Changes in anti-SARS-CoV-2 antibody titers of pooled plasma derived from donors in Japan: a potential tool for mass-immunity evaluation.

The anti-spike (S), anti-nucleocapsid (N), and neutralizing activities of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) of pooled plasma derived from donors in Japan from January 2021 to April 2022 were evaluated. Anti-S titers and neutralizing activities showed a wave-like trend affected by daily vaccinations and/or the number of reported cases of SARS-CoV-2 infections, whereas anti-N titers remained at negative levels. These results suggest that anti-S and neutralizing titers would fluctuate in pooled plasma in future. Pooled plasma may be potentially used for mass-immunity evaluation, and titer estimation in intravenous immunoglobulin, a derivative of pooled plasma.

Antiphospholipid antibodies in convalescent plasma of donors recovered from mild COVID-19 infection.

BACKGROUND AND OBJECTIVES: Passive immunization by the infusion of convalescent plasma (CP) obtained from patients who have recently recovered from COVID-19, thus having antibodies to severe acute respiratory syndrome coronavirus 2, is a potential strategy to reduce the severity of illness. A high prevalence of antiphospholipid antibodies (APLA) in patients with COVID-19 has been reported during the pandemic, raising a concern whether the use of CP could increase the risk of thrombosis in transfused patients. We aimed to evaluate the prevalence of APLA in COVID-19 CP (CCP) in order to assess the potential prothrombotic influence of transfused CCP to COVID-19 patients. MATERIALS AND METHODS: We studied the prevalence of APLA in 122 CCP samples collected from healthy donors who recovered from mild-COVID-19 at two time periods: September 2020-January 2021 (defined as 'early period' samples) and April-May 2021 (defined as 'late period' samples). Thirty-four healthy subjects unexposed to COVID-19 were used as controls. RESULTS: APLA were present in 7 of 122 (6%) CCP samples. One donor had anti-ß2-glycoprotein 1(anti-ß2GP1) IgG, one had anti-ß2GP1 IgM and five had lupus anticoagulant (LAC) using silica clotting time (SCT), all in 'late period' donors. In the control group, one subject had anti-ß2GP1 IgG, two had LAC using dilute Russell viper venom time (dRVVT) and four had LAC SCT (both LAC SCT and LAC dRVVT in one subject). CONCLUSION: The low prevalence of APLA in CCP donors reassures the safety of CCP administration to patients with severe COVID-19.

SARS-CoV-2 Related Antibody-Dependent Enhancement Phenomena In Vitro and In Vivo.

Antibody-dependent enhancement (ADE) is a phenomenon in which antibodies produced in the body after infection or vaccination may enhance subsequent viral infections in vitro and in vivo. Although rare, symptoms of viral diseases are also enhanced by ADE following infection or vaccination in vivo. This is thought to be due to the production of antibodies with low neutralizing activity that bind to the virus and facilitate viral entry, or antigen-antibody complexes that cause airway inflammation, or a predominance of T-helper 2 cells among the immune system cells which leads to excessive eosinophilic tissue infiltration. Notably, ADE of infection and ADE of disease are different phenomena that overlap. In this article, we will describe the three types of ADE: (1) Fc receptor (FcR)-dependent ADE of infection in macrophages, (2) FcR-independent ADE of infection in other cells, and (3) FcR-dependent ADE of cytokine production in macrophages. We will describe their relationship to vaccination and natural infection, and discuss the possible involvement of ADE phenomena in COVID-19 pathogenesis.

Monitoring of SARS-CoV-2 Infection in Ragusa Area: Next Generation Sequencing and Serological Analysis.

The coronavirus disease 19 (COVID-19) post pandemic evolution is correlated to the development of new variants. Viral genomic and immune response monitoring are fundamental to the surveillance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Since 1 January to 31 July 2022, we monitored the SARS-CoV-2 variants trend in Ragusa area sequencing n.600 samples by next generation sequencing (NGS) technology: n.300 were healthcare workers (HCWs) of ASP Ragusa. The evaluation of anti-Nucleocapside (N), receptor-binding domain (RBD), the two subunit of S protein (S1 and S2) IgG levels in 300 exposed vs. 300 unexposed HCWs to SARS-CoV-2 was performed. Differences in immune response and clinical symptoms related to the different variants were investigated. The SARS-CoV-2 variants trend in Ragusa area and in Sicily region were comparable. BA.1 and BA.2 were the most representative variants, whereas the diffusion of BA.3 and BA.4 affected some places of the region. Although no correlation was found between variants and clinical manifestations, anti-N and anti-S2 levels were positively correlated with an increase in the symptoms number. SARS-CoV-2 infection induced a statistically significant enhancement in antibody titers compared to that produced by SARS-CoV-2 vaccine administration. In post-pandemic period, the evaluation of anti-N IgG could be used as an early marker to identify asymptomatic subjects.

Leveraging Serologic Testing to Identify Children at Risk For Post-Acute Sequelae of SARS-CoV-2 Infection: An Electronic Health Record-Based Cohort Study from the RECOVER Program.

Using an electronic health record-based algorithm, we identified children with Coronavirus disease 2019 (COVID-19) based exclusively on serologic testing between March 2020 and April 2022. Compared with the 131 537 polymerase chain reaction-positive children, the 2714 serology-positive children were more likely to be inpatients (24% vs 2%), to have a chronic condition (37% vs 24%), and to have a diagnosis of multisystem inflammatory syndrome in children (23% vs <1%). Identification of children who could have been asymptomatic or paucisymptomatic and not tested is critical to define the burden of post-acute sequelae of severe acute respiratory syndrome coronavirus 2 infection in children.

Presence of anti-nuclear antibody associated with worse clinical outcomes of anti-NMDAR encephalitis.

Purpose: Systemic autoantibodies are important for the diagnosis of autoimmune diseases, but their roles in anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis are unknown. The purpose of our study is to investigate the characteristics and a prognosis of anti-NMDAR encephalitis with the prevalence of autoantibodies. Methods: Systemic autoantibodies were evaluated in 64 patients with anti-NMDAR encephalitis and 14 patients with autoimmune encephalitis with other forms. Then, according to systemic autoantibodies, patients with anti-NMDAR encephalitis were divided into an anti-nuclear antibody (ANA) positive group and an ANA negative group. The clinical outcome was assessed by a modified Rankin score at 12 months after the disease onset. Results: A total of 64 patients with anti-NMDAR encephalitis were enrolled, of which 28.13% (18/64) were positive for ANA. The titers of a positive anti-NMDAR antibody in CSF (p = 0.041) and serum (p = 0.031) in the ANA-positive group were significantly higher than the ANA-negative group. Patients with ANA positive than those with ANA negative showed lower rates of headache (p = 0.047) and speech disorder (p = 0.049). The presence of ANA was associated with a worse clinical outcome at 12 months (p = 0.043). Conclusion: ANA was prevalent in patients with anti-NMDAR encephalitis, and associated with a worse prognosis and impaired neurological recovery.

SARS-CoV-2 antibody response after BBIBP-CorV (Sinopharm) vaccination in cancer patients: A case-control study.

Background: Long-term safety and efficacy of BBIBP-CorV vaccine especially in individuals with chronic diseases, like cancer, is under investigation. In the present prospective study, we aimed to evaluate severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) antibody response with BBIBP-CorV vaccine in Iranian cancer patients. Methods: All the patients registered to receive BBIBP-CorV (Sinopharm) vaccine were divided into two groups of with (cases = 107) and without (controls = 45) history of cancer. Serum levels of SARS-CoV anti-spike recombinant receptor binding domain (anti-sRBD) and anti-nucleocapsid (anti-N) IgG serum levels were measured on days 0 (phase 0), 28-32 (phase I), and 56-64 (phase II) of vaccination. The data were analyzed using SPSS, version 22. Results: Totally, 152 individuals (67.1% females) with the mean age of 46.71 ± 15.36 years were included. Solid cancers included 87.8% of the cancer cases (46.7% gynecological and 31.8% gastrointestinal cancer). At Phases I and II, positive anti-sRBD IgG and anti-N IgG were significantly lower among the cases in total analysis. Side effects were not significantly different between the cases and controls. The lowest positive anti-sRBD IgG test was observed among the cancer patients who were simultaneously receiving chemotherapy (35.3%). Anti-sRBD IgG and anti-N IgG serum levels significantly increased at phases I and II in total analysis and in each group. In addition, serum anti-sRBD IgG increased during the three phases and it was significantly higher in the control group. Conclusion: Full vaccination of COVID-19 by BBIBP-CorV in immunocompromised patients such as cancer patients is safe and effective and could induce antibody response but in lower levels compared to healthy people. Probable causes to have minor antibody response found in males, older ages, individuals with BMI ≥ 25, those without past history of COVID-19 and with hematologic cancers. No significant side effects after vaccination were seen.

The COVID-19 wave was already here: High seroprevalence of SARS-CoV-2 antibodies among staff and students in a Cameroon University.

Background: Seroprevalence studies, to estimate the proportion of people that has been infected by SARS-CoV-2 are importance in African countries, where incidence is among the lowest in the world. Objective: This study aimed at evaluating the exposure to SARS-CoV-2 within a university setting of Cameroon. Methods: A cross-sectional study performed in December 2020 - December 2021, among students and staffs of the Evangelical University of Cameroon. COVID-19 antigen rapid detection test (RDT) was performed using Standard Q Biosensor, and one year after SARS-CoV-2 antibody-test was performed within the same population using RDT and chemiluminescence immunoassay (CLIA). Results: 106 participants were enrolled (80% students), female sex was the most represented. Positivity to SARS-CoV-2 was 0.0% based on antigen RDTs. The seroprevalence of SARSCoV- 2 antibodies was estimated at 73.6% (95% CI. 64.5-81.0) for IgG and 1.9% (95% CI. 0.2-6.8) for IgM/IgG with RDTs, and 91.9% (95% CI. 84.7-96.4) for anti-nucleocapsid with CLIA. 95.3% (101) reported having developed at least one of the known COVID-19 symptoms (cough and headache being the most common). 90.3% (28) of people who experienced at least one of these symptoms developed IgG antibodies. 40.6% (43) of participants took natural herbs, whereas 55.7% (59) took conventional drugs. The most used herb was Zingiber officinale, while the most used drugs were antibiotics. Conclusion: In this Cameroonian University community, SARS-CoV-2 seroprevalence is high, with a greater detection using advanced serological assays. This indicates a wide viral exposure, and the need to adequate control measures especially for those experiencing any related COVID-19 symptoms.

Monitoring algorithm of hospitalized patients in a medical center with SARS-CoV-2 (Omicron variant) infection: clinical epidemiological surveillance and immunological assessment.

Purpose: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a major healthcare threat worldwide. Since it was first identified in November 2021, the Omicron (B.1.1.529) variant of SARS-CoV-2 has evolved into several lineages, including BA.1, BA.2-BA.4, and BA.5. SARS-CoV-2 variants might increase transmissibility, pathogenicity, and resistance to vaccine-induced immunity. Thus, the epidemiological surveillance of circulating lineages using variant phenotyping is essential. The aim of the current study was to characterize the clinical outcome of Omicron BA.2 infections among hospitalized COVID-19 patients and to perform an immunological assessment of such cases against SARS-CoV-2. Patients and Methods: We evaluated the analytical and clinical performance of the BioIC SARS-CoV-2 immunoglobulin (Ig)M/IgG detection kit, which was used for detecting antibodies against SARS-CoV-2 in 257 patients infected with the Omicron variant. Results: Poor prognosis was noted in 38 patients, including eight deaths in patients characterized by comorbidities predisposing them to severe COVID-19. The variant-of-concern (VOC) typing and serological analysis identified time-dependent epidemic trends of BA.2 variants emerging in the outbreak of the fourth wave in Taiwan. Of the 257 specimens analyzed, 108 (42%) and 24 (9.3%) were positive for anti-N IgM and IgG respectively. Conclusion: The VOC typing of these samples allowed for the identification of epidemic trends by time intervals, including the B.1.1.529 variant replacing the B.1.617.2 variant. Moreover, antibody testing might serve as a complementary method for COVID-19 diagnosis. The combination of serological testing results with the reverse transcription-polymerase chain reaction cycle threshold value has potential value in disease prognosis, thereby aiding in epidemic investigations conducted by clinicians or the healthcare department.

Asymptomatic versus symptomatic SARS-CoV-2 infection: a cross-sectional seroprevalence study.

BACKGROUND: Although symptomatic SARS-CoV-2 infection predisposes patients to develop complications, the asymptomatic SARS-CoV-2 infection state is of public health importance being a hidden source of infection. Moreover, the asymptomatic state may camouflage the actual burden of the disease. METHODS: Data of 1434 seropositive participants for SARS-CoV-2 spike (anti-S) and/or nucleocapsid antibodies (anti-N) were retrieved from a larger cross-sectional survey on COVID-19. Relevant data were retrieved from records including socio-demographic, medical, and behavioral characteristics of seropositive participants as well as history of COVID-19 symptoms during the last 6 months. Symptomatic/asymptomatic SARS-CoV-2 infection was categorized based on the history of the presence or absence of COVID-19 symptoms. RESULTS: The rate of asymptomatic SARS-CoV-2 infection was 34.9%. There was a statistically significant difference between symptomatic and asymptomatic participants regarding age, residence, medical conditions, habits, and infection control measures. The number of symptoms was positively correlated with anti-S titer and both were positively correlated with adult body mass index. Slum areas residence, client-facing occupation or being a healthcare worker, having lung disease, having blood group type A, never practicing exercise or social distancing, never using soap for hand washing, and minimal engagement in online working/studying were independent factors associated with the symptomatic state. Patients having less than three symptoms were less likely to be diagnosed by any means. CONCLUSIONS: One-third of SARS-CoV-2 infections in our study were asymptomatic. This mandates applying proper measures to prevent transmission even from apparently healthy individuals. Modifiable factors associated with symptomatic infection should be controlled to reduce the risk of COVID-19 complications.

Clinical Presentation of COVID-19 and Antibody Responses in Bangladeshi Patients Infected with the Delta or Omicron Variants of SARS-CoV-2.

The clinical presentation of COVID-19 and the specific antibody responses associated with SARS-CoV-2 variants have not been investigated during the emergence of Omicron variants in Bangladesh. The Delta and Omicron variants were identified by post-PCR melting curve analysis of the spike (S) protein receptor binding domain amplicons. Anti-S-protein immunoglobulin-G anti-nucleocapsid (N)-protein immunoglobulin-G and immunoglobulin-A levels were measured by ELISA. The Delta variant was found in 40 out of 40 (100%) SARS-CoV-2 RT-PCR positive COVID-19 patients between 13 September and 23 October 2021 and Omicron variants in 90 out of 90 (100%) RT-PCR positive COVID-19 patients between 9 January and 10 February 2022. The Delta variant associated with hospitalization (74%, 80%, and 40%) and oxygen support (60%, 57%, and 40%) in the no vaccine, dose-1, and dose-2 vaccinated cases, respectively, whereas the Omicron COVID-19 required neither hospitalization nor oxygen support (0%, p < 0.0001). Fever, cough, and breathlessness were found at a significantly higher frequency among the Delta than Omicron variants (p < 0.001). The viral RNA levels of the Delta variant were higher than that of the Omicron variants (Ct median 19.9 versus 23.85; p < 0.02). Anti-spike protein immunoglobulin-G and anti-N-protein immunoglobulin-G within 1 week post onset of Delta variant COVID-19 symptoms indicate prior SARS-CoV-2 infection. The Delta variant and Omicron BA.1 and BA.2 breakthrough infections in the Dhaka region, at 240 days post onset of COVID-19 symptoms, negatively correlated with the time interval between the second vaccine dose and serum sampling. The findings of lower anti-spike protein immunoglobulin-G reactivity after booster vaccination than after the second vaccine dose suggest that the booster vaccine is not necessarily beneficial in young Bangladeshi adults having a history of repeated SARS-CoV-2 infections.

The Proportion of Long-term Response to Anti-N IgG Antibody after 12 Months for COVID-19 Subclinical Infections and a Longitudinal Survey for COVID-19 Subclinical Infections in 2021.

Objective To examine the continuation of antibody prevalence status after 12 months and background factors in antibody-positive subjects following asymptomatic infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods We initially determined the SARS-CoV-2 anti-nucleocapsid protein immunoglobulin G (anti-N IgG) antibody prevalence in 1,603 patients, doctors, and nurses at 65 medical institutions in Kanagawa Prefecture, Japan. We then obtained consent from 33 of the 39 subjects who tested positive and performed follow-up for 12 months. Results Follow-up for up to 12 months showed that a long-term response of the anti-N IgG antibody could be detected in 6 of the 33 participants (18.2%). The proportions with hypertension, using an angiotensin-receptor blocker, and without a drinking habit were higher among the participants with a long-term anti-N IgG antibody response for up to 12 months than among those without a long-term antibody response. Conclusions The proportion of individuals with subclinical COVID-19 who continuously had a positive result for the anti-N IgG antibody at 12 months was low.

Seroprevalence of SARS-CoV-2 infection in the Tyrolean district of Schwaz at the time of the rapid mass vaccination in March 2021 following B.1.351-variant outbreak.

In order to curb the rapid dissemination of the B.1.351 variant of SARS-CoV-2 in the district of Schwaz and beyond, the EU allocated additional vaccine doses at the beginning of March 2021 to implement a rapid mass vaccination of the population (16+). The aim of our study was to determine the seroprevalence of SARS-CoV-2 among the adult population in the district of Schwaz at the time of the implementation. Data on previous history of infections, symptoms and immunization status were collected using a structured questionnaire. Blood samples were used to determine SARS-CoV-2 specific anti-spike, anti-nucleocapsid and neutralizing antibodies. We recruited 2,474 individuals with a median age (IQR) of 42 (31-54) years. Using the official data on distribution of age and sex, we found a standardized prevalence of undocumented infections at 15.0% (95% CI: 13.2-16.7). Taken together with the officially documented infections, we estimated that 24.0% (95% CI: 22.5-25.6) of the adult population had prior SARS-CoV-2 infection. Hence, the proportion of undocumented infections identified by our study was 55.8% (95% CI: 52.7-58.5). With a vaccination coverage of 10% among the adults population at that time, we imply that a minimum of two-thirds of the target popuation was susceptible to the circulating threat when this unique campaign started.

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.

[Autoimmune encephalitis in pediatric population]

Autoimmune encephalitis can be defined as central nervous system inflammation, secondary to multiple causes, where we can possibly identify the formation of auto-antibody against neurotransmitter receptors or neuronal surface proteins. Approximately 50% of patients are seropositive;the auto-antibody against N-methyl-D-aspartate receptor (NMDAR) are the most common. In the pediatric population, the clinical presentation is characterized by movement disorders and seizures, psychiatric manifestations are more commonly found in young adults. An early intervention is associated with a better prognosis in these patients. In contrast to the seropositive group, seronegative autoimmune encephalitis is linked with less movement alterations and is related with a worse cognitive outcome. Much remains to be discovered about possible etiologies, molecular processes, detection, and interaction of yet undescribed antibodies,as well as increasing our knowledge about clinical manifestations in early disease and new diagnostic techniques that could improve the diagnosis of autoimmune encephalitis. The main goal of this document is to review the updates of the molecular field about the antibody against GluK2 and its clinical presentation in pediatric population;COVID-19 as a possible cause of autoimmune encephalitis;recognize the importance of psychiatric manifestation in early disease, especially catatonia as a marker of severity;additionally consider new imaging diagnostic method such as positron emission tomography (PET), which has shown to be more sensible than MRI (goal standard).

Seroprevalence of antibodies against SARS-CoV-2 and risk of COVID-19 in Navarre, Spain, May to July 2022.

In Navarre, Spain, in May 2022, the seroprevalence of anti-nucleocapsid (N) and anti-spike (S) antibodies of SARS-CoV-2 was 58.9% and 92.7%, respectively. The incidence of confirmed COVID-19 thereafter through July was lower in people with anti-N antibodies (adjusted odds ratio (aOR) = 0.08; 95% confidence interval (CI): 0.05-0.13) but not with anti-S antibodies (aOR = 1.06; 95% CI: 0.47-2.38). Hybrid immunity, including anti-N antibodies induced by natural exposure to SARS-CoV-2, seems essential in preventing Omicron COVID-19 cases.

Cooccurrence of anti-N-methyl-D-aspartate receptor encephalitis and COVID-19 infection – Case series of two patients with a brief review of literature

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a clinical condition characterized by a myriad of psychiatric symptoms, abnormal movements, autonomic instability, seizures, and encephalopathy. Coronavirus disease-19 (COVID-19) infection is infrequently present with altered mental status. As the days of the COVID-19 pandemic pass, more and more awareness of its different types of immunological reactions are unveiled. A wide spectrum of clinical, pathological, and radiological manifestations has been reported. However, there have only been a few cases where anti-NMDAR antibodies have been found in people who have COVID-19. Herein, we reported two cases with simultaneous anti-NMDAR antibody and COVID-19 infection detection. Both cases clinically responded after treatment with an immunomodulator, showing significant improvement, and were discharged in a conscious and ambulatory state. Autoimmune encephalitis should be thought about if there are neurological symptoms associated with SARS-CoV-2 infection, and immunomodulators should be given to such patients. [ FROM AUTHOR] Copyright of Asian Journal of Medical Sciences is the property of Manipal Colleges of Medical Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

[Immune-mediated encephalitis in a child with a history of SARS-CoV-2 infection]. / Encefalitis inmunomediada en un niño con antecedente de infección por SARS-CoV-2.

Encephalitis are frequent clinical pictures in pediatric age. They can be divided into those caused by infection of the central nervous system and those of immune-mediated etiology (some of which may be para- or post-infectious). In March 2020, the WHO declared a SARS-CoV-2 pandemic. Pediatric reports of disease caused by this agent describe a wide range of clinical manifestations: respiratory and gastrointestinal compromise, neurological symptoms, among others; and a multisystemic inflammatory syndrome in children associated with COVID-19 (MIS-C). We describe the case of a 2-year-old boy with a diagnosis of anti-NMDAR antibody encephalitis, in whom a recent SARS-CoV-2 infection was serologically proven. The presence of positive serological markers for SARS-CoV-2 in a patient who presented encephalitis due to anti-NMDAR antibodies could be interpreted as a temporal association; establishing the possibility that the virus has acted as a trigger for an autoimmune disease.

Las encefalitis son cuadros clínicos frecuentes en la edad pediátrica. Pueden dividirse en aquellas causadas por la infección del sistema nervioso central y en las de etiología inmunomediada (algunas de las cuales pueden ser para- o posinfecciosas). En marzo de 2020 la Organización Mundial de la Salud declaró la pandemia por el coronavirus de tipo 2 del síndrome respiratorio agudo grave (SARS-CoV-2, por su sigla en inglés). Los reportes pediátricos de enfermedad por dicho agente describen una amplia gama de manifestaciones clínicas: compromiso respiratorio, gastrointestinal, síntomas neurológicos, entre otros; y el síndrome inflamatorio multisistémico asociado a COVID-19 (SIM-C). Describimos el caso de un niño de 2 años con diagnóstico de encefalitis por anticuerpos antirreceptor N-metil-d-aspartato (anti-NMDAR), en quien se comprobó, mediante serología, una infección reciente por SARS-CoV-2. La presencia de marcadores serológicos positivos para SARS-CoV-2 en un paciente que presentó encefalitis por anticuerpos anti-NMDAR podría interpretarse como una asociación temporal, estableciéndose la posibilidad de que el virus haya actuado como gatillo de una enfermedad autoinmunitaria.

SARS-CoV-2 Antinucleocapsid Antibody Response of mRNA and Inactivated Virus Vaccines Compared to Unvaccinated Individuals.

Comparative studies of SARS-CoV-2 antinucleocapsid (anti-N) antibody response in the context of inactivated virus vaccines versus natural infection are limited. This study aims to determine and compare the anti-N antibody levels in people vaccinated with Sinopharm's (Wuhan, China) inactivated virus vaccine in comparison with naturally infected unvaccinated and Pfizer's spike (S) mRNA-based vaccinated subjects. Two hundred ninety-nine Jordanian adults participated in the study including unvaccinated COVID-19-infected patients (n = 99), Pfizer-vaccinated (n = 100), and Sinopharm-vaccinated recipients (n = 100). Serum samples were assayed for anti-N IgG, anti-N IgM, and anti-S IgG. Sera of 64.6% of naturally infected unvaccinated participants had positive anti-S IgG (median = 36.35 U/mL; range: 0.04-532.5 U/mL) compared to 88% of Pfizer-vaccinated (Manhattan, NY, USA) (median = 26.52 U/mL; range: 0.39-1265 U/mL) and 58% of Sinopharm-vaccinated subjects (median = 14.35 U/mL; range: 0.39-870.17 U/mL). Samples of 60.6% of naturally infected unvaccinated people had positive anti-N IgG (median = 15.03 U/mL; range: 0-265.1 U/mL) compared to 25% of Pfizer-vaccinated (median = 0.02 U/mL; range: 0-68 U/mL) and 48% of Sinopharm-vaccinated subjects (median = 0.8 U/mL; range: 0-146.3 U/mL). Anti-N titers among the three groups were significantly different (p < 0.05). Anti-N IgM antibodies appeared in 23.2% of the naturally infected unvaccinated group (median = 0.29 U/mL; range: 0-15 U/mL) compared to only 9.0% of Pfizer-vaccinated (median = 018 U/mL; range: 0-33 U/mL) and 7.0% of Sinopharm-vaccinated subjects (median = 0.2 U/mL; range: 0-12.02 U/mL). A significant negative correlation was found between anti-S and age for both vaccines and between anti-S and the presence of chronic disease in Sinopharm-vaccinated subjects. A significant positive correlation between anti-N and anti-S titers was found among the three groups. This study shows that the inactivated virus vaccine, Sinopharm, induces an anti-N response that can boost that of natural infection or vice versa. On the other hand, the Pfizer mRNA-based vaccine induces a significantly stronger anti-S Ab response.

Seroprevalence, Waning and Correlates of Anti-SARS-CoV-2 IgG Antibodies in Tyrol, Austria: Large-Scale Study of 35,193 Blood Donors Conducted between June 2020 and September 2021.

There is uncertainty about the seroprevalence of anti-SARS-CoV-2 antibodies in the general population of Austria and about the waning of antibodies over time. We conducted a seroepidemiological study between June 2020 and September 2021, enrolling blood donors aged 18-70 years across Tyrol, Austria (participation rate: 84.0%). We analyzed serum samples for antibodies against the spike or the nucleocapsid proteins of SARS-CoV-2. We performed a total of 47,363 samples taken from 35,193 individuals (median age, 43.1 years (IQR: 29.3-53.7); 45.3% women; 10.0% with prior SARS-CoV-2 infection). Seroprevalence increased from 3.4% (95% CI: 2.8-4.2%) in June 2020 to 82.7% (95% CI: 81.4-83.8%) in September 2021, largely due to vaccination. Anti-spike IgG seroprevalence was 99.6% (95% CI: 99.4-99.7%) among fully vaccinated individuals, 90.4% (95% CI: 88.8-91.7%) among unvaccinated individuals with prior infection and 11.5% (95% CI: 10.8-12.3%) among unvaccinated individuals without known prior infection. Anti-spike IgG levels were reduced by 44.0% (95% CI: 34.9-51.7%) at 5-6 months compared with 0-3 months after infection. In fully vaccinated individuals, they decreased by 31.7% (95% CI: 29.4-33.9%) per month. In conclusion, seroprevalence in Tyrol increased to 82.7% in September 2021, with the bulk of seropositivity stemming from vaccination. Antibody levels substantially and gradually declined after vaccination or infection.