Each prefecture was responsible for using its civil sign up data to randomly select participants
Each prefecture was responsible for using its civil sign up data to randomly select participants. severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by May 31, 2020, indicating a national cumulative incidence of 0.013% ( em 1 /em , em 2 /em ) (Appendix Figure). To establish a surveillance method in low PQ 401 prevalence settings, we assessed the seroprevalence PQ 401 of SARS-CoV-2 illness in Japan in early June 2020. The Study By October 2020, no standard antibody test or standardized method for estimating the seroprevalence of SARS-CoV-2 illness had been founded. We used 2 serologic checks, a neutralizing antibody assay, and participant questionnaires to estimate the seroprevalence of SARS-CoV-2 illness in Japan. We carried out a seroprevalence survey of SARS-CoV-2 illness in 3 prefectures of Japan during June 1C7, 2020. We selected 2 prefectures with a relatively high cumulative incidence of confirmed COVID-19 cases as of May 31, 2020: Tokyo, with an incidence of 0.039% (5,408 cases/13.9 million population) and Osaka, with an incidence of 0.020% (1,785 cases/8.8 million populace). To better estimate the range of seroprevalence of SARS-CoV-2 illness in Japan, we also chose a prefecture with a relatively low cumulative incidence, Miyagi, with an incidence of 0.004% (88 cases/2.3 million populace). Each prefecture was responsible for using its civil sign up data to randomly select participants. The Tokyo metropolitan authorities used random sampling PQ 401 stratified by age and sex in 3 towns having a cumulative incidence resembling the average of the Tokyo metropolitan area. The Miyagi prefectural authorities used its residence registry to conduct random sampling with stratification for age, sex, and geographic region. The Osaka prefecture used age-adjusted random sampling to select resident users of an existing smartphone software on general health (Number). Open in a separate windows Number Flowchart of participants and results of SARS-CoV-2Cspecific antibody survey, Japan, 2020. Dagger (?) indicates sum of values designated with asterisks (*). SARS-CoV-2, severe acute respiratory syndrome coronavirus 2. Eligible participants were persons 20 years of age living in Japan. The Tokyo and Miyagi prefectures excluded normally qualified participants with temps 37.5C. All participants provided written educated consent. The study was authorized by the internal review boards of the Research Institute of Tuberculosis (authorization no. RIT/IRB 2020C04, 2020C05) and the National Institute of Infectious Diseases (authorization no. 1140). First, we asked participants to total a questionnaire (Appendix Table 1). Trained healthcare workers collected blood samples from the participants. After centrifuging the samples, the workers collected serum and tested the samples with 2 commercially available antibody checks to detect the SARS-CoV-2 nucleocapsid antigen: a chemiluminescent microparticle immunoassay with published specificity results of 99.6%C99.9% at a cutoff index of 1 1.4 (SARS-CoV-2 IgG assay; Abbott, https://www.abbott.com) ( em 3 /em PQ 401 , em 4 /em ) and an electrochemiluminescence immunoassay for the qualitative detection of antibodies with 99.8% specificity and 100% (manufacturer identified) sensitivity (Elecsys Anti-SARS-CoV-2 immunoassay; F. Hoffmann-La Roche Ltd, https://www.roche.com) ( em 5 /em ). Samples that were positive or borderline bad by 1 assay (research range 1.20C1.39 for the Abbott test and 0.70C0.99 titer for the Roche test) were sent to Japans National Institute of Infectious Diseases (Tokyo) for any neutralizing antibody assay with VeroE6/TMPRSS2 cells (JCRB Cell Lender accession no. JCRB1819) ( em 6 /em ). For the neutralizing antibody assay, we used an in vitro cytopathic effect assay, which is definitely more accurate than serologic checks and therefore well-suited for confirmation of results; however, only a few laboratories in Japan have the resources to conduct the assay. We compared the 2 2 organizations using the 2 2 test, considering ideals with p 0.05 to be significant. We compared ordinal scales by using the Mann-Whitney U test. We used Excel (Microsoft, https://www.microsoft.com) to conduct statistical analyses. In total, 13,547 individuals were invited to participate in the study; 7,950 (58.7%) accepted and gave informed consent. Of the participants, 3,660 (46.0%) were men and 4,290 (54.0%) were ladies. Persons 20C29 years of age (877 of 1 1,875 invitees) or 80C99 years of age (337 of 1 1,102 invitees) experienced the lowest response rate (Appendix Table 2). Participants from Osaka were more likely to have a history of fever within the past 4 weeks (2.7%) than participants from Tokyo (2.2%) and Miyagi (1.2%) (Appendix Table 1). Of the 7,950 serum samples, 8 tested positive by both checks and 30 samples tested positive by only 1 1 test (15 by Abbott and 15 by Roche) (Table). All 8 specimens that were positive for both commercial checks also tested positive in the neutralizing antibody assay. No additional specimens, including those that tested positive or borderline bad in 1 assay, tested positive from the neutralizing antibody assay. Table Serologic results TNFSF13 of 2 antibody checks for severe acute respiratory syndrome coronavirus 2, Japan, June 2020* thead th rowspan=”2″ valign=”bottom” colspan=”2″ align=”remaining” scope=”colgroup” Characteristic hr / /th th rowspan=”2″ valign=”bottom” align=”center”.