after two consecutive negative results requires proper discrimination of reinfection from reactivation. In this review, we summarized the current evidence for possible mechanisms leading to viral reactivation or test re-positivity. We also pointed out risk factors associated with both reinfection and reactivation.

The impact of the COVID-19 pandemic on people living with HIV in Zimbabwe

The COVID-19 pandemic was reported from March 2020 in Zimbabwe. COVID-19 containment measures which included repeated lockdowns have disrupted community interactions, reduced working hours, restricted travel and restricted HIV services for people living with HIV (PLHIV), among others. The study adopted a cross-sectional design. Both qualitative and quantitative data were collected in all the 10 provinces and analysed. A sample size of 480 was calculated for the cross-sectional survey. Secondary data on HIV early warning indicators from 2018 to 2021 were extracted from 20 randomly selected health facilities and used for modelling. Mathematical modelling was conducted to assess the impact of COVID-19 on PLHIV. AIDS-related deaths increased from 20 100 in 2019 to 22 200 in 2020. In addition, there were significant years of life lost (yLLs) from premature mortality and years of life lost due to disability (yLDs) from COVID-19. Prevalence of COVID-19 among PLHIV was 4%. COVID-19 vaccination coverage was 64%, which is higher than the national average of 42%. Stress and breach of confidentiality as ARV medicines were given out in open spaces and fear of contracting COVID-19 were the perceived psychological issues. COVID-19 disrupted HIV service provision, increased AIDS-related deaths and caused psychological challenges.

Influence of Information Sources on Chinese Parents Regarding COVID-19 Vaccination for Children: An Online Survey

(1) Aims: This study explored the mechanism by which exposure to different information sources on social media influences Chinese parents' intention to vaccinate their children against COVID-19. (2) Methods: We developed a research framework based on the Stimulus-Organism-Response (SOR) theory to illustrate how exposure to information sources on social media increases vaccine confidence and, as a result, parents' intentions regarding pediatric vaccination. The partial least square structural equation modeling (PLS-SEM) method was used to test the data collected through an online survey (687 valid samples). (3) Results: The government approval of vaccines fuels vaccination confidence and acts as a mediator between (a) mass media, government new media, and key opinion leaders, and (b) perceived effectiveness and side effects (safety) of vaccines. (4) Conclusions: The mass media, government new media, and key opinion leaders are crucial sources for encouraging parents to vaccinate their children since they boost the vaccination trust. The focus of COVID-19 vaccination promotion should be to strengthen parents' trust in the government, combined with publicizing the effectiveness and side effects (safety) of vaccines.

Exploring the trends of acute appendicitis following recovery or vaccination from COVID-19

Introduction

The relationship that vaccination against corona virus disease 19 (COVID-19) or recovery from the acute form of the illness may have with the incidence or severity of acute appendicitis (AA) has not been explored. The aim of this study was to evaluate this relationship.

Methods

A single centre retrospective study of all consecutive adult patients presenting with AA in the 6 mo after the initiation of a national vaccination program was performed. The presenting characteristics and pathological data of patients who had either been vaccinated against or recovered from COVID-19 were compared with those who had not. In addition, historical data from the equivalent period 12 and 24 mo beforehand was also extracted. The incidence of AA was compared between each of these time-frames.

Results

Of the 258 patients initially identified, 255 were included in the analysis of which 156 had either been vaccinated and/or recovered from COVID-19 (61.2%) whilst 99 (38.8%) patients had not. When comparing these two groups, there were no significant differences in the presenting characteristics, operative findings or postoperative courses. There was also no significant change in the incidence of AA when comparing the study dates with historical data (median weekly incidence of AA 8.0 versus 8.0 versus 8.0 respectively, P = 0.672).

Conclusions

Based on the data presented here, we failed to find a relationship between a national vaccination program and both the nature and incidence of AA presenting to a busy urban hospital.

Characteristics of COVID-19 Breakthrough Infections among Vaccinated Individuals and Associated Risk Factors: A Systematic Review

We sought to assess breakthrough SARS-CoV-2 infections in vaccinated individuals by variant distribution and to identify the common risk associations. The PubMed, Web of Science, ProQuest, and Embase databases were searched from 2019 to 30 January 2022. The outcome of interest was breakthrough infections (BTIs) in individuals who had completed a primary COVID-19 vaccination series. Thirty-three papers were included in the review. BTIs were more common among variants of concern (VOC) of which Delta accounted for the largest number of BTIs (96%), followed by Alpha (0.94%). In addition, 90% of patients with BTIs recovered, 11.6% were hospitalized with mechanical ventilation, and 0.6% resulted in mortality. BTIs were more common in healthcare workers (HCWs) and immunodeficient individuals with a small percentage found in fully vaccinated healthy individuals. VOC mutations were the primary cause of BTIs. Continued mitigation approaches (e.g., wearing masks and social distancing) are warranted even in fully vaccinated individuals to prevent transmission. Further studies utilizing genomic surveillance and heterologous vaccine regimens to boost the immune response are needed to better understand and control BTIs.

Protective effect conferred by prior infection and vaccination on COVID-19 in a healthcare worker cohort in South India

BACKGROUND

The emergence of newer variants with the immune escape potential raises concerns about breakthroughs and re-infections resulting in future waves of infection. We examined the protective effect of prior COVID-19 disease and vaccination on infection rates among a cohort of healthcare workers (HCW) in South India during the second wave driven mainly by the delta variant.

METHODS AND FINDINGS

Symptomatic HCWs were routinely tested by RT-PCR as per institutional policy. Vaccination was offered to all HCWs in late January, and the details were documented. We set up a non-concurrent cohort to document infection rates and estimated protective efficacy of prior infection and vaccination between 16th Apr to 31st May 2021, using a Cox proportional hazards model with time-varying covariates adjusting for daily incidence. Between June 2020 and May 2021, 2735 (23.9%) of 11,405 HCWs were infected, with 1412, including 32 re-infections, reported during the second wave. 6863 HCWs received two doses of vaccine and 1905 one dose. The protective efficacy of prior infection against symptomatic infection was 86.0% (95% CI 76.7%-91.6%). Vaccination combined with prior infection provided 91.1% (95% CI 84.1%-94.9%) efficacy. In the absence of prior infection, vaccine efficacy against symptomatic infection during the second wave was 31.8% (95% CI 23.5%- 39.1%).

CONCLUSIONS

Prior infection provided substantial protection against symptomatic re-infection and severe disease during a delta variant driven second wave in a cohort of health care workers.

Reinfection in patients with COVID-19: a systematic review

BACKGROUND

With the continuation of the COVID-19 pandemic, some COVID-19 patients have become reinfected with the virus. Viral gene sequencing has found that some of these patients were reinfected by the different and others by same strains. This has raised concerns about the effectiveness of immunity after infection and the reliability of vaccines. To this end, we conducted a systematic review to assess the characteristics of patients with reinfection and possible causes.

METHODS

A systematic search was conducted across eight databases: PubMed, Embase, Web of Science, The Cochrane Library, CNKI, WanFang, VIP and SinoMed from December 1, 2019 to September 1, 2021. The quality of included studies were assessed using JBI critical appraisal tools and Newcastle-Ottawa Scale.

RESULTS

This study included 50 studies from 20 countries. There were 118 cases of reinfection. Twenty-five patients were reported to have at least one complication. The shortest duration between the first infection and reinfection was 19 days and the longest was 293 days. During the first infection and reinfection, cough (51.6% and 43.9%) and fever (50% and 30.3%) were the most common symptoms respectively. Nine patients recovered, seven patients died, and five patients were hospitalized, but 97 patients' prognosis were unknown. B.1 is the most common variant strain at the first infection. B.1.1.7, B.1.128 and B.1.351 were the most common variant strains at reinfection. Thirty-three patients were infected by different strains and 9 patients were reported as being infected with the same strain.

CONCLUSIONS

Our research shows that it is possible for rehabilitated patients to be reinfected by SARS-COV-2. To date, the causes and risk factors of COVID-19 reinfection are not fully understood. For patients with reinfection, the diagnosis and management should be consistent with the treatment of the first infection. The public, including rehabilitated patients, should be fully vaccinated, wear masks in public places, and pay attention to maintaining social distance to avoid reinfection with the virus.

Recurrent viral RNA positivity and candidiasis findings in hospitalized patients with COVID-19

Background: The aim of this study was to evaluate reinfection and fungal infections among 785 patients with COVID-19 disease admitted to Baqiyatallah Hospital in Northeastern Iran after the onset of the COVID-19 epidemic. Materials & Methods: In this descriptive-analytic study (20 February-21 July 2020), reinfection and fungal infections among 785 patients were investigated using epidemiological questionnaire, clinical trials, Real-time PCR and CT scan (chest computed tomography) from the hospital HIS (hospital's information system) and collected samples. Results: Reinfection and one oral candidiasis were diagnosed in one 68-year-old man and one 47-year-old man 63 and 42 days after the initial infection, respectively. Conclusion: The research results showed that exposure to COVID-19 may not establish long-term protective immunity to all patients.

Qualitative examination of the attitudes of healthcare workers in Turkey regarding COVID-19 vaccines

PURPOSE

The attitudes of healthcare workers toward COVID-19 vaccines ensure that health services are able to run without interruption and potentially have a role in the messaging about vaccination that they convey to the public. Hence, healthcare workers' attitudes ultimately have a significant role in controlling the pandemic. This study aimed to qualitatively investigate the attitudes of healthcare workers in Turkey in relation to COVID-19 vaccines.

METHODS

The study used the phenomenological approach. The sample consisted of 36 healthcare workers who were employed during the COVID-19 pandemic. Data were collected online using focus group interviews. A total of four focus group interviews were conducted.

FINDINGS

Following analysis of the data, the attitudes of healthcare workers in Turkey toward the COVID-19 vaccine were divided into three themes: "influencing factors," "priority group" and "trust."

CONCLUSIONS

Vaccination was found to create negative emotions among some of the healthcare workers. Their opinions about the COVID-19 vaccines were affected by the negative emotions and burnout they experienced during the pandemic. In addition, they saw the vaccination process as impacted by contraindications and uncertainty about the duration of the protection, the balance of the benefits and harm of the vaccines, and by vaccine myths and prejudices about the country where the vaccine was developed. Healthcare professionals expressed the need for trust to be established in the whole vaccination process. They suggested that different vaccine options should be offered, that the appointment and process notification system for vaccination should be improved, that evidence-based information about vaccines should be provided and that a safe environment should be created.

PRACTICE IMPLICATIONS

Vaccine hesitancy can be addressed by careful attention to the application of vaccination programs, correct and effective use of social media, transparent, and precise management of political processes, and the provision of evidence-based information about the vaccines.

COVID-19 reinfection in Liberia: Implication for improving disease surveillance

COVID-19 remains a serious disruption to human health, social, and economic existence. Reinfection with the virus intensifies fears and raises more questions among countries, with few documented reports. This study investigated cases of COVID-19 reinfection using patients’ laboratory test results between March 2020 and July 2021 in Liberia. Data obtained from Liberia’s Ministry of Health COVID-19 surveillance was analyzed in Excel 365 and ArcGIS Pro 2.8.2. Results showed that with a median interval of 200 days (Range: 99–415), 13 out of 5,459 cases were identified and characterized as reinfection in three counties during the country’s third wave of the outbreak. Eighty-six percent of the COVID-19 reinfection cases occurred in Montserrado County within high clusters, which accounted for over 80% of the randomly distributed cases in Liberia. More cases of reinfection occurred among international travelers within populations with high community transmissions. This study suggests the need for continued public education and surveillance to encourage longer-term COVID-19 preventive practices even after recovery.

Predictive determinants of overall survival among re-infected COVID-19 patients using the elastic-net regularized Cox proportional hazards model: a machine-learning algorithm

BACKGROUND

Narrowing a large set of features to a smaller one can improve our understanding of the main risk factors for in-hospital mortality in patients with COVID-19. This study aimed to derive a parsimonious model for predicting overall survival (OS) among re-infected COVID-19 patients using machine-learning algorithms.

METHODS

The retrospective data of 283 re-infected COVID-19 patients admitted to twenty-six medical centers (affiliated with Shiraz University of Medical Sciences) from 10 June to 26 December 2020 were reviewed and analyzed. An elastic-net regularized Cox proportional hazards (PH) regression and model approximation via backward elimination were utilized to optimize a predictive model of time to in-hospital death. The model was further reduced to its core features to maximize simplicity and generalizability.

RESULTS

The empirical in-hospital mortality rate among the re-infected COVID-19 patients was 9.5%. In addition, the mortality rate among the intubated patients was 83.5%. Using the Kaplan-Meier approach, the OS (95% CI) rates for days 7, 14, and 21 were 87.5% (81.6-91.6%), 78.3% (65.0-87.0%), and 52.2% (20.3-76.7%), respectively. The elastic-net Cox PH regression retained 8 out of 35 candidate features of death. Transfer by Emergency Medical Services (EMS) (HR=3.90, 95% CI: 1.63-9.48), SpO2≤85% (HR=8.10, 95% CI: 2.97-22.00), increased serum creatinine (HR=1.85, 95% CI: 1.48-2.30), and increased white blood cells (WBC) count (HR=1.10, 95% CI: 1.03-1.15) were associated with higher in-hospital mortality rates in the re-infected COVID-19 patients.

CONCLUSION

The results of the machine-learning analysis demonstrated that transfer by EMS, profound hypoxemia (SpO2≤85%), increased serum creatinine (more than 1.6 mg/dL), and increased WBC count (more than 8.5 (×109 cells/L)) reduced the OS of the re-infected COVID-19 patients. We recommend that future machine-learning studies should further investigate these relationships and the associated factors in these patients for a better prediction of OS.

Reinfection by SARS CoV2 in Valle Del Cauca, Colombia: A Descriptive Retrospective Study

Introduction: In coronavirus cases, reinfection has been associated with short-term immunity and genetic changes in viruses which allow them to escape from immune response, viral genotyping is required to make the precise diagnosis of reinfection, but the suspicion occurs in patients with more than 90 days between the tests and total improvement between them. We made a descriptive retrospective study with the cases of reinfection in Valle del Cauca, Colombia. Results: We found up to June 30, 3249 cases with suspected reinfection, 1.1% of all cases. During the first infection episode, 68% of the patients had symptoms, while at the moment of reinfection, the percentage was 73.4%. 55% of the analyzed cases had symptoms in both infection episodes, hospitalization of reinfection cases was 2% during the first episode and 2.2% in the second one. Conclusion: the reinfection percentage was low, as well as the hospitalization and ICU cases. These results allow to define that in terms of the provision of healthcare services, reinfection defined in this study, does not generate any differences in care required vs the first episode.

Epidemiologic characteristics of cases with reinfection, recurrence, and hospital readmission due to COVID-19: A systematic review and meta-analysis

Recent studies reported that some recovered COVID-19 patients have tested positive for virus nucleic acid again. A systematic search was performed in Web of Science, PubMed, Scopus, and Google Scholar up to March 6, 2021. The pooled estimation of reinfection, recurrence, and hospital readmission among recovered COVID-19 patients was 3, 133, and 75 per 1000 patients, respectively. The overall estimation of reinfection among males compared to females was greater. The prevalence of recurrence in females compared to males was more common. Also, hospital readmission between sex groups was the same. There is uncertainty about long-term immunity after SARS-Cov-2 infection. Thus, the possibility of reinfection and recurrence after recovery is not unexpected. In addition, there is a probability of hospital readmission due to adverse events of COVID-19 after discharge. However, with mass vaccination of people and using the principles of prevention and appropriate management of the disease, frequent occurrence of the disease can be controlled.

COVID-19 reinfection: A multicenter retrospective study in Saudi Arabia

INTRODUCTION:

There are limited direct data on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) long-term immune responses and reinfection. This study aimed to evaluate the rate, risk factors, and severity of COVID-19 reinfection.

METHODS:

This retrospective cohort study included five hospitals across Saudi Arabia. All subjects who were presented or admitted with positive SARS-CoV-2 real-time polymerase chain reaction (RT-PCR) tests were evaluated between March 2020 and August 2021. Reinfection was defined as a patient who was infected followed by clinical recovery, and later became infected again 90 days post first infection. The infection was confirmed with a positive SARS-CoV-2 (RT-PCR). Four hundred and seventeen recovered cases but with no reinfection were included as a control.

RESULTS:

A total of 35,288 RT-PCR-confirmed COVID-19 patients were observed between March 2020 and August 2021. Based on the case definition, (0.37%) 132 patients had COVID-19 reinfection. The mean age in the reinfected cases was 40.95 ± 19.48 (range 1–87 years); Females were 50.76%. Body mass index was 27.65 ± 6.65 kg/m²; diabetes and hypertension were the most common comorbidities. The first infection showed mild symptoms in 91 (68.94%) patients; and when compared to the control group, comorbidities, severity of infection, and laboratory investigations were not statistically different. Hospitalization at the first infection was higher, but not statistically different when compared to the control group (P = 0.093).

CONCLUSION:

COVID-19 reinfection is rare and does not carry a higher risk of severe disease. Further studies are required, especially with the continuously newly emerging variants, with the unpredictable risk of reinfection.

Mechanism of olfactory deficit in neurotrauma and its related affective distress: A narrative review

Traumatic brain injury (TBI) is among the leading causes of death and disability all over the globe. TBI is also commonly associated with clinical sequelae of posttraumatic depression, and reports of other subsequent affective distress are common. Similarly, posttraumatic changes in chemoreceptive sensory functions, primarily due to coup-contrecoup injury induced shearing of the olfactory nerve fibers, leading to anosmia and ageusia are also well documented in the literature. However, the current literature is limited in addressing the intersections between said variables. The aim of this study was to provide a focused narrative review of the literature, to address these intersections found in clinical sequelae of TBI. As chemoreceptive sensory deficits are also linked to significant affective distress of their own, this review addresses the bidirectionality between sensory deficit and affective distress. Prevalence, demographics, mechanisms, and clinical implications are presented. Previous research is presented and discussed, in an effort to highlight the importance of consideration for all factors in TBI patient care and future research.

Clinical and Epidemiological Characteristics of COVID-19 Patients with SARS-CoV-2 Re-Detected on PCR Test after Discharge from Isolation

There have been multiple reports of patients with coronavirus disease (COVID-19) testing positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after discharge; however, information on the characteristics of such cases is limited. In this case report, we aimed to identify clinical and epidemiological characteristics of patients who had a repeat positive polymerase chain reaction (PCR) test for SARS-CoV-2. We analyzed data of 22 COVID-19 patients who tested positive for SARS-CoV-2 on polymerase chain reaction (PCR) testing after two consecutive negative PCR results following discharge from hospitals. The interval between the two positive tests in the episodes of COVID-19 ranged from 4 to 117 days. More than one-third of the cases were healthcare workers (HCWs) and one-third of them had comorbidities. The main symptoms were cough and fever, and we noticed that males experienced more symptoms and signs of COVID-19 than females. Individuals with repeat SARS-CoV-2 positivity tend to experience milder illness during the second episode than the first episode. To confirm the reinfection of SARS-CoV-2, the results of other tests, such as viral culture and immunological assays of immunoglobulin G (IgG) and immunoglobulin M (IgM), need to be considered. Recovered COVID-19 patients should continue social distancing, using face masks, and practicing hand hygiene, especially HCWs who are more likely to be exposed to SARS-CoV-2.

A Case Report: Genetically Distinct Severe Acute Respiratory Syndrome Coronavirus-2 Variant Causing Reinfection

Background: The emergence of novel variants has been a great deal of international concern since the recently published data suggest that previous infections with SARS-CoV-2 may not protect an individual from new variants. We report a patient had two distinct episodes of COVID-19 with different variants of SARS-CoV-2. Methods: The nasopharyngeal samples collected from the two episodes were subjected to whole-genome sequencing and comparative genome analysis. Results: The first infection presented with mild symptoms, while the second infection presented with severe outcomes which occurred 74 days after the patient recovered from the first episode. He had elevated C-reactive protein, ferritin, and bilateral consolidation as a sign of acute infection. Genome analysis revealed that the strains from the first and second episodes belonged to two distinct Nexstrain clades 20B and 20I and Pangolin lineages B.1.1.25 and B.1.1.7, respectively. A total of 36 mutations were observed in the episode-2 strain when compared with the reference strain Wuhan-Hu-1. Among them, eight mutations were identified in the receptor-binding domain (RBD). Conclusion: Our findings concern whether the immunity acquired by natural infection or mass vaccination could confer adequate protection against the constantly evolving SARS-CoV-2. Therefore, continuous monitoring of genetic variations of SARS-CoV-2 strains is crucial for interventions such as vaccine and drug designs, treatment using monoclonal antibodies, and patient management.

Recurrent SARS-CoV-2 infections and their potential risk to public health - a systematic review

OBJECTIVE

To inform quarantine and contact-tracing policies concerning re-positive cases-cases testing positive among those recovered.

MATERIALS AND METHODS

We systematically reviewed and appraised relevant literature from PubMed and Embase for the extent of re-positive cases and their epidemiological characteristics.

RESULTS

In 90 case reports/series, a total of 276 re-positive cases were found. Among confirmed reinfections, 50% occurred within 90 days from recovery. Four reports related onward transmission. In thirty-five observational studies, rate of re-positives ranged from zero to 50% with no onward transmissions reported. In eight reviews, pooled recurrence rate ranged from 12% to 17.7%. Probability of re-positive increased with several factors.

CONCLUSION

Recurrence of a positive SARS-CoV-2 test is commonly reported within the first weeks following recovery from a first infection.

Prior aerosol infection with lineage A SARS-CoV-2 variant protects hamsters from disease, but not reinfection with B.1.351 SARS-CoV-2 variant

The circulation of SARS-CoV-2 has resulted in the emergence of variants of concern (VOCs). It is currently unclear whether the previous infection with SARS-CoV-2 provides protection against reinfection with VOCs. Here, we show that low dose aerosol exposure to hCoV-19/human/USA/WA-CDC-WA1/2020 (WA1, lineage A), resulted in a productive mild infection. In contrast, a low dose of SARS-CoV-2 via fomites did not result in productive infection in the majority of exposed hamsters and these animals remained non-seroconverted. After recovery, hamsters were re-exposed to hCoV-19/South African/KRISP-K005325/2020 (VOC B.1.351) via an intranasal challenge. Seroconverted rechallenged animals did not lose weight and shed virus for three days. They had a little infectious virus and no pathology in the lungs. In contrast, shedding, weight loss and extensive pulmonary pathology caused by B.1.351 replication were observed in the non-seroconverted animals. The rechallenged seroconverted animals did not transmit the virus to naïve sentinels via direct contact transmission, in contrast to the non-seroconverted animals. Reinfection with B.1.351 triggered an anamnestic response that boosted not only neutralizing titres against lineage A, but also titres against B.1.351. Our results confirm that aerosol exposure is a more efficient infection route than fomite exposure. Furthermore, initial infection with SARS-CoV-2 lineage A does not prevent heterologous reinfection with B.1.351 but prevents disease and onward transmission. These data suggest that previous SARS-CoV-2 exposure induces partial protective immunity. The reinfection generated a broadly neutralizing humoral response capable of effectively neutralizing B.1.351 while maintaining its ability to neutralize the virus to which the initial response was directed against.

The mystery of COVID-19 reinfections: A global systematic review and meta-analysis

BACKGROUND

As the COVID-19 pandemic rages on, reports on disparities in vaccine roll out alongside COVID-19 reinfection have been emerging. We conducted a systematic review to assess the determinants and disease spectrum of COVID-19 reinfection.

MATERIALS AND METHODS

A comprehensive search covering relevant databases was conducted for observational studies reporting Polymerase Chain Reaction (PCR) confirmed infection and reinfection cases. A quality assessment tool developed by the National Institute of Health (NIH) for the assessment of case series was utilized. Meta-analyses were performed using RevMan 5.3 for pooled proportions of findings in first infection and reinfection with a 95% confidence interval (CI).

RESULTS

Eighty-one studies reporting 577 cases were included from 22 countries. The mean age of patients was 46.2 ± 18.9 years and 179 (31.0%) cases of comorbidities were reported. The average time duration between first infection and reinfection was 63.6 ± 48.9 days. During first infection and reinfection, fever was the most common symptom (41.4% and 36.4%, respectively) whilst anti-viral therapy was the most common treatment regimen administered (44.5% and 43.0%, respectively). Comparable odds of symptomatic presentation and management were reported for the two infections. However, a higher Intensive Care Unit (ICU) admission rate was observed in reinfection compared to first infection (10 vs 3). Ten deaths were reported with respiratory failure being the most common cause of death (7/10 deaths).

CONCLUSION

Our findings support immunization practices given increased ICU admissions and mortality in reinfections. Our cohort serves as a guide for clinicians and authorities in devising an optimal strategy for controlling the pandemic. (249 words).

The clinical outcomes of COVID-19 in HIV-positive patients: A systematic review of current evidence

INTRODUCTION

Patients with chronic underlying diseases are more susceptible to coronavirus disease 2019 (COVID-19) complications. Recent studies showed people living with HIV (PLWH) are not at greater risk than the general population. Few studies have reviewed the impacts of COVID-19 on PLWH. The purpose of this systematic review was to investigate the impact of COVID-19 on patients infected with HIV.

METHODS

We executed a systematic search using four databases of PubMed, Scopus, Science Direct, and Web of Science and screened the records in two steps based on their title/abstract and full text. This study follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist to elevate the validity and reliability of its results.

RESULTS

We reviewed 36 studies. The patients' age was above 20 years in all studies. In almost all studies, the inflammatory parameters were reported high. In most of the studies, all HIV patients completely recovered from the COVID 19 infection. Although CD4 count was not recorded in all studies, the minimum level was reported as 12 cells/µl.

CONCLUSION

Based on the current review, we concluded that HIV patients at advanced stages (3 or 4) of the disease, whose CD4 counts are low, may show less severe COVID-19 infection symptoms. Similarly, Interference can reduce the severity of immune reactions and subsequent cytokine storms and consequently mitigate the symptoms. Therefore, in most of the studies, the majority of HIV patients showed no severe symptoms and completely recovered from COVID 19 infection.

Acceptance of COVID-19 vaccination and correlated variables among global populations: A systematic review and meta-analysis

Introduction

The most awaited solution is an efficient COVID-19 vaccine. COVID-19 vaccine acceptance has not been studied in a meta-analysis. The objective of this research was to find the acceptance of COVID-19 vaccination and correlated variables.

Methods

A systematic review of studies on acceptance of COVID-19 vaccination and correlated variables in the ProQuest, PubMed, and EBSCO to find relevant articles published between January 2020 and March 2021. Using fixed and random-effect models, the risk factors Pooled Odds Ratio (POR) were measured. The heterogeneity was calculated using the I-squared formula. Egger's and Begg's tests were utilised to determine publication bias. STATA 16.0 was used for all data processing and analysis.

Results

This study results showed the related factors for COVID-19 vaccination acceptance, high income has the highest odd ratio (POR = 2.36), followed by encountered with COVID-19 (POR = 2.34), fear about COVID-19 (POR = 2.07), perceived benefits (POR = 1.81), flu vaccine during the previous season (POR = 1.69), healtcare workers (POR = 1.62), male (POR = 1.61), married (POR = 1.59), perceived risk (POR = 1.52), trust in health system (POR = 1.52), chronic diseases (POR = 1.47), high education (POR = 1.46), high level of knowledge (POR = 1.39), female (1.39), and older age (POR = 1.07). The heterogeneity calculation showed homogenous among studies in high income, fear about COVID-19, healthcare workers, married, chronic diseases, and female (I² ≤ 50%). For the studies included in this review, there was no apparent publication bias.

Conclusion

The analysis of this review may be useful to the nation in determining the best method for implementing COVID-19 mass vaccination programs based on relevant factors that influence vaccine acceptance.

Strategies to increase downloads of COVID-19 exposure notification apps: A discrete choice experiment

Exposure notification apps have been developed to assist in notifying individuals of recent exposures to SARS-CoV-2. However, in several countries, such apps have had limited uptake. We assessed whether strategies to increase downloads of exposure notification apps should emphasize improving the accuracy of the apps in recording contacts and exposures, strengthening privacy protections and/or offering financial incentives to potential users. In a discrete choice experiment with potential app users in the US, financial incentives were more than twice as important in decision-making about app downloads, than privacy protections, and app accuracy. The probability that a potential user would download an exposure notification app increased by 40% when offered a $100 reward to download (relative to a reference scenario in which the app is free). Financial incentives might help exposure notification apps reach uptake levels that improve the effectiveness of contact tracing programs and ultimately enhance efforts to control SARS-CoV-2. Rapid, pragmatic trials of financial incentives for app downloads in real-life settings are warranted.

Distinguishing repeated polymerase chain reaction positivity from re-infections in COVID-19

BACKGROUND

Possibility of reinfection with SARS-CoV-2 changes our view on herd immunity and vaccination and can impact worldwide quarantine policies. We performed real-time polymerase chain reaction (RT-PCR) follow-up studies on recovered patients to assess possible development of reinfections and re-positivity.

METHODS

During a 6-month period, 202 PCR-confirmed recovering COVID-19 patients entered this study. Follow-up RT-PCR tests and symptom assessment were performed 1 month after the initial positive results. Patients who tested negative were tested again 1 and 3 months later. The serum IgG and IgM levels were measured in the last follow-up session.

RESULTS

In the first two follow-up sessions, 82 patients continued their participation, of which four patients tested positive. In the second follow-up 44 patients participated, three of whom tested positive. None of the patients who tested positive in the first and second follow-up session were symptomatic. In the last session, 32 patients were tested and four patients were positive, three of them were mildly symptomatic and all of them were positive for IgG.

CONCLUSIONS

A positive RT-PCR in a recovering patient may represent reinfection. While we did not have the resources to prove reinfection by genetic sequencing of the infective viruses, we believe presence of mild symptoms in the three patients who tested positive over 100 days after becoming asymptomatic, can be diagnosed as reinfection. The immune response developed during the first episode of infection (e.g., IgG or T-cell mediated responses that were not measured in our study) may have abated the symptoms of the reinfection, without providing complete protection.

Persistence of Antibody Responses to the SARS-CoV-2 in Dialysis Patients and Renal Transplant Recipients Recovered from COVID-19

Nephropathic subjects with impaired immune responses show dramatically high infection rates of coronavirus disease 2019 (COVID-19). This work evaluated the ability to acquire and maintain protective antibodies over time in 26 hemodialysis patients and 21 kidney transplant recipients. The subjects were followed-up through quantitative determination of circulating SARS-CoV-2 S1/S2 IgG and neutralizing antibodies in the 6-month period after clinical and laboratory recovery. A group of 143 healthcare workers with no underlying chronic pathologies or renal diseases recovered from COVID was also evaluated. In both dialysis and transplanted patients, antibody titers reached a zenith around the 3rd month, and then a decline occurred on average between the 270th and 300th day. Immunocompromised patients who lost antibodies around the 6th month were more common than non-renal subjects, although the difference was not significant (38.5% vs. 26.6%). Considering the decay of antibody levels below the positivity threshold (15 AU/mL) as "failure", a progressive loss of immunisation was found in the overall population starting 6 months after recovery. A longer overall antibody persistence was observed in severe forms of COVID-19 (p = 0.0183), but within each group, given the small number of patients, the difference was not significant (dialysis: p = 0.0702; transplant: p = 0.1899). These data suggest that immunocompromised renal patients recovered from COVID-19 have weakened and heterogeneous humoral responses that tend to decay over time. Despite interindividual variability, an association emerged between antibody persistence and clinical severity, similar to the subjects with preserved immune function.

Comparative Analysis of Susceptibility and Severity of COVID-19 in Countries from the Eastern and the Western World Till March '21

Majority of the world’s human population today is affected by Covid-19. The disease has not only exhibited differences in susceptibility among people of different countries, but also the mortality rate. In general, Western world has been reporting a greater number of infected cases than eastern countries. Even the mortality rates are quite high there. The aim of this study was to analyse the data available on the infectivity and mortality rates of Covid-19 in different countries till March’21 and then reviewed the literature to find reasons for the differences in susceptibility and severity in eastern and western countries. The reasons for the observed differences may be: (i) Eastern countries followed stricter modalities and got grace period to create better healthcare facilities to tackle COVID-19. This probably also slowed the transmission of virus and its evolution, (ii) Vaccination policies in the east may have provided some immunity due to cross reactivity, (iii) Frequent exposure to infections at young age in eastern countries might be helping in better immunity, (iv) Mutations in viral genome may be geography based and (v) Genetic differences in the immune system of the hosts with respect to ACE receptors and MHC may be playing an important role. In this article, an attempt has been made to put forth and discuss these plausible reasons along with suitable evidences. These findings may help in future research on the diagnosis, treatment and prevention of Covid-19.

Development and Evaluation of a Set of Spike and Receptor Binding Domain-Based Enzyme-Linked Immunosorbent Assays for SARS-CoV-2 Serological Testing

The implementation and validation of anti-SARS-CoV-2 IgG serological assays are reported in this paper. S1 and RBD proteins were used to coat ELISA plates, and several secondary antibodies served as reporters. The assays were initially validated with 50 RT-PCR positive COVID-19 sera, which showed high IgG titers of mainly IgG1 isotype, followed by IgG3. Low or no IgG2 and IgG4 titers were detected. Then, the RBD/IgG assay was further validated with 887 serum samples from RT-PCR positive COVID-19 individuals collected at different times, including 7, 14, 21, and 40 days after the onset of symptoms. Most of the sera were IgG positive at day 40, with seroconversion happening after 14–21 days. A third party conducted an additional performance test of the RBD/IgG assay with 406 sera, including 149 RT-PCR positive COVID-19 samples, 229 RT-PCR negative COVID-19 individuals, and 28 sera from individuals with other viral infections not related to SARS-CoV-2. The sensitivity of the assay was 99.33%, with a specificity of 97.82%. All the sera collected from individuals with infectious diseases other than COVID-19 were negative. Given the robustness of this RBD/IgG assay, it received approval from the sanitary authority in Mexico (COFEPRIS) for production and commercialization under the name UDISTEST-V2G^®.

Severe Acute Respiratory Syndrome Coronavirus 2 Reinfection Cases Corroborated by Sequencing

Evaluating cases of reinfection may offer some insight into areas for further investigation regarding durability of immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Sixty cases of reinfection with viral sequencing were identified in PubMed, Embase, Web of Science, and medRxiv before May 1, 2021.Episodes of infection were separated by a median of 116 days. Severity of illness was greater among individuals reinfected within 90 days of initial infection, no asymptomatic initial cases developed severe reinfection, nearly half of cases had suspected escape variants, and nearly all individuals tested following reinfection were found to have detectable levels of anti-SARS-CoV-2 antibodies. This analysis is limited by the heterogeneous methods used among reports. Reinfection continues to be relatively rare. As the case rate presumably increases over time, this review will inform measurements to determine the natural history and causal determinants of reinfection in more rigorous observational cohort studies and other standardized surveillance approaches.

Laboratory-confirmed SARS-CoV-2 reinfection in the population treated at social security

The scientific community has questioned whether reinfection with SARS-CoV-2 is possible. Gradually, cases of reinfection have been documented. In Mexico, people with SARS-CoV-2 reinfection have not been officially identified. To allow a retrospective investigation of patients with PCR-confirmed SARS-CoV-2 and to identify how reinfected with this virus occurs in a population that requires medical attention. A retrospective search of the epidemiological surveillance system was performed to identify people who met the clinical criteria based on laboratory diagnosis of SARS-CoV-2 and temporality to identify cases of reinfection. Clinical information was collected from clinical records. Seven people with two separate COVID-19 events were identified in medical units in Quintana Roo, Mexico between April and December 2020. The overall median interval between the two events was 156 days (61-191 days). Six people were health workers, and one was a member of the general population. This is one of the first reports of reinfection in health personnel in Mexico, revealing that the frequency of reinfection is low among positive cases and that the interval between infection episodes was three months. There are several scenarios in the natural history of the disease that must be considered based on adequate anamnesis with a clinical-epidemiological approach to determine the correct diagnostic category.

SARS-CoV-2-directed antibodies persist for more than six months in a cohort with mild to moderate COVID-19

OBJECTIVE

To follow serological immune responses of front-line healthcare workers after PCR-confirmed COVID-19 for a mean of 30 weeks, describe the time-course of SARS-CoV-2 spike protein-specific IgG, IgA and IgM levels and to identify associations of the immune response with symptoms, demographic parameters and severity of disease.

METHODS

Anti-SARS-CoV-2 S protein-specific IgG, IgA and IgM antibodies were measured at three time points during the 30-week follow-up. COVID-19-specific symptoms were assessed with standardized questionnaires.

RESULTS

95% of the participants mounted an IgG response with only modest decline after week 12. IgG-type antibodies were still detectable in almost 90% of the subjects at 30 weeks. IgA and IgM responses were less robust and antibody titers decreased more rapidly. At 30 weeks, only 25% still had detectable IgA-type and none had IgM-type antibodies. Higher age and higher disease severity were independently associated with higher IgG antibody levels, albeit with wide variations.

CONCLUSION

Serological immune responses after COVID-19 show considerable inter-individual variability, but show an association with increasing age and higher severity of disease. IgG-type anti-SARS-CoV-2 antibodies remain positive in 90% of the individuals 30 weeks after onset of symptoms.

Severe acute respiratory syndrome coronavirus 2 reinfection in a coronavirus disease 2019 recovered young adult: a case report

BACKGROUND

Coronavirus disease 2019 has been a public health threat and a worldwide emergency for more than a year. Unfortunately, many questions concerning the pathophysiology, management, and long-term side effects remain unanswered, and novel aspects of the disease keep on emerging. Of concern to healthcare providers are the recent reported cases of reinfection. Serum coronavirus disease 2019 antibodies have been detected within a few days after onset of the disease. However, it remains unclear whether this immune response is universal, or whether it can lead to latent immunity.

CASE PRESENTATION

A previously healthy 27-year-old white man presented with fever, chills, back pain, and other constitutional symptoms, 2 days after being exposed to coronavirus disease 2019 positive patients. His severe acute respiratory syndrome coronavirus 2 polymerase chain reaction was positive, and his symptoms resolved over the next 2 weeks. One month after a confirmatory negative severe acute respiratory syndrome coronavirus 2 polymerase chain reaction, he was found to be ineligible for plasma donation as his anti-severe acute respiratory syndrome coronavirus 2 serology was negative. The patient redeveloped symptoms similar to his first infection 3 weeks after the negative serology test. He and his wife both tested positive via polymerase chain reaction. Their symptoms resolved over the next few days, and they had a negative polymerase chain reaction test 10 days after the positive polymerase chain reaction.

CONCLUSION

While studies showed that anti-severe acute respiratory syndrome coronavirus 2 immunoglobulins start to develop early after infection, our healthy young patient's immune system failed to mount latent immunity against the virus. This left him, especially amid widespread social and medical misconceptions, vulnerable to reinfection by severe acute respiratory syndrome coronavirus 2. Our case disputes the timelines for immune response that were set and supported by research studies. Our case also raises questions regarding prioritizing vaccinating other individuals over those with prior infection.

Effects of COVID-19 prevention procedures on other common infections: a systematic review

INTRODUCTION

Since the outbreak of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) began, necessary measures to prevent virus transmission and reduce mortality have been implemented, including mandatory public use of masks, regular hand-sanitizing and hand-washing, social distancing, avoidance of crowds, remote work, and cancellation of public events. During and after the introduction of COVID-19 lockout, we performed a systematic review of available published literature to investigate the incidence of seasonal influenza and other respiratory viral infections.

METHODS

PubMed, Embase, Web of Science, Scopus, Science Direct, Google Scholar, Research Gate, and the World Health Organization databases and websites were systematically searched for original studies concerning the impact of COVID-19 prevention means and measures on other common respiratory infectious diseases during the pandemic published by March 2021.

RESULTS

The findings showed that the adherence to health protocols to prevent COVID-19 could help to reduce the incidence of other infectious diseases such as influenza, pneumonia, and Mycobacterium tuberculosis.

CONCLUSION

The implemented prevention measures and protocols might have reduced the incidence of influenza and some other common respiratory infections. However, controversies exist on this matter and future large population-based studies might provide further information to address these controversies.