SARS-CoV-2 re-infection: development of an epidemiological definition from India

Genomic surveillance of SARS-CoV-2 and emergence of XBB.1.16 variant in Rajasthan

PURPOSE

Genomic surveillance of positive SARS-CoV-2 samples is important to monitor the genetic changes occurring in virus, this was enhanced after the WHO designation of XBB.1.16 as a variant under monitoring in March 2023. From 5th February till May 6, 2023 all positive SARS-CoV-2 samples were monitored for genetic changes.

METHODS

A total of 1757 samples having Ct value <25 (for E and ORF gene) from different districts of Rajasthan were processed for Next Generation Sequencing (NGS). The FASTA files obtained on sequencing were used for lineage determination using Nextclade and phylogenetic tree construction.

RESULTS AND CONCLUSIONS

Sequencing and lineage identification was done in 1624 samples. XBB.1.16 was the predominant lineage in 1413 (87.0%) cases while rest was other XBB (207, 12.74%) and other lineages (4, 0.2%). Of the 1413 XBB.1.16 cases, 57.47% were males and 42.53% were females. Majority (66.53%) belonged to 19-59 year age. 84.15% of XBB.1.16 cases were infected for the first time. Hospitalization was required in only 2.2% cases and death was reported in 5 (0.35%) patients. Most of the cases were symptomatic and the commonest symptoms were fever, cough and rhinorrhea. Co-morbidities were present in 414 (29.3%) cases. Enhanced genomic surveillance helped to rapidly identify the spread of XBB variant in Rajasthan. This in turn helped to take control measures to prevent spread of virus and estimate public health risks of the new variant relative to the previously circulating lineages. XBB variant was found to spread rapidly but produced milder disease.

Clinico-Epidemiological Characteristics of Healthcare Workers with SARS-CoV-2 Infection during the First and Second Waves in a Teaching Hospital from Eastern India: A Comparative Analysis

In this retrospective observational study, we have performed a comparative analysis of the demographic, clinical and epidemiological characteristics of the HCWs affected with SARS-CoV-2 infection during first two waves in India. The overall prevalence of SARS-CoV-2 infection among HCWs was found to be 15.24% (14.20-16.33) and 23.38% (22.14-25.65) during first and second waves respectively. The second wave showed an adjusted odds ratio of 0.04(0.02-0.07) and 2.09(1.49-2.93) for hospitalization and being symptomatic, respectively. We detected significantly higher level of C-reactive protein (CRP) among admitted HCWs during the second wave (5.10 -14.60 mg/dl) as compared to the first wave (2.00 - 2.80 mg/dl). Our study found the relative risk of SARS-CoV-2 reinfection among HCWs during the second wave to be 0.68 [0.57-0.82, p < 0.001)]. Although, the prevalence of SARS CoV-2 infection and risk of being symptomatic was higher during second wave, the risk of hospitalization was less when compared with the first wave.

Assessing efficacy of instructor based orientation to donning doffing protocols and modifications to doffing area infrastructure in reducing SARS-CoV-2 infection among Doctors assigned to COVID-19 patient care

Background

We assess the efficacy of orientation programmes for doctors of proper donning, doffing techniques for personal protective equipment (PPE) and safe practices inside the COVID-19 hospital in reducing the COVID-19 infection rate among doctors.

Methods

A total of 767 resident doctors and 197 faculty visits on weekly rotation were recorded over a six month period. Doctors were guided through orientation sessions before their entry into the COVID-19 hospital from 1 August 2020.The infection rate among doctors was used to study the efficacy of the programme. McNemars Chi-square test was used to compare the infection rate in the two groups before and after orientation sessions were commenced.

Discussion

A statistically significant reduction in SARS-CoV-2 infection was seen among resident doctors after orientation programmes and infrastructure modification (3% vs 7.4%, p=0.03). Twenty-eight of 32 (87.5%) doctors who tested positive developed asymptomatic to mild infection. The infection rate was 3.65% and 2.1% among residents and faculty respectively. There was no mortality recorded.

Conclusion

Orientation programme for healthcare workers for PPE donning and doffing protocols with practical demonstration and trial of PPE usage can significantly reduce COVID-19infection. Such sessions should be mandatory for all workers on deputation in designated area for Infectious Diseases and in pandemic situations.

Reinfection of COVID-19 among doctors at a tertiary care centre in Northern India: A report from a resource-limited setting

Background and Aims

There is an increasing recognition of reinfection in coronavirus disease 2019 (COVID-19). We studied the reinfection of COVID-19 disease among doctors at a tertiary care centre in Northern India.

Methods

All COVID-19 patients readmitted for COVID-19 disease after any duration with at least a positive Real time- polymerase chain reaction (RT-PCR) for severe acute respiratory syndrome coronavirus 2 were included. Their clinical profile, vaccination status, outcome and Centre for disease control (CDC), Atlanta, USA reinfection criteria screening were recorded.

Results

A total of 57 (0.53%) doctors were identified and 56 of them satisfied the CDC criteria. It included 13 (20.3%) females and 89.3% of cases were from clinical specialities; 98.2% of individuals had the first infection in 2020 and mean duration between 2 infections was 156.29 ± 76.02 (35-298) days. Duration between two episodes of the disease with more than 90 days apart was in 80.3% cases. One (1.8%) patient developed severe disease and two (3.6%) cases were of moderate severity. Symptoms were similar in both infections except significantly higher number of extra-respiratory complaints (2.2% vs. 9.1%). There were 37.5% cases who had received first dose of vaccination of any duration at the time of second infection. Nine (16.1%) and four (7.1%) patients with more than 4 weeks after the first and second dose of vaccination developed the second infection, respectively.

Conclusion

Majority of reinfection were symptomatic and developed after 90 days and so majority followed CDC criteria. Breakthrough infections among vaccinated healthcare worker are real, and with sustained exposure to the virus, they should continue to use precaution including hand hygiene and mask in order to prevent reinfection.

Surge of mucormycosis during the COVID-19 pandemic

Patients with respiratory viral infections are more likely to develop co-infections leading to increased fatality. Mucormycosis is an epidemic amidst the COVID-19 pandemic that conveys a 'double threat' to the global health fraternity. Mucormycosis is caused by the Mucorales group of fungi and exhibits acute angioinvasion generally in immunocompromised patients. The most familiar foci of infections are sinuses (39%), lungs (24%), and skin tissues (19%) where the overall dissemination occurs in 23% of cases. The mortality rate in the case of disseminated mucormycosis is found to be 96%. Symptoms are mostly nonspecific and often resemble other common bacterial or fungal infections. Currently, COVID-19-associated mucormycosis (CAM) is being reported from a number of countries such as the USA, Turkey, France, Mexico, Iran, Austria, UK, Brazil, and Italy, while India is the hotspot for this deadly co-infection, accounting for approximately 28,252 cases up to June 8, 2021. It strikes patients within 12-18 days after COVID-19 recovery, and nearly 80% require surgery. Nevertheless, the mortality rate can reach 94% if the diagnosis is delayed or remains untreated. Sometimes COVID-19 is the sole predisposing factor for CAM. Therefore, this study may provide a comprehensive resource for clinicians and researchers dealing with fungal infections, intending to link the potential translational knowledge and prospective therapeutic challenges to counter this opportunistic pathogen.

Evaluation of possible COVID-19 reinfection in children: A multicenter clinical study

BACKGROUND

Although it was originally unknown whether there would be cases of reinfection of coronavirus disease 2019 (COVID-19) as seen with other coronaviruses, cases of reinfection were reported from various regions recently. However, there is little information about reinfection in children.

METHODS

In this study, we aimed to investigate the incidence and clinical findings of reinfection in pediatric patients who had recovered from COVID-19. We retrospectively evaluated all patients under 18 years of age with COVID-19 infection from a total of eight healthcare facilities in Turkey, between March 2020 and July 2021. Possible reinfection was defined as a record of confirmed COVID-19 infection based on positive reverse transcription-polymerase chain reaction (RT-PCR) test results at least 3 months apart.

RESULTS

A possible reinfection was detected in 11 out of 8840 children, which yielded an incidence of 0.12%. The median duration between two episodes of COVID-19 was 196 (92-483) days. When initial and second episodes were compared, the rates of symptomatic and asymptomatic disease were similar for both, as was the severity of the disease (p = 1.000). Also, there was no significant difference in duration of symptoms (p = 0.498) or in hospitalization rates (p = 1.000). Only one patient died 15 days after PCR positivity, which resulted in a 9.1% mortality rate for cases of reinfection in pediatric patients.

CONCLUSION

We observed that children with COVID-19 were less likely to be exposed to reinfection when compared with adults. Although the clinical spectrum of reinfection was mostly similar to the first episode, we reported death of a healthy child during the reinfection.

Risk of reinfection and disease after SARS-CoV-2 primary infection: Meta-analysis

INTRODUCTION

A precise estimate of the frequency and severity of SARS-CoV-2 reinfections would be critical to optimize restriction and vaccination policies for the hundreds of millions previously infected subjects. We performed a meta-analysis to evaluate the risk of reinfection and COVID-19 following primary infection.

METHODS

We searched MedLine, Scopus and preprint repositories for cohort studies evaluating the onset of new infections among baseline SARS-CoV-2-positive subjects. Random-effect meta-analyses of proportions were stratified by gender, exposure risk, vaccination status, viral strain, time between episodes, and reinfection definition.

RESULTS

Ninety-one studies, enrolling 15,034,624 subjects, were included. Overall, 158,478 reinfections were recorded, corresponding to a pooled rate of 0.97% (95% CI: 0.71%-1.27%), with no substantial differences by definition criteria, exposure risk or gender. Reinfection rates were still 0.66% after ≥12 months from first infection, and the risk was substantially lower among vaccinated subjects (0.32% vs. 0.74% for unvaccinated individuals). During the first 3 months of Omicron wave, the reinfection rates reached 3.31%. Overall rates of severe/lethal COVID-19 were very low (2-7 per 10,000 subjects according to definition criteria) and were not affected by strain predominance.

CONCLUSIONS

A strong natural immunity follows the primary infection and may last for more than one year, suggesting that the risk and health care needs of recovered subjects might be limited. Although the reinfection rates considerably increased during the Omicron wave, the risk of a secondary severe or lethal disease remained very low. The risk-benefit profile of multiple vaccine doses for this subset of population needs to be carefully evaluated.

Dynamicity and persistence of severe acute respiratory syndrome coronavirus-2 antibody response after double dose and the third dose with BBV-152 and AZD1222 vaccines: A prospective, longitudinal cohort study

Introduction

Vaccines are available worldwide to combat coronavirus disease-19 (COVID-19). However, the long-term kinetics of the vaccine-induced antibodies against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have not been sufficiently evaluated. This study was performed to investigate the persistence and dynamicity of BBV-152 (Covaxin)- and AZD1222 (Covishield)-induced immunoglobulin-G (IgG) antibodies over the year and neutralizing antibodies’ status after 1-month of booster dose.

Materials and methods

This 52-week longitudinal cohort study documented antibody persistence and neutralizing antibodies status among 304 healthcare workers (HCWs) from six hospitals and research facilities in Odisha, enrolled during January 2021 and continued till March 2022. IgG antibodies against spike receptor-binding domain (RBD) of SARS-CoV-2 were quantified in an automated chemiluminescence immune assay-based (CLIA) platform and a surrogate virus neutralization test (sVNT) was performed by enzyme-linked immunosorbent assay (ELISA).

Results

Among these 304 HCWs vaccinated with double doses, 154 HCWs (50.66%) were Covaxin recipients and the remaining 150 (49.34%) were Covishield recipients. During the follow-ups for seven times, a total of 114 participants were identified as vaccine breakthrough cases. In 190 non-infected HCWs, the median antibody titer was significantly waned from DD2 to DD10, both for Covaxin (231.8 vs. 42.7 AU/ml) and Covishield (1,884.6 vs. 369.2 AU/ml). No statistically significant differences in antibody titers were observed based on age, gender, comorbidities, and blood groups. The median inhibition activity of sVNT increased from 23.8 to 91.3% for Covaxin booster recipients and from 41.2 to 96.0% for Covishield booster recipients. Among 146 booster dose recipients, 48 were breakthrough cases after booster and all were contracted by the omicron variant.

Conclusion

This year-long follow-up study found a 7- and 5-fold antibody waning in Covaxin and Covishield recipients, respectively, without any breakthrough infection history. However, individuals with booster breakthrough had mild symptoms and did not require hospital admission. The data also indicate the possible escape of omicron variants despite the presence of vaccine-induced neutralizing antibodies.

Theaflavin 3-gallate inhibits the main protease (Mpro) of SARS-CoV-2 and reduces its count in vitro

The main protease (M^pro) of SARS-CoV-2 has been recognized as an attractive drug target because of its central role in viral replication. Our previous preliminary molecular docking studies showed that theaflavin 3-gallate (a natural bioactive molecule derived from theaflavin and found in high abundance in black tea) exhibited better docking scores than repurposed drugs (Atazanavir, Darunavir, Lopinavir). In this study, conventional and steered MD-simulations analyses revealed stronger interactions of theaflavin 3-gallate with the active site residues of M^pro than theaflavin and a standard molecule GC373 (a known inhibitor of M^pro and novel broad-spectrum anti-viral agent). Theaflavin 3-gallate inhibited M^pro protein of SARS-CoV-2 with an IC₅₀ value of 18.48 ± 1.29 μM. Treatment of SARS-CoV-2 (Indian/a3i clade/2020 isolate) with 200 μM of theaflavin 3-gallate in vitro using Vero cells and quantifying viral transcripts demonstrated reduction of viral count by 75% (viral particles reduced from Log10^6.7 to Log10^6.1). Overall, our findings suggest that theaflavin 3-gallate effectively targets the M^pro thus limiting the replication of the SARS-CoV-2 virus in vitro.

Risk factors for mortality in kidney transplant recipients with COVID-19: a single centre experience and case-control study

BACKGROUND

COVID-19 infection is considered to cause high mortality in kidney transplant recipients (KTR). Old age, comorbidities and acute kidney injury are known risk factors for increased mortality in KTR. Nevertheless, mortality rates have varied across different regions. Differences in age, comorbidities and varying standards of care across geographies may explain some variations. However, it is still unclear whether post-transplant duration, induction therapy, antirejection therapy and co-infections contribute to increased mortality in KTR with COVID-19. The present study assessed risk factors in a large cohort from India.

METHODS

A matched case-control study was performed to analyze risk factors for death in KTR (N = 218) diagnosed with COVID-19 between April 2020 to July 2021 at the study centre. Cases were KTR who died (non-survivors, N = 30), whereas those who survived were taken as controls (survivors, N = 188).

RESULTS

A high death-to-case ratio of 13.8% was observed amongst study group KTR infected with COVID-19. There was a high incidence (12.4%) of co-infections, with cytomegalovirus being the most common co-infection among non-survivors. Diarrhea, co-infection, high oxygen requirement, and need for mechanical ventilation were significantly associated with mortality on regression analyses. Antirejection therapy, lymphopenia and requirement for renal replacement therapy were associated with worse outcomes.

CONCLUSIONS

The mortality was much higher in KTR who required mechanical ventilation and had co-infections. Mortality did not vary with the type of transplant, post-transplant duration and usage of depletion induction therapy. An aggressive approach has to be taken for an early diagnosis and therapeutic intervention of associated infections.

Confirmed SARS-CoV-2 reinfections after a second wave with predominance of Lambda in Lima and Callao, Peru

Background

Coronavirus disease 2019 (COVID-19) infection is a major public health problem in the world and reinfections are becoming more frequent. Our main objective was to describe the epidemiological, clinical, and genomic characteristics of the confirmed cases of reinfection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the capital of Lima and Callao, Peru.

Methods

We searched in the Peruvian laboratory information system from April 2020 up to May 2021, looking for cases having 2 positive molecular tests for SARS-CoV-2 with more than 90 days between them. We performed genomic sequencing to the available pairs of samples and described the clinical characteristics, epidemiological impact, and genomic analysis of the confirmed reinfections.

Results

There were 1 694 164 people with a positive diagnostic test for SARS-CoV-2 in Lima/Callao during the study period. Of these, 1695 had 2 positive molecular tests with more than 90 days between them. Two hundred eleven had both samples available for genomic analysis according to our selection criteria, and these were retrieved and submitted to sequencing. Thirty cases were confirmed to be SARS-CoV-2 reinfections with 2 different lineages in the 2 episodes. The variant Lambda (C.37) was the most common during the second infection and accounted for 19 (63.3%) of the 30 cases.

Conclusions

We report 30 cases of confirmed SARS-CoV-2 reinfections. The Lambda variant was the most common cause of the second infections, in concordance with its predominant circulation during Peru’s second wave. This report describes the largest series of confirmed reinfections by SARS-CoV-2 in Latin America.

We describe the epidemiological, clinical, and genomic characteristics of the confirmed cases of reinfection by severe acute respiratory syndrome coronavirus 2 in Lima and Callao, durante la segunda ola en Peru. The Lambda variant (C.37) was the most common cause of the second infections.

Reinfection rates among patients previously infected by SARS-CoV-2: systematic review and meta-analysis

BACKGROUND

Asymptomatic or symptomatic infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be followed by reinfection. The protection conferred by prior infection among coronavirus disease 2019 (COVID-19) patients is unclear. We assessed the incidence of SARS-CoV-2 reinfection and the protection effect of previous infection against reinfection.

METHODS

We searched PubMed, EMBASE, Cochrane, Scopus, Web of Science, and ClinicalTrials.gov for publications up until the end date of May 1, 2021. The reinfection rate of recovered patients and the protection against reinfection were analyzed using meta-analysis.

RESULTS

Overall, 19 studies of 1096 reinfection patients were included. The pooled reinfection rate was 0.65% (95% confidence interval [CI] 0.39-0.98%). The symptomatic reinfection rate was a bit lower (0.37% [95% CI 0.11-0.78%], I2 = 99%). The reinfection rate was much higher in high-risk populations (1.59% [95% CI 0.30-3.88%], I2 = 90%). The protection against reinfection and symptomatic reinfection was similar (87.02% [95% CI 83.22-89.96%] and 87.17% [95% CI 83.09-90.26%], respectively).

CONCLUSIONS

The rate of reinfection with SARS-CoV-2 is relatively low. The protection against SARS-CoV-2 after natural infection is comparable to that estimated for vaccine efficacy. These data may help guide public health measures and vaccination strategies in response to the COVID-19 pandemic. High-quality clinical studies are needed to establish the relevant risk factors in recovered patients.

SARS-CoV-2 Reinfection Rate and Estimated Effectiveness of the Inactivated Whole Virion Vaccine BBV152 Against Reinfection Among Health Care Workers in New Delhi, India

Importance

A surge of COVID-19 occurred from March to June 2021, in New Delhi, India, linked to the B.1.617.2 (Delta) variant of SARS-CoV-2. COVID-19 vaccines were rolled out for health care workers (HCWs) starting in January 2021.

Objective

To assess the incidence density of reinfection among a cohort of HCWs and estimate the effectiveness of the inactivated whole virion vaccine BBV152 against reinfection.

Design, Setting, and Participants

This was a retrospective cohort study among HCWs working at a tertiary care center in New Delhi, India.

Exposures

Vaccination with 0, 1, or 2 doses of BBV152.

Main Outcomes and Measures

The HCWs were categorized as fully vaccinated (with 2 doses and ≥15 days after the second dose), partially vaccinated (with 1 dose or 2 doses with <15 days after the second dose), or unvaccinated. The incidence density of COVID-19 reinfection per 100 person-years was computed, and events from March 3, 2020, to June 18, 2021, were included for analysis. Unadjusted and adjusted hazard ratios (HRs) were estimated using a Cox proportional hazards model. Estimated vaccine effectiveness (1 - adjusted HR) was reported.

Results

Among 15 244 HCWs who participated in the study, 4978 (32.7%) were diagnosed with COVID-19. The mean (SD) age was 36.6 (10.3) years, and 55.0% were male. The reinfection incidence density was 7.26 (95% CI: 6.09-8.66) per 100 person-years (124 HCWs [2.5%], total person follow-up period of 1696 person-years as time at risk). Fully vaccinated HCWs had lower risk of reinfection (HR, 0.14 [95% CI, 0.08-0.23]), symptomatic reinfection (HR, 0.13 [95% CI, 0.07-0.24]), and asymptomatic reinfection (HR, 0.16 [95% CI, 0.05-0.53]) compared with unvaccinated HCWs. Accordingly, among the 3 vaccine categories, reinfection was observed in 60 of 472 (12.7%) of unvaccinated (incidence density, 18.05 per 100 person-years; 95% CI, 14.02-23.25), 39 of 356 (11.0%) of partially vaccinated (incidence density 15.62 per 100 person-years; 95% CI, 11.42-21.38), and 17 of 1089 (1.6%) fully vaccinated (incidence density 2.18 per 100 person-years; 95% CI, 1.35-3.51) HCWs. The estimated effectiveness of BBV152 against reinfection was 86% (95% CI, 77%-92%); symptomatic reinfection, 87% (95% CI, 76%-93%); and asymptomatic reinfection, 84% (95% CI, 47%-95%) among fully vaccinated HCWs. Partial vaccination was not associated with reduced risk of reinfection.

Conclusions and Relevance

These findings suggest that BBV152 was associated with protection against both symptomatic and asymptomatic reinfection in HCWs after a complete vaccination schedule, when the predominant circulating variant was B.1.617.2.

SARS-CoV-2 and HIV-1: So Different yet so Alike. Immune Response at the Cellular and Molecular Level

In the past half century, humanity has experienced two devastating pandemics; the HIV-1 pandemic and the recent pandemic caused by SARS-CoV-2. Both emerged as zoonotic pathogens. Interestingly, SARS-CoV-2 has rapidly migrated all over the world in less than two years, much as HIV-1 did almost 40 years ago. Despite these two RNA viruses being different in their mode of transmission as well as the symptoms they generate, recent evidence suggests that they cause similar immune responses. In this mini review, we compare the molecular basis for CD4⁺ T cell lymphopenia and other effects on the immune system induced by SARS-CoV-2 and HIV-1 infections. We considered features of the host immune response that are shared with HIV-1 and could account for the lymphopenia and other immune effects observed in COVID-19. The information provided herein, may cast the virus-induced lymphopenia and cytokine storm associated with the acute SARS-CoV-2 infection and pathogenesis in a different light for further research on host immune responses. It can also provide opportunities for the identification of novel therapeutic targets for COVID-19. Furthermore, we provide some basic information to enable a comparative framework for considering the overlapping sets of immune responses caused by HIV-1 and SARS-CoV-2.

Coronavirus reinfections: An outlook on evidences and effects

After recovery from COVID-19, a person may become infected again due to reactivation of the virus inside the human body or reinfection with a genetically distinct mutant virus owing to reinfection. The COVID-19 reinfection has been recorded all around the world, albeit it is still uncommon. The reinfection with COVID-19 raises several questions about virus characteristics such as mutation, growth, functioning, and transmissibility, level and durability of immunity, diagnosis, therapy, and efficacy of vaccine(s) on genetically modified viruses and their durability and safety. This chapter focuses on various aspects of COVID-19 reinfection, including its severity, frequency, immunopathogenesis, immune responses, effect on vaccine development, Corona waves and herd immunity, management and prevention strategies. COVID-19 reinfections are often asymptomatic or mildly symptomatic, and are milder than first infections, with a few exceptions. The management of reinfection should be the same as the treatment of the first COVID-19 infection. The deep, extensive, rapid and real-time whole-genome sequencing studies, as well as an enhanced vaccination drive, and rigorous adherence to COVID-19 appropriate behavior, would be critical in limiting the severity of transmission and reinfection.

An update on host immunity correlates and prospects of re-infection in COVID-19

Reinfection with SARS-CoV-2 is not frequent yet the incidence rate of it is increasing globally owing to the slow emergence of drift variants that pose a perpetual threat to vaccination strategies and have a greater propensity for disease reoccurrence. Long-term protection against SARS-CoV-2 reinfection relies on the induction of the innate as well as the adaptive immune response endowed with immune memory. However, a multitude of factors including the selection pressure, the waning immunity against SARS-CoV-2 over the first year after infection possibly favors evolution of more infectious immune escape variants, amplifying the risk of reinfection. Additionally, the correlates of immune protection, the novel SARS-CoV-2 variants of concern (VOC), the durability of the adaptive and mucosal immunity remain major challenges for the development of therapeutic and prophylactic interventions. Interestingly, a recent body of evidence indicated that the gastrointestinal (GI) tract is another important target organ for SARS-CoV-2 besides the respiratory system, potentially increasing the likelihood of reinfection by impacting the microbiome and the immune response via the gut-lung axis. In this review, we summarized the latest development in SARS-CoV-2 reinfection, and explored the untapped potential of trained immunity. We also highlighted the immune memory kinetics of the humoral and cell-mediated immune response, genetic drift of the emerging viral variants, and discussed the current challenges in vaccine development. Understanding the dynamics and the quality of immune response by unlocking the power of the innate, humoral and cell-mediated immunity during SARS-CoV-2 reinfection would open newer avenues for drug discovery and vaccine designs.

SARS-CoV-2 re-infection rate in Iranian COVID-19 cases within one-year follow-up

Since the COVID-19 pandemic initiation, the possibility of re-infection has been unclearly present. Although herd immunity has a potential reliance through natural infection, human corona viruses has the ability to subvert immunity and re-infection happens for seasonal corona viruses. Currently, the frequency of SARS-CoV-2 re-infection incidence is not exactly defined. In this study we aimed at determination of SARS-CoV-2 re-infection rate in Iranian population. In a total of 5696 COVID-19 suspicious individuals, RT-PCR was applied to diagnose the infection. The confirmed patients were followed for 12 months and serology tests were applied to measure the specific antibodies. Among 1492 confirmed COVID-19 cases, five individuals experienced the subsequent infection. The re-infection/reactivation incidence rate was totally 0.33% after one year of follow-up. The interval ranged from 63 to 156 days. All the cases had viral mutations in the second episode of the infection. All of them were symptomatic cases with moderate severity. The estimated rate of SARS-CoV-2 in Persian population is therefore rare and natural infection seems to induce good protection against re-infection which clarifies that mass vaccination can hugely affect the society.

A case with SARS-CoV-2 reinfection from India

A healthcare worker presented with fever, cough, headache and tested positive by SARS-CoV-2 real time reverse transcriptase polymerase chain reaction (qRT-PCR). He got admitted to hospital and recovered after 14 days. After 2 months, as a screening protocol considering the high risk setup he got tested and again found to be positive for SARS-CoV-2 by qRT-PCR. Our patient had detectable levels of Anti-SARS-CoV-2 IgG antibodies during the reinfection but found negative for Neutralizing antibodies (NAb). Our findings suggest that the person after the initial infection might not develop the desired protective immunity to prevent the reinfection as demonstrated by absence of NAb.

Consecutive Hits of COVID-19 in India: The Mystery of Plummeting Cases and Current Scenario

The novel coronavirus disease 2019 (COVID-19)-related pandemic has been in existence for almost 2 years now after its possible emergence from a wet market in the city of Wuhan of the Chinese mainland. Evidence of the emergence and transmission of this virus was attributed to bats and pangolins. The causative virus, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has rapidly spread globally, affecting humans considerably with its current death toll to be over 4.7 million out of more than 233 confirmed cases as of September 2021. The virus is constantly mutating and continuously trying to establish itself in humans by increasing its transmissibility and virulence through its numerous emerging variants. Several countries have been facing multiple waves of COVID-19 outbreaks one after the other, putting the medical and healthcare establishments under tremendous stress. Although very few drugs and vaccines have been approved for emergency use, their production capabilities need to meet the needs of a huge global population. Currently, not even a quarter of the world population is vaccinated. The situation in India has worsened during the ongoing second wave with the involvement of virus variants with a rapid and huge surge in COVID-19 cases, where the scarcity of hospital infrastructure, antiviral agents, and oxygen has led to increased deaths. Recently, increased surveillance and monitoring, strengthening of medical facilities, campaigns of awareness programs, progressive vaccination drive, and high collaborative efforts have led to limiting the surge of COVID-19 cases in India to a low level. This review outlines the global status of the pandemic with special reference to the Indian scenario.

AK, Kumari MP, Biswas D, Iravane J, Raut S, Dutta S, Devi S, Barua P, Gupta P, Borkakoty B, Kalita D, Dhingra K, Fomda B, Joshi Y, Goyal K, John R, Munivenkatappa A, Dhodapkar R, Pandit P, Devi S, Dudhmal M, Kinariwala D, Khandelwal N, Tiwari YK, Khatri PK, Gupta A, Khatri H, Malhotra B, Nagasundaram M, Dar L, Sheikh N, Shastri J, Aggarwal N, Abraham P. Clinical Characterization and Genomic Analysis of Samples from COVID-19 Breakthrough Infections during the Second Wave among the Various States of India

From March to June 2021, India experienced a deadly second wave of COVID-19, with an increased number of post-vaccination breakthrough infections reported across the country. To understand the possible reason for these breakthroughs, we collected 677 clinical samples (throat swab/nasal swabs) of individuals from 17 states/Union Territories of the country who had received two doses (n = 592) and one dose (n = 85) of vaccines and tested positive for COVID-19. These cases were telephonically interviewed and clinical data were analyzed. A total of 511 SARS-CoV-2 genomes were recovered with genome coverage of higher than 98% from both groups. Analysis of both groups determined that 86.69% (n = 443) of them belonged to the Delta variant, along with Alpha, Kappa, Delta AY.1, and Delta AY.2. The Delta variant clustered into four distinct sub-lineages. Sub-lineage I had mutations in ORF1ab A1306S, P2046L, P2287S, V2930L, T3255I, T3446A, G5063S, P5401L, and A6319V, and in N G215C; Sub-lineage II had mutations in ORF1ab P309L, A3209V, V3718A, G5063S, P5401L, and ORF7a L116F; Sub-lineage III had mutations in ORF1ab A3209V, V3718A, T3750I, G5063S, and P5401L and in spike A222V; Sub-lineage IV had mutations in ORF1ab P309L, D2980N, and F3138S and spike K77T. This study indicates that majority of the breakthrough COVID-19 clinical cases were infected with the Delta variant, and only 9.8% cases required hospitalization, while fatality was observed in only 0.4% cases. This clearly suggests that the vaccination does provide reduction in hospital admission and mortality.

Clinical Characterization and Genomic Analysis of Samples from COVID-19 Breakthrough Infections during the Second Wave among the Various States of India

From March to June 2021, India experienced a deadly second wave of COVID-19, with an increased number of post-vaccination breakthrough infections reported across the country. To understand the possible reason for these breakthroughs, we collected 677 clinical samples (throat swab/nasal swabs) of individuals from 17 states/Union Territories of the country who had received two doses (n = 592) and one dose (n = 85) of vaccines and tested positive for COVID-19. These cases were telephonically interviewed and clinical data were analyzed. A total of 511 SARS-CoV-2 genomes were recovered with genome coverage of higher than 98% from both groups. Analysis of both groups determined that 86.69% (n = 443) of them belonged to the Delta variant, along with Alpha, Kappa, Delta AY.1, and Delta AY.2. The Delta variant clustered into four distinct sub-lineages. Sub-lineage I had mutations in ORF1ab A1306S, P2046L, P2287S, V2930L, T3255I, T3446A, G5063S, P5401L, and A6319V, and in N G215C; Sub-lineage II had mutations in ORF1ab P309L, A3209V, V3718A, G5063S, P5401L, and ORF7a L116F; Sub-lineage III had mutations in ORF1ab A3209V, V3718A, T3750I, G5063S, and P5401L and in spike A222V; Sub-lineage IV had mutations in ORF1ab P309L, D2980N, and F3138S and spike K77T. This study indicates that majority of the breakthrough COVID-19 clinical cases were infected with the Delta variant, and only 9.8% cases required hospitalization, while fatality was observed in only 0.4% cases. This clearly suggests that the vaccination does provide reduction in hospital admission and mortality.

Elucidating reasons of COVID-19 re-infection and its management strategies

BACKGROUND AND AIMS

Reinfection is gradually being recognised after symptomatic or asymptomatic COVID-19 infection. We try to elucidate various explanations behind COVID-19 reinfection and suggest possible strategies to counteract this threat.

METHODS

We carried out a comprehensive review of the literature using suitable keywords such as 'COVID-19', 'Pandemics', 'Reinfection', 'Vaccines' and 'India' on the search engines of PubMed, SCOPUS, Google Scholar and Research Gate in March 2021 and first half of April 2021 during the current COVID-19 pandemic. Epidemiology, risk factors and trends of reinfection were assessed.

RESULTS

A multitude of factors have been associated with rising incidence of COVID-19 reinfection in India and across the world. Emergence of 'Variants of Concern (VOC)', pandemic fatigue and disregard of infection prevention strategies appear to be the most obvious reasons.

CONCLUSIONS

COVID-19 reinfection is an emerging concern amongst the worldwide population with newer mutant strains demonstrating increasing transmissibility and responsible for continuing waves of the pandemic. COVID Appropriate Behaviour (CAB), improvised vaccines and enhanced vaccination drives are necessary to mitigate global threat.