Serological surveillance for SARS-CoV-2 antibodies among students,faculty and staff within a large university system during the pandemic

BACKGROUND At the end of December 2019,the world faced severe acute respiratory syndrome-coronavirus 2(SARS-CoV-2),which led to the outbreak of coronavirus disease 2019(COVID-19),associated with respiratory issues.This virus has shown significant challenges,especially for senior citizens,patients with other underlying illnesses,or those with a sedentary lifestyle.Serological tests conducted early on have helped identify how the virus is transmitted and how to curb its spread.The study hypothesis was that the rapid serological test for SARS-CoV-2 antibodies could indicate the immunoreactive profile during the COVID-19 pandemic in a university population.AIM To conduct active surveillance for serological expression of anti-SARS-CoV-2 antibodies in individuals within a university setting during the COVID-19 pandemic.METHODS This sectional study by convenience sampling was conducted in a large university in Niteroi-RJ,Brazil,from March 2021 to July 2021.The study population consisted of students,faculty,and administrative staff employed by the university.A total of 3433 faculty members,60703 students,and 3812 administrative staff were invited to participate.Data were gathered through rapid serological tests to detect immunoglobulin(Ig)M and IgG against SARS-CoV-2.Theχ²or Fisher's exact test was used to conduct statistical analysis.A 0.20 significance level was adopted for variable selection in a multiple logistic regression model to evaluate associations.RESULTS A total of 1648 individuals were enrolled in the study.The proportion of COVID-19 positivity was 164/1648(9.8%).The adjusted logistic model indicate a positive association between the expression of IgM or IgG and age[odds ratio(OR)=1.16,95%CI:1.02-1.31](P<0.0024),individuals who had been in contact with a COVID-19-positive case(OR=3.49,95%CI:2.34-5.37)(P<0.001),those who had received the COVID-19 vaccine(OR=2.33,95%CI:1.61-3.35)(P<0.001)and social isolation(OR=0.59,95%CI:0.41-0.84)(P<0.004).The likelihood of showing a positive result increased by 16%with every ten-year increment.Conversely,adherence to social distancing measures decreased the likelihood by 41%.CONCLUSION These findings evidenced that the population became more exposed to the virus as individuals discontinued social distancing practices,thereby increasing the risk of infection for themselves.

Development of donor specific antibodies after SARS-CoV-2 vaccination:What do we know so far?

Vaccination against Coronavirus disease-19(COVID-19)was pivotal to limit spread,morbidity and mortality.Our aim is to find out whether vaccines against COVID-19 lead to an immunological response stimulating the production of de novo donor specific antibodies(DSAs)or increase in mean fluorescence intensity(MFI)of pre-existing DSAs in kidney transplant recipients(KTRs).This study involved a detailed literature search through December 2nd,2023 using PubMed as the primary database.The search strategy incorporated a combination of relevant Medical Subject Headings terms and keywords:"COVID-19","SARS-CoV-2 Vaccination","Kidney,Renal Transplant",and"Donor specific antibodies".The results from related studies were collated and analyzed.A total of 6 studies were identified,encompassing 460 KTRs vaccinated against COVID-19.Immunological responses were detected in 8 KTRs of which 5 had increased MFIs,1 had de novo DSA,and 2 were categorized as either having de novo DSA or increased MFI.There were 48 KTRs with pre-existing DSAs prior to vaccination,but one study(Massa et al)did not report whether pre-existing DSAs were associated with post vaccination outcomes.Of the remaining 5 studies,35 KTRs with pre-existing DSAs were identified of which 7 KTRs(20%)developed de novo DSAs or increased MFIs.Overall,no immunological response was detected in 452(98.3%)KTRs.Our study affirms prior reports that COVID-19 vaccination is safe for KTRs,especially if there are no pre-existing DSAs.However,if KTRs have pre-existing DSAs,then an increased immunological risk may be present.These findings need to be taken cautiously as they are based on a limited number of patients so further studies are still needed for confirmation.

Symptomatic and Asymptomatic SARS-CoV-2 Infection and Follow-up of Neutralizing Antibody Levels

Objective To investigate neutralizing antibody levels in symptomatic and asymptomatic patients with coronavirus disease 2019(COVID-19)at 6 and 10 months after disease onset.Methods Blood samples were collected at three different time points from 27 asymptomatic individuals and 69 symptomatic patients infected with severe acute respiratory syndrome coronavirus 2(SARS-Co V-2).Virus-neutralizing antibody titers against SARS-CoV-2 in both groups were measured and statistically analyzed.Results The symptomatic and asymptomatic groups had higher neutralizing antibodies at 3 months and 1–2 months post polymerase chain reaction confirmation,respectively.However,neutralizing antibodies in both groups dropped significantly to lower levels at 6 months post-PCR confirmation.Conclusion Continued monitoring of symptomatic and asymptomatic individuals with COVID-19 is key to controlling the infection.

Cross-species recognition of bat coronavirus RsYN04 and cross-reaction of SARS-CoV-2 antibodies against the virus

Following the outbreak of coronavirus disease 2019(COVID-19),several severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)-related coronaviruses have been discovered.Previous research has identified a novel lineage of SARS-CoV-2-related CoVs in bats,including RsYN04,which recognizes human angiotensin-converting enzyme 2(ACE2)and thus poses a potential threat to humans.Here,we screened the binding of the RsYN04receptor-binding domain(RBD)to ACE2 orthologs from 52animal species and found that the virus showed a narrower ACE2-binding spectrum than SARS-CoV-2.However,the presence of the T484W mutation in the RsYN04 RBD broadened its range.We also evaluated 44 SARS-CoV-2antibodies targeting seven epitope communities in the SARS-CoV-2 RBD,together with serum obtained from COVID-19 convalescents and vaccinees,to determine their cross-reaction against RsYN04.Results showed that no antibodies,except for the RBD-6 and RBD-7 classes,bound to the RsYN04 RBD,indicating substantial immune differences from SARS-CoV-2.Furthermore,the structure of the RsYN04 RBD in complex with cross-reactive antibody S43 in RBD-7 revealed a potently broad epitope for the development of therapeutics and vaccines.Our findings suggest RsYN04 and other viruses belonging to the same clade have the potential to infect several species,including humans,highlighting the necessity for viral surveillance and development of broad anticoronavirus countermeasures.

Clinical application of SARS-CoV-2 antibody detection and monoclonal antibody therapies against COVID-19

The purpose of this study was to investigate the clinical application of severe acute respiratory distress syndrome coronavirus-2(SARS-CoV-2)specific antibody detection and anti-SARS-CoV-2 specific monoclonal antibodies(mAbs)in the treatment of coronavirus infectious disease 2019(COVID-19).The dynamic changes of SARS-CoV-2 specific antibodies during COVID-19 were studied.Immunoglobulin M(IgM)appeared earlier and lasted for a short time,while immunoglobulin G(IgG)appeared later and lasted longer.IgM tests can be used for early diagnosis of COVID-19,and IgG tests can be used for late diagnosis of COVID-19 and identification of asymptomatic infected persons.The combination of antibody testing and nucleic acid testing,which complement each other,can improve the diagnosis rate of COVID-19.Monoclonal anti-SARS-CoV-2 specific antibodies can be used to treat hospitalized severe and critically ill patients and non-hospitalized mild to moderate COVID-19 patients.COVID-19 convalescent plasma,highly concentrated immunoglobulin,and anti-SARS-CoV-2 specific mAbs are examples of anti-SARS-CoV-2 antibody products.Due to the continuous emergence of mutated strains of the novel coronavirus,especially omicron,its immune escape ability and infectivity are enhanced,making the effects of authorized products reduced or invalid.Therefore,the optimal application of anti-SARS-CoV-2 antibody products(especially anti-SARS-CoV-2 specific mAbs)is more effective in the treatment of COVID-19 and more conducive to patient recovery.

Neutralizing Antibody Responses against Five SARS-CoV-2 Variants and T Lymphocyte Change after Vaccine Breakthrough Infections from the SARS-CoV-2 Omicron BA.1 Variant in Tianjin, China: A Prospective Study

Objective To investigate whether Omicron BA.1 breakthrough infection after receiving the SARS-CoV-2 vaccine could create a strong immunity barrier.Methods Blood samples were collected at two different time points from 124 Omicron BA.1 breakthrough infected patients and 124 controls matched for age,gender,and vaccination profile.Live virus-neutralizing antibodies against five SARS-CoV-2 variants,including WT,Gamma,Beta,Delta,and Omicron BA.1,and T-lymphocyte lymphocyte counts in both groups were measured and statistically analyzed.Results The neutralizing antibody titers against five different variants of SARS-CoV-2 were significantly increased in the vaccinated population infected with the Omicron BA.1 variant at 3 months after infection,but mainly increased the antibody level against the WT strain,and the antibody against the Omicron strain was the lowest.The neutralizing antibody level decreased rapidly 6 months after infection.The T-lymphocyte cell counts of patients with mild and moderate disease recovered at 3 months and completely returned to the normal state at 6 months.Conclusion Omicron BA.1 breakthrough infection mainly evoked humoral immune memory in the original strain after vaccination and hardly produced neutralizing antibodies specific to Omicron BA.1.Neutralizing antibodies against the different strains declined rapidly and showed features similar to those of influenza.Thus,T-lymphocytes may play an important role in recovery.

A SARS-CoV-2 neutralizing antibody discovery by single cell sequencing and molecular modeling

Although vaccines have been developed,mutations of SARS-CoV-2,especially the dominant B.1.617.2(delta)and B.1.529(omicron)strains with more than 30 mutations on their spike protein,have caused a significant decline in prophylaxis,calling for the need for drug improvement.Antibodies are drugs preferentially used in infectious diseases and are easy to get from immunized organisms.The current study combined molecular modeling and single memory B cell sequencing to assess candidate sequences before experiments,providing a strategy for the fabrication of SARS-CoV-2 neutralizing antibodies.A total of 128 sequences were obtained after sequencing 196 memory B cells,and 42 sequences were left after merging extremely similar ones and discarding incomplete ones,followed by homology modeling of the antibody variable region.Thirteen candidate sequences were expressed,of which three were tested positive for receptor binding domain recognition but only one was confirmed as having broad neutralization against several SARS-CoV-2 variants.The current study successfully obtained a SARS-CoV-2 antibody with broad neutralizing abilities and provided a strategy for antibody development in emerging infectious diseases using single memory B cell BCR sequencing and computer assistance in antibody fabrication.

SARS-CoV-2 in inflammatory bowel disease population:Antibodies,disease and correlation with therapy

BACKGROUND Guidelines recommend to cease inflammatory bowel disease(IBD)biologic therapy during coronavirus disease 2019(COVID-19).AIM To investigate severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)antibody positivity in an IBD cohort,COVID-19 disease severity and to evaluate the correlation with clinical/therapeutic variables.METHODS Prospective observational cohort study.IBD patients were tested for SARS-CoV-2 IgG.Data on COVID-19 disease,demographics/therapeutics and clinical features of the IBD population were collected.IgG≥7 was set for SARS-CoV-2 antibody positivity.Throat swab was performed in cases of IgG positivity.Correlations between antibody positivity or COVID-19 symptoms and therapeutic/clinical data were assessed.RESULTS In total,103 IBD patients were enrolled.Among them,18.4%had IgG≥7.Multivariate analysis of antibody positivity correlated only with IBD treatment.For IgG≥7,the odds ratio was 1.44 and 0.16 for azathioprine and mesalazine,respectively,vs biologic drugs(P=0.0157 between them).COVID-19 related symptoms were reported in 63%of patients with IgG positivity.All but one patient with COVID-19 symptoms did not require ceasing IBD treatment or hospitalization. IBDtreatment and body mass index correlated with COVID-19 disease development with symptoms.CONCLUSIONThe IBD population does not have a higher risk of severe COVID-19. The relative risk of havingSARS-CoV-2 antibodies and symptoms was higher for patients taking azathioprine, then biologictherapy and lastly mesalazine. None of the patients under biologic therapy developed severeCOVID-19.

Persistence of Anti-SARS-CoV-2 IgM Antibody up to 8 Months Post-COVID-19

Here, we present a longitudinal analysis of two patients who recovered from COVID-19 more than 8 months prior but showed persistent serological detection of anti-SARS-CoV-2 IgM. We still do not know the exact reason for this prolonged persistence of IgM in these patients. To our knowledge, these are the first reports of IgM persistence in the context of SARS-CoV-2 infection and point to the need for no longer using IgM as a diagnostic criterion for acute or recent COVID-19. One should opt for gold standard molecular methodologies due to their high sensitivity and specificity.

追踪分析1种SARS-CoV-2总抗体ELISA试剂诊断效能

目的追踪分析1种严重急性呼吸系统综合征冠状病毒2(severe acute respiratorysyndrome coronavirus 2,SARS-CoV-2)抗体酶联免疫吸附实验(enzyme linked immunosorbent assay,ELISA)试剂盒临床检测结果及诊断效能。方法应用SARS-CoV-2总抗体(TAb)ELISA试剂,筛查献血者血浆,采血1月后追踪TAb阳性献血者。TAb阳性献血者第1次采集标本以及追踪标本补充SARS-CoV-2特异性IgG、IgM及SARS-CoV-2假病毒中和试验(pseudotype lentivirus-based neutralization test,ppNAT)。以ppNAT阳性标本及其追踪标本ppNAT及IgG抗体同时阳性作为抗体确认标准,分析SARS-CoV-2总抗体ELISA试剂灵敏度、特异度、阳性预测值、阴性预测值、正确率和约登指数。结果2020年1月31日~4月28日16016人次献血者血浆标本中,61例SARS-CoV-2总抗体ELISA试剂阳性,6例ppNAT阳性,其中2例ppNAT和IgG抗体同时阳性;追踪检测46例总抗体阳性献血者,4例ppNAT阳性,其中2例IgG抗体同时阳性。SARS-CoV-2总抗体试剂灵敏度100.00%,特异度99.60%,阳性预测值3.28%,阴性预测值100.00%,正确率99.60%,约登指数99.60%,假阳性率0.40%,假阴性率0.00。结论SARS-CoV-2总抗体ELISA试剂具有较高灵敏度,较好的临床诊断效能,但在低危献血人群中假阳性率相对较高,在临床应用时,应综合ppNAT,IgG及追踪检测结果,更准确判断既往感染状况,分析阳性结果。

胶体金免疫层析法检测SARS-CoV-2血清抗体的临床价值探讨

目的通过对新型冠状病毒(SARS-CoV-2)免疫球蛋白(Ig)M和总抗体(即IgM/IgG)的检测,探讨应用胶体金免疫层析法(GICA法)在新型冠状病毒肺炎(COVID-19)诊断中的应用价值。方法收集76例患者共计83份血清,其中32例为SARS-CoV-2核酸阳性患者(确诊组),44例为SARS-CoV-2核酸阴性患者(对照组)。确诊组中7例患者为两次时间点采集标本。采用GICA法检测SARS-CoV-2 IgM和总抗体。结果GICA法检测SARS-CoV-2 IgM的灵敏度50.00%(16/32),特异度90.91%(40/44),符合率73.68%(56/76),阳性预测值80.00%(16/20)、阴性预测值71.43%(40/56);SARS-CoV-2总抗体检测的灵敏度68.75%(22/32)、特异度97.73%(43/44)、符合率85.53%(65/76)、阳性预测值95.65%(22/23)、阴性预测值81.13%(43/53)。GICA法检测SARS-CoV-2 IgM和总抗体的特异度均大于90%,符合率均大于70%,满足临床需求。结论GICA法检测SARS-CoV-2 IgM和总抗体,标本采集易标准化,报告时间快,灵敏度不高,但特异度较高,有辅助诊断的价值。

Assessment of the binding interactions of SARS-CoV-2 spike glycoprotein variants

Severe acute respiratory syndrome-associated coronavirus 2 is a major global health issue and is driving the need for new therapeutics.The surface spike protein,which plays a central role in virus infection,is currently the target for vaccines and neutralizing treatments.The emergence of novel variants with multiple mutations in the spike protein may reduce the effectiveness of neutralizing antibodies by altering the binding activity of the protein with angiotensin-converting enzyme 2(ACE2).To understand the impact of spike protein mutations on the binding interactions required for virus infection and the effectiveness of neutralizing monoclonal antibody(mAb)therapies,the binding activities of the original spike protein receptor binding domain(RBD)sequence and the reported spike protein variants were investigated using surface plasmon resonance.In addition,the interactions of the ACE2 receptor,an antispike mAb(mAb1),a neutralizing mAb(mAb2),the original spike RBD sequence,and mutants D614G,N501Y,N439K,Y453F,and E484K were assessed.Compared to the original RBD,the Y453F and N501Y mutants displayed a significant increase in ACE2 binding affinity,whereas D614G had a substantial reduction in binding affinity.All mAb-RBD mutant proteins displayed a reduction in binding affinities relative to the original RBD,except for the E484K-mAb1 interaction.The potential neutralizing capability of mAb1 and mAb2 was investigated.Accordingly,mAb1 failed to inhibit the ACE2-RBD interaction while mAb2 inhibited the ACE2-RBD interactions for all RBD mutants,except mutant E484K,which only displayed partial blocking.

Human IgM and IgG Responses to an Inactivated SARS-CoV-2 Vaccine

Objective:The ongoing COVID-19 pandemic warrants accelerated efforts to test vaccine candidates.To explore the influencing factors on vaccine-induced effects,antibody responses to an inactivated SARS-CoV-2 vaccine in healthy individuals who were not previously infected by COVID-19 were assessed.Methods:All subjects aged 18-60 years who did not have SARS-CoV-2 infection at the time of screening from June 19,2021,to July 02,2021,were approached for inclusion.All participants received two doses of inactivated SARS-CoV-2 vaccine.Serum IgM and IgG antibodies were detected using a commercial kit after the second dose of vaccination.A positive result was defined as 10 AU/mL or more and a negative result as less than 10 AU/mL.This retrospective study included 97 infection-naive individuals(mean age 35.6 years;37.1%male,62.9%female).Results:The seropositive rates of IgM and IgG antibody responses elicited after the second dose of inactivated SARS-CoV-2 vaccine were 3.1%and 74.2%,respectively.IgG antibody levels were significantly higher than IgM levels(P<0.0001).Sex had no effect on IgM and IgG antibody response after the second dose.The mean anti-IgG level in older persons(≥42 years)was significantly lower than that of younger recipients.There was a significantly lower antibody level at>42 days compared to that at 0-20 days(P<0.05)and 21-31 days(P<0.05)after the second dose.Conclusion:IgG antibody response could be induced by inactivated SARS-CoV-2 vaccine in healthy individuals(>18 years),which can be influenced by age and detection time after the second dose of vaccination.

化学发光法检测SARS-CoV-2抗体试剂诊断效能比较及抗体筛查策略探讨

目的研究新型冠状病毒肺炎(COVID-19)患者特异性抗体免疫球蛋白(Ig)M、免疫球蛋白(Ig)G及总抗体动态变化规律,评价应用化学发光在COVID-19诊断中的可靠性及诊断效能,并通过抗体血清学转化探讨普通人群筛查策略,为科学地防治COVID-19提供理论依据。方法收集我院2020年1月25日至3月17日就诊患者89例,共计142份血清,其中16例确诊COVID-19患者的不同采血时间点共69份血清作为病例组,73例核酸阴性的排除患者共73份血清作为对照组。采用全自动化学发光免疫分析技术对收集血清进行新型冠状病毒(SARS-CoV-2)IgM、IgG和总抗体检测。结果IgM检测的敏感度为40.58%(28/69),特异度为98.63%(72/73),符合率为70.42%(100/142);IgG检测的敏感度为89.86%(62/69),特异度为98.63%(72/73),符合率为94.37%(134/142);总抗体检测的敏感度为95.65%(66/69);特异度为98.63%(72/73);符合率为97.18%(138/142)。所有抗体在发病1周内检测阳性率较低,从第2周开始,抗体阳性率逐步升高。IgM抗体在第5周阳性率达70%的峰值,从第6周开始逐渐降低;IgG从第3周开始阳性率持续维持在100%,总抗体从第2周开始阳性率持续维持在100%。结论化学发光法检测SARS-CoV-2抗体可作为COVID-19感染的有效筛查和诊断指标,相比较而言总抗体检测效能优于单独检测IgM或IgG。作为普通人群筛查时,抗体检测结果应进行动态监测及跟踪随访。

Insights into the virologic and immunologic features of SARS-COV-2

The host immunity is crucial in determining the clinical course and prognosis of coronavirus disease 2019,where some systemic and severe manifestations are associated with excessive or suboptimal responses.Several antigenic epitopes in spike,nucleocapsid and membrane proteins of severe acute respiratory syndrome coronavirus 2 are targeted by the immune system,and a robust response with innate and adaptive components develops in infected individuals.High titer neutralizing antibodies and a balanced T cell response appears to constitute the optimal immune response to severe acute respiratory syndrome coronavirus 2,where innate and mucosal defenses also contribute significantly.Following exposure,immunological memory seems to develop and be maintained for substantial periods.Here,we provide an overview of the main aspects in antiviral immunity involving innate and adaptive responses with insights into virus structure,individual variations pertaining to disease severity as well as long-term protective immunity expected to be attained by vaccination.

Local Transmission of SARS-CoV-2 Virus in Rome, Italy: A Single Center Experience

In the present study, we analysed the results from the use of serological tests for the evaluation of the antibody response to SARS-CoV-2 virus, with the aim of verifying the seroprevalence for SARS-CoV-2 virus infection in Rome. Evaluations related to the seroprevalence are important for defining the epidemiological parameters of this disease. We therefore analysed the data deriving from 1586 subjects, residing in the geographical area of Rome, subjected to a rapid test, capable of detecting the presence of specific IgM and IgG class antibodies directed against the SARS-CoV-2 virus. Among the 1586 cases, 83 had positive conversion of IgM antibody and/or IgG antibody and 1503 tested negative. Out of 83 positive cases, 48% (40/83) samples resulted positively for both IgM and IgG, while 45% (37/83) were positive for IgG only, and 7% (6/83) for IgM only. The prevalence of anti-SARS-CoV-2 antibodies in the considered geographical area was 5% (83/1586), and 54% (45/83) of our population was an asymptomatic carrier. The study was performed to better evaluate the population prevalence in the studied geographic area. To our knowledge, this is the first study carried out in the Lazio region reporting data related to the asymptomatic carriers.

New and Newer Vaccines for SARS-CoV-2 Variants. Are the Major Vaccine Developers on the Right Track, Or Is Delipidation the Answer?

Background: Global Covid-19 pandemic has led to remarkable scientific achievements resulting in the development and rapid implementation of vaccines towards the original wild-type SARS-CoV-2 virus. Most Covid-19 vaccines are targeted to only one protein (the Spike protein) on the virus. SARS-CoV-2 that causes Covid-19 naturally undergoes multiple mutations over time. Such mutations can be inconsequential or have dire consequences. The lack of effectiveness of current vaccines towards mutated variants of Covid-19 is of major concern. The objective of this study is to describe an optimal solvent system that creates, via delipidation, a non-synthetic, host-derived or nonhost-derived modified viral particle that has its lipid envelope removed, exposing hidden undenatured proteins from within the virus, that generate a positive immunologic response when administered into a host, thereby providing a vaccine that offers strong and broad protection against the virus. Methods: Lipid removal from viruses by specific procedures renders the exposure of hidden proteins. Protection by antibodies to all of the virus’ protein types has shown to be far superior to protection by antibodies that are created by a single protein type. Results: Published studies with the Hepatitis virus, Pestivirus and HIV virus have reported the wide range of applications with this delipidation approach resulting in effectively long-term and broad protection vaccines. Conclusion: Mutations are rendering existing vaccines less effective. New approaches to obtain a more permanent vaccine that minimizes the effects of mutation are obtainable by delipidation of the viral particle and thereby creating vaccines that are more permanent with broad protection.

Biology of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)and the humoral immunoresponse:a systematic review of evidence to support global policy-level actions and research

Background Both population-level epidemiological data and individual-level biological data are needed to control the coronavirus disease 2019(COVID-19)pandemic.Population-level data are widely available and efforts to combat COVID-19 have generated proliferate data on the biology and immunoresponse to the causative pathogen,severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).However,there remains a paucity of systemized data on this subject.Objective In this review,we attempt to extract systemized data on the biology and immuno-response to SARS-CoV-2 from the most up-to-date peer-reviewed studies.We will focus on the biology of the virus and immunological variations that are key for determining long-term immunity,transmission potential,and prognosis.Data Sources and Methods Peer-reviewed articles were sourced from the PubMed database and by snowballing search of selected publications.Search terms included:“Novel Coronavirus”OR“COVID-19”OR“SARS-CoV-2”OR“2019-nCoV”AND“Immunity”OR“Immune Response”OR“Antibody Response”OR“Immunologic Response”.Studies published from December 31,2019 to December 31,2020 were included.To ensure validity,papers in pre-print were excluded.Results Of 2889 identified papers,36 were included.Evidence from these studies suggests early seroconversion in patients infected with SARS-CoV-2.Antibody titers appear to markedly increase two weeks after infection,followed by a plateau.A more robust immune response is seen in patients with severe COVID-19 as opposed to mild or asymptomatic presentations.This trend persists with regard to the length of antibody maintenance.However,overall immunity appears to wane within two to three months post-infection.Conclusion Findings of this study indicate that immune responses to SARS-CoV-2 follow the general pattern of viral infection.Immunity generated through natural infection appears to be short,suggesting a need for long-term efforts to control the pandemic.Antibody testing will be essential to gauge the epidemic and inform decision-making on effective strategies for treatment and prevention.Further research is needed to illustrate immunoglobulin-specific roles and neutralizing antibody activity.

Seroprevalence of SARS-CoV-2 among Blood Donors in the Republic of Congo

Corona Virus Disease 2019 (COVID-19) is a highly transmissible and pathogenic viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which erupted in Wuhan, China, in 2019 and has spread worldwide [1]. The objective of this study was to assess the seroprevalence of SARS-CoV-2 among blood donors in the Republic of Congo. Method: This is an analytical and cross-sectional study that was carried out during the period from July to December 2021. Biological analyses were performed with the serological tests n2019 rapid IgG/IgM from Beijing Diagreat Biotechnologies and antigen tests from Abbot using the serum for the detection of anti-SARS-Cov-2 antibodies and nasal mucus for the detection of SARS-Cov-2 antigens. Statistical analysis was performed using SPSS version 22. The Results: Out of 2553 donors recruited in our study, we observed a predominance of male sex with 86.1% or a ratio of 6.19, the age group of 18 - 30 years was dominant with 45.9%, family donation represented 59.2%, the dominant profession was workers with 46.9% and the dominant blood group was O Rh positive with 54%. The prevalence of anti-SRAS-CoV-2 antibodies and antigens were respectively 31.4% for anti-SRAS CoV-2 IgG antibodies, 36.7% for anti-SRAS CoV-2 IgM antibodies and 2.93% for SARS-CoV-2 antigen.

Diagnostic Performance of Five Rapid Serological Tests for SARS-CoV-2

We conducted a study to evaluate the sensitivity (Se), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) of five serologic tests. Subjects with negative or positive COVID-19 polymerase chain reaction (PRC) test results were tested with each of the serological tests. The results were compared with the reference PCR test. For the five tests evaluated, the Se ranged from 55.0% to 70.0% and the Sp ranged from 67.2% to 86.2%. PPV ranged from 53.2% to 80% and NPV from 75.0% to 86.2%. One test, the Wantai, had better specificity and sensitivity. None of the five tests had performance values of more than 90% in the entire sample. In symptomatic positive cases, the Wantai test reported excellent sensitivity. Overall, the low level of diagnostic performance of these tests does not support their use as an alternative to PCR for COVID-19 diagnostic. Test with better performance can be used for mass screening in low prevalence populations, to limit the indiscriminate use of PCR in context of resource-limited countries. Given the excellent sensitivity of Wantai in symptomatic cases, this test could be used as a referral test only in health facilities to discriminate suspected cases before PCR confirmation.