Custom Boosting Schedule Provides Comparable Protection for Many Cancer Patients

Many Americans have returned to their normal lives, with declining COVID-19 cases linked to significant population immunity due to vaccination and prior infection. But, as pharmacists are aware, that is not the case, however, for those whose immune systems are compromised by cancer or cancer treatments. A new study quantifies customized vaccine booster schedules to help those patients achieve greater protection. Here are more details.

NEW HAVEN, CT – Despite the availability of vaccines and other mitigation efforts, the risk of severe COVID-19 remains very real for patients whose immune systems are compromised by cancer or by cancer therapies.

A new study from the Yale School of Public Health and the University of North Carolina at Charlotte proposes a vaccine-boosting strategy to help lower some of those risks. The article in the Journal of the National Cancer Institute points out that current guidance from the national Centers for Disease Control and Prevention (CDC) recommends only that immunocompromised patients receive COVID-19 booster shots "as needed."

“While this flexibility is useful for patients with complex medical conditions, more specific guidance is lacking as to when additional COVID-19 boosting would be most effective,” the authors write.

The researchers write that, instead, the rate at which additional COVID-19 boosters are needed for cancer patients depends on the treatment they are receiving. To determine that, the study quantified the long-term risk of future infection among cancer patients undergoing typical therapies after they received updated Pfizer vaccine booster shots.

With increased boosting, many cancer patients can achieve protection similar to those without cancer, according to the study, which predicts that one out of every three people who forgo boosting will be infected within two years compared to 1 in 20 of those who boost every six months.

 "It turns out that most cancer patients are protected nearly as well as the non-cancer population by COVID-19 boosting," said Yale School of Public Health Professor Jeffrey Townsend, PhD, the study's lead author. "But there is a big exception."

"Some cancer therapies directly attack immune cells," added co-leader Alex Dornburg, PhD, an assistant professor at the University of North Carolina at Charlotte. "This is great for battling blood cancers such as some lymphomas, but the death of immune cells also opens a window not only for COVID-19 infection but for severe infection."

Integrating antibody data following vaccination with long-term antibody data from other coronaviruses in an evolutionary framework, the study team estimated infection probabilities based on antibody levels and calculated cumulative probabilities of breakthrough infection for alternate booster schedules over two years.

The research found that annual boosting reduced risks for targeted or hormonal treatments, immunotherapy, and chemotherapy-immunotherapy combinations similar to the general population. “Patients receiving no treatment or chemotherapy exhibited higher risks, suggesting that accelerated vaccination schedules should be considered,” the authors added. “Patients treated with rituximab therapy posed the highest infection risk, suggesting that a combination of frequent boosting and additional interventions may be warranted for mitigating SARS-CoV-2 infection.”

"These results are based on a typical patient with a typical immune response receiving common therapies," Townsend said. "It remains the case that every patient may have mitigating factors that doctors must consider when advising whether and when an additional COVID-19 booster schedule may be appropriate."