Older individuals with many underlying medical conditions and immunosuppression are more likely to contract coronavirus and would develop a severe case of COVID-19 even after being fully vaccinated, according to a world-first study conducted in Israel.
A minority of vaccinated individuals will contract coronavirus, and a small percentage of those will end up hospitalized because of the virus. This is called a breakthrough infection.
But who are these people?
A team of Israeli doctors led by Prof. Tal Brosh, head of the Infectious Disease Unit at Samson Assuta Ashdod Hospital, studied 152 fully vaccinated patients from 17 hospitals who developed COVID-19 more than seven days after they received their second vaccine dose and required hospitalization before the end of April.
The cohort was small because not many vaccinated people who contract coronavirus develop a severe infection, as the vaccine is 97% to 98% effective against the standard variant – and is proving to be almost as effective against the Delta variant. So far, despite a rapid spike in coronavirus cases in Israel, the number of serious cases seems to be climbing slowly.
“Overall, we can say that the main thing is that these are not healthy people,” Brosh told The Jerusalem Post in an interview. “Almost all of them (96%) had comorbidities: heart disease, lung disease, renal disease, dementia, cancer, or other common ailments. So, people who get breakthrough infections and are admitted are sicker than a usual person.”
Of those who were hospitalized, 38 had what were defined as “poor outcomes,” meaning they were mechanically ventilated or had died.
Specifically, 71% had hypertension; 48% diabetes; 27% congestive heart failure; 24% chronic kidney disease; 24% chronic lung disease; 19% dementia; and 24% cancer. Only 6% did not have any underlying medical condition.
Moreover, the study showed that 40% of patients were immunocompromised.
“If your immune system does not function well, you are at higher risk for not developing protection from vaccination,” Brosh said, adding that some 35% of patients had no detectable antibodies – meaning they had failed to mount an immune response to the vaccine.
The median time that elapsed from the second dose to hospitalization was 40 days. The median age of the patients was 71. In most cases the source of the patient’s infection was unknown.
Brosh said that although this study was conducted when the Alpha variant was active in Israel and the majority of cases had that virus strain, he said it is likely that the characteristics still apply currently – to those who are infected with the Delta variant that now accounts for more than 90% of infections in Israel.
He said that the Delta variant seems to break through the vaccine more than its Alpha predecessor, but it is still unclear if the variant causes more severe infections – despite some suggestions of this by the Health Ministry.
Still, he said there is an important message that the public should heed:
“If you are older and have comorbidities – and definitely, if you have a lot of comorbidities – or are immunocompromised, you cannot assume you will be well protected by the vaccine,” Brosh said. “When there is a lot of transmission in the community, you should take care of yourself.”