Persistence of robust humoral immune response in COVID-19 convalescent individuals over 12 months after infection

SARS-CoV-2 infection elicits varying degrees of protective immunity conferred by neutralizing antibodies (nAbs). Here we report the persistence of nAb responses over 12 months after infection despite its decreasing trend noticed from 6 months. The study included sera from 358 individuals who had been infected with SARS-CoV-2 between January and May 2020. Samples were collected at 6 and 12 months after onset. The titers of IgG to the viral nucleocapsid protein (NP) and receptor-binding domain of the spike protein (RBD) were measured by CLEIA. The nAb titer was determined using lentivirus-based pseudovirus or authentic virus. Antibody titers of NP-IgG, RBD-IgG, and nAbs were higher in severe and moderate cases than in mild cases at 12 months after onset. While the nAb levels were likely to confer adequate protection against wild-type viral infection, the neutralization activity to recently circulating variants in some of the mild cases ([~]30%) was undermined, implying the susceptibility of reinfection to the variants of concerns (VOCs). COVID-19 convalescent individuals have robust humoral immunity even at 12 months after infection albeit that the medical history and background of patients could affect the function and dynamics of antibody response to the VOCs.

Mite avoidance decreased mite-specific IgE levels and ameliorated asthma symptoms in subjects who lived in temporary housing after natural disasters.

BACKGROUND: We previously reported an increased prevalence of asthma among patients who had lived in temporary housing after the 2011 Great East Japan Earthquake. We investigated the prognosis of asthma in former residents of temporary housing after allergen avoidance. METHODS: Asthma was diagnosed in adults ≥ 15 years from 2014 to 2019 who had lived in temporary housing in Ishinomaki City for at least 1 year. The disease prognosis after the intervention of allergen avoidance in cases that were followed for more than 3 years during the 6-year study period was analyzed. We measured the Dermatophagoides farinae -specific immunoglobulin E (IgE) levels in serum, and the amount of Dermatophagoides group 1 (Der 1) antigen on their futons or mattresses. We instructed residents in an allergen avoidance strategy that included 32 tasks, including using microfiber bedding covers. RESULTS: Of the 202 examinees who were followed for at least 3 years during the 6-year study period, 72(35.6%) were asthmatic during at least one examination. Of these 72 asthmatics, 55(76.4%) developed the disease after the earthquake, and more than half of the cases that we diagnosed at the examination were mild intermittent asthma. After the allergen-avoidance intervention, both the Der 1 level on the futons or mattresses of residents who were diagnosed with asthma but who were nonasthmatic at the final screening and their serum Der f-specific IgE levels significantly decreased (P < 0.01) at the final examination. CONCLUSION: Antigen avoidance ameliorated mild asthma that was prevalent among residents of temporary housing after the earthquake.

Development of an automated chemiluminescence assay system for quantitative measurement of multiple anti-SARS-CoV-2 antibodies

ObjectiveSerological tests for COVID-19 have been instrumental in studying the epidemiology of the disease. However, the performance of the currently available tests is plagued by the problem of variability. We have developed a high-throughput serological test capable of simultaneously detecting total immunoglobulins (Ig) and immunoglobulin G (IgG) against two of the most immunologically relevant SARS-CoV-2 antigens, nucleocapsid protein (NP) and spike protein (SP) and report its performance in detecting COVID-19 in clinical samples. MethodsWe designed and prepared reagents for measuring NP-IgG, NP-Total Ig, SP-IgG, and SP-Total Ig (using N-terminally truncated NP ({Delta}N-NP) or receptor-binding domain (RBD) antigen) on the advanced chemiluminescence enzyme immunoassay system TOSOH AIA-CL. After determining the basal thresholds based on 17 sera obtained from confirmed COVID-19 patients and 600 negative sera. Subsequently, the clinical validity of the assay was evaluated using independent 202 positive samples and 1,000 negative samples from healthy donors. ResultsAll of the four test parameters showed 100% specificity individually (1,000/1,000; 95%CI, 99.63-100). The sensitivity of the assay increased proportionally to the elapsed time from symptoms onset, and all the tests achieved 100% sensitivity (153/153; 95%CI, 97.63-100) after 13 days from symptoms onset. NP-Total Ig was the earliest to attain maximal sensitivity among the other antibodies tested. ConclusionOur newly developed serological testing exhibited 100% sensitivity and specificity after 13 days from symptoms onset. Hence, it could be used as a reliable method for accurate detection of COVID-19 patients and to evaluate seroprevalence and possibly for surrogate assessment of herd immunity.

Current national policies for infant universal bacille CalmetteGuérin vaccination were associated with lower mortality from coronavirus disease 2019

An exciting debate has emerged whether bacille Calmette-Guérin (BCG) vaccination is effective for the coronavirus disease 2019 (COVID-19) pandemic. Some advocated that BCGvaccinated people are less suffered from the virus because BCG vaccination is recommendedin COVID-19 high burden countries. However, the others objected because this seemingly attractive relationship is explainable with confounding factors. In a multiple regression with 171 countries adjusting socioeconomical and climatic covariates, countries with current universal pediatric BCG policy were associated with 30-fold (95% confidence interval, 17–52) decrease of COVID-19 mortality per population compared to countries without the policy.

Current national policies for infant universal bacille CalmetteGuérin vaccination were associated with lower mortality from coronavirus disease 2019

An exciting debate has emerged whether bacille Calmette-Guérin (BCG) vaccination is effective for the coronavirus disease 2019 (COVID-19) pandemic. Some advocated that BCGvaccinated people are less suffered from the virus because BCG vaccination is recommendedin COVID-19 high burden countries. However, the others objected because this seemingly attractive relationship is explainable with confounding factors. In a multiple regression with 171 countries adjusting socioeconomical and climatic covariates, countries with current universal pediatric BCG policy were associated with 30-fold (95% confidence interval, 17–52) decrease of COVID-19 mortality per population compared to countries without the policy.