Blood Cancer Patients at Risk of COVID-19 Breakthrough Cases

Blood cancer patients have a risk of developing breakthrough COVID-19 cases, even after they are fully vaccinated, new research shows. Researchers at the Università Cattolica del Sacro Cuore in Italy found 113 reported cases out of 4,000 of COVID-19 infection occurring after vaccination, according to the study published in Blood.

The study drew data from an open online registry, EPICOVIDEHA, which collects reports of patients with blood cancers who developed COVID-19 infection. More than three out of four of the breakthrough cases occurred in fully vaccinated people (people who had received one dose of one-dose vaccines such as AstraZeneca, and two doses of two-dose mRNA vaccines such as Moderna or Pfizer). Around 23% had been partially vaccinated, receiving just one dose of an mRNA vaccine, when they became infected with COVID-19.

Within the group of breakthrough cases, 79 patients experienced severe or critical COVID-19 infection, and 75 required hospitalization. After a follow up of 30 days post-COVID-19 diagnosis, 12.4% of patients died, and COVID-19 was deemed the cause of death for all but one of the patients.

Although the mortality rate in patients with breakthrough COVID-19 cases was high, it was still much lower than before vaccines were available, the researchers noted. During the pre-vaccination period of the pandemic, people with blood cancers and COVID-19 had mortality rates ranging from 30% to 50%, depending on type of underlying blood cancer.

Livio Pagano, M.D.

“Before vaccination, if our patients with hematologic malignancies developed COVID-19, they died in a lot of cases,” Livio Pagano, M.D., author of the study and associate professor at the Università Cattolica del Sacro Cuore in Italy, said in a news release from the American Society of Hematology, which publishes Blood. “With these preliminary data, we showed that vaccination is not able to completely protect, but surely it has a strong role in reducing the mortality for COVID-19 for people with blood cancers.”

The study also found that the level of COVID-19 vaccine response was associated with the type of underlying blood cancer. People with myeloproliferative disorders (disorders of red blood cells and platelets) were the least likely to develop COVID-19 after vaccination, and people with lymphoproliferative disorders (disorders of lymphocytes, the white blood cells of the immune system) were the most likely.

Of the 113 breakthrough COVID-19 cases, 80% occurred in people with lymphoproliferative conditions such as chronic lymphocytic leukemia, non-Hodgkin lymphoma, Hodgkin lymphoma, and multiple myeloma.

“Unfortunately, people with lymphomas are more likely to have suppressed immune systems and to develop infections, and it is no different for COVID-19,” Pagano said. “In future studies we will look at the efficacy of additional vaccine doses to understand if they can reduce infection in our patients, especially those with lymphoproliferative disorders.”

Notably, the type of COVID-19 vaccine did not affect the risk of breakthrough cases. Around 70% of the patients in this study received an mRNA vaccine such as the Moderna or Pfizer vaccine, and the remaining patients received the AstraZeneca vector-based vaccine or the Sinovac inactivated vaccine.

As a result, "we must make a great effort to vaccinate as many people as we can,” Pagano said. “We can’t only vaccinate our patients with hematologic malignancies; it is also important to vaccinate their caregivers so we can form a barrier of protection around them, because their own immunity from the vaccine is not enough.”