Risk of sars-cov-2 reinfection in sicily: A population-based evaluation of covid-19 events using current health databases
 
More details
Hide details
1
University of Palermo Department of Health Promotion, Mother and Child Care, Internal Medicine, and Medical Specialties "G. D'Alessandro" Via del Vespro, 133 - Palermo (PA) Italy
 
2
University of Palermo
 
 
Publication date: 2023-04-26
 
 
Popul. Med. 2023;5(Supplement):A465
 
ABSTRACT
Background and Objective:
Worldwide, the COVID-19 outbreak resulted in more than 640 million cases as of 15 December 2022. As immunity to natural infection deteriorates with time and SARS-CoV-2 strains mutate, reinfections began to occur. The current study sought to assess the probability of SARS-CoV-2 reinfection among residents of Sicily, Italy, in relation to sex, age, number of mRNA COVID-19 vaccine doses administered, and occurrence of hospitalization during a previous infection.

Methods:
A population-based retrospective cohort analysis was designed using the Sicilian COVID-19 monitoring system run by the National Institute of Health and vaccination flows acquired through a regional registry in Sicily. Only Sicilian adults were included in the study, and hazard ratios were calculated using Cox regression.

Results:
After an average of 198 days, there were 39,509 reinfections among 1,089,782 previously infected people (overall cumulative incidence: 3.62%) from the start of the pandemic to 3 September 2022. Almost all reinfections (37,084; 93.9%) occurred during the Omicron variant period, with the remaining 6.1% attributed almost entirely to the period in which Delta and Omicron variants co-circulated (2,011; 5.1%). The risk of reinfection was significantly lower among males than females (HR:0.74, 95%C.I.:0.73-0.76), decreased with age (from HR:1.24, 95%C.I.:1.20-1.28 for 30-39 years old people to HR:0.36, 95%C.I.:0.33-0.38 for 80+ individuals compared to 18-29 group), and lower for people receiving two or more mRNA vaccine doses (HR:0.39, 95%C.I.:0.38-0.40 compared to the individuals who did not receive vaccination). Interestingly, those who were hospitalized during their previous SARS-CoV-2 infection exhibited a significantly lower chance of reinfection (HR:0.74, 95%C.I.:0.70-0.78).

Conclusion:
SARS-CoV-2 reinfection was found to be a relatively common occurrence, predominantly caused by the Omicron strain. COVID-19 vaccination provides significant protection against reinfection. Furthermore, the lower risk observed in the elderly and previously hospitalized persons reflects more stringent adherence to the use of personal protective equipment.

ISSN:2654-1459
Journals System - logo
Scroll to top