Now-casting the COVID-19 epidemic: The use case of Japan, March 2020

Stephan Gloeckner; Gerard Krause; Michael Hoehle

Public awareness is likely to have a major impact on surveillance sensitivity and also timeliness 18 : The WHO reported the first Corona case in Japan on January 20 th 2020, with four additional cases on January 25 th . During this time, the media had already reported intensively about COVID-19 and therefore public awareness was likely to have been already high. When the first case of SARS-CoV-2 was reported in China on December 1 st 2019, the Japanese National Institute of Diseases established a real time PCR for this type of virus until January 16 th 2020. Furthermore, a telephone hotline for professionals within the health system and public communications were activated. 19 These and other activities may explain why the reporting delay in Japan was fairly short to begin with and diminished further as the outbreaks progressed, compared to COVID-19 outbreaks in other countries. 3 The delays displayed for calendar week nine as part of the imputation might experience a small downwards bias due to cases with long delays not being available at the date of query, however, this is then later taken into account by nowcasting.