The objective of our study was to determine the joint protective effect of a previous SARS-
CoV-2 infection and vaccination on the risk of a new infection and hospitalization. Two case …

Background The impact of vaccination prior to infection on postacute sequelae of
coronavirus disease 2019 (COVID-19, PASC), also known as long COVID, remains unclear …

Immunization against COVID-19 is needed in patients with immune-mediated inflammatory
diseases (IMIDs). However, data on long-term immunity kinetics remain scarce. This study …

Objectives To compare the long-term cumulative risk of SARS-CoV-2 infection associated
with natural and vaccine-induced immunity. Methods Retrospective population-based cohort …

Introduction Immunocompromised individuals have been shown to mount a reduced
response to vaccination, resulting in reduced vaccine effectiveness in this cohort. Therefore …

Pandemic preparedness is an important issue in relation to future pandemics. The two
studies described here aimed to identify factors predicting the presence and severity of …

Emerging infectious diseases like COVID-19 will remain a concern for the foreseeable
future, and determinants of vaccination and other mitigation behaviors are therefore critical …

Objective There is a probability that vaccination may lead to reduction in the severity and
complications associated with COVID-19 infection among hospitalized patients. This study …

Background: Many previous studies have reported COVID-19 vaccine effectiveness, but
there are few studies in Japan. This community-based, retrospective observational study …

The coronavirus (COVID-19) vaccine is key to reducing the probability of contracting COVID-
19. The vaccine is generally known to prevent severe illness, death, and hospitalization as a …