Studies Show Low Immune Response to COVID-19 Vaccine in Cancer Patients

About half of Americans have received at least the first dose of a COVID-19 vaccine. Among seniors age 65 years and older, 75% are fully vaccinated, according to the Centers for Disease Control and Prevention (CDC).

In fact, many places have already lifted COVID-19 restrictions: capacity limits, curfews, quarantining after traveling. Even mask-wearing has become optional — President Joe Biden ceremoniously took his off with the news from the CDC that people who are fully vaccinated can resume activities without wearing a mask or physically distancing.

However, several studies have shown that people with blood cancer are at an increased risk of COVID-19 vaccine failure.

A recent analysis of patients with blood cancer at the University of Pittsburgh Medical Center (UPMC) Hillman Cancer Center found that approximately three weeks after their second dose of the Pfizer or Moderna vaccine, nearly half had not produced any antibodies.

The results were even worse for patients with chronic lymphocytic leukemia (CLL). Only three in 13 patients produced measurable antibodies, even though 70% weren’t undergoing any form of cancer therapy that would impact their immune system. 

The findings prompted clinicians at the UPMC and University of Pittsburgh School of Medicine to issue a statement in medRxiv (an online distributor of complete but unpublished and non-peer reviewed manuscripts) urging patients with blood cancers and those who interact with them to continue wearing masks and practicing social distancing even after they are fully vaccinated. 

“As we see more national guidance allowing for unmasked gatherings among vaccinated people, clinicians should counsel their immunocompromised patients about the possibility that COVID-19 vaccines may not fully protect them against SARS-CoV-2,” senior author Ghady Haidar, MD, a transplant and infectious diseases physician at UPMC, said in a news release. “Our results show that the odds of the vaccine producing an antibody response in people with hematologic malignancies are the equivalent of a coin flip.”

The results echo the findings of other studies, including one published in the hematology journal Blood that found that patients with CLL may not be optimally protected after receiving Pfizer’s COVID-19 vaccine.

In the study, just 39.5% of the 167 patients with CLL had an adequate antibody response after the second vaccine dose. Those undergoing treatment at the time of vaccination had the lowest rate (16%), followed by 55.2% among those who were in the “watch and wait” period, and 79.2% among those who had obtained clinical remission.

The findings should not discourage patients with cancer from getting the vaccine, said lead study author Yair Herishanu, MD, an associate professor in hematology at the Tel Aviv Sourasky Medical Center in Israel.

“Even though response rates were not optimal, patients with CLL should still get the vaccine and, if appropriate, it may be better to do so before CLL treatment starts, although the disease itself may affect the response,” he said in a news release. “Equally important is continuing to take precautions — wearing a mask, avoiding crowds, keeping a social distance, and being sure close contacts get vaccinated against COVID-19.”

However, a study by the Leukemia & Lymphoma Society earlier in 2021 found that only half of patients and survivors of blood cancers were “very likely” to get a COVID-19 vaccine. The most common reasons were fear of side effects and a belief that the vaccines had not been tested properly. There is no evidence that the vaccines are less safe in patients with cancer.

“My approach would be to [those patients], say ‘OK, well, without a vaccine, my patients had 0 percent chance of being protected against the virus,’” Mikkael A. Sekeres, MD, a spokesperson for the American Society of Hematology, said in an interview with Patient Power. “With a vaccine, they have somewhere between 20 percent and 40 percent chance of being protected against the virus. Given the incredibly low side effect profile of these vaccines, I’ll take 20 percent to 40 percent protection versus 0 percent protection any day.”

The CDC does not currently recommend antibody testing for those who are immunocompromised to see if the vaccination worked, nor revaccination for those who received vaccines during chemotherapy or treatment with other immunosuppressive drugs. Instead, the agency says healthcare providers should counsel patients about the potential for reduced immune responses and the need to continue to follow current guidance to protect themselves.

Dr. Sekeres, who is chief of the Division of Hematology at the Sylvester Comprehensive Cancer Center at the University of Miami Miller School of​ Medicine, said that while the studies published so far are informative, they include only a small number of patients. He said there are still several unanswered questions, such as how long the response to the vaccine lasts, whether a booster will be necessary at some point, or if even a small immune response is enough to protect someone from the virus. He urged people with cancer not to lose hope.

“What we've seen on the bright side are scientific advancements that we've never seen before in the history of vaccine development — the rapidity with which we were able to develop vaccines and … with which we're vaccinating people,” he said. “I would predict that as we're going into the summer and then into the fall, we're going to be at a point where people can feel safer with going back to their normal lives.”

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