Meta-analysis of diagnostic performance of serological tests for SARS-CoV-2 antibodies up to 25 April 2020 and public health implications.

We reviewed the diagnostic accuracy of SARS-CoV-2 serological tests. Random-effects models yielded a summary sensitivity of 82% for IgM, and 85% for IgG and total antibodies. For specificity, the pooled estimate were 98% for IgM and 99% for IgG and total antibodies. In populations with ≤ 5% of seroconverted individuals, unless the assays have perfect (i.e. 100%) specificity, the positive predictive value would be ≤ 88%. Serological tests should be used for prevalence surveys only in hard-hit areas.

SARS-CoV-2: The Self-Nonself Issue and Diagnostic Tests.

Objective At present, false negatives/positives have been reported in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostics. Searching for the molecular basis of such tests' unreliability, this study aimed at defining how specific are the sequences used in serological and polymerase chain reaction (PCR) tests to detect SARS-CoV-2. Materials and Methods Analyses were performed on the leading SARS-CoV-2 biomarker spike glycoprotein (gp). Sharing of peptide sequences between the spike antigen and the human host was analyzed using the Peptide Search program from Uniprot database. Sharing of oligonucleotide sequences was investigated using the nucleotide Basic Local Alignment Search Tool (BLASTn) from National Center for Biotechnology Information (NCBI). Results Two main points stand out: (1) a massive pentapeptide sharing exists between the spike gp and the human proteome, and only a limited number of pentapeptides (namely 107) identify SARS-CoV-2 spike gp as nonself when compared with the human proteome, and (2) the small phenetic difference practically disappears at the genetic level. Indeed, almost all of the 107 pentadecameric nucleotide sequences coding for the pentapeptides unique to SARS-CoV-2 spike gp are present in human nucleic acids too. Conclusion The data are of immunological significance for defining the issue of the viral versus human specificity and likely explain the fact that false positives can occur in serological and PCR tests for SARS-CoV-2 detection.

A longitudinal analysis of humoral, T cellular response and influencing factors in a cohort of healthcare workers: Implications for personalized SARS-CoV-2 vaccination strategies.

Introduction: SARS-CoV-2 mRNA vaccinations elicit both virus-specific humoral and T-cell responses, but a complex interplay of different influencing factors, such as natural immunity, gender, and age, guarantees host protection. The present study aims to assess the immune dynamics of humoral, T-cell response, and influencing factors to stratify individual immunization status up to 10 months after Comirnaty-vaccine administration. Methods: To this aim, we longitudinally evaluated the magnitude and kinetics of both humoral and T-cell responses by serological tests and enzyme-linked immunospot assay at 5 time points. Furthermore, we compared the course over time of the two branches of adaptive immunity to establish an eventual correlation between adaptive responses. Lastly, we evaluated putative influencing factors collected by an anonymized survey administered to all participants through multiparametric analysis. Among 984 healthcare workers evaluated for humoral immunity, 107 individuals were further analyzed to describe SARS-CoV-2-specific T-cell responses. Participants were divided into 4 age groups: <40 and ≥40 years for men, <48 and ≥48 years for women. Furthermore, results were segregated according to SARS-CoV-2-specific serostatus at baseline. Results: The disaggregated evaluation of humoral responses highlighted antibody levels decreased in older subjects. The humoral responses were higher in females than in males (p=0.002) and previously virus-exposed subjects compared to naïve subjects (p<0.001). The vaccination induced a robust SARS-CoV-2 specific T-cell response at early time points in seronegative subjects compared to baseline levels (p<0.0001). However, a contraction was observed 6 months after vaccination in this group (p<0.01). On the other hand, the pre-existing specific T-cell response detected in natural seropositive individuals was longer-lasting than the response of the seronegative subjects, decreasing only 10 months after vaccination. Our data suggest that T-cell reactiveness is poorly impacted by sex and age. Of note, SARS-CoV-2-specific T-cell response was not correlated to the humoral response at any time point. Discussion: These findings suggest prospects for rescheduling vaccination strategies by considering individual immunization status, personal characteristics, and the appropriate laboratory tests to portray immunity against SARS-CoV-2 accurately. Deepening our knowledge about T and B cell dynamics might optimize the decision-making process in vaccination campaigns, tailoring it to each specific immune response.

Main Diagnostic Methods for Covid-19: Integrative Review.

BACKGROUND: COVID-19 has reached more than 20 million people since its appearance in December 2019. As a result of the infection process by the Sars-CoV-2 virus, patients manifest initial symptoms easily mistaken for common flu. However, in a small group of the population, the condition may progress to pneumonia or Severe Acute Respiratory Syndrome (SARS). OBJECTIVE: The objective of this study was to carry out an integrative review on laboratory and imaging diagnostics for COVID-19, in the period from 2019 to 2021. METHOD: Electronic databases PubMed, Google Scholar, SciELO, Virtual Library, LILACS, MEDLINE, ScienceDirect and the official website of the World Health Organization were used. RESULTS: RT-qPCR identifies fragments of viral RNA in the initial stage of the disease since the genes E and RdRp are the most used, given the great sensitivity. Imaging and serological methods can be used as complementary exams. The main radiographic findings are reticular and ground-glass opacity patterns, reversed halo sign, mosaic attenuation, and consolidations. The antibody levels are detected after the seventh day of symptom onset. CONCLUSION: Caution should be exercised when interpreting the results for the diagnosis of COVID-19, since the onset of clinical symptoms and laboratory and imaging tests must be taken into account.

Virology, clinical features and diagnosis of covid 19: Review analysis

COVID-19 requires unprecedented mobilization of the health systems to prevent the rapid spread of this unique virus, which spreads via respiratory droplet and causes respiratory disease. There is an urgent need for an accurate and rapid test method to quickly identify many infected patients and asymptomatic carriers to prevent virus transmission and assure timely treatment of the patients. This article aims as an outcome of review of the evidence on viral load and its virulence of SARS-CoV2,so that it will help in further understanding the fact useful for investigating and managing the COVID-19 cases. A search of available evidence was conducted in pub-med "COVID-19 viral load and virulence" and its associated characters world-wide and Google Scholar to capture the most recently published articles. The WHO and Centre for Disease Control and Prevention (CDC) database of publications on novel coronavirus were also screened for relevant publications. s of 55 articles were screened by two authors and 15 were included in this study based on the inclusion criteria. SARS-coV2, the causative agent of COVID-19 falls under the coronavirus family but it has higher infectivity compared to SARS and MERS with higher reproduction numbers(Ro). Virulence has been found to be different throughout the world,however lower compared to SARS and MERS,till date. The most common clinical features have been found to be cough and fever. RT - PCR remains the most sensitive and specific method for the diagnosis of COVID-19 although it is time consuming, costly and requires highly skilled human resources. Hence, newer modalities like RT-LAMP can be alternative for point of care diagnosis as this is both cost effective and requires less skilled human resources. Despite recent advances in disease diagnosis and treatment outcomes using latest technological advances in molecular biology, the global pandemic COVID-19 remains a major headache for governments across the world due to limited testing capacity and lack of appropriate treatment and vaccine. Copyright © 2020, Kathmandu University. All rights reserved.

Peptide microarray analysis of in-silico predicted B-cell epitopes in SARS-CoV-2 sero-positive healthcare workers in Bulawayo, Zimbabwe.

Immunogenic peptides that mimic linear B-cell epitopes coupled with immunoassay validation may improve serological tests for emerging diseases. This study reports a general approach for profiling linear B-cell epitopes derived from SARS-CoV-2 using an in-silico method and peptide microarray immunoassay, using healthcare workers' SARS-CoV-2 sero-positive sera. SARS-CoV-2 was tested using rapid chromatographic immunoassays and real-time reverse-transcriptase polymerase chain reaction. Immunogenic peptides mimicking linear B-cell epitopes were predicted in-silico using ABCpred. Peptides with the lowest sequence identity with human protein and proteins from other human pathogens were selected using the NCBI Protein BLAST. IgG and IgM antibodies against the SARS-CoV-2 spike protein, membrane glycoprotein and nucleocapsid derived peptides were measured in sera using peptide microarray immunoassay. Fifty-three healthcare workers included in the study were RT-PCR negative for SARS-CoV-2. Using rapid chromatographic immunoassays, 10 were SARS-CoV-2 IgM sero-positive and 7 were SARS-CoV-2 IgG sero-positive. From a total of 10 SARS-CoV-2 peptides contained on the microarray, 3 (QTH34388.1-1-14, QTN64908.1-135-148, and QLL35955.1-22-35) showed reactivity against IgG. Three peptides (QSM17284.1-76-89, QTN64908.1-135-148 and QPK73947.1-8-21) also showed reactivity against IgM. Based on the results we predicted one peptide (QSM17284.1-76-89) that had an acceptable diagnostic performance. Peptide QSM17284.1-76-89 was able to detect IgM antibodies against SARS-CoV-2 with area under the curve (AUC) 0.781 when compared to commercial antibody tests. In conclusion in silico peptide prediction and peptide microarray technology may provide a platform for the development of serological tests for emerging infectious diseases such as COVID-19. However, we recommend using at least three in-silico peptide prediction tools to improve the sensitivity and specificity of B-cell epitope prediction, to predict peptides with excellent diagnostic performances.

A comparative study of eight serological methods shows that spike protein-based ELISAs are the most accurate tests for serodiagnosing SARS-CoV-2 infections in cats and dogs.

Introduction: Coronavirus disease 2019 (COVID-19) is an infectious zoonotic disease caused by SARS-CoV-2. Monitoring the infection in pets is recommended for human disease surveillance, prevention, and control since the virus can spread from people to animals during close contact. Several diagnostic tests have been adapted from humans to animals, but limited data on the validation process are available. Methods: Herein, the first comparative study of six "in house" and two commercial serological tests developed to monitor SARS-CoV-2 infection in pets was performed with a well-coded panel of sera (61 cat sera and 74 dog sera) with a conservative criterion (viral seroneutralisation and/or RT-qPCR results) as a reference. Four "in house" tests based on either the RBD fragment of the spike protein (RBD-S) or the N-terminal fragment of the nucleoprotein (N) were developed for the first time. The analytical specificity (ASp) of those tests that showed the best diagnostic performance was assessed. The validation included the analysis of a panel of sera obtained pre-pandemic from cats and dogs infected with other coronaviruses to determine the analytical Sp (17 cat sera and 41 dog sera). Results and discussion: ELISAS based on the S protein are recommended in serosurveillance studies for cats (RBD-S SALUVET ELISA, ELISA COVID UNIZAR and INgezim® COVID 19 S VET) and dogs (INgezim® COVID 19 S VET and RBD-S SALUVET ELISA). These tests showed higher diagnostic sensitivity (Se) and DSp in cats (>90%) than in dogs. When sera obtained prior to the pandemic and from animals infected with other coronaviruses were analyzed by RBD-S and N SALUVET ELISAs and INgezim® COVID 19 S VET, a few cross reactors or no cross reactions were detected when dog and cat sera were analyzed by tests based on the S protein, respectively. In contrast, the number of cross reactions increased when the test was based on the N protein. Thus, the use of tests based on the N protein was discarded for serodiagnosis purposes. The results obtained revealed the most accurate serological tests for each species. Further studies should attempt to improve the diagnostic performance of serological tests developed for dogs.

COVID-19 in a Pre-Omicron Era: A Cross-Sectional Immuno-Epidemical and Genomic Evaluation.

The seventh human coronavirus was discovered and reported primarily in Wuhan, China. After intense seasons with repercussions in all areas of humanity, the pandemic demonstrates a new perspective. In Brazil, the pandemic concept had impacts in vast areas, including healthcare hospitals. This present study aims to describe and synthesize data from a determined period from the year 2021 that correlate the symptoms of passive and/or active patients for COVID-19 and their respective results of IgG/IgM serological tests in hospitals in the city of Cruzeiro, São Paulo, Brazil. The form had been applied to 333 people and obtained conclusive results and several symptoms were presented; in addition, asymptomatic cases were also analyzed and directed in the genomic study of variants of concern, as well as vaccination data in the study region.

Accuracy of serological tests for COVID-19: A systematic review and meta-analysis.

Objective: To determine the diagnostic accuracy of serological tests for coronavirus disease-2019 (COVID-19). Methods: PubMed, Embase and the Cochrane Library were searched from January 1 2020 to September 2 2022. We included studies that measured the sensitivity, specificity or both qualities of a COVID-19 serological test and a reference standard of a viral culture or reverse transcriptase polymerase chain reaction (RT-PCR). The risk of bias was assessed by using quality assessment of diagnostic accuracy studies 2 (QUADAS-2). The primary outcomes included overall sensitivity and specificity, as stratified by the methods of serological testing [enzyme-linked immunosorbent assays (ELISAs), lateral flow immunoassays (LFIAs) or chemiluminescent immunoassays (CLIAs)] and immunoglobulin classes (IgG, IgM, or both). Secondary outcomes were stratum-specific sensitivity and specificity within the subgroups, as defined by study or participant characteristics, which included the time from the onset of symptoms, testing via commercial kits or an in-house assay, antigen target, clinical setting, serological kit as the index test and the type of specimen for the RT-PCR reference test. Results: Eight thousand seven hundred and eighty-five references were identified and 169 studies included. Overall, we judged the risk of bias to be high in 47.9 % (81/169) of the studies, and a low risk of applicability concerns was found in 100% (169/169) of the studies. For each method of testing, the pooled sensitivity of the ELISAs ranged from 81 to 82%, with sensitivities ranging from 69 to 70% for the LFIAs and 77% to 79% for the CLIAs. Among the evaluated tests, IgG (80-81%)-based tests exhibited better sensitivities than IgM-based tests (66-68%). IgG/IgM-based CLIA had the highest sensitivity [87% (86-88%)]. All of the tests displayed high specificity (97-98%). Heterogeneity was observed in all of the analyses. The detection of nucleocapsid protein (77-80%) as the antigen target was found to offer higher sensitivity results than surface protein detection (66-68%). Sensitivity was higher in the in-house assays (78-79%) than in the commercial kits (47-48%). Conclusion: Among the evaluated tests, ELISA and CLIA tests performed better in terms of sensitivity than did the LFIA. IgG-based tests had higher sensitivity than IgM-based tests, and combined IgG/IgM test-based CLIA tests had the best overall diagnostic test accuracy. The type of sample, serological kit and timing of use of the specific tests were associated with the diagnostic accuracy. Due to the limitations of the serological tests, other techniques should be quickly approved to provide guidance for the correct diagnosis of COVID-19.

Comparison of the Performance of 24 Severe Acute Respiratory Syndrome Coronavirus 2 Antibody Assays in the Diagnosis of Coronavirus Disease 2019 Patients.

Background: The accurate detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the key to control Coronavirus Disease-2019 (COVID-19). The performance of different antibody detection methods for diagnosis of COVID-19 is inconclusive. Methods: Between 16 February and 28 February 2020, 384 confirmed COVID-19 patients and 142 healthy controls were recruited. 24 different serological tests, including 4 enzyme-linked immunosorbent assays (EIAs), 10 chemiluminescent immunoassays (CLIAs), and 10 lateral flow immunoassays (LFIAs), were simultaneously performed. Results: The sensitivities of anti-SARS-CoV-2 IgG and IgM antibodies with different reagents ranged from 75 to 95.83% and 46.09 to 92.45%, respectively. The specificities of both anti-SARS-CoV-2 IgG and IgM were relatively high and comparable among different reagents, ranged from 88.03 to 100%. The area under the curves (AUCs) of different tests ranged from 0.733 to 0.984, and the AUCs of EIAs or CLIAs were significantly higher than those of LFIAs. The sensitivities of both IgG and IgM gradually increased with increase of onset time. After 3-4 weeks, the sensitivities of anti-SARS-CoV-2 IgG were maintained at a certain level but the sensitivities of IgM were gradually decreased. Six COVID-19 patients who displayed negative anti-SARS-CoV-2 results were associated with the factors such as older age, having underlying diseases, and using immunosuppressant. Conclusion: Besides the purpose of assessing the impact of the SARS-CoV-2 pandemic in the population, SARS-CoV-2 antibody assays may have an adjunct role in the diagnosis and exclusion of COVID-19, especially by using high-throughput technologies (EIAs or CLIAs).

COVID-19 Vaccination Campaign in Cancer Patients and Healthcare Workers-Results from a French Prospective Multicenter Cohort (PAPESCO-19).

In this prospective, real-life cohort study, we followed 523 cancer patients (CP) and 579 healthcare workers (HCW) from two cancer centers to evaluate the biological and clinical results of the COVID-19 vaccination campaign. Seventy percent of the CP and 90% of the HCW received an mRNA vaccine or the AZD1222 vaccine. Seropositivity was high after the first vaccine among HCW and poor among CP. The second dose resulted in almost 100% seropositivity in both cohorts. Antibody response was higher after the second injection than the first in both populations. Despite at least two doses, 8 CP (1.5%) and 14 HCW (2.4%) were infected, corresponding either to a weak level of antibody or a new strain of virus (particularly the Omicron variant of concern). Sixteen CP and three HCW were hospitalized but none of them died from COVID-19. To conclude, this study showed that two doses of COVID-19 vaccines were crucially necessary to attain sufficient seropositivity. However, the post-vaccination antibody level declines in individuals from the two cohorts and could not totally prevent new SARS-CoV-2 infections.

Sero-prevalence of anti-SARS-CoV-2 Antibodies in Addis Ababa, Ethiopia

Background: Anti-SARS-CoV-2 antibody tests are increasingly used for sero-epidemiological purposes to provide a better understanding of the extent of the infection in the community, and to monitor the progression of the COVID-19 epidemic. A sero-prevalence study was conducted to estimate prior infections with SARS-CoV-2 in Addis Ababa. Methods: A cross-sectional study was conducted from April 23 to 28, 2020 among 301 randomly selected residents of Addis Ababa;sub-city health offices, health facilities and health extension workers were contacted, to obtain a population profile and to conduct the random selection of study participants. Participants were selected, who had not been in direct contact with people who had contracted COVID-19, to maintain consistency among the study population. Interviews on socio demographic and behavioural risk factors, followed by serological tests were performed for SARS-CoV-2 IgM, and IgG antibodies, using the COVID-19 IgG/IgM Rapid Test Cassette. Based on the manufacturer information, the test has a sensitivity of 87·9% and specificity of 100% for lgM;and a sensitivity of 97·2% and specificity of 100% for IgG. A Polymerase chain reaction (RT-PCR) test was also done on combined nasopharyngeal and oropharengeal swabs. Findings: The unadjusted antibody-based crude SARS-CoV-2 prevalence was 7·6% and the adjusted (weighted average) SARS-CoV-2 prevalence was estimated at 8·8% (95% CI 5·5%-11·6%) for the study population. Higher sero-prevalence were observed for males (9.0%), age below 50 years (8.2%), students and unemployed (15.6%), as well as those with primary education (12.1%), educated above high school (37·9%), non- smokers (78·7%), with no history of regular alcohol (53·8%), no chat (70·8%), and no shisha use (94·7%). According to the findings, a significantly higher number of individuals had been infected in Addis Ababa as compared to what was being detected and reported by the RT-PCR test, which is suggestive of community transmission.

Seroprevalence of SARS-CoV-2 in children and factors affecting the sero-positivity

912 Table 1Association of demographic and clinical features with serology status of SARS-CoV-2Results88 pediatric patients up to the age of 18 years attending the pediatric department at AIIMS Patna were enrolled for the study. Only two patients had history of positive RT-PCR test for COVID-19 infection in the past. 63.6% (56 out of 88) had seropositive status against SARS-Cov-2. Various demographic and clinical variables described in table 1 were analysed and none of the demographic features had statistically significant association with serology status of SARS-CoV-2. Out of 88 children, 57 (64.8%) were males and 31(35.2%) were females. 58% of the children were from urban areas and 42% were from rural areas. The majority of the patients i.e 58 (65.9%) belonged to lower socioeconomic class and 30 (34.0%) belonged to upper class according to modified Kuppuswamy scale 2021. The corticosteroid therapy was received by 13 patients for various clinical indications among which 5 (38%) had seropositive status and 8(61.5%) had seronegative status against SARS-CoV-2 and the association was statistically significant with p-value of 0.041and Odd’s ratio ( 95% CI) of 0.29 (0.087-0.994) suggesting that patients who received corticosteroid therapy had 29% lesser chances of getting seropositive status compared to those who did not receive the therapy.ConclusionAmong the participants, 63.6% were seropositive against SARS-CoV-2 while only 2.2% had history of COVID 19 RTPCR positivity in past. The patients who received corticosteroids had lesser chances of getting positive antibody status against SARS-CoV-2 infection compared to those who did not receive the same.

ROLE OF REAL TIME PCR (RT-PCR) IN CLINICAL DIAGNOSIS FOR COVID-19 REVIEW

The pandemic of Coronavirus Disease 2019 (COVID19) has compelled scientists to create highly reliable diagnostic tools quickly in order to successfully and properly diagnose this pathology and thereby prevent infection transmission. Even though structural and molecular properties of the severe acute respiratory syndrome coronavirus 2 (SARSCoV2) were previously unknown, private research institutes and biomedical firms quickly developed numerous diagnostic procedures beneficial for making a correct detection of COVID19. Rapid antigen or antibody testing, immunoenzymatic serological tests, and RT-PCR based molecular assays are the most frequently used and validated procedures now available. The PCR has grown in popularity in molecular diagnostics to the point where it is still considered the gold standard for finding nucleotides from a variety of sources becoming an indispensable tool in the research lab. Because of its improved speed, sensitivity, reproducibility, and lower likelihood of carry-over contamination, real-time PCR has gained greater popularity. Currently, five different chemistries are employed to detect PCR product during real-time PCR. The selffluorescing amplicons, DNA binding fluorophores, 5' endonuclease, neighbouring linear and hairpin oligoprobes, and self-fluorescing amplicons are all detailed in depth. We also go through the problems that have hampered the development of multiplex real-time PCR and the importance of real-time PCR in nucleic acid quantification.

Health technology assessment to employ COVID-19 serological tests as companion diagnostics in the vaccination campaign against SARS-CoV-2.

OBJECTIVES: In scenarios of vaccine scarcity or contexts of organizational complexity, it is necessary to define prioritization strategies for allocating vaccine doses in compliance with the criterion of equity and efficiency of health resources. In this context, the COVIDIAGNOSTIX project, based on the health technology assessment (HTA), assessed the role of SARS-CoV-2 serological tests as a companion diagnostic in the definition of the vaccination strategies for the vaccine administration. To guarantee evidence support for health policy choices, two different vaccine strategies were analyzed, one based on administering the vaccine booster dose to the entire population (VACCINE strategy) and the other based on allocation criteria (TEST&VACCINE strategy). METHODS: The decision-oriented HTA (DoHTA) method, integrated with specific modeling and simulation techniques, helped define the perimeter to make health policy choices. RESULTS: The processing of the scores attributed to the key performance indicators concerning all the evaluation domains shows a performance of 94.34% for the TEST&VACCINE strategy and 83.87% for the VACCINE strategy. CONCLUSIONS: TEST&VACCINE strategy can be the most advantageous in various scenarios due to greater speed from an operational and an economic point of view. The assessment schemes defined by COVIDIAGNOSTIX (i.e., technologies/intended use/settings) can easily and quickly be exported and adapted to respond to similar health "policy questions".

Diagnosis of COVID-19 by Serology in Admitted Patients with Negative RT-PCR Assay

Considering the increasing prevalence and burden of coronavirus disease 2019 (COVID-19) disease and false-negative results in routine reverse transcription-polymerase chain reaction (RT-PCR) tests, additional diagnostic methods are needed to diagnose active cases of this disease. This prospective study was conducted on patients, in whom clinical and radiological symptoms/signs were in favor of COVID-19 while their first PCR test was negative. Later on, a second RT-PCR was performed and serological evaluation was carried out and results were compared with each other. Out of 707 patients who had been referred to the hospital and were clinically and radiologically suspicious of disease, 137 patients with negative RT-PCR tests entered the study. RT-PCR assay became positive for the second time in 45 (32.8%). Anti-COVID-19 IgM and IgG antibodies were positive in 83 (60.6%) and 86 (62.8%) patients, respectively. Finally, it was determined that serological test was diagnostic in 73% of patients and the diagnostic yield of serology was significantly higher after the first week of illness (54.8% in the first week and 88% after that). Taking advantage of both serological tests and RT-PCR helps in diagnosing 83.9% of cases. Based on the present study, the serology may be useful as a complementary test and in parallel to RT-PCR assay for diagnosis of COVID-19 among admitted symptomatic cases.

INDICATORS OF ANTIBODIES IgM AND IgG TO SARS-COV-2 IN RESIDENTS OF YAKUTSK AFTER RECOVERY FROM COVID-19

A study of IgM and IgG antibodies to SARS-COV-2 was carried out in 161 residents of Yakutsk at the age from 20 to 72 years old who had a new coronavirus infection COVID-19 from 3, 6, 9 and 12 months ago. The aim of the work was to assess the content of serum immunoglobulins IgM and IgG to SARS-COV-2 in persons who have had COVID-19, depending on the duration and severity of the disease. The intensity of the immune response was assessed using the coefficient of positivity (CP) as the ratio of the optical density of the sample to the critical value of the optical density. According to the results of the study, the seroprevalence in all 4 groups of patients with Covid-19 was 100%. Antibodies IgG and IgM to SARS-CoV-2 in those who had been ill with COVID-19 persisted up to 12 months and depended on the postcovid period, age and severity of lung lesions on CT.

Post-infectious encephalitis due to previous Covid-19 infection

More than a year into the pandemic of severe acute respiratory syndrome-related Corona virus-2 (SARS-Cov-2), there is a growing body of evidence for the involvement of the virus in the nervous system by different mechanisms. Here we report on a previously healthy 39-year-old man who presented with clinical symptoms suggesting encephalitis including fever, impaired consciousness, confusion, and seizures. Cerebrospinal fluid analysis confirmed the diagnosis. Repeated serological tests were positive for IgM and IgG to SARS-Cov-2 despite negative polymerase chain reaction (PCR) test result for the virus in the nasopharyngeal swabs and CSF samples. An extensive work-up for other infectious, inflammatory, or paraneoplastic causes was negative. The patient was intubated and sedated due to impaired consciousness and received supportive treatment. The patient was extubated after 3 days and recovered gradually over 3 weeks. This case suggests the development of post-infectious encephalitis due to previous Covid-19 infection, like the development of post-infectious encephalitis after infection with other viruses.

SARS-CoV2 infection in symptomatic patients: interest of serological tests and predictors of mortality: experience of DR Congo.

BACKGROUND: In symptomatic patients, the diagnostic approach of COVID-19 should be holistic. We aimed to evaluate the concordance between RT-PCR and serological tests (IgM/IgG), and identify the factors that best predict mortality (clinical stages or viral load). METHODS: The study included 242 patients referred to the University hospital of Kinshasa for suspected COVID-19, dyspnea or ARDS between June 1st, 2020 and August 02, 2020. Both antibody-SARS-CoV2 IgM/IgG and RT-PCR method were performed on the day of admission to hospital. The clinical stages were established according to the COVID-19 WHO classification. The viral load was expressed by the CtN2 (cycle threshold value of the nucleoproteins) and the CtE (envelope) genes of SARS- CoV-2 detected using GeneXpert. Kappa test and Cox regression were used as appropriate. RESULTS: The GeneXpert was positive in 74 patients (30.6%). Seventy two patients (29.8%) had positive IgM and 34 patients (14.0%) had positive IgG. The combination of RT-PCR and serological tests made it possible to treat 104 patients as having COVID-19, which represented an increase in cases of around 41% compared to the result based on GeneXpert alone. The comparison between the two tests has shown that 57 patients (23.5%) had discordant results. The Kappa coefficient was 0.451 (p < 0.001). We recorded 23 deaths (22.1%) among the COVID-19 patients vs 8 deaths (5.8%) among other patients. The severe-critical clinical stage increased the risk of mortality vs. mild-moderate stage (aHR: 26.8, p < 0.001). The values of CtE and CtN2 did not influence mortality significantly. CONCLUSION: In symptomatic patients, serological tests are a support which makes it possible to refer patients to the dedicated COVID-19 units and treat a greater number of COVID-19 patients. WHO Clinical classification seems to predict mortality better than SARS-Cov2 viral load.