Severe Covid-19 breakthrough cases tend to be in older and sicker people, Yale study finds

From CNN’s Maggie Fox

Vaccinated people who get infected with coronavirus anyway and suffer severe symptoms tend to be older – 80 on average – and also suffer from other conditions such as obesity or diabetes, researchers said Tuesday.

Dr. Hyung Chang at the Yale School of Medicine and colleagues studied close to 1,000 patients hospitalized between the end of March and July of this year. Everyone admitted to the hospital got tested for coronavirus, whether that was the reason for admission or not.

About 18% of the patients who tested positive had been given at least one dose of vaccine, they found, and about a third of these were fully vaccinated, Chang and colleagues said in a commentary in the journal Lancet Infectious Diseases.

“Those deemed to be ‘breakthrough cases,’ namely patients who were fully vaccinated who tested positive, were evaluated for illness severity. Among this cohort, we found that 25/54 patients were asymptomatic (hospitalized for a non-COVID-19 related diagnosis but with an incidental positive PCR test for SARS-CoV-2), 4/54 had mild disease, 11/54 had moderate disease, and 14/54 had severe/critical illness,” they wrote.

“We found that nearly a fifth of patients had received at least one dose of the vaccine, and we observed that many patients had not completed the full vaccine course,” they added.

The median age of those with severe illness was 80, they said. More than half were overweight, most had cardiovascular disease, half had lung disease and half had diabetes.

Note: The patients would not be fully representative of everyone with breakthrough cases, as everyone studied was sick enough to show up to the hospital for treatment. Plus the study did not cover the time when the Delta variant was the dominant circulating strain of virus.