It appeared for a while that we were past the worst of the pandemic, but the situation in the U.S. has shifted dramatically in the last couple of weeks and hospitals across the country are once again being flooded with COVID patients. As of July 23, coronavirus hospitalization rates are rising in 45 states, according to data from the The New York Times. And while the large majority of these patients are unvaccinated, that's not necessarily true of all of them. The Centers for Disease Control and Prevention (CDC) reports that of the more than 159 million people who'd been fully vaccinated as of July 12, when they last collected the data, nearly 5,500 have been hospitalized with COVID in the U.S. That's only .003 percent of fully vaccinated people who get severe COVID, but new research is showing that half of them share one interesting commonality.
A study released on medRxiv earlier this month, which has not yet been peer reviewed but was funded by the CDC, looked at the effectiveness of the COVID vaccine in preventing virus-related hospitalizations in the U.S. The researchers analyzed 1,210 U.S. adults hospitalized between March 11 and May 5, comparing COVID-positive patients with patients who tested negative for the virus. According to the study, nearly half of the hospitalized COVID patients who were infected after being vaccinated were immunocompromised. Of the 45 patients with breakthrough COVID infections, 44.4 percent were immunosuppressed.
"All of the patients that have been fully vaccinated that I've admitted to the ICU have been immunocompromised. Every single one of them," Todd Rice, MD, co-author of the study and director of the medical intensive care unit at Vanderbilt University Medical Center in Nashville, Tennessee, told NBC News this week. He added that all of the other hospitalized COVID patients at his hospital have not been vaccinated.
A study published in the medical journal Clinical Microbiology and Infection earlier this month similarly found that out of 152 severe breakthrough infections in Israel, 40 percent were among immunocompromised people.
Rice and his team also confirmed that vaccine effectiveness was lower among immunosuppressed patients. According to their data, vaccines were 86.9 percent effective at preventing COVID hospitalization overall, but only 59.2 percent effective among immunocompromised patients.
"Immunosuppressive conditions affect millions of adults in the United States," the study states. According to the CDC's Advisory Committee on Immunization Practices (ACIP), immunocompromised people make up about 2.7 percent of the country's population and includes those who have solid tumor and hematologic malignancies, HIV, severe primary immunodeficiencies, have received a solid-organ or hematopoietic stem cell transplant, or are taking immunosuppressive medications.
Another large study published in the medical journal Cancer Cell in June set out to determine how effective the COVID vaccines are for cancer patients. The results showed that while most cancer patients in the study responded well to the shots, 30 percent of those taking immunosuppressants had no antibody production in response to their vaccine.
These findings add to mounting evidence that the roughly six million people in the U.S. who rely on medications that suppress their immune systems—which includes not only those with cancer, but also people with arthritis, psoriasis, and those who've received organ transplants—are not having strong reactions to their COVID vaccines after two doses.
The authors behind the new CDC study concluded that "future work is needed to understand vaccine effectiveness among people with specific immunocompromising conditions and the durability of protection in this population to inform the need for booster vaccines and/or non-vaccine preventative interventions, such as mask use and social distancing."
It's research like this that led the ACIP to meet on July 22 to discuss whether or not immunocompromised people need a third shot to combat their higher rate of severe breakthrough infections.
The committee cited the CDC study in their meeting notes, and also referenced four smaller studies that showed that anywhere from 16 to 80 percent of people with weakened immune systems did not develop detectable antibodies against COVID after getting their recommended vaccine doses. But among those who had no response to their initial shots, 33 to 50 percent developed antibodies after a third dose.
"Emerging data suggest that an additional COVID-19 vaccine dose in immunocompromised people enhances antibody response and increases the proportion who respond," the ACIP concluded in their presentation. However, the CDC has not yet formally recommended that healthcare providers give immunosuppressed individuals a third COVID vaccine dose.