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An immunochromatographic assay that has been developed for the detection of antibodies in blood-derived specimens is raising expectations for the diagnosis of COVID-19, the disease caused by the novel corona virus SARS-CoV-2 Herein, we studied the interval from symptom onset to the first positive results of the immunochromatographic assay for IgM and IgG antibodies in 52 patients with a definitive diagnosis of COVID-19 (disease confirmed by the PCR test) Furthermore, we also examined the test results in 35 patients with acute fever and pneumonia who were negative by the PCR test All patients with a definitive diagnosis of COVID-19 were confirmed to be antibody-positive The mean time from symptom onset to the first positive result for IgM antibody was 11 9 days (minimum: 5, median: 11), and that to the first positive result for IgG antibody was 11 2 days (minimum: 5, median: 11) No significant difference was observed between the tests for IgM and IgG antibodies in terms of the percentage of positive patients or the interval from first onset to the first positive test result There were no patients in whom the test for IgM became positive before the test for IgG In 45 patients (87%), both IgM and IgG became positive at the same time, and in the remaining 7 patients (13%), the test for IgG became positive before that for IgM Of 35 patients with acute fever and pneumonia who tested negative by the PCR test for SARS-CoV-2, not COVID-19, 6 (17 1%) and 1 (2 8%) showed positive results for anti-IgG antibody and anti-IgM antibody, respectively Our study results were quite limited, and we do not intend to conduct a performance evaluation of the reagents contained in the detection kits Assessment of antibody detection reagents for the immunochromatographic assay, which can be used as a complementary test to PCR, is expected in the future;however, the findings should be reviewed carefully

Antibody levels decrease substantially at 6 months after the BNT162b2 vaccine. The factors influencing titer of antibodies against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) among healthcare workers for coronavirus disease 2019 (COVID-19) is unclear.We conducted a 6-month longitudinal prospective study in Japanese healthcare workers in a tertiary care hospital for COVID-19. Participants in the study were tested for the presence of anti-spike protein (SP) IgG antibodies before and at 1 and 6 months after the last vaccination dose.Among 1076 healthcare workers, 794 received the vaccine, and 469 entered the study. Five were infected with SARS-CoV-2 (none among COVID-19 section workers) by the end of the study and 451 participants were finally analyzed (mean age, 42.5 years; 27.3 % male; 18.8 % COVID-19 section workers). Median SP IgG index values were 0.0, 44.4, and 5.5 before and at 1 and 6 months after the last dose, respectively. Regression analysis revealed a negative correlation of SP IgG antibody levels with age (P 0.0001), and higher levels in COVID-19 section workers (P = 0.0185) and in females (P = 0.0201).In healthcare workers at a COVID-19 hospital, IgG antibody titer was substantially lower at 6 months after receipt of the last dose of the BNT162b2 vaccine compared with that 1 month after the last dose, but was better preserved among younger participants, COVID-19 section workers and females.

We experienced a 72-year-old man who developed laboratory-confirmed human coronavirus HKU1 pneumonia. PCR testing for SARS-CoV-2 from a nasopharyngeal specimen was negative twice, and rapid immunochromatographic antibody test (RIAT) using a commercially available kit for IgM and IgG against SARS-CoV-2 showed him turning positive for IgG against SARS-CoV-2. We then performed RIAT in stored serum samples from other patients who suffered laboratory-confirmed human common cold coronaviruses (n = 6) and viruses other than coronavirus (influenza virus, n = 3; rhinovirus, n = 3; metapneumovirus, n = 1; adenovirus, n = 1) admitted until January 2019. Including the present case, four of 7 (57%) showed false-positive RIAT results due to human common cold coronaviruses infection. Two of the 4 patients showed initial negative to subsequent positive RIAT results, indicating seroconversion. RIAT was positive for IgG and IgM in viruses other than coronavirus in 2 (25.0%) and 1 (12.5%) patient. Because of high incidence of false positive RIAT results, cross antigenicity between human common cold coronaviruses and SARS-CoV-2 can be considered. Results of RIAT should be interpreted in light of epidemics of human common cold coronaviruses infection. Prevalence of past SARS-CoV-2 infection may be overestimated due to high incidence of false-positive RIAT results.

This paper proposes a Virtual Reality application for playing with blocks. Players can create their own decorative castle in a virtual world, by only stacking simple physical blocks in the system.We designed a tangible interface such that a player can experience seamless interaction between the real world and a virtual world when playing with toy blocks. The system gives players a revolutionarily enjoyable experience where blocks are stack in the real world and blocks stacked in the real world are dynamically transformed into a castle in a virtual world. The system enables players to create a realistic castle that reflects the shape of the blocks. Moreover, the system smoothly connects the physical-world to the virtual-world by means of a tangible interface and real-time computer graphics. The system was exhibited at "Ishikawa Dream Festival" for two days. The evaluation of the system was done survey by a carried out using questionnaire at the event. The evaluation found that the system was easy to play and most of the players enjoyed the system.