Characteristics of COVID-19 Breakthrough Infections among Vaccinated Individuals and Associated Risk Factors: A Systematic Review

Abstract

We sought to assess breakthrough SARS-CoV-2 infections in vaccinated individuals by variant distribution and to identify the common risk associations. The PubMed, Web of Science, ProQuest, and Embase databases were searched from 2019 to 30 January 2022. The outcome of interest was breakthrough infections (BTIs) in individuals who had completed a primary COVID-19 vaccination series. Thirty-three papers were included in the review. BTIs were more common among variants of concern (VOC) of which Delta accounted for the largest number of BTIs (96%), followed by Alpha (0.94%). In addition, 90% of patients with BTIs recovered, 11.6% were hospitalized with mechanical ventilation, and 0.6% resulted in mortality. BTIs were more common in healthcare workers (HCWs) and immunodeficient individuals with a small percentage found in fully vaccinated healthy individuals. VOC mutations were the primary cause of BTIs. Continued mitigation approaches (e.g., wearing masks and social distancing) are warranted even in fully vaccinated individuals to prevent transmission. Further studies utilizing genomic surveillance and heterologous vaccine regimens to boost the immune response are needed to better understand and control BTIs.

First COVID-19 Booster Dose in the General Population: A Systematic Review and Meta-Analysis of Willingness and Its Predictors

“…The emergence of breakthrough infections and new highly contagious variants of SARS-CoV-2 threaten the immunization in individuals who had completed the primary COVID-19 vaccination [ 1 , 2 ]. Moreover, breakthrough infections are more common in immunodeficient patients, causing significant clinical outcomes, e.g., hospitalization and mortality [ 3 , 4 ]. Importantly, evidence shows that new SARS-CoV-2 variants of concern may have reduced COVID-19 vaccine susceptibility and have increased infectivity [ 5 , 6 ].…”

Effectiveness of the available early therapies in reducing severe COVID-19 in non-hospitalized patients with solid tumors on active treatment

“…Despite coronavirus disease 2019 (COVID-19) vaccination being effective for patients with cancer ( 1 ), a systematic review has reported that the occurrence of breakthrough infections (BTIs) is more common in immunocompromised individuals than in fully vaccinated healthy individuals ( 2 ). Emergency use authorization of drugs against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by regulatory authorities has provided new options to treat high-risk outpatients with mild-to-moderate COVID-19.…”

Humoral and cellular immune response after severe acute respiratory syndrome coronavirus 2 messenger ribonucleic acid vaccination in heart transplant recipients: An observational study in France

“…In a recent review, BTIs due to the variant delta were shown to be more common in immunodeficient individuals and HCWs than in healthy individuals. Immunosuppressed individuals were more likely to be hospitalized after infection, however, no specific variant was associated with severe disease and the majority of patients recovered ( 59 , 60 ). A better knowledge of immunity after vaccination and BTI in fragile populations is essential to face emerging variants of SARS-CoV-2.…”