Molecular Epidemiology of SARS-CoV-2 Genome Sentinel Surveillance in Commercial COVID-19 Testing Sites Targeting Asymptomatic Individuals During Japan’s Seventh Epidemic Wave (preprint)

Eight peaks of coronavirus disease 2019 (COVID-19) outbreak occurred in Japan, each associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern. The National Epidemiological Surveillance of Infectious Diseases (NESID) analyzed viral genome sequences from symptomatic patients and submitted the results to GISAID. Meanwhile, commercial testing services occasionally sequence samples from asymptomatic individuals. We compared a total of 1,248 SARS-CoV-2 full-genome sequences obtained from the SB Coronavirus Inspection Center Corp. (SBCVIC) during Japan’s seventh wave, which was dominated by Omicron variants, with 1,764 sequences obtained in Japan from GISAID during the same period using chronological phylogenies and molecular transmission networks. The number of SBCVIC sequences was consistent with the number of cases reported by NESID. The SBCVIC detected a shift in the PANGO lineage from BA.2 to BA.5 earlier than that of GISAID. BA.2 lineages from the SBCVIC were distributed at different locations in the transmission network dominated by GISAID entries, whereas BA.5 lineages from SBCVIC and GISAID often formed distinct subclusters. Test-based sentinel surveillance of asymptomatic individuals may be a more manageable approach compared to notifiable disease surveillance; however, it may not necessarily capture all infection populations throughout Japan.

COVID-19 and the Employment Gender Gap (preprint)

This paper examines how the COVID-19 pandemic affected female employment in Japan. Our estimates indicate that the employment rate of married women with children decreased by 4 percentage points, while that of those without children decreased by only 1 percentage point, implying that increased childcare responsibilities caused a sharp decline in mothers’ employment. Further, mothers who left or lost their jobs appear to have dropped out of the labor force even several months after school reopening. In contrast to women, the employment rate of married men with children was not affected, which hindered progress in narrowing the employment gender gap.