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

[tetano]

Vaccine


. 2022 May 8;S0264-410X(22)00572-2.
doi: 10.1016/j.vaccine.2022.05.002. Online ahead of print.
Impact of national Covid-19 vaccination Campaign, South Korea


Seonju Yi ¹ , Young June Choe ² , Do Sang Lim ¹ , Hye Roen Lee ¹ , Jia Kim ¹ , Yoo-Yeon Kim ¹ , Ryu Kyung Kim ¹ , Eun Jung Jang ¹ , Sangwon Lee ¹ , Eunjoo Park ¹ , Seung-Jin Kim ¹ , Young-Joon Park ³



Affiliations

• PMID: 35570077
• DOI: 10.1016/j.vaccine.2022.05.002

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.

Keywords: COVID-19; Coronavirus; Effectiveness; SARS-CoV-2; Vaccine.