COVID-19 vaccination stimulates immune response in seniors, but fails in many blood cancer patients, Pitt studies find

As the nation’s vaccination race accelerates, a big question remains: How well do the shots work in people with weakened immune systems?

University of Pittsburgh researchers took a step toward an answer by measuring the antibody response in elderly residents of long-term care facilities and in blood cancer patients who got the Moderna or Pfizer vaccine.

All 70 elderly volunteers had measurable, although varied, levels of disease-fighting antibodies, the researchers said Friday during a Zoom news conference.

In contrast, almost half of the 67 patients with blood cancers did not produce any antibodies. The response rate was even worse in patients with chronic lymphocytic leukemia, a slow-progressing malignancy of the blood and bone marrow. Only 3 out of 13 made antibodies, even though most of them were not undergoing cancer therapy that could suppress or damage their immune systems.

The response was “strikingly low,” said Mounzer Agha, lead author of the cancer study and a hematologist at the University of Pittsburgh Medical Center (UPMC). “We’re still working to determine why people with hematologic [blood] malignancies have a lower antibody response, and if this low response also extends to patients with solid tumors.”

While the elderly volunteers all produced antibodies, the researchers do not know what level insures protection from the coronavirus, or for how long.

It is clear, however, that older adults who get the seasonal flu shot generally have a less robust antibody response than younger people, and the antibodies tend to fade over the course of several months. The second-line immune defense, which involves T cells, also is known to weaken in old age.

The pandemic has taken a disproportionately large toll on people over age 65, especially those in nursing homes. Only 1% of the U.S. population is in long-term care, but they account for 33% of the nation’s COVID-19 deaths, noted David A. Nace, lead author of the geriatric study and chief medical officer of UPMC Senior Communities.

Infections and deaths have fallen sharply as immunization rates have risen in long-term care facilities, but Nace and other experts are grappling with how to safely resume visitation, social activities, and communal dining.

“We should proceed with reopening. We should start to decrease the negative impact of isolation,” Nace said. “But we still need to mask and social distance, and we still need to test.”

Nace said some nursing home residents have tested positive for COVID-19 after vaccination, but were asymptomatic. “That is really telling us the importance of vaccination,” he said.

Any resident with COVID-19 symptoms should be tested immediately, regardless of their vaccination status, he said, “because prompt treatment with monoclonal antibodies could prevent hospitalization and death.”

Cancer survivors who are long done with treatment, as well as newly diagnosed patients undergoing treatment, are at high risk for severe COVID-19, studies show. That’s why the American Association for Cancer Research recommended in December that cancer patients be considered for priority access to vaccines.

Ghady Haidar, an infectious disease and transplant specialist at UPMC, said physicians should counsel their immunocompromised patients that COVID-19 vaccination may not adequately protect them.

“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,” he said.

The results also point to the importance of “herd immunity” — building enough protection through vaccination or natural infection that even people who don’t respond to the vaccine or decline to get it still won’t be exposed to the virus.

“Vaccination rates are far less than desirable” among long-term care workers, Nace said. “This helps us to continue to work on those staff members to get the vaccine.”

Both Pitt studies, which have not yet been independently reviewed, are posted on medRxiv, a website for sharing data before publication in a journal. The Pitt researchers plan to expand their work to evaluate vaccine response in other immunocompromised people, including those with HIV infection, organ transplants, and autoimmune diseases.

Haidar said the Pitt researchers thought it was important to release the information before peer review to “alert the world” and “emphasize to patients like this that you may not be fully protected.”

Staff writer Stacey Burling contributed to this article.