A comparison of antibody response in kidney transplant recipients and healthcare workers who had PCR-confirmed COVID-19 infection.

BACKGROUND: Data on antibody response following COVID-19 in kidney transplant recipients is scarce. This crosssectional study aims to investigate the antibody response to COVID-19 among kidney transplant recipients. METHODS: We recruited 46 kidney transplant recipients with RT-PCR-confirmed COVID-19 and 45 recipients without COVID-19 history. We also constructed two control groups (COVID-19 positive and negative) from a historical cohort of healthcare workers. We used age and sex-based propensity score matching to select the eligible subjects to the control groups. We measured the SARS-CoV-2 IgG levels quantitatively using the Abbott ARCHITECT system. An antibody level above 1.4 S/C was defined as positivity. RESULTS: Transplant recipients with COVID-19 had a higher BMI, and COVID-19 history in a household member was more common than that of the transplant recipient without COVID-19. IgG seropositivity rate (69.6% vs. 78.3%, p = 0.238) and the median IgG level (3.28 [IQR: 0.80-5.85] vs. 4.59 [IQR: 1.61-6.06], p = 0.499) were similar in COVID-19-positive transplant recipients and controls. Kidney transplant recipients who had a longer duration between RT-PCR and antibody testing had lower antibody levels (r = -0.532, p < 0.001). DISCUSSION: At the early post-COVID-19 period, kidney transplant recipients have a similar antibody response to controls. However, these patients' antibody levels and immunity should be closely monitored in the long term.

Long-Term Humoral Response After a Second Dose of SARS-CoV-2 mRNA Vaccine in Japanese Kidney Transplant Recipients.

Background: The mortality rate due to COVID-19 in kidney transplant recipients (KTRs) is 16.8 to 32%. Vaccination against COVID-19 is expected to contribute to the prevention of infection, severe disease, and mortality; however, it has been reported that the humoral response to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccine in KTRs is poor. Vaccination strategies against COVID-19 vary from country to country, and in Japan, the third dose is given 6 months after the second dose. Few studies have evaluated long-term humoral responses after the second dose of SARS-CoV-2 mRNA vaccine. In addition, the superiority of BNT162b2 vaccine and mRNA-1,273 vaccine in KTRs regarding humoral response is controversial. Methods: Ninety-four KTRs were administered a second dose of the BNT162b2 or mRNA-1,273 vaccines, and anti-spike (anti-S) and anti-nucleocapsid (anti-N) SARS-CoV-2 antibody levels were measured 5 months (149.2 ± 45.5 days) later. The cutoff value of anti-S antibodies was defined ≥50 AU/ml and 1.4 Index for anti-N antibodies. The primary outcome was the rate of seropositivity, and factors associated with an appropriate humoral response were assessed by univariate and multivariate analysis. Results: Of 94 KTRs, only 45 (47.9%) patients were positive for anti-S antibodies. The median anti-S SARS-CoV-2 IgG antibody titers was 35.3 (Interquartile range 3.8 to 159.7). Anti-N SARS-CoV-2 IgG antibodies in all patients were < 1.4 Index. Response to SARS-CoV-2 mRNA vaccines were 43.2 and 65% for BNT162b2 and mRNA-1,273, respectively (p = 0.152). In comparison with high-dose, low-dose of mycophenolic acid was a robust factor associated with an adequate humoral response. Conclusion: The long-term humoral response after a second dose of SARS-CoV-2 mRNA vaccine in Japanese KTRs was poor. In comparison with high-dose, low-dose mycophenolic acid was related to an appropriate humoral response. Five months is too long to wait for a 3rd dose after 2nd dose of SARS-CoV-2 vaccine in KTRs. In this cohort, there was no statistical difference in humoral response to the BNT162b2 and mRNA-1,273 vaccines. Additional large observational studies and meta-analyses are needed to clarify the factors related to an appropriate humoral immune response to COVID-19 vaccination.

Bipolar silica nanochannel array confined electrochemiluminescence for ultrasensitive detection of SARS-CoV-2 antibody.

Ultrasensitive, specific, and early identification of Coronavirus Disease (2019) (COVID-19) infection is critical to control virus spread and remains a global public health problem. Herein, we present a novel solid-state electrochemiluminescence (ECL) platform targeting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody with rapidity and ultrahigh sensitivity, in which a bipolar silica nanochannel array (bp-SNA) is fabricated on indium tin oxide (ITO) electrode for the first time to stably confine the ECL probe of tris(2,2'-bipyridyl) ruthenium (Ru(bpy)32+) under dual electrostatic force. The bp-SNA consists of tightly packed bilayer silica nanochannel array (SNA) with asymmetric surface charges, namely an inner negatively charged SNA (n-SNA) and an outer positively charged SNA (p-SNA), serving as an "electrostatic lock" to enrich and stabilize the cationic Ru(bpy)32+ probe without leakage from the electrode surface. The detection of SARS-CoV-2 IgG antibody could be realized via immobilization of SARS-CoV-2 spike protein on the utmost of Ru(bpy)32+-confined solid-state ECL platform (Ru@bp-SNA). Upon the capture of target SARS-CoV-2 IgG by immune recognition, the formed immunocomplex will block the nanochannel, leading to the hindered diffusion of the co-reactant (tri-n-propylamine, TPrA) and further producing a decreased ECL signal. The developed solid-stated ECL immunosensor is able to determine SARS-CoV-2 IgG with a wide linear range (5 pg mL-1 to 1 µg mL-1), a low limit-of-detection (2.9 pg mL-1), and a short incubation time (30 min). Furthermore, accurate analysis of SARS-CoV-2 IgG in real serum samples is also obtained by the sensor.

Comparison of antibody response following the second dose of SARS-CoV-2 mRNA vaccine in elderly patients with late-stage chronic kidney disease.

Background: Currently, it is unclear whether the progression of chronic kidney disease (CKD) could be an independent predictor of antibody response after administration of a COVID-19 vaccine. This study aimed to investigate the immune response to COVID-19 vaccination in patients with CKD stage G4 to G5 without renal replacement therapy and G5D using the recommended dose and schedule. Methods: This retrospective single-center cohort study evaluated immunogenicity regarding antibody response after COVID-19 vaccination in our hospital for late-stage CKD patients aged ≥ 60 years. We evaluated antibody responses in 48 patients with CKD G4, 35 patients with CKD G5, and 70 patients undergoing hemodialysis (HD; CKD G5D). Results: After the second vaccination, anti-SARS-CoV-2-S (Spike) IgG levels were found to be positive (> 0.8 U/mL) in all CKD G4 and G5 patients (100%), and 69 of 70 HD patients (98.5%). The median (interquartile range [IQR] S-IgG level (Ab titers) was 358 [130.2-639.2], 218 [117-377], and 185.5 [95.1-323.5] U/mL in the CKD G4, G5, and HD groups, respectively. The median S-IgG levels were significantly lower in the HD group than in the CKD G4 group (p < 0.01). However, there was no significant difference in the antibody titers between the CKD G4 and G5 groups. To further analyze the decline in S-IgG levels after 6 months, we additionally assessed and compared antibody titers at 1 month and 6 months after the second vaccination in the HD group. Compared with the median S-IgG levels of 185.5 [95.1-323.5] U/mL 1 month after the second dose, the median S-IgG level 6 months thereafter was significantly decreased at 97.4 [62.5-205.5] U/mL (p < 0.05). Conclusions: We highlight two major factors of variability in the vaccine response. First, in elderly patients with late-stage CKD, antibody titers tended to be lower in the G5D group than in the G4 and G5 groups despite the shorter time since vaccination; therefore, CKD stage progression might cause a decline in antibody titers. Second, waning immune responses were observed 6 months after second dose administration in HD patients advocating a potential need for a third booster dose vaccine after 6 months.

Inactivated Vaccines Against SARS-CoV-2: Neutralizing Antibody Titers in Vaccine Recipients.

Background: Although effective vaccines have been developed against coronavirus disease 2019 (COVID-19), the level of neutralizing antibodies (NAbs) induced after vaccination in the real world is still unknown. The aim of this work was to evaluate the level and persistence of NAbs induced by two inactivated COVID-19 vaccines in China. Methods: Serum samples were collected from 1,335 people aged 18 years and over who were vaccinated with an inactivated COVID-19 vaccine at Peking University People's Hospital from January 19 to June 23, 2021, for the detection of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies. Results: The positive rate for NAbs against SARS-CoV-2 was 79-91% from the first month to the second month after the second vaccine dose. The gradual decline in positivity rate for NAb response was observed from 78% at 3 months post-vaccination to 0% at 12 months post-vaccination. When there was a 21-day interval between the two doses of vaccine, the NAb positivity rate was 0% 6 months after the second dose. NAb levels were significantly higher when the interval between two doses were 3-8 weeks than when it was 0-3 weeks (χ2 = 14.04, p < 0.001). There was a linear correlation between NAbs and IgG antibodies in 1,335 vaccinated patients. NAb levels decreased in 31 patients (81.6%) and increased in 7 patients (18.4%) over time in the series of 38 patients after the second vaccination. The NAb positivity rate was significantly higher in 18- to 40-year-old subjects than in 41- to 60-year-old subjects (t = -1.959, p < 0.01; t = 0.839, p < 0.01). Conclusion: The NAb positivity rate was the highest at the first and second month after the second dose of vaccine, and gradually decreased over time. With a 21-day interval between two doses of vaccine, neutralizing antibody levels persisted for only 6 months after the second dose of vaccine. Therefore, a third vaccine dose is recommended. Our results suggest that in cases in which NAbs cannot be detected, IgM/IgG antibodies can be detected instead. The level of NAbs produced after vaccination was affected by age but not by sex. Our results suggest that an interval of 21 to 56 days between shots is suitable for vaccination.

Comparing Immune Responses to Inactivated Vaccines against SARS-CoV-2 between People Living with HIV and HIV-Negative Individuals: A Cross-Sectional Study in China.

This study compared the immunogenicity of inactivated SARS-CoV-2 vaccines between people living with HIV (PLWH) and HIV-negative individuals. We recruited 120 PLWH and 53 HIV-negative individuals aged 18-59 years who had received an inactivated SARS-CoV-2 vaccine in two Chinese cities between April and June 2021. Blood samples were tested for immunogenicity of the inactivated SARS-CoV-2 vaccines. The prevalence and severity of adverse events associated with SARS-CoV-2 vaccines were similar between PLWH and HIV-negative individuals. The seropositivity of neutralizing activity against authentic SARS-CoV-2, of the total amount of antibody (total antibody) and of S-IgG were 71.3%, 81.9%, and 92.6%, respectively, among fully vaccinated PLWH. Among all participants, PLWH had lower neutralizing activity, total antibody, S-IgG, and T-cell-specific immune response levels, compared to HIV-negative individuals, after controlling for types of vaccine, time interval between first and second dose, time after receiving the second dose, and sociodemographic factors. PLWH with a longer interval since HIV diagnosis, who received their second dose 15-28 days prior to study commencement, and who had an interval of ≥21 days between first and second dose had higher neutralizing activity levels. The immunogenicity of the inactivated SARS-CoV-2 vaccines was lower among PLWH as compared to HIV-negative individuals. Vaccination guideline specific for PLWH should be developed.

Study on Continuation of Antibody Prevalence Six Months after Detection of Subclinical Severe Acute Respiratory Syndrome Coronavirus 2 Infections.

Objective To examine the continuation of antibody prevalence and background factors in antibody-positive subjects after asymptomatic infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods A study was carried out to investigate the SARS-CoV-2 antibody (IgG) prevalence. SARS-CoV-2 antibodies (IgG) were measured and analyzed with immunochromatographic tests. Patients Among 1,603 subjects, comprising patients, physicians, and nurses at 65 medical institutes in Kanagawa, Japan, 39 antibody-positive subjects received follow-up for 6 months. Results Of the 33 subjects who consented to the follow-up (23 patients and 10 medical professionals), continued positivity of IgG antibodies was confirmed in 11 of 32 cases (34.4%) after 2 months, 8 of 33 (24.2%) after 4 months, and 8 of 33 (24.2%) after 6 months. A significant difference was found in the sleeping time, drinking habits, hypertension, and use of angiotensin-receptor blockers on comparing subject background characteristics among three groups: patients with antibody production that continued for six months after the first detection of positivity, patients in whom antibody production stopped at four months, and patients in whom antibody production stopped at two months. Conclusion The continuation rate of IgG antibody prevalence was 24.2% at 6 months after the first detection of antibody positivity in cases with asymptomatic coronavirus disease 2019 (COVID-19) infections. This percentage is low compared with the antibody continuation rate in patients who have recovered from symptomatic COVID-19 infection.

Humoral immune response to COVID-19 vaccines in people with secondary progressive multiple sclerosis treated with siponimod.

OBJECTIVE: The aim of this study is to determine a development of humoral response after COVID-19 vaccination in persons with secondary progressive multiple sclerosis (pwSPMS) on siponimod, compared to healthy controls (HC). METHODS: In 13 pwSPMS taking siponimod and 11 HC, testing for SARS-CoV2 antibodies was performed after vaccination against COVID-19. RESULTS: pwSPMS taking siponimod had a significantly lower titer of SARS-CoV2 antibodies compared to healthy controls (19.4 (0-250) vs. 250 (250), p>0.001). Two (15.4%) pwSPMS on siponimod had unmeasurable titers of SARS-CoV2-2 antibodies, while all HC had positive titers. CONCLUSION: Although the results of this study are limited by a small sample size, results have consistently shown low titers of SARS-CoV-2 IgG after COVID-19 vaccinations in pwSPMS on siponimod.

Seroprevalence of SARS-CoV-2 IgG antibody among healthy blood donors: a single centre study.

BACKGROUND: Severe acute respiratory syndrome corona virus 2(SARS-CoV-2), the causative agent of corona virus disease-2019(COVID- 19) which has led to a global pandemic. The true extent of the burden of COVID-19 may be underestimated, and there is need to know the current prevalence of SARS-CoV-2 antibody in population. METHODS: The present study was a cross-sectional study to assess prevalence of SARS-CoV- 2 IgG antibody among 586 healthy voluntary blood donors who donated whole blood between mid-December 2020 to January 2021. A chemiluminescence assay was used to detect the presence of SARS-CoV-2 IgG antibody in serum samples in addition to recommended transfusion transmitted infections tests and Signal to Cut Off (S/C) > 1 was considered as reactive for antibody as per manufacturer's instructions. RESULTS: In the present study, 586 healthy voluntary blood donors were enrolled and were screened for SARS- CoV-2 IgG antibody. Out of 586 donors, 52 donors had indeterminate values of SARS-CoV-2 IgG antibody. A total of 534 healthy voluntary blood donors' samples were included in the present study for analysis. Out of total 534 healthy blood donors, 42.88% (229) were found to be seropositive while 57.11% (305) were found to be seronegative. CONCLUSION: A 43% positivity of SARS-CoV-2 IgG antibody among healthy blood donors was detected which is an indication of presence of infection at community level and majority of the population already has been exposed to SARS-CoV-2 infection. However, there was no statistically significant association of type of blood group and age with seropositivity.

Multicenter Study of Antibody Seroprevalence against COVID-19 in Patients Presenting to Iranian Cancer Centers after One Year of the COVID-19 Pandemic.

Patients with cancer are at significantly greater risk of COVID-19 and its complications than the general population. Since IgG antibodies remain detectable well after infection with the SARS-CoV-2 virus, seroprevalence can be used to estimate the proportion of the cancer population previously infected and potentially immune to SARS-CoV-2. The current study is a multi-center, prospective observational study to assess the seroprevalence of SARS-CoV-2 IgG antibody in a cancer population referred for vaccination between April and June 2021. Of a total of 270 adult patients with cancer accrued, 16% reported a history of COVID-19 more than four weeks previously confirmed by PCR. At the same time, serologic positivity for SARSCoV2 IgG was found in 29% of patients prior to vaccination including nearly 20% of patients without a history of confirmed COVID-19. Seropositivity was significantly greater in females consistent with higher rates in patients with breast cancer and gynecologic cancers. A seroconversion rate of 79.5% was observed in cancer patients with a history of PCR confirmed COVID-19, less than observed in the general population. In multivariable analysis, gender and prior history of COVID-19 were both independently associated with seropositivity prior to vaccination. Follow-up is continuing of this cohort of patients with cancer following vaccination to assess antibody and clinical outcomes.

Half-Year Longitudinal Seroprevalence of SARS-CoV-2-Antibodies and Rule Compliance in German Hospital Employees.

COVID-19, which is caused by SARS-CoV-2, is an occupational health risk, especially for healthcare employees due to their higher exposure and consequently higher risk of symptomatic and asymptomatic infections. This study was designed to determine the longitudinal seroprevalence of specific immunoglobulin-G (IgG) antibodies in employees in a hospital setting. All employees in a secondary care hospital, including healthcare and non-healthcare workers, were invited to participate in this single-center study. After an initial screening, a 6-month follow-up was carried out, which included serological examination for SARS-CoV-2 IgG antibodies and a questionnaire for self-reported symptoms, self-perception, and thoughts about local and national hygiene and pandemic plans. The seroprevalence of SARS-CoV-2 IgG antibodies was 0.74% among 406 hospital employees (0.75% in healthcare workers, 0.72% in non-healthcare workers), initially recruited in April 2020, in their follow-up blood specimens in October 2020. In this study, 30.54% of the participants reported using the official German coronavirus mobile application and the majority were content with the local and national rules in relation to coronavirus-related restrictions. At the 6-month follow-up, the 0.74% seroprevalence was below the reported seroprevalence of 1.35% in the general German population. The prevalence in healthcare workers in direct patient care compared with that in workers without direct patient contact did not differ significantly. Further follow-up to monitor the seroprevalence in the high-risk healthcare sector during the ongoing global pandemic is essential.

SARS COV-2- IgG antibodies in blood donors in pandemic - A game changer for policy makers.

BACKGROUND: A novel beta coronavirus, named Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), has been identified as the causative pathogen for the present pandemic. The objective of the study was to measure the levels of IgG antibodies targeting the SARS-CoV-2 during the peak period of the COVID-19 pandemic in Odisha State, India to know the magnitude of SARS-CoV-2 exposure, the prevalence of herd immunity in the population, the distribution of IgG-positive cases examined according to ABO blood groups and the number of blood donors with higher neutralizing IgG antibody titre who later on were converted into Plasma Donors donating Convalescent Plasma (CP). METHOD: This observational prospective study was conducted for a duration of three months on 1032 number of Blood donors consisting of 1025 number of males and 07 number of females. The samples of donors were subjected to Electro- chemiluminescence immunoassay (ECLIA) to detect SARS-CoV-2 IgG antibodies. RESULT: Out of 1032 Donors, 370(35.9%) were SARS-COV-2 IgG positive which included 303 donors (29.36%) with neutralizing antibody titre of SARS-COV2 IgG antibodies above 1:80. SARS-COV-2 IgG positive cases consisted of 367(35.8%) male and 3(42.9%) female donors. The number of IgG positive cases were highest in 21-40 years' age group i.e. 323 out of 869(37.2%). In terms of Blood group, 145(42.4%) out of 342 were from B RhD positive group. Out of 22 donors who were positive with COVID 19 in the past with neutralizing IgG antibody titre more than 1:80, 6(27.3%) persons came for voluntary convalescent plasma(CP) donation. CONCLUSION: A high prevalence of SARS-CoV-2 antibodies was detected among blood donors which indicated a high level of exposure to the virus within the population and development of innate immunity against the virus. Policy makers can add the protocol of antibody testing in the screening of blood donors to enhance the number of Plasma Donation cases for the treatment of serious COVID patients.

Hematological and Biochemical Parameters along with IgG Antibody against SARS-CoV-2 in Patients visiting a referral laboratory for recovery check up after COVID-19 infection in Nepal.

BACKGROUND: The laboratory abnormalities for hospitalized patients with the SARS-CoV-2 have been described in various studies. Limited data are available for the recovered patients. This study aimed to evaluate various laboratory findings in the recovered SARS-CoV-2 patients. METHODS: In this cross sectional study, the laboratory findings of various hematological and biochemical parameters along with antibody against SARS-CoV-2 of 150 patients who visited Samyak Diagnostic Pvt. Ltd for recovery check up after SARS-CoV-2 were studied from October 2020 to March 2021. RESULTS: Out of total 150 participants, 84% of SARS-CoV-2 recovered patients, who had mild or moderate illness, reported persistence of milder symptoms. Persistence of high serum inflammatory markers such as CRP, Ferritin and LDH along with abnormal cell count and morphology of leukocyte lineage was present in 45.4% of these patients. Similarly, 98.7 % had SARS-CoV-2 IgG antibody after 37 median days of recovery. CONCLUSIONS: Various laboratory abnormalities may persist after SARS-CoV-2 recovery in addition to the presence of SARS-CoV-2 IgG antibody. Follow up study is needed to determine the period up to which these abnormalities are present and the protection from antibody is conferred.

Humoral immune response in convalescent COVID-19 people with multiple sclerosis treated with high-efficacy disease-modifying therapies: A multicenter, case-control study.

AIM: To determine the influence of high-efficacy disease modifying therapy (DMT) on the development of IgG SARS-CoV-2 antibody response in COVID-19 convalescent people with multiple sclerosis (pwMS). METHODS: Seventy-four pwMS taking high-efficacy DMTs (specifically natalizumab, fingolimod, alemtuzumab, ocrelizumab, cladribine and ublituximab) and diagnosed with COVID-19 and 44 healthy persons (HC) were enrolled. SARS-CoV2 antibodies were tested with Elecsys® Anti-SARSCoV-2 S assay. RESULTS: pwMS taking high-efficacy DMTs had a significantly higher chance of having negative titer of SARS-CoV2 antibodies compared to healthy controls (33 negative pwMS [44.6%] compared to one negative HC [2.3%], p < 0.001). pwMS taking B-cell depleting therapy (ocrelizumab and ublituximab) had a significantly higher chance of having negative titer of SARS-CoV2 antibodies compared to pwMS on all other DMTs (29 negative pwMS on B-cell therapy [64.4%] compared to four negative pwMS on all other DMTs [13.8%], p < 0.001). Out of other DMTs, two (33.3%) pwMS taking fingolimod and two (16.7%) pwMS taking cladribine failed to develop IgG SARS-COV-2 antibodies. B-cell depleting therapy independently predicted negative titer of IgG SARS-CoV-2 antibody (Exp[B] =0.014, 95%CI 0.002-0.110, p < 0.001). CONCLUSIONS: A significant proportion of convalescent COVID-19 pwMS on high-efficacy DMTs will not develop IgG SARS-CoV-2 antibodies. B-cell depleting therapies independently predict negative and low titer of IgG SARS-CoV-2 antibody.

COVID-19 infection in kidney transplant recipients at the epicenter of pandemics.

We investigated the prevalence and clinical outcomes of COVID-19 in recipients of kidney transplants in the Bronx, New York, one of the epicenters of the pandemic. Between March 16 and June 2, 2020, 132 kidney transplant recipients tested positive by SARS-CoV-2 RT-PCR. From May 3 to July 29, 2020, 912 kidney transplant recipients were screened for SARS-CoV-2 IgG antibodies during routine clinic visits, of which 16.6% tested positive. Fifty-five of the 152 patients had previously tested positive by RT-PCR, while the remaining 97 did not have significant symptoms and had not been previously tested by RT-PCR. The prevalence of SARS-CoV-2 infection was 23.4% in the 975 patients tested by either RT-PCR or SARS-CoV-2 IgG. Older patients and patients with higher serum creatinine levels were more likely diagnosed by RT-PCR compared to SARS-CoV-2 IgG. Sixty-nine RT-PCR positive patients were screened for SARS-CoV-2 IgG antibodies at a median of 44 days post-diagnosis (Inter Quartile Range 31-58) and 80% were positive. Overall mortality was 20.5% but significantly higher (37.8%) in the patients who required hospitalization. Twenty-three percent of the hospitalized patients required kidney replacement therapy and 6.3% lost their allografts. In multivariable analysis, older age, receipt of deceased-donor transplantation, lack of influenza vaccination in the previous year and higher serum interleukine-6 levels were associated with mortality. Thus, 42% of patients with a kidney transplant and with COVID-19 were diagnosed on antibody testing without significant clinical symptoms; 80% of patients with positive RT-PCR developed SARS-CoV-2 IgG and mortality was high among patients requiring hospitalization.

Survey of the current status of subclinical coronavirus disease 2019 (COVID-19).

OBJECTIVES: We investigated relationships between subclinical COVID-19 (coronavirus disease 2019) and background factors. METHODS: We determined SARS-CoV-2 antibody (IgG) prevalence in 1603 patients, doctors, and nurses in 65 medical institutions in Kanagawa Prefecture, Japan and investigated their background factors. Antibodies (IgG) against SARS-CoV-2 were analyzed by Immunochromatographic test. RESULTS: The 39 subjects (2.4%) were found to be IgG antibody-positive: 29 in the patient group (2.9%), 10 in the doctor/nurse group (2.0%), and 0 in the control group. After adjustment for age, sex, and the antibody prevalence in the control group, antibody prevalence was 2.7% in the patient group and 2.1% in the doctor/nurse group. There was no significant difference between the antibody-positive subjects and the antibody-negative subjects in any background factors investigated including overseas travel, contact with overseas travelers, presence/absence of infected individuals in the living area, use of trains 5 times a week or more, BCG vaccination, and use of ACE inhibitor and ARB. CONCLUSIONS: Antibody prevalence in the present survey at medical institution is higher than that in Tokyo and in Osaka measured by the government suggesting that subclinical infections are occurring more frequently than expected. No background factor that influenced antibody-positive status due to subclinical infection was identified.

A comparison study of SARS-CoV-2 IgG antibody between male and female COVID-19 patients: A possible reason underlying different outcome between sex.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in China at the end of 2019 has spread throughout the world and caused many thousands of deaths. The previous study reported a higher severe status rate and mortality rate in male patients in China. However, the reason underlying this difference has not been reported. The convalescent plasma containing a high level of SARS-CoV-2 immunoglobulin G (IgG) antibody has been used in clinical therapy and achieved good effects in China. In this study, to compare the differences of the SARS-CoV-2 IgG antibody between male and female patients, a total number of 331 patients confirmed SARS-CoV-2 infection were enrolled. The serum of these patients was collected during hospitalization and detected for the SARS-CoV-2 IgG antibody. Our data showed that the concentration of IgG antibody in mild, general, and recovering patients showed no difference between male and female patients. In severe status, compared with male patients, there were more female patients having a relatively high concentration of serum SARS-CoV-2 IgG antibody. In addition, the generation of IgG antibody in female patients was stronger than male patients in disease early phase. Our study identified a discrepancy in the SARS-CoV-2 IgG antibody level in male and female patients, which may be a potential cause leading to a different outcome of Coronavirus Disease 2019 between sex.