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Multicenter Study
. 2023 Mar:128:98-101.
doi: 10.1016/j.ijid.2022.12.025. Epub 2022 Dec 26.

Time from last immunity event against infection during Omicron-dominant period in Malaysia

Su Lan Yang  1 , Adiratna Mat Ripen  2 , Jen Ven Lee  3 , Karina Koh  4 , Chia How Yen  5 , Avinash Kumar Chand  6 , Nur Aisyah Binti Abdul Rahim  7 , Varaalakshmy Gokilavanan  8 , Nik Nur Eliza Binti Mohamed  9 , Raj Kumar A/L Sevalingam  10 , Kalaiarasu M Peariasamy  11
Affiliations
Multicenter Study

Time from last immunity event against infection during Omicron-dominant period in Malaysia

Su Lan Yang et al. Int J Infect Dis. 2023 Mar.

Abstract

Objectives: To study the incidence of Omicron infections in Malaysia and the exposures that could reduce the hazard of attaining Omicron infection.

Methods: We used a multicenter, prospective cohort to study 482 healthcare workers vaccinated with two and three doses of BNT162b2 for SARS-CoV-2 infection during the Omicron-dominant period in Malaysia.

Results: Between January 31 and July 31, 2022, the cumulative incidence was 44.6% (95% CI 40.2-49.1%), and the incidence rate was 3.33 (95% CI 2.91-3.80) per 1000 person-days. Our study found that protection against Omicron infection was significantly higher for persons with previous SARS-CoV-2 infection (hazard ratio [HR] 0.41, 95% CI 0.27-0.62) and persons with a more recent immunity event (<30 days [reference] vs >90 days, HR 3.82, 95%CI 1.34-10.90) from the beginning of the Omicron period.

Conclusion: Pre-Omicron natural infection and a recent immunity event protect against future Omicron infections.

Keywords: Healthcare workers; Hybrid immunity; Malaysia; Omicron; Previous SARS-CoV-2 infection; Vaccination.

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Figures

Figure 1
Figure 1
Kaplan-Meier curve of cumulative incidence probability by pre-Omicron natural infection and time since last immunity event.
See this image and copyright information in PMC

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