Effectiveness of Second mRNA COVID-19 Booster Vaccine in Immunocompromised Persons and Long-Term Care Facility Residents
Yoo-Yeon Kim, Young June Choe, Jia Kim, Ryu Kyung Kim, Eun Jung Jang, Seon Kyeong Park, Dosang Lim, Seonju Yi, Sangwon Lee, Geun‐Yong Kwon, Jee Yeon Shin, Sang‐Yoon Choi, Mi Jin Jeong, Young-Joon Park
Abstract
We used a nationwide population registry in South Korea to estimate the effect of a second booster dose of mRNA COVID-19 vaccine on the risk for laboratory-confirmed SARS-CoV-2 infection, critical infection, and death in immunocompromised persons and long-term care facility (LTCF) residents. During February 16-May 7, 2022, among 972,449 eligible persons, 736,439 (75.7%) received a first booster and 236,010 (24.3%) persons received a second booster. Compared with the first booster group, at 30-53 days, the second booster recipients had vaccine effectiveness (VE) against all infections of 22.28% (95% CI 19.35%-25.11%), VE against critical infection of 56.95% (95% CI 29.99%-73.53%), and VE against death of 62.96% (95% CI 34.18%-79.15%). Our findings provide real-world evidence that a second booster dose of mRNA vaccine substantially increases protection against critical infection and death in these high-risk population groups.