WEDNESDAY, Dec. 15, 2021 (HealthDay News) -- COVID-19 vaccine breakthrough infections are rare among fully vaccinated individuals, but they are more common and more severe in those who are immunocompromised, according to a study published online Nov. 30 in the Journal of Medical Economics.

Manuela Di Fusco, from Pfizer Inc. in New York City, and colleagues used the U.S. HealthVerity database (Dec. 10, 2020, to July 8, 2021) to identify 1,277,747 individuals ages 16 years and older vaccinated against COVID-19 with two doses of BNT162b2. Breakthrough infections among immunocompromised individuals (225,796) were assessed.

The researchers found that overall, there were 978 breakthrough infections during the study period (0.08 percent of fully vaccinated people), including 124 (12.7 percent) that resulted in hospitalization and two (0.2 percent) inpatient deaths. Of all breakthrough infections, immunocompromised individuals accounted for 38.2 percent, as well as 59.7 percent of resulting hospitalizations and both inpatient deaths. In the immunocompromised group, the proportion with breakthrough infections was three times higher than that for the nonimmunocompromised group (0.18 percent and 0.06 percent, respectively). The highest breakthrough infection incidence rate was seen among organ transplant recipients. Among immunocompromised individuals, incidence rates were higher in those 65 years and older versus those younger than 65 years.

"The findings from this large study support the Food and Drug Administration authorization and the Centers for Disease Control and Prevention recommendations to offer a third vaccine dose to increase protection among immunocompromised individuals," the authors write.

The authors reported financial ties to Pfizer, which makes the BNT162b2 vaccine and funded the study.

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