Israeli study on breakthrough infections after full BNT-Pfizer vaccination, 40% immunocompromised

According to a recent study by Israeli researchers published in the journal, severe forms of coronavirus disease (COVID-19) linked to high death rates could occur in a minority of fully vaccinated individuals with many concomitant medical conditions. Clinical microbiology and infection.

In phase III clinical trials, two COVID-19 mRNA vaccines (BNT162b2 from Pfizer / BioNTech and mRNA-1273 from Moderna) were shown to be 94-95% effective in preventing symptomatic forms of the disease. In addition, similar efficacy has been observed in different age groups, as well as in people over 75 years of age and those with co-morbidities.

Israel’s vaccination campaign was swift, effective, and had a significant impact on the local dynamics of COVID-19. The factors that played a huge role here were the small geographic and demographic size, advanced computerization, as well as effective cooperation between government and community health funds.

However, there is not enough data on the nature of the breakthrough infections with COVID-19 vaccines that we have started to observe even in highly vaccinated populations like Israel. In addition, we lack data on the clinical features and serological correlates of protection of people hospitalized with COVID-19 after receiving their vaccine.

According to the Israeli Ministry of Health’s register, at the end of April 2021, a total of 397 fully vaccinated patients had been hospitalized with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after their second dose of the vaccine – including 234. suffering from severe COVID-19 and 90 of them succumb to the disease.

Using a subset of inpatients, a research group led by Dr Tal Brosh-Nissimov from Samson Assuta Ashdod University Hospital in Israel aimed to characterize vaccinated and hospitalized patients with breakthrough COVID-19 infection, but also to define the main risk factors linked to poor results in this group.

A multicenter cohort study

This study used a cohort approach to study patients in seventeen different hospitals. The people who were included in the study received two doses of Pfizer / BioNTech vaccine, they tested positive for SARS-CoV-2 on the PCR test and were hospitalized in a COVID-19 unit.

In addition, clinical data was extracted from the medical records of patients according to a predefined questionnaire. Along with PCR testing, even viral genomic sequencing was continued in order to identify the variants of concern in the samples.

A mixture of mechanical ventilation or hospital death was considered a bad outcome, which was the main interest of this study. On the other hand, a favorable outcome was defined as discharge of the patient or hospitalization without the need for ventilation.

Revolutionary infections linked to co-morbidities

Out of a total of 152 patients included in the study, a poor prognosis was observed in 38 of them and the mortality rate reached 22%. The clinical profile of these people resembled other COVID-19 hospital patients, meaning they were mostly older men with a plethora of comorbidities associated with the severity of COVID-19.

Nevertheless, comorbidities were more common in patients with breakthrough vaccine infections compared to a large series of cases in unvaccinated hospitalized patients – including hypertension, diabetes, heart failure, chronic kidney disease, chronic lung disease, dementia and cancer. In addition, 40% of the patients were immunocompromised.

A higher viral load of SARS-CoV-2 was linked to a significantly higher risk of poor outcome, which was also increased (although not significantly) in patients receiving a specific treatment regimen with anti- monoclonal antibodies. CD20, as well as in patients with low titers of protective antibodies.

Implications for people at high risk

The results of this study clearly imply that a small minority of individuals fully vaccinated with the Pfizer / BioNTech vaccine could still have severe SARS-CoV-2 infection and need hospital care – despite the vaccine’s high efficacy. Specifically, the outcome of the patients included in the study was comparable to that of unvaccinated hospitalized COVID-19 patients.

“Further prospective longitudinal studies are urgently needed to identify predictors of breakthrough vaccine infection and simple correlates of vaccine protection, to allow identification of those at higher risk, who would require continued strict precautions and possibly repeated active vaccination or other prophylactic measures, such as passive vaccination ”, state the authors of the study.

Such research efforts will help develop directions to improve the protection of these patients. In the meantime, we must be aware that mass vaccination (leading to herd immunity) is an optimal way to indirectly protect vulnerable people.