SARS-CoV-2 reinfection in patients negative for immunoglobulin G following recovery from COVID-19

A study on the side effects caused by the Pfizer/BioNTech COVID-19 vaccine: Focus on IgG antibodies and serological biomarkers

Introduction

The SARS-CoV-2 pandemic that spread swiftly is now a major global public health issue. Vaccines are currently being distributed in an effort to limit the viral transmission and mortality. The aim of the study was monitoring of both safety and efficacy in determining the overall effectiveness of the vaccine and identifying any potential safety concerns.

Material and methods

A retrospective, cross-sectional study employing a validated 13-item structured questionnaire divided into two sections was performed between March 2022 and September 2022. Different post-vaccination side effects (SE) according to symptoms severity in terms of age and sex for participants were reported. Additionally, some pertinent serological assays for participants' post-vaccinations were investigated.

Results

A total of 502 participants (male: 262, female: 240) with comorbidity (healthy: 258, morbid: 244) who received two Pfizer/BioNTech mRNA vaccine doses were included. Importantly, second dose (D2) vaccination was associated with significantly more SE than single dose (D1) vaccination (p < 0.0001). In D1 vaccination injection site pain (ISP) (45%), followed by equal proportions of headache and fever (40%) were the most common vaccine SE, while in D2 vaccination, ISP (66%) and nausea (57%) were reported. In all, 97% (p < 0.0001) of participants were IgG antibody positive at D2 vaccination. Similarly, serum CR protein level was elevated significantly (p < 0.0001) corresponding to the severity of SE between D1 and D2. Significant differences in IgG concentration were found between D1 and D2 vaccination in different gender and age groups (p < 0.0001).

Conclusions

In light of the extensive data from this study, it is evident that mRNA vaccines, particularly the Pfizer/BioNTech vaccine, have proven to be highly safe and effective in mitigating the impact of the SARS-CoV-2 pandemic.

The influence of SARS-CoV-2 on male reproduction and men's health

BACKGROUND

SARS-CoV-2, the virus responsible for COVID-19, primarily affects the respiratory system by targeting the Angiotensin-converting enzyme 2 (ACE2) receptor and TMPRSS2. However, these receptors are also present in other organs, including the testes, where a higher concentration of ACE2 receptors has been observed. This raises concerns about the potential impact of the virus on male fertility.

AIMS

In this study, we aimed to assess the effects of SARS-CoV-2 on semen parameters by comparing samples during and after infection in the same patients.

MATERIALS & METHOD

The study enrolled 51 individuals who had contracted COVID-19 and analysed various parameters related to sperm quality and quantity, including C-reactive protein, testosterone levels, total sperm concentration, motility and morphology. A comparison was made between these parameters during the initial infection with SARS-CoV-2 and after a 2- and 5-month recovery period.

RESULTS

The results indicated that all of the mentioned parameters were significantly affected during COVID-19 infection (PCR-ct, CRP, WBCs LH, FSH and testosterone levels, p-value = .0001). Furthermore, the study assessed TC, TM and sperm morphology in patients infected with SARS-CoV-2 and found that these parameters were also significantly influenced during the infection, (p-value = .0001; Morphology, p-value = .0004). We observed significant alterations in sperm count and morphology during infection, suggesting a potential negative impact on sperm quality. Additionally, lower hormone levels were observed during COVID-19 infection, possibly due to increased inflammatory cytokines. However, both hormones and inflammation markers returned to normal following recovery. Our findings indicate a statistically significant change in total sperm count, motility and morphology post-infection, which aligns with previous studies. Discussion, COVID-19 have a transient impact on sperm parameters and fertility, emphasizing the importance of further investigation into the long-term implications.

Clinical outcomes and phylogenetic analysis in reflection with three predominant clades of SARS-CoV-2 variants

BACKGROUND

The pandemic of coronavirus disease 2019 (COVID-19) has a broad spectrum of clinical manifestations. The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) undergoes continuous evolution, resulting in the emergence of several variants. Each variant has a different severity and mortality rate.

MATERIALS AND METHODS

In this study, 1174 COVID-19 patients were studied for mortality and severity over three SARS-CoV-2 predominating variant periods in 2021 and 2022 in Sulaimani Province, Iraq. In each period, a representative, variant virus was subjected to phylogenetic and molecular and clinical analysis.

RESULTS

Phylogenetic analysis revealed three SARS-CoV-2 variants, belonging to: Delta B.1.617.2, Omicron BA.1.17.2, and Omicron BA.5.6. The Delta variants showed more severe symptoms and a lower PCR-Ct value than Omicron variants regardless of gender, and only 4.3% of the cases were asymptomatic. The mortality rate was lower with Omicron (.5% for BA.5.2 and 1.3% for BA.1.17.2) compared with Delta variants (2.5%). The higher mortality rate with Delta variants was in males (2.84%), while that with Omicron BA1.17.2 and BA.5.2 was in females, 1.05% and .0%, respectively. Age group (≥70) years had the highest mortality rate; however, it was (.0%) in the age group (30-49) years with Omicron variants, compared with (.96%) in Delta variants.

CONCLUSIONS

There has been a surge in COVID-19 infection in the city due to the predominant lineages of SARS-CoV-2, B.1.617, Omicron BA.1.17.2 and Omicron BA.5.6, respectively. A higher PCR-Ct value and severity of the Delta variant over Omicron BA.1.17.2 and/or BA.5.2 variants were significantly correlated with a higher death rate in the same order.

SARS-CoV-2 Reinfection and Severity of the Disease: A Systematic Review and Meta-Analysis

Since the discovery of SARS-CoV-2, changes in genotype and reinfection with different variants have been observed in COVID-19-recovered patients, raising questions around the clinical pattern and severity of primary infection and reinfection. In this systematic review, we summarize the results of 23 studies addressing SARS-CoV-2 reinfections. A total of 23,231 reinfected patients were included, with pooled estimated reinfection rates ranging from 0.1 to 6.8%. Reinfections were more prevalent during the Omicron variant period. The mean age of reinfected patients was 38.0 ± 6. years and females were predominant among reinfected patients (M/F = 0.8). The most common symptoms during the first and second infection were fever (41.1%), cough (35.7% and 44.6%), myalgia (34.5% and 33.3%), fatigue (23.8% and 25.6%), and headaches (24.4% and 21.4%). No significant differences of clinical pattern were observed between primary infection and reinfection. No significant differences in the severity of infection were observed between primary infection and reinfection. Being female, being a patient with comorbidities, lacking anti-nucleocapsid IgG after the first infection, being infected during the Delta and Omicron wave, and being unvaccinated were associated with a higher risk of reinfection. Conflicting age-related findings were found in two studies. Reinfection with SARS-CoV-2 suggests that natural immunity is not long-lasting in COVID-19 patients.

An update on SARS-CoV-2 immunization and future directions

Millions of people have died as a result of SARS-CoV-2, which was first discovered in China and has since spread globally. Patients with SARS-CoV-2 infection may show a range of symptoms, including fever, coughing, and shortness of breath, or they may show no symptoms at all. To treat COVID-19 symptoms and avoid serious infections, many medications and vaccinations have been employed. However, to entirely eradicate COVID-19 from the world, next-generation vaccine research is required because of the devastating consequences it is having for humanity and every nation's economy. Scientists are working hard to eradicate this dangerous virus across the world. SARS-CoV-2 has also undergone significant mutation, leading to distinct viral types such as the alpha, beta, gamma, delta, and omicron variants. This has sparked discussion about the effectiveness of current vaccines for the newly formed variants. A proper comparison of these vaccinations is required to compare their efficacy as the number of people immunized against SARS-CoV-2 globally increases. Population-level statistics evaluating the capacity of these vaccines to reduce infection are therefore being developed. In this paper, we analyze the many vaccines on the market in terms of their production process, price, dosage needed, and efficacy. This article also discusses the challenges of achieving herd immunity, the likelihood of reinfection, and the importance of convalescent plasma therapy in reducing infection.

Humoral SARS-CoV-2 Immune Response in COVID-19 Recovered Vaccinated and Unvaccinated Individuals Related to Post-COVID-Syndrome

BACKGROUND

The duration of anti-SARS-CoV-2-antibody detectability up to 12 months was examined in individuals after either single convalescence or convalescence and vaccination. Moreover, variables that might influence an anti-RBD/S1 antibody decline and the existence of a post-COVID-syndrome (PCS) were addressed.

METHODS

Forty-nine SARS-CoV-2-qRT-PCR-confirmed participants completed a 12-month examination of anti-SARS-CoV-2-antibody levels and PCS-associated long-term sequelae. Overall, 324 samples were collected. Cell-free DNA (cfDNA) was isolated and quantified from EDTA-plasma. As cfDNA is released into the bloodstream from dying cells, it might provide information on organ damage in the late recovery of COIVD-19. Therefore, we evaluated cfDNA concentrations as a biomarker for a PCS. In the context of antibody dynamics, a random forest-based logistic regression with antibody decline as the target was performed and internally validated.

RESULTS

The mean percentage dynamic related to the maximum measured value was 96 (±38)% for anti-RBD/S1 antibodies and 30 (±26)% for anti-N antibodies. Anti-RBD/S1 antibodies decreased in 37%, whereas anti-SARS-CoV-2-anti-N antibodies decreased in 86% of the subjects. Clinical anti-RBD/S1 antibody decline prediction models, including vascular and other diseases, were cross-validated (highest AUC 0.74). Long-term follow-up revealed no significant reduction in PCS prevalence but an increase in cognitive impairment, with no indication for cfDNA as a marker for a PCS.

CONCLUSION

Long-term anti-RBD/S1-antibody positivity was confirmed, and clinical parameters associated with declining titers were presented. A fulminant decrease in anti-SARS-CoV-2-anti-N antibodies was observed (mean change to maximum value 30 (±26)%). Anti-RBD/S1 antibody titers of SARS-CoV-2 recovered subjects boosted with a vaccine exceeded the maximum values measured after single infection by 235 ± 382-fold, with no influence on preexisting PCS. PCS long-term prevalence was 38.6%, with an increase in cognitive impairment compromising the quality of life. Quantified cfDNA measured in the early post-COVID-19 phase might not be an effective marker for PCS identification.

High Seroprevalence of Anti-SARS-CoV-2 IgM/IgG among Inhabitants of Sakaka City, Aljouf, Saudi Arabia

(1) Backgrounds and Objectives: The global battle to contain the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) is still ongoing. This cross-sectional study aimed to detect the seroprevalence of anti-SARS-CoV-2 IgM/IgG among previously symptomatic/asymptomatic and vaccinated/unvaccinated inhabitants of Sakaka City, Aljouf, Saudi Arabia. (2) Methods: Blood samples of 400 participants were tested for the presence of anti-SARS-CoV-2 IgM/IgG using colloidal gold immuno-chromatography lateral flow immunoassay cards. (3) Results: The prevalence of anti-SARS-CoV-2 IgM and IgG positivity was 45.8% and 42.3%, respectively. Statistically significant correlations (p < 0.05) were found between the previous RT-PCR testing for SARS-CoV-2-RNA and positivity for IgM and/or IgG. The highest seroprevalence of IgM and IgG were detected among smokers, participants aged ≥40 years, and patients with chronic diseases. Although most of the participants (58.5%) did not previously experience COVID-19 like symptoms, the anti-SARS-CoV-2 IgM and IgG seropositivity amongst them was 49.1% and 25.6%, respectively, with higher seroprevalence among males than females. At the time of the study, the SARS-CoV-2 vaccination rate at our locality in Saudi Arabia was 43.8% with statistically significant correlation (p < 0.001) between being vaccinated and anti-SARS-CoV-2 IgM and/or IgG positivity, with more positivity after receiving the second vaccine dose. (4) Conclusions: Public assessment reflects the real scale of the disease exposure among the community and helps in identifying the asymptomatic carriers that constitute a major problem for controlling the SARS-CoV-2. To limit the spread of the virus, rigorous implementation of large-scale SARS-CoV-2 vaccination and anti-SARS-CoV-2 serological testing strategies should be empowered.

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.

Nucleocapsid and spike antibody responses following virologically confirmed SARS-CoV-2 infection: an observational analysis in the Virus Watch community cohort

OBJECTIVES

Seroprevalence studies can provide a measure of SARS-CoV-2 cumulative incidence, but a better understanding of spike and nucleocapsid (anti-N) antibody dynamics following infection is needed to assess the longevity of detectability.

METHODS

Adults aged ≥18 years, from households enrolled in the Virus Watch prospective community cohort study in England and Wales, provided monthly capillary blood samples, which were tested for spike antibody and anti-N. Participants self-reported vaccination dates and past medical history. Previous polymerase chain reaction (PCR) swabs were obtained through Second Generation Surveillance System linkage data. The primary outcome variables were seropositivity and total anti-N and spike antibody levels after PCR-confirmed infection.

RESULTS

A total of 13,802 eligible individuals provided 58,770 capillary blood samples. A total of 537 of these had a previous positive PCR-confirmed SARS-CoV-2 infection within 0-269 days of antibody sample date, among them 432 (80.45%) having a positive anti-N result. Median anti-N levels peaked between days 90 and 119 after PCR results and then began to decline. There is evidence of anti-N waning from 120 days onwards, with earlier waning for females and younger age categories.

CONCLUSION

Our findings suggest that anti-N has around 80% sensitivity for identifying previous COVID-19 infection, and the duration of detectability is affected by sex and age.

Relationship between Humoral Response in COVID-19 and Seasonal Influenza Vaccination

There is evidence that vaccination against seasonal influenza can improve innate immune responses to COVID-19 and decrease disease severity. However, less is known about whether it could also impact the humoral immunity in SARS-CoV-2 infected patients. The present study aimed to compare the SARS-CoV-2 specific humoral responses (IgG antibodies against nucleocapsid; anti-N, receptor binding domain; anti-RBD, subunit S2; anti-S2, and envelope protein; anti-E) between non-hospitalized, COVID-19 unvaccinated, and mild COVID-19 convalescent patients who were and were not vaccinated against influenza during the 2019/2020 epidemic season (n = 489 and n = 292, respectively). The influenza-vaccinated group had significantly higher frequency and titers of anti-N antibodies (75 vs. 66%; mean 559 vs. 520 U/mL) and anti-RBD antibodies (85 vs. 76%; mean 580 vs. 540 U/mL). The prevalence and concentrations of anti-S2 and anti-E antibodies did not differ between groups (40-43%; mean 370-375 U/mL and 1.4-1.7%; mean 261-294 U/mL) and were significantly lower compared to those of anti-RBD and anti-N. In both groups, age, comorbidities, and gender did not affect the prevalence and concentrations of studied antibodies. The results indicate that influenza vaccination can improve serum antibody levels produced in response to SARS-CoV-2 infection.

SARS-CoV-2 reinfections during the first three major COVID-19 waves in Bulgaria

BACKGROUND

The COVID-19 pandemic has had a devastating impact on the world over the past two years (2020-2021). One of the key questions about its future trajectory is the protection from subsequent infections and disease conferred by a previous infection, as the SARS-CoV-2 virus belongs to the coronaviruses, a group of viruses the members of which are known for their ability to reinfect convalescent individuals. Bulgaria, with high rates of previous infections combined with low vaccination rates and an elderly population, presents a somewhat unique context to study this question.

METHODS

We use detailed governmental data on registered COVID-19 cases to evaluate the incidence and outcomes of COVID-19 reinfections in Bulgaria in the period between March 2020 and early December 2021.

RESULTS

For the period analyzed, a total of 4,106 cases of individuals infected more than once were observed, including 31 cases of three infections and one of four infections. The number of reinfections increased dramatically during the Delta variant-driven wave of the pandemic towards the end of 2021. We observe a moderate reduction of severe outcomes (hospitalization and death) in reinfections relative to primary infections, and a more substantial reduction of severe outcomes in breakthrough infections in vaccinated individuals.

CONCLUSIONS

In the available datasets from Bulgaria, prior infection appears to provide some protection from severe outcomes, but to a lower degree than the reduction in severity of breakthrough infections in the vaccinated compared to primary infections in the unvaccinated.

Disease severity and efficacy of homologous vaccination among patients infected with SARS-CoV-2 Delta or Omicron VOCs, compared to unvaccinated using main biomarkers

From March 2021, various countries including Iraq issued prompted recommendations for increased COVID-19 vaccine protection in individuals especially those at risk of catching the virus (i.e., lifestyle, health sector workers, and chronic diseases). It is critically important to understand the impact of COVID-19 vaccinations with the most commonly used vaccines (Pfizer and AstraZeneca) among populations either on the severity of the disease or the transmissibility of SARS-CoV-2 variants of concern (VOCs) and in sequential waves. This study was conducted to establish the clinical severity of COVID-19 caused by Delta and Omicron SARS-CoV-2 variants among patients who either attended or were admitted to hospitals and to compare the effectiveness of Pfizer and AstraZeneca COVID-19 vaccines (single or double doses) at least to prevent hospitalizations if not eradicating the pandemic. A case-control study was done of 570 hospitalized patients; including 328 COVID-19 confirmed patients (166 males, 160 females) who received homologous vaccinations and 242 unvaccinated patients (128 males, 114 females) during the studied waves. The study showed that unvaccinated COVID-19 patients in both waves had expressed significantly a higher number and longer periods of symptoms than vaccinated ones. Additionally, there was no significant effect of vaccine types, Pfizer and AstraZeneca or vaccine shot numbers on the PCR-Ct in the last (Omicron) wave of the pandemic. However, in the previous (Delta) wave of the pandemic, fully vaccinated (double doses) COVID-19 patients had higher PCR-Ct values. Whether among vaccinated or unvaccinated patients, lower CRP levels recorded during the Omicron wave than that of the Delta wave, and regardless of the vaccine type or shot numbers, there were no significant differences between the two waves. Lower WBCs were observed in patients (vaccinated and unvaccinated) infected with the Delta variant in comparison to those infected with the Omicron variant and without any remarkable effect of the vaccine type or shot numbers. This is the first molecular and investigational study of the Delta variant and circulated Omicron in Iraq, regarding the severity of these two waves of SARS-CoV-2 pandemic and the efficacy of homologous vaccination, indicating the insufficiency of two doses and the demand for booster dose(s) as the most effective way of keeping on the safe-side against SARS-CoV-2.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)-Specific T Cells and Antibodies in Coronavirus Disease 2019 (COVID-19) Protection: A Prospective Study

BACKGROUND

During the ongoing coronavirus disease 2019 (COVID-19) pandemic, many individuals were infected with and have cleared the virus, developing virus-specific antibodies and effector/memory T cells. An important unanswered question is what levels of T-cell and antibody responses are sufficient to protect from the infection.

METHODS

In 5340 Moscow residents, we evaluated anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin M (IgM)/immunoglobulin G (IgG) titers and frequencies of the T cells specific to the membrane, nucleocapsid, and spike proteins of SARS-CoV-2, using interferon gamma (IFN-γ) enzyme-linked immunosorbent spot (ELISpot) assay. Additionally, we evaluated the fractions of virus-specific CD4+ and CD8+ T cells using intracellular staining of IFN-γ and interleukin 2 followed by flow cytometry. We analyzed the COVID-19 rates as a function of the assessed antibody and T-cell responses, using the Kaplan-Meier estimator method, for up to 300 days postinclusion.

RESULTS

We showed that T-cell and antibody responses are closely interconnected and are commonly induced concurrently. Magnitudes of both responses inversely correlated with infection probability. Individuals positive for both responses demonstrated the highest levels of protectivity against the SARS-CoV-2 infection. A comparable level of protection was found in individuals with antibody response only, whereas the T-cell response by itself granted only intermediate protection.

CONCLUSIONS

We found that the contribution of the virus-specific antibodies to protection against SARS-CoV-2 infection is more pronounced than that of the T cells. The data on the virus-specific IgG titers may be instructive for making decisions in personalized healthcare and public anti-COVID-19 policies. Clinical Trials Registration. NCT04898140.

Clinical laboratory parameters and comorbidities associated with severity of coronavirus disease 2019 (COVID-19) in Kurdistan Region of Iraq

Background

The pandemic coronavirus disease (COVID-19) dramatically spread worldwide. Considering several laboratory parameters and comorbidities may facilitate the assessment of disease severity. Early recognition of disease progression associated with severe cases of COVID-19 is essential for timely patient triaging. Our study investigated the characteristics and role of laboratory results and comorbidities in the progression and severity of COVID-19 cases.

Methods

The study was conducted from early-June to mid-August 2020. Blood samples and clinical data were taken from 322 patients diagnosed with COVID-19 at Qala Hospital, Kalar, Kurdistan Region of Iraq. Biological markers used in this study include complete blood count (CBC), D-dimer, erythrocyte sedimentation rate (ESR), serum ferritin, blood sugar, C-reactive protein (CRP) and SpO2.

Results

The sample included 154 males (47.8%) and 168 females (52.2%). Most females were in the mild and moderate symptom groups, while males developed more severe symptoms. Regarding comorbidities, diabetes mellitus was considered the greatest risk factor for increasing the severity of COVID-19 symptoms. As for biological parameters, WBC, granulocytes, ESR, Ferritin, CRP and D-Dimer were elevated significantly corresponding to the severity of the disease, while lymphocytes and SpO2 showed the opposite pattern. Higher RBC was significantly associated with COVID-19 severity, especially in females.

Conclusion

Gender, age and diabetes mellitus are important prognostic risk factors associated with severity and mortality of COVID-19. Relative to non-severe COVID-19, severe cases are characterized by an increase of most biological markers. These markers could be used to recognize severe cases and to monitor the clinical course of COVID-19.

The prevalence of adaptive immunity to COVID-19 and reinfection after recovery - a comprehensive systematic review and meta-analysis

This study aims to estimate the prevalence and longevity of detectable SARS-CoV-2 antibodies and T and B memory cells after recovery. In addition, the prevalence of COVID-19 reinfection and the preventive efficacy of previous infection with SARS-CoV-2 were investigated. A synthesis of existing research was conducted. The Cochrane Library, the China Academic Journals Full Text Database, PubMed, and Scopus, and preprint servers were searched for studies conducted between 1 January 2020 to 1 April 2021. Included studies were assessed for methodological quality and pooled estimates of relevant outcomes were obtained in a meta-analysis using a bias adjusted synthesis method. Proportions were synthesized with the Freeman-Tukey double arcsine transformation and binary outcomes using the odds ratio (OR). Heterogeneity was assessed using the I² and Cochran's Q statistics and publication bias was assessed using Doi plots. Fifty-four studies from 18 countries, with around 12,000,000 individuals, followed up to 8 months after recovery, were included. At 6-8 months after recovery, the prevalence of SARS-CoV-2 specific immunological memory remained high; IgG - 90.4% (95%CI 72.2-99.9, I² = 89.0%), CD4+ - 91.7% (95%CI 78.2-97.1y), and memory B cells 80.6% (95%CI 65.0-90.2) and the pooled prevalence of reinfection was 0.2% (95%CI 0.0-0.7, I² = 98.8). Individuals previously infected with SARS-CoV-2 had an 81% reduction in odds of a reinfection (OR 0.19, 95% CI 0.1-0.3, I² = 90.5%). Around 90% of recovered individuals had evidence of immunological memory to SARS-CoV-2, at 6-8 months after recovery and had a low risk of reinfection.RegistrationPROSPERO: CRD42020201234.

Severe COVID-19 is a T cell immune dysregulatory disorder triggered by SARS-CoV-2

INTRODUCTION

COVID-19 has had a calamitous impact on the global community. Apart from at least 6M deaths, hundreds of millions have been infected and a much greater number have been plunged into poverty. Vaccines have been effective but financial and logistical challenges have hampered their rapid global deployment. Vaccine disparities have allowed the emergence of new SARS-CoV-2 variants including delta and omicron, perpetuating the pandemic.

AREAS COVERED

The immunological response to SARS-CoV-2 has been the subject of intense study and is now better understood. Many of the clinical manifestations of severe disease are a consequence of immune dysregulation triggered by the virus. This may explain the lack of efficacy of antiviral treatments such as convalescent plasma infusions, given later in the disease.

EXPERT OPINION

T cells play a crucial role in both the outcome of COVID-19 as well as the protective response to vaccines. Vaccines do not prevent infection but reduce the risk of a chaotic and destructive cellular immune response to the virus. Severe COVID-19 should be considered a virus-induced secondary immune dysregulatory disorder of cellular immunity, with broad host susceptibility. This perspective of COVID-19 will lead to better diagnostic tests, vaccines and therapeutic strategies in the future.

Does a humoral correlate of protection exist for SARS-CoV-2? A systematic review

BACKGROUND

A correlate of protection (CoP) is an immunological marker associated with protection against infection. Despite an urgent need, a CoP for SARS-CoV-2 is currently undefined.

OBJECTIVES

Our objective was to review the evidence for a humoral correlate of protection for SARS-CoV-2, including variants of concern.

METHODS

We searched OVID MEDLINE, EMBASE, Global Health, Biosis Previews and Scopus to January 4, 2022 and pre-prints (using NIH iSearch COVID-19 portfolio) to December 31, 2021, for studies describing SARS-CoV-2 re-infection or breakthrough infection with associated antibody measures. Two reviewers independently extracted study data and performed quality assessment.

RESULTS

Twenty-five studies were included in our systematic review. Two studies examined the correlation of antibody levels to VE, and reported values from 48.5% to 94.2%. Similarly, several studies found an inverse relationship between antibody levels and infection incidence, risk, or viral load, suggesting that both humoral immunity and other immune components contribute to protection. However, individual level data suggest infection can still occur in the presence of high levels of antibodies. Two studies estimated a quantitative CoP: for Ancestral SARS-CoV-2, these included 154 (95% confidence interval (CI) 42, 559) anti-S binding antibody units/mL (BAU/mL), and 28.6% (95% CI 19.2, 29.2%) of the mean convalescent antibody level following infection. One study reported a CoP for the Alpha (B.1.1.7) variant of concern of 171 (95% CI 57, 519) BAU/mL. No studies have yet reported an Omicron-specific CoP.

CONCLUSIONS

Our review suggests that a SARS-CoV-2 CoP is likely relative, where higher antibody levels decrease the risk of infection, but do not eliminate it completely. More work is urgently needed in this area to establish a SARS-CoV-2 CoP and guide policy as the pandemic continues.

SARS-CoV-2 reinfection and COVID-19 severity

SARS-CoV-2 reinfection rate is low. The relative severity of the first and second episodes of infection remains poorly studied. In this study, we aimed at assessing the frequency of SARS-CoV-2 reinfections and comparing the severity of the first and second episodes of infection. We retrospectively included patients with SARS-CoV-2 positive RT-PCR at least 90 days after clinical recovery from a COVID-19 episode and with at least one negative RT-PCR after the first infection. Whole genome sequencing and variant-specific RT-PCR were performed and clinical symptoms and severity of infection were retrospectively documented from medical files. A total of 209 COVID-19 reinfected patients were identified, accounting for 0.4% of positive cases diagnosed from 19 March 2020 to 24 August 2021. Serology was performed in 64 patients, of whom 39 (60.1%) had antibodies against SARS-CoV-2 when sampled at the early stage of their second infection. Only seven patients (3.4%) were infected twice with the same variant. We observed no differences in clinical presentation, hospitalization rate, and transfer to ICU when comparing the two episodes of infections. Our results suggest that the severity of the second episode of COVID-19 is in the same range as that of the first infection, including patients with antibodies.

Boosting of the SARS-CoV-2-Specific Immune Response after Vaccination with Single-Dose Sputnik Light Vaccine

Despite measures taken world-wide, the coronavirus disease 2019 (COVID-19) pandemic continues. Because efficient antiviral drugs are not yet widely available, vaccination is the best option to control the infection rate. Although this option is obvious in the case of COVID-19-naive individuals, it is still unclear when individuals who have recovered from a previous SARS-CoV-2 infection should be vaccinated and whether the vaccination raises immune responses against the coronavirus and its novel variants. In this study, we collected peripheral blood from 84 healthy human donors of different COVID-19 status who were vaccinated with the Sputnik Light vaccine and measured the dynamics of the Ab and T cell responses, as well as the virus-neutralizing activity (VNA) in serum, against two SARS-CoV-2 variants, B.1.1.1 and B.1.617.2. We showed that vaccination of individuals previously exposed to the virus considerably boosts the existing immune response. In these individuals, receptor-binding domain (RBD)-specific IgG titers and VNA in serum were already elevated on the 7th day after vaccination, whereas COVID-19-naive individuals developed the Ab response and VNA mainly 21 d postvaccination. Additionally, we found a strong correlation between RBD-specific IgG titers and VNA in serum, and according to these data vaccination may be recommended when the RBD-specific IgG titers drop to 142.7 binding Ab units/ml or below. In summary, the results of the study demonstrate that vaccination is beneficial for both COVID-19-naive and recovered individuals, especially since it raises serum VNA against the B.1.617.2 variant, one of the five SARS-CoV-2 variants of concern.

Serum troponin, D-dimer, and CRP level in severe coronavirus (COVID-19) patients

BACKGROUND

Abnormal inflammation coagulation biomarker levels of troponin, C-reactive protein (CRP), and D-dimer levels in serum have been demonstrated to be associated and involved in the disease progression of coronavirus disease 2019 (COVID-19).

METHODS

First: the study aimed to investigate the correlation of troponin, CRP, d-dimer, white blood cell (WBC) and polymerase chain reaction-cycle threshold (PCR-Ct) within COVID-19 survivors (143 patients; 79 males, 64 females) and in deceased (30 patients; 12 males, 18 females) group. Also, assessing any differences between both groups in studied parameters. Second: a correlation study of studied parameters' level has been conducted within families (41 patients; 23 males [seven deaths] and 18 females [eight deaths]) that lost more than one member due to the severity of the disease. Also, differences between these family and control group (132 patients; 69 males and 63 females) group in studied parameters have been assessed.

RESULTS

In the first week of hospitalization, there were significant differences in D-dimer, CRP and troponin level between survived and deceased patient groups. In the second week of the admission, both groups had significant differences in the level of all studied parameters; troponin I, D-dimer, CRP, and WBCs. WBC levels positively correlated to CRP in male survivors (r = 0.75, p < 0.0001), and to troponin in deceased male patients (r = 0.74, p = 0.007). The second week of patient admission was critical in the group of families who lost more than one person, when troponin was correlated positively with D-dimer, CRP, and WBCs.

CONCLUSION

Troponin, D-dimer, CRP, and WBCs level were significantly higher in COVID-19 patients who died than in COVID-19 survivors. High troponin and WBC levels, were considerably associated with families that lost more than one member, when compared with the unrelated COVID-19 patient control.

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.

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).

SARS-CoV-2 Reinfection Is a New Challenge for the Effectiveness of Global Vaccination Campaign: A Systematic Review of Cases Reported in Literature

Reinfection with SARS-CoV-2 seems to be a rare phenomenon. The objective of this study is to carry out a systematic search of literature on the SARS-CoV-2 reinfection in order to understand the success of the global vaccine campaigns. A systematic search was performed. Inclusion criteria included a positive RT-PCR test of more than 90 days after the initial test and the confirmed recovery or a positive RT-PCR test of more than 45 days after the initial test that is accompanied by compatible symptoms or epidemiological exposure, naturally after the confirmed recovery. Only 117 articles were included in the final review with 260 confirmed cases. The severity of the reinfection episode was more severe in 92/260 (35.3%) with death only in 14 cases. The observation that many reinfection cases were less severe than initial cases is interesting because it may suggest partial protection from disease. Another interesting line of data is the detection of different clades or lineages by genome sequencing between initial infection and reinfection in 52/260 cases (20%). The findings are useful and contribute towards the role of vaccination in response to the COVID-19 infections. Due to the reinfection cases with SARS-CoV-2, it is evident that the level of immunity is not 100% for all individuals. These data highlight how it is necessary to continue to observe all the prescriptions recently indicated in the literature in order to avoid new contagion for all people after healing from COVID-19 or becoming asymptomatic positive.