Yale study observed fully vaccinated individuals who were hospitalized with COVID and found they had some things in common.
Vaccinated individuals who contract COVID-19 and develop a so-called breakthrough case that results in severe disease are more likely to be older and have preexisting health issues, according to a recent study.
“Overall, older population with underlying heart or lung disease, or with weakened immune system were the most highly represented in those with breakthrough cases with symptoms,” Dr. Hyung Chun of the Yale School of Medicine, who led the study.
Chun and his Yale colleagues identified 969 patient who were admitted to hospitals in the Yale New Haven Health System and who tested positive for COVID across a 14-day period from March 23 to July 1, according to commentary posted on the Lancet Infectious Disease website on Sept. 7. All patients were required to get tested when they were admitted and may have come to the hospital for illness other than COVID.
Chun and his Yale colleagues found 969 patients admitted to hospitals within the Yale-New Haven Health System between March 23 and July 1 who tested positive for COVID, according to a commentary published on the Lancet Infectious Disease website. All patients who were admitted who may have been admitted for a reason other than COVID were obliged to be tested.
According to data, approximately 18 percent of individuals who tested positive received at least one vaccine dose, and a third were fully vaccinated.
The scientists concentrated on those who had received all vaccines and discovered that a quarter of them (14 individuals) had severe or critical illness and required oxygen therapy support. Four of the patients were admitted to the intensive care unit, one was placed on a mechanical ventilator, and three died.
The researchers noted that the patients with severe illness ranged in age from 65 to 95 years, with a median age of 80.5. They were predisposed to comorbid conditions such as cardiovascular disease, lung disease, obesity, and type 2 diabetes. Certain individuals were using immunosuppressive drugs, which may impair vaccine efficacy.
Although a large body of data indicates that COVID-19 vaccines are effective and have been critical in containing the pandemic, people who are fully vaccinated occasionally get the virus and develop what are known as breakthrough cases. Even more rarely, a breakthrough case leads to a life-threatening illness.
The Centers for Disease Control and Prevention have received reports of 14,115 persons hospitalized or dying as a result of COVID-19 vaccination breakthrough infection.
This is a negligible proportion of the 178 million individuals in the United States who have received both doses.
“Vaccines continue to remain highly effective in preventing severe illness due to COVID-19,” Chun wrote. “The likelihood of developing severe COVID-19 infection remains far lower for those vaccinated compared to those unvaccinated. Emerging data on breakthrough cases will need to be closely followed to determine the most effective strategies for booster vaccines.”
The investigation was conducted prior to the highly transmissible delta COVID variation becoming the most prevalent in the United States.
Chun stated that additional research is necessary to determine the delta variant’s impact on breakthrough cases.