More than 85% of cancer patients developed COVID-19 antibodies after a second dose of Pfizer

Cancer patients are likely to develop protection against COVID-19 when they receive two doses of a vaccine, a new study suggests.

Researchers found that, out of 232 patients who were vaccinated with the Pfizer-BioNTech shot, 29 percent developed antibodies compared to 84 percent of the healthcare workers.

But, after a second dose of the vaccine, 86 percent of patients tested positive for Covid-fighting antibodies. 

As research continues on vaccine effectiveness for cancer patients – who are at high risk for being infected with COVID-19 and falling severely ill – some scientists have suggested booster shots as a way to ensure full protection.

Cancer patients do develop antibodies after being vaccinated against Covid, a new study finds. Pictured: A cancer patient receives her shot at a center in Louisville, Kentucky

Cancer patients are highly vulnerable to Covid.

Many common treatments for these patients can weaken the immune system, making cancer patients more likely to have a severe Covid case if they are infected.

Some specific types of cancer, including lung cancer and cancers of the blood or bone marrow, have been identified as especially high risk factors.

As a result, doctors and public health experts consider cancer patients to be a priority group for vaccination.

But the clinical trials for Covid vaccines did not include these patients, leading to limited data on how well the vaccines work for this group.

Scientists have worried that the same immune system weakness – also called immunosuppression – that causes cancer patients to be more vulnerable to Covid may also prevent the vaccines from working.

Past studies on the topic have shown that the Covid vaccines can provide cancer patients with some immunity, although the level of protection may vary based on cancer type and treatment regimens.

The new study – published Thursday in JAMA Oncology – focused on the Pfizer vaccine, which was the first to be approved in Israel.

After the Pfizer vaccine’s approval in early January, the country kicked off a mass vaccination campaign focusing on healthcare workers and high-risk populations, including cancer patients.

The researchers studied cancer patients receiving treatment at the Division of Oncology of Rambam Health Care Campus, a major medical center in northern Israel, treating patients from across the country.

The patient group included 232 cancer patients with solid tumors.

In addition to the cancer patients, the researchers also studied a group of 261 healthy healthcare workers with a similar age range to the cancer patient group.

All patients were vaccinated in January 2021, with tests and follow-ups through March.

The researchers collected blood samples from their patients after both vaccine doses and tested these samples for antibodies – those immune system molecules that indicate a patient has protection against a disease.

The second antibody test occurred two weeks after patients’ second dose, when vaccine recipients are considered to be fully vaccinated.

Cancer patients may be slower to build up immunity after vaccination. Pictured: A cancer patient gets her shot at a clinic in Louisville, Kentucky

Cancer patients may be slower to build up immunity after vaccination. Pictured: A cancer patient gets her shot at a clinic in Louisville, Kentucky

After their first dose, only 29 percent of the cancer patients tested positive for Covid antibodies. Meanwhile, 84 percent of the healthcare workers tested positive after their first dose.

After their second dose, however, far more of the cancer patients had developed immunity with 86 percent testing positive for antibodies.

These results indicate that cancer patients may build up immunity more slowly after vaccination, the researchers wrote.

The researchers also found that certain treatments and cancer types may make Covid immunity less likely. 

For example, breast cancer patients made up 29 percent of those who did not develop Covid antibodies.

In the group of cancer patients who were antibody-negative, 74 percent were going through chemotherapy. This type of treatment is known to weaken patients’ immune systems.

Still, 55 percent of the patients who tested positive for antibodies were also going through chemotherapy. 

The researchers suggest that more work is needed to identify specific types of chemotherapy that may be more likely to inhibit antibody production. 

The cancer patients had mild vaccine side effects including sore arms and fatigue

The cancer patients had mild vaccine side effects including sore arms and fatigue

The cancer patients had mild side effects, in line with common vaccine side effects for the general population.

The most common side effect was a sore arm, reported by 69 percent of patients. 

Other common side effects included fatigue (24 percent), muscle and joint pain (13 percent), and headaches (10 percent).

These mild side effects – combined with the antibody test results – indicate that cancer patients can safely get vaccinated.

More research is needed, however, to determine if these vulnerable patients may need extra vaccine doses to boost their immune systems.

In France, healthcare providers are routinely giving third doses to organ transplant recipients and other patients with weakened immune systems.

Some booster shot studies are underway in the U.S. as well, though scientists believe there should be a more concerted, national effort to investigate this issue.

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