Risk factors for critical forms of SARS-CoV-2 infection in fully vaccinated patients: a prospective observational study

The novel coronavirus disease of 2019 (COVID-19) vaccination is a critical prevention measure to help sort out the COVID-19 crisis. Nonetheless, since the beginning of the pandemic, it has been well-documented that older adults as well as people enduring an immunocompromised condition are the most likely to develop a severe COVID-19 form owing to a less robust immune system and therefore a weaker immunologic response to COVID-19 vaccination. Herein, we report an observational prospective monocentric study of a series made up of 30 patients fully vaccinated against Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) out of a total of 139 patients admitted to the medical intensive care unit (ICU) for a critical form of COVID-19 between February 2021 and October 2021. This observational study was conducted during the peak of the pandemic outbreak and therefore its main aim was to describe the epidemiological and sociodemographic features of fully vaccinated patients who endured critical forms of COVID-19. Immunocompromised people as well as those with chronic underlying comorbidities are more likely to develop critical forms of COVID-19. Moreover, it seems that vaccine efficacy decreases gradually over time. SARS-CoV-2 variants may also undermine vaccine effectiveness. Supplemental doses would be of paramount in higher-risk people to build on protective immunity against COVID-19. Further randomized controlled trials are also desperately needed to determine the optimal interval between primary series and booster doses of the several COVID-19 vaccines chiefly for the vulnerable people.