Dataset Information

Impact of national Covid-19 vaccination Campaign, South Korea.

ABSTRACT:

Background

We evaluate the overall effectiveness of the nationwide vaccination campaign using ChAdOx1 nCoV-19, BNT162b2, mRNA-1273, and Ad26.COV2.S vaccines in preventing Covid-19 in South Korea.

Methods

The National Surveillance System with the National Immunization Registry were linked to form a large-linked database for assessment. Age-adjusted incidence of SARS-CoV-2 infection, severe disease, and death by vaccination status are calculated. Weekly vaccine effectiveness was calculated based on incidence rate ratio (IRR) between fully-vaccinated and unvaccinated persons, as: IRR = incidence rate of vaccinated / incidence rate of unvaccinated. We estimate the cumulative SARS-CoV-2 outcome overtime comparing the observed case with predicted cases without vaccination.

Results

Age-adjusted incidence in unvaccinated persons (5.69 per 100,000 person-day) was 2.7 times the rate in fully vaccinated (2.13 per 100,000 person-day) persons, resulting effectiveness against SARS-CoV-2 infection of 63%. Vaccine effectiveness against severe disease and death were 93% and 95%, respectively. Between March and October 2021, estimated Covid-19 related outcomes averted by vaccinations were: 46,508 infections, 3,424 severe diseases, and 718 deaths.

Conclusions

We found significant protection for national Covid-19 vaccination campaign against Covid-19 severe disease, and death in target populations, but there was an unexpected decreased protection against SARS-CoV-2 infection, highlighting the importance of continued surveillance and assessment.

SUBMITTER: Yi S

PROVIDER: S-EPMC9080122 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Publications

Impact of national Covid-19 vaccination Campaign, South Korea.

Yi Seonju S Choe Young June YJ Lim Do Sang DS Lee Hye Roen HR Kim Jia J Kim Yoo-Yeon YY Kim Ryu Kyung RK Jang Eun Jung EJ Lee Sangwon S Park Eunjoo E Kim Seung-Jin SJ Park Young-Joon YJ

Vaccine 20220508 26

<h4>Background</h4>We evaluate the overall effectiveness of the nationwide vaccination campaign using ChAdOx1 nCoV-19, BNT162b2, mRNA-1273, and Ad26.COV2.S vaccines in preventing Covid-19 in South Korea.<h4>Methods</h4>The National Surveillance System with the National Immunization Registry were linked to form a large-linked database for assessment. Age-adjusted incidence of SARS-CoV-2 infection, severe disease, and death by vaccination status are calculated. Weekly vaccine effectiveness was cal ...[more]

PMID: 35570077

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Project description:BackgroundA number of highly effective COVID-19 vaccines have been developed and approved for mass vaccination. We evaluated the impact of vaccination on COVID-19 outbreak and disease outcomes in Ontario, Canada.MethodsWe used an agent-based transmission model and parameterized it with COVID-19 characteristics, demographics of Ontario, and age-specific clinical outcomes. We implemented a two-dose vaccination program according to tested schedules in clinical trials for Pfizer-BioNTech and Moderna vaccines, prioritizing healthcare workers, individuals with comorbidities, and those aged 65 and older. Daily vaccination rate was parameterized based on vaccine administration data. Using estimates of vaccine efficacy, we projected the impact of vaccination on the overall attack rate, hospitalizations, and deaths. We further investigated the effect of increased daily contacts at different stages during vaccination campaigns on outbreak control.ResultsMaintaining non-pharmaceutical interventions (NPIs) with an average of 74% reduction in daily contacts, vaccination with Pfizer-BioNTech and Moderna vaccines was projected to reduce hospitalizations by 27.3% (95% CrI: 22.3% - 32.4%) and 27.0% (95% CrI: 21.9% - 32.6%), respectively, over a one-year time horizon. The largest benefits of vaccination were observed in preventing deaths with reductions of 31.5% (95% CrI: 22.5% - 39.7%) and 31.9% (95% CrI: 22.0% - 41.4%) for Pfizer-BioNTech and Moderna vaccines, respectively, compared to no vaccination. We found that an increase of only 10% in daily contacts at the end of lockdown, when vaccination coverage with only one dose was 6%, would trigger a surge in the outbreak. Early relaxation of population-wide measures could lead to a substantial increase in the number of infections, potentially reaching levels observed during the peak of the second wave in Ontario.ConclusionsVaccination can substantially mitigate ongoing COVID-19 outbreaks. Sustaining population-wide NPIs, to allow for a sufficient increase in population-level immunity through vaccination, is essential to prevent future outbreaks.

Project description:Background Annual vaccination for influenza is globally recommended for some prioritized groups due to its high morbidity and mortality. Until 2019, South Korea has provided free influenza vaccination to children aged ≤12, adults aged ≥65, and pregnant women to enhance vaccination coverage. In 2020, with the COVID-19 pandemic, free flu vaccination was temporarily broadened to adults aged 62–64 and children aged 13–18. We analyzed the trends in influenza vaccination coverages in South Korea and evaluated the impact of the COVID-19 pandemic and the expansion of the free vaccination policy on influenza vaccination coverage. Methods We conducted a cross-sectional study with nationwide survey data from Korea National Health and Nutrition Examination Survey (KNHANES). We evaluated the trends in influenza vaccination coverages of target populations from 2010 to 2020. Influenza vaccination coverages of children aged 13–18, adults aged 62–64, and adults aged ≥65 were compared between 2019 and 2020. Results In total, 72,443 individuals were analyzed. From 2019 to 2020, with the expansion of free influenza vaccination and the COVID-19 pandemic, the vaccination coverage of children aged 13–18 increased from 27.8% to 43.5% (P<0.001) but that of people aged 62–64 showed insignificant change from 57.4% to 51.5% (P = 0.266). Furthermore, the vaccination coverage in adults aged ≥65 declined from 87.2% to 79.1% (P<0.001). Conclusion In 2020, along with COVID-19 outbreaks, a decline of influenza vaccination coverage in older adults was observed regardless of free immunizations. It is likely due to behavioral changes to reduce the risk of COVID-19 transmission. This is supported by a greater reduction of influenza vaccination coverage in regions with higher COVID-19 outbreaks, as well as by South Korea’s high medical accessibility and highly congested medical facilities. To sustain a high level of vaccination coverage of high-risk population during epidemics, additional efforts beyond free vaccination policies should be implemented.

Dataset Information

Impact of national Covid-19 vaccination Campaign, South Korea.

Background

Methods

Results

Conclusions

Publications

Impact of national Covid-19 vaccination Campaign, South Korea.

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