- French researchers found that 83% of stem cell transplant recipients developed high antibody levels after receiving both shots of the Pfizer COVID-19 vaccine
- More than half of study participants developed an appropriate antibody response after just one shot
- Stem cell transplant recipients often get a type of blood cancer, making them particularly vulnerable to the virus.
- Previous studies found people with blood cancer developing lower COVID-19 antibody levels from vaccines
Despite previous concerns, COVID-19 vaccines are likely to be effective in people who have received stem cell transplants, a new study has found.
Researchers at Nantes University Hospital in France used antibody testing to find out whether people who had received transplants were producing an appropriate antibody response to the shots.
Previous studies had shown people with blood-based cancers – who often receive stem cell transplants as a treatment – did not produce high antibody levels after vaccination.
The team found that 64 percent of stem cell transplant recipients were developing an antibody response after receiving one dose and that 83 percent were doing so after both doses.
French researchers found that 54% of stem cell transplant recipients developed high antibody responses after one shot of the virus (middle bar), and 83% after both shots (right bar).
The researchers, who published their findings Tuesday in the JAMA Network Open, gathered 117 participants who had recently received allogeneic stem cell transplantation and had no history of COVID-19.
Many stem cell transplant recipients are receiving treatment for blood-related cancers such as leukemia.
Transplants are used to replace blood cells that are damaged while a person receives chemotherapy or other treatments that can destroy the cells.
Allogeneic means that the stem cells come from the donor bone marrow instead of the patient’s bone marrow.
The transplant can also help replace blood cells that work as part of a person’s immune system to fight off infections and viruses.
Each patient was given a complete two-shot regimen of the Pfizer-BioNTech vaccine.
Participants were tested for antibodies before receiving any vaccine shots, the day they received the second shot — testing the generation of antibodies after the first shot — and about 35 days after getting the second jab.
The team found that after the first shot, 54 percent of the participants — 63 out of 117 — had developed an appropriate antibody response.
After two shots, 83 percent, or 97 out of 117, were found to develop high antibody responses.
Of those who received both shots, only 62 percent reached the highest classification of antibody levels, however, reaching general population levels after both shots.
The results are promising, and could mean that many people with stem cell transplants may be just as protected from the virus as the general population.
Blood cancer patients are significantly more likely to die from COVID, and previous studies have found that they are less likely to develop antibodies to the vaccine.
While scientists have yet to develop a solid link between higher antibody levels and greater protection against the virus, they do believe there is a link.
Despite the potential for low protection, cancer patients are still recommended to receive the COVID-19 vaccine as soon as possible.
Currently in the US, more than 63 percent of the total population has received at least one shot of the vaccine and 54 percent are fully vaccinated.
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