SARS-CoV-2 Infection Breakthrough among the non-vaccinated and vaccinated: a Real World Evidence study based on Big Data

Background

SARS-CoV-2 infection after vaccination can occur because COVID-19 vaccines do not offer 100% protection. The aim of this study was to assess vaccination coverage among people nasopharyngeal swabs, disease symptoms and type of hospitalisation (Intensive Care Unit) between the non-vaccinated and the effective dose vaccinated and to evaluate vaccination trend over time.

Methods

A retrospective cohort study was carried out among people tested positive for COVID-19 in Campania Region using collected information from Health Information System of Campania Region (Sinfonia).

The status of vaccination was assess according to the following timetable: “non-vaccinated”; “Ineffective dose” vaccination; “Effective dose” vaccination.

Univariate and multivariate logistic regression models were conducted to evaluate the association between Intensive Care Unit (ICU) to COVID-19 and gender, age groups and vaccine.

To determine vaccine coverage in subjects who received an effective dose, trend changes over time were investigated using segmented linear regression models and breakpoints estimations.

Vaccination coverage was assessed by analysing the trend in the percentage of covid 19 positive subjects in the 9 months after vaccination with an effective dose stratified by age group and type of vaccine. Statistical analyses were performed using R platform

Results

A significant association with the risk of hospitalisation in Intensive Care Unit was the vaccination status of the subjects: subjects with ineffective dose (adjusted OR: 3.68) and subjects no-vaccination (adjusted OR: 7.14) were at three- and seven-times higher risk of hospitalisation in Intensive Care Unit, respectively, than subjects with an effective dose.

Regarding subjects with an effective dose of vaccine, the vaccine’s ability to protect against infection in the months following vaccination decreased.

The first breakpoints is evident five months after vaccination (β =1.441, p<0.001). This increase was most evident after the seventh month after vaccination (β =3.110, p<0.001).

Conclusions

COVID19 vaccines protect from symptomatic infection by significantly reducing the risk of ICU hospitalization for severe disease. However, it seems they have trend to decrease their fully protection against SARS-COV-2 after five months regardless age, sex or type of vaccine. Therefore it seems clear that those not undergoing vaccine had higher risk to develop clinically significant disease and being at risk of ICU stay. Thus, considering highest percentage of asymptomatic patients and that few data about their capacity to transmit SARS-CoV-2, third dose vaccination should be introduced as soon as possible while awaiting antivirals.Finally, a surveillance approach based on the use of integrated BIG Data system to match all clinical conditions too, offer a precise and real analysis with low incidence of errors in the categorization of subjects.