The therapeutic use of messenger RNA (mRNA) has fueled great hope to combat a wide
range of incurable diseases. Recent rapid advances in biotechnology and molecular …

To date, the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory
syndrome coronavirus 2 (SARS-CoV-2) has determined 399,600,607 cases and 5,757,562 …

Objectives To characterize the clinical severity of covid-19 associated with the alpha, delta,
and omicron SARS-CoV-2 variants among adults admitted to hospital and to compare the …

Immunological memory is the basis of protective immunity provided by vaccines and
previous infections. Immunological memory can develop from multiple branches of the …

Background Vaccine effectiveness against COVID-19 beyond 6 months remains
incompletely understood. We aimed to investigate the effectiveness of COVID-19 …

Breakthrough infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-
2) in fully vaccinated individuals are receiving intense scrutiny because of their importance …

Importance The incidence of SARS-CoV-2 infection, including among individuals who have
received 2 doses of COVID-19 vaccine, increased substantially following the emergence of …

Background Vaccines are critical cost-effective tools to control the coronavirus disease 2019
(COVID-19) pandemic. However, the emergence of variants of the severe acute respiratory …

Background The duration of protection afforded by coronavirus disease 2019 (Covid-19)
vaccines in the United States is unclear. Whether the increase in postvaccination infections …

We report severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine
effectiveness against infection (VE-I) and death (VE-D) by vaccine type in 780,225 veterans …