Impact of national Covid-19 vaccination Campaign, South Korea

Yi, Seonju; Choe, Young June; Lim, Dosang; Lee, Hye Roen; Kim, Jia; Kim, Yoo-Yeon; Kim, Ryu Kyung; Jang, Eun Jung; Lee, Sang‐Won; Park, Eun-Joo; Kim, Seung-Jin; Park, Young-Joon

doi:10.1016/j.vaccine.2022.05.002

Cited by 27 publications

(20 citation statements)

References 18 publications

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“…T he COVID-19 pandemic has severely affected skilled nursing facility (SNF) residents and healthcare personnel (HCP) (1,2). HCP are at high risk for SARS-CoV-2 exposure during patient care (3,4), and were among the earliest groups prioritized for COV-ID-19 vaccination starting in mid-December 2020 (5). Through June 2021, all SNF HCP in California, regardless of vaccination status or symptoms, were required to undergo at least weekly screening testing for SARS-CoV-2 infection (6).…”

Section: About the Authorsmentioning

confidence: 99%

“…We retrieved epidemiologic data, merged with the national immunization registry of household contacts of persons infected with SARS-CoV-2, to describe the difference in secondary attack rates (SARs) by vaccination status. Details of the surveillance system, vaccination program, and dataset employed in this study are described in a previous study (3). Persons who had household contact with laboratory-confirmed SARS-CoV-2-positive patients underwent mandatory PCR testing, regardless of the presence of symptoms, and were put under active surveillance for 10 days.…”

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confidence: 99%

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Household Secondary Attack Rates of SARS-CoV-2 Omicron Variant, South Korea, February 2022

Lim¹,

Choe²,

Kim³

et al. 2022

Emerg. Infect. Dis.

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Section: About the Authorsmentioning

confidence: 99%

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confidence: 99%

Household Secondary Attack Rates of SARS-CoV-2 Omicron Variant, South Korea, February 2022

Lim¹,

Choe²,

Kim³

et al. 2022

Emerg. Infect. Dis.

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“…During week 1 of 2022, the percentages of adults presumed to have no immunity were 11.8% (18–59 years), 6.6% (60–74 years), and 10.0% (≥75 years), while these percentages were higher in children, at 91.6% (0–4 years), 98.2% (5–11 years), and 65.0% (12–17 years). Vaccination in the adult population started in February 2021, whereas the vaccines have been offered to the age groups of 12 to 17 years and 5 to 11 years since October 2021 and March 2022, respectively, which partly explains the population susceptibility in children [ 5 ]. The disproportionate distribution of COVID-19 vaccination between age groups likely resulted in the observed discrepancy in population immunity, as demonstrated in a previous study [ 7 ].…”

Section: Discussionmentioning

confidence: 99%

“…In South Korea, as of May 2022, more than 17 million COVID-19 confirmed cases had been reported (33% of total population), while 85% of its population had received at least 2 doses of COVID-19 vaccines [ 4 ]. We used the national COVID-19 infection and vaccination registry from South Korea, as described in a previous study, to define individuals with a previous history of COVID-19 infection, vaccination, or both, as persons with presumed immunity [ 5 ]. We excluded 141,690 persons who had more than 2 reports of infection, errors in vaccination records, and those who received vaccines outside of the country.…”

Section: Methodsmentioning

confidence: 99%

Presumed population immunity to SARS-CoV-2 in South Korea, April 2022

Jang¹,

Choe²,

Choe³

et al. 2022

PHRP

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Objectives: We estimated the overall and age-specific percentages of the Korean population with presumed immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as of April 2022 using the national registry. Methods: We used the national coronavirus disease 2019 (COVID-19) infection and vaccination registry from South Korea, as described to define individuals with a previous history of COVID-19 infection, vaccination, or both, as persons with presumed immunity.Results: Of a total of 53,304,627 observed persons, 24.4% had vaccination and infection, 58.1% had vaccination and no infection, 7.6% had infection and vaccination, and 9.9% had no immunity,. The SARS-CoV-2 Omicron variant emerged at a time when the presumed population immunity ranged from 80% to 85%; however, nearly half of the children were presumed to have no immunity.Conclusion: We report a gap in population immunity, with lower presumed protection in children than in adults. The approach presented in this work can provide valuable informed tools to assist vaccine policy-making at a national level.

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“…pfizer.com) and mRNA-1273 (Moderna, https:// www.moderna.com); and 1 protein subunit vaccine (Novavax, https://www.novavax.com) were introduced. Since February 2021, all immunocompromised persons and LTCF residents have been prioritized to receive COVID-19 vaccines (11). The first booster dose of Pfizer-BioNTech or Moderna vaccine has been offered since October 2021, and the second booster dose of Pfizer-BioNTech or Moderna vaccine has been offered since February 2022.…”

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confidence: 99%

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

Kim¹,

Choe²,

Kim³

et al. 2022

Emerg. Infect. Dis.

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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).

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Impact of national Covid-19 vaccination Campaign, South Korea

Cited by 27 publications

References 18 publications

Household Secondary Attack Rates of SARS-CoV-2 Omicron Variant, South Korea, February 2022

Household Secondary Attack Rates of SARS-CoV-2 Omicron Variant, South Korea, February 2022

Presumed population immunity to SARS-CoV-2 in South Korea, April 2022

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

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