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Examining the Risk of COVID-19 in the Vaccinated

Researchers at Cleveland Clinic evaluated whether a bivalent COVID-19 vaccine protects against both strains of the virus - the original virus strain and a component of the omicron variant.

Risk of COVID-19 may increase with time depending when the virus was previously contracted for folks who have been vaccinated, according to a recent Cleveland Clinic study.

In the cohort study, the bivalent COVID-19 vaccine booster was given to Cleveland Clinic employees. The working-aged adults afforded modest protection overall against COVID-19.

Researchers at Cleveland Clinic evaluated whether a bivalent COVID-19 vaccine protects against both strains of the virus - the original virus strain and a component of the omicron variant.

Found was the bivalent COVID-19 vaccine booster was 30% effective in preventing infection among 51,011 Cleveland Clinic employees when the virus strains dominant in the community were represented in the vaccine.

This data was collected from employees of the hospital system in employement on September 12, 2022 - the day the bivalent COVID-19 vaccine first became available to them. The employees were then monitored for any virus contraction no matter the vaccine or booster intake. Results were collected until December 12, 2022.

Among the more than 50,000 employees, 20,689 (41%) had a previous documented episode of COVID-19, and 42,064 (83%) had received at least two doses of a COVID-19 vaccine. COVID-19 occurred in 2,452 (5%) during the study. Risk of COVID-19 increased with time since the most recent prior COVID-19 episode and with the number of vaccine doses previously received.

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Compared to employees last exposure of COVID-19 within 90 days, last exposure of 6-9 months previously was associated with twice the risk of COVID-19, and last exposure of 9-12 months previously with 3.5 times the risk.

Though, the study states that vaccines remain “very effective” against severe disease and death.

Authors are, however, unaware why the employees who have had more vaccines are more prone to getting the virus more often and said the association was unexpected.

It was stated further research is needed to either confirm or deny the findings.

This article originally appeared on Managed Healthcare Executive.


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