2022 Volume 25 Issue 2 Pages 126-132
SARS-CoV-2 continues to spread; thus, information about variants, which may affect the virus’ properties, has become increasingly important for the management of COVID-19. The first SARS-CoV-2 variant in Japan was recognized in December 2020 and the strains detected in the country were replaced by the δ variant carrying the L452R mutation before October 2021. As a newly emergent variant can rapidly propagate, national authorities and local hospitals have to be involved in monitoring and assessing changes to the virus. In this study, we randomly selected a total of 116 SARS-CoV-2 RT-LAMP-positive nasopharyngeal swabs obtained in our hospital between July 2020 and September 2021 and investigated them for the presence of variant strains using RT-pPCR primer/probe sets for detection of N501Y, E484K, and L452R mutations. Of 37 samples obtained during the 3rd wave of the COVID-19 pandemic, 34 (91.9%) were negative for the mutations. On the other hand, of 20 samples obtained during the 4th wave, 11 (55.0%) had N501Y and five (25.0%) had E484K mutations, and of 59 samples obtained during the 5th wave, 28 (47.5%) had N501Y and 29 (49.2%) had L452 mutations. This study indicates that evolution of SARS-CoV-2 observed in a local hospital occurred in a similar pattern to global trends of the spread of the variant strains.
