BMC Infect Dis . Risk factors for severe Covid-19 breakthrough infections: an observational longitudinal study

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BMC Infect Dis


. 2022 Nov 28;22(1):894.
doi: 10.1186/s12879-022-07859-5.
Risk factors for severe Covid-19 breakthrough infections: an observational longitudinal study

Sihem Ben Fredj ^{1 2} , Rim Ghammem ^{1 2} , Nawel Zammit ^{1 2} , Amani Maatouk ³ , Nihel Haddad ² , Nouha Haddad ² , Manel Kachroudi ² , Senda Rebai ² , Hafsia Laadhari ⁴ , Mohamed Mizouni Ghodhbani ⁴ , Jihen Maatoug ^{1 2} , Hassen Ghannem ^{1 2}


Affiliations

• PMID: 36443699
• PMCID: PMC9706846
• DOI: 10.1186/s12879-022-07859-5

Abstract

Background: The drive to vaccinate large populations is nowadays the main instrument for combating the pandemic and preventing serious disease and death. However, breakthrough infection (post-vaccination infection) still happens after vaccination among fully vaccinated people. We aimed to assess the severity outcomes and to determine its associated factors among vaccinated COVID-19 cases in the governorate of Sousse, Tunisia.
Methods: We carried out a five-month observational longitudinal study including all the population of Sousse. Confirmed infections of SARS-CoV-2 and the vaccination status are recorded in the daily COVID- 19 database of the Regional Office of the Tunisian Ministry of Health. We included all post-vaccination COVID-19 cases for the analysis of the COVID-19 serious outcomes. Data were collected via 15-min telephonic call interviews conducted by trained interviewers. Descriptive analysis with calculating incidence rates of confirmed COVID-19 cases per 100,000 inhabitants was conducted. In binary logistic regression, adjusted odds ratios along with 95% intervals confidence were performed to determine factors related to severe or critical COVID-19.
Results: As of 31 July 2021, 107,545 persons over 19 years old have received at least one dose of COVID-19 vaccination. Among the vaccinated population, we traced and included 765 breakthrough infection cases, and the incidence rate was 711.3 per week. The majority were female (sex-ratio = 0.8), and the average age of the overall cases was 55.7 years. The prevalence of severe or critical cases in vaccinated COVID-19 patients occurs in 10.8% of cases. Patients with a medical history of cardiovascular diseases had more than two times increased odds to have a severe or critical disease. We also found the highest self-estimation of adherence to preventive measures was inversely correlated to serious cases and having an incomplete vaccination schema was strongly associated with complications.
Conclusions: We tried to provide evidence about the breakthrough infections to improve measures of prevention and control of COVID-19. Boosting immunity for vulnerable patients added to maintaining and promoting preventive measures are not only essential to prevent severe cases of breakthrough infections of COVID-19, but also other influenza-like diseases.

Keywords: COVID-19; COVID-19 breakthrough infections; COVID-19 vaccines; Risk factors.