SARS-CoV-2 antibody response to symptoms indicative of COVID-19 in a non-infected population in Japan: A cross-sectional study.

This study aimed to investigate the difference in antibody titers indicative of the presence of SARS-CoV-2 between those who had experienced symptoms of Coronavirus Disease of 2019 (COVID-19) infection and those who had never shown symptoms. The study used data from a cross-sectional survey conducted at the National Cancer Center Japan in 434 individuals who reported no previous infection with COVID-19. Participants provided self-reported symptoms beginning from the start of 2020. A generalized linear model was used to compare the mean SARS-CoV-2-specific IgG nucleocapsid protein (N-IgG) titer with estimated confidence intervals (CI) according to the onset of symptoms indicative of COVID-19. We observed a tendency toward an association between higher mean N-IgG titers and having had a high fever within the past eight months (p = 0.053). The mean N-IgG titer was higher for those with a history of symptoms (p = 0.03) and for those with more than three symptoms (p < 0.01) than for those with no symptoms. We demonstrated that the mean N-IgG titer was higher in those who had any symptom and a greater number of symptoms that might indicate COVID-19, relative to those without symptoms, suggesting that transient but contained SARS-CoV-2 infection had occurred.

Real-world Data on the Incidence of Coronavirus Disease (COVID-19) in Patients With Advanced Thoracic Cancer During the Early Phase of the Pandemic in Japan.

BACKGROUND/AIM: The severity and associated mortality of coronavirus disease 2019 (COVID-19) are higher in patients with thoracic cancer than in healthy populations and those with other cancer types. Here, we investigated real-world data on the incidence of COVID-19 and false-negative cases using severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) real-time reverse-transcription polymerase chain reaction (rRT-PCR) testing in patients with thoracic cancer. PATIENTS AND METHODS: We retrospectively reviewed patients with advanced thoracic cancer at the National Cancer Center Hospital between March 2020-May 2021. Blood samples were collected and evaluated for IgM and IgG antibodies specific for nucleocapsid (N) and spike (S) protein SARS-CoV-2 before and after rRT-PCR testing. False-negative cases were assessed based on anti-SARS-CoV-2 antibody levels before and after rRT-PCR testing. RESULTS: A total of 2,107 patients with thoracic cancer were identified between March 2020 and May 2021, 7 (0.3%) of whom developed COVID-19. Among the 218 patients who underwent at least one rRT-PCR test because of suspected COVID-19 symptoms or as a screening test at our institute, the most common diagnosis was non-COVID-19 pneumonia (34.4%), followed by tumor fever (30.7%). Furthermore, of the 218 patients, 120 paired serum samples before and after rRT-PCR testing were available. Seroconversion was identified in all three patients with positive SARS-CoV-2 rRT-PCR results but was only observed in 1 out of the 117 patients who tested negative; the rate of false-negative cases was low (0.9%). CONCLUSION: COVID-19 incidence among patients with advanced thoracic cancer was low during the early phase of the pandemic in Japan.

Difference in SARS-CoV-2 Antibody Status Between Patients With Cancer and Health Care Workers During the COVID-19 Pandemic in Japan.

Importance: Patients with cancer and health care workers (HCWs) are at high risk of SARS-CoV-2 infection. Assessing the antibody status of patients with cancer and HCWs can help understand the spread of COVID-19 in cancer care. Objective: To evaluate serum SARS-CoV-2 antibody status in patients with cancer and HCWs during the COVID-19 pandemic in Japan. Design, Setting, and Participants: Participants were enrolled for this prospective cross-sectional study between August 3 and October 30, 2020, from 2 comprehensive cancer centers in the epidemic area around Tokyo, Japan. Patients with cancer aged 16 years or older and employees were enrolled. Participants with suspected COVID-19 infection at the time of enrollment were excluded. Exposures: Cancer of any type and cancer treatment, including chemotherapy, surgery, immune checkpoint inhibitors, radiotherapy, and targeted molecular therapy. Main Outcomes and Measures: Seroprevalence and antibody levels in patients with cancer and HCWs. Seropositivity was defined as positivity to nucleocapsid IgG (N-IgG) and/or spike IgG (S-IgG). Serum levels of SARS-CoV-2 IgM and IgG antibodies against the nucleocapsid and spike proteins were measured by chemiluminescent enzyme immunoassay. Results: A total of 500 patients with cancer (median age, 62.5 years [range, 21-88 years]; 265 men [55.4%]) and 1190 HCWs (median age, 40 years [range, 20-70 years]; 382 men [25.4%]) were enrolled. In patients with cancer, 489 (97.8%) had solid tumors, and 355 (71.0%) had received anticancer treatment within 1 month. Among HCWs, 385 (32.3%) were nurses or assistant nurses, 266 (22.4%) were administrative officers, 197 (16.6%) were researchers, 179 (15.0%) were physicians, 113 (9.5%) were technicians, and 50 (4.2%) were pharmacists. The seroprevalence was 1.0% (95% CI, 0.33%-2.32%) in patients and 0.67% (95% CI, 0.29%-1.32%) in HCWs (P = .48). However, the N-IgG and S-IgG antibody levels were significantly lower in patients than in HCWs (N-IgG: ß, -0.38; 95% CI, -0.55 to -0.21; P < .001; and S-IgG: ß, -0.39; 95% CI, -0.54 to -0.23; P < .001). Additionally, among patients, N-IgG levels were significantly lower in those who received chemotherapy than in those who did not (median N-IgG levels, 0.1 [interquartile range (IQR), 0-0.3] vs 0.1 [IQR, 0-0.4], P = .04). In contrast, N-IgG and S-IgG levels were significantly higher in patients who received immune checkpoint inhibitors than in those who did not (median N-IgG levels: 0.2 [IQR, 0.1-0.5] vs 0.1 [IQR, 0-0.3], P = .02; S-IgG levels: 0.15 [IQR, 0-0.3] vs 0.1[IQR, 0-0.2], P = .02). Conclusions and Relevance: In this cross-sectional study of Japanese patients with cancer and HCWs, the seroprevalence of SARS-CoV-2 antibodies did not differ between the 2 groups; however, findings suggest that comorbid cancer and treatment with systemic therapy, including chemotherapy and immune checkpoint inhibitors, may influence the immune response to SARS-CoV-2.

A novel highly quantitative and reproducible assay for the detection of anti-SARS-CoV-2 IgG and IgM antibodies.

The quantitative range and reproducibility of current serological tests for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are not optimized. Herein, we developed a diagnostic test that detects SARS-CoV-2 IgG and IgM with high quantitativeness and reproducibility and low interference. The system was based on the high-sensitivity chemiluminescence enzyme immunoassay (HISCL) platform and detects IgG and IgM specific to SARS-CoV-2 spike and nucleocapsid proteins. Quantification accuracy and reproducibility were evaluated using serially diluted samples from 60 SARS-CoV-2-infected patients. Assay performance was evaluated using serum samples from the SARS-CoV-2-infected patients and 500 SARS-CoV-2-negative serum samples collected before the emergence of SARS-CoV-2. The system showed high quantification accuracy (range, 102), high reproducibility (within 5%), and no cross-reaction between SARS1- and MERS-S proteins. Detection accuracy was 98.3% and 93.3% for IgG and IgM against spike proteins and 100% and 71.7% for IgG and IgM against nucleocapsid proteins, respectively. Mean antibody levels were > 10 times that in negative samples upon admission and > 100 times that at convalescent periods. Clinical severity upon admission was not correlated with IgG or IgM levels. This highly quantitative, reproducible assay system with high clinical performance may help analyze temporal serological/immunological profiles of SARS-CoV-2 infection and SARS-CoV-2 vaccine effectiveness.