U.S. data show rising 'breakthrough' infections among fully vaccinated

US officials reported on Tuesday that some 25% of COVID-19 infections among residents in Los Angeles County occurred in fully vaccinated residents from May through July 25, as reported by the National Post.

The data, published in the US Centers for Disease Control and Prevention’s (CDC) weekly report on death and disease, involved more than 43,000 reported infections among Los Angeles County residents aged 16 and older. Of them, 25.3% occurred in fully vaccinated individuals, 3.3% were in partially vaccinated persons, and 71.4% were in unvaccinated individuals.

However, the vaccines did protect individuals from more severe cases. According to the study, 3.2% of fully vaccinated individuals who were infected with the virus were hospitalized, 0.05% were admitted to an ICU and 0.25% were placed on a ventilator.

Among the unvaccinated who were infected with the virus, 7.5% were hospitalized, 1.5% were admitted to an ICU and 0.5% required a ventilator.

The CDC also released an update on the HEROES cohort study among healthcare workers that showed a significant drop in vaccine effectiveness among vaccinated frontline workers in eight states who became infected with the virus.

According to the report, vaccine efficacy during the period when Delta was predominant fell to 66% from 91% prior to the arrival of the Delta variant.