Effectiveness of Second mRNA COVID-19 Booster Vaccine in Immunocompromised Persons and Long-Term Care Facility Residents

Abstract

B ooster doses of mRNA vaccines have been shown to reduce the risk for severe SARS-CoV-2 infection (1,2); however, protection wanes a few months after vaccination, particularly in high-risk populations (3,4). A second booster dose at least 4 months after the first booster dose of mRNA vaccine was found to increase immunity against COVID-19; thus, the second booster has been introduced in some countries (5).Other studies have postulated that additional doses of the COVID-19 vaccine can enhance cellular and humoral immunity against the Omicron variant (6,7), and some studies have already shown the effectiveness of second boosters in preventing COVID-19 infections (5,8,9). However, population-based studies are needed to assess the effect of the second booster vaccine on COVID-19 in high-risk groups.During February-April 2022, a second booster of mRNA vaccine was recommended for immunocompromised persons and long-term care facility (LTCF) residents in South Korea. We used a nationwide population registry to estimate the effect of a second booster dose of mRNA vaccine on risk for laboratoryconfirmed SARS-CoV-2 infection, critical infection, and death in immunocompromised persons and LTCF residents. MethodsIn South Korea, COVID-19 is a notifiable disease; all laboratory-confirmed cases are reported to the Korea Disease Control and Prevention Agency (KDCA). COVID-19 vaccination records, including the date of vaccination and type of vaccine, are also collected and maintained by the KDCA. All suspected COVID-19 case-patients (anyone with a history of close contact with a COVID-19 patient) or SARS-CoV-2-infected persons, regardless of symptoms, were mandated to be tested by PCR or rapid antigen test during the observation period. By linking the vaccination registry and the surveillance database, we created a largelinked database through unique resident registration number. The observation period was February-May 2022, when 100% of SARS-CoV-2 detected in South Korea was identified as an Omicron variant (BA1.1, BA2, and BA2.3 subvariants) (10).

Second monovalent SARS-CoV-2 mRNA booster restores Omicron-specific neutralizing activity in both nursing home residents and health care workers

“…There are at least four related studies on clinical effectiveness of 4th dose in NH population [16] , [17] , [18] , [19] demonstrating protection but none have immunogenicity data in NH residents and HCWs. Our study offers biologic evidence that these findings arise at least in part from an immune response in a population that suffers from immunosenescence and disease that vaccines help overcome.…”

Risk Factors Related to COVID-19 Reinfection and Fatality During the Omicron (BA.1/BA.2) Period in Korea

“…In our study, the 4-doses vaccination of reinfection in the elderly over 75 years of age was 5.7%, which was higher than other age groups, and long-term care facility residents was 9.3%, which was higher than other health status groups ( Supplementary Table 1 ). In a study on the prevention effect of the 4-doses vaccination, the death prevention effect of the 4th vaccination was 62% (34–79%) compared to the 3-doses vaccination for immunocompromised patients and long-term care facility residents in Korea, 15 and 31% (14–45%) of long-term care facility residents in Sweden. 16 The effect of preventing death compared to the 3-doses vaccination of the population in their 60s or older who received the 4-doses vaccination was 76% (48–91%).…”

Effectiveness of A Fourth Dose of COVID-19 mRNA Vaccine in the Elderly Population During the Omicron BA.2 and BA.5 Circulation: A Nationwide Cohort Study in Korea (K-COVE)

“…The large, linked database was formed to create a national cohort to evaluate vaccine effectiveness in Korea (Korea COVID-19 Vaccine Effectiveness [K-COVE]). A detailed summary of the data set was described previously [ 3 ]. The input of the K-COVE dataset was made upon epidemiological investigation in individual cases reported as SARS-CoV-2.…”