Nearly 85% of stem cell transplant recipients develop high antibody levels after two doses of Pfizer's Covid vaccine 

• French researchers found that 83% of stem cell transplant recipients develop high antibody levels after receiving both shots of the Pfizer COVID-19 vaccine
• More than half of participants in the study developed appropriate antibody responses after only one shot
• Stem cell transplant recipients often have a type of blood cancer, leaving them especially vulnerable to the virus
• Previous studies found that those with blood cancers are developing low COVID-19 antibody levels from the vaccines

Despite previous worries, COVID-19 vaccines are likely effective in people who received stem cell transplants, a new study finds.

Researchers from Nantes University Hospital in France used antibody testing to find whether or not those who had received the transplants were generating an appropriate antibody response to the shots.

Previous studies had shown people with blood based cancers - who often receive stem cell transplants as treatment - do not produce high antibody levels after inoculation.

The team found 64 percent of stem cell transplant recipients were developing antibody responses after receiving one dose and 83 percent were doing so after both doses.

Researchers, who published their findings in JAMA Network Open on Tuesday, gathered 117 participants who had received allogenic stem cell transplants recently and had no history of COVID-19.

Many stem cell transplant recipients are receiving the treatment due to a blood related cancer like leukemia. 

The transplants are used to replace blood cells that are damaged while a person received chemotherapy or other treatment that can destroy the cells.  

Allogenic means the stem cells come from donor bone marrow rather than from the patient's bone marrow.

Transplants can also help replace blood cells that work as a part of a person's immune system to fight off infections and viruses. 

Each patient was given the full two-shot regimen of the Pfizer-BioNTech vaccine.

Participants were then tested for antibodies before receiving any vaccine shot, on the day they received the second shot - testing the generation of antibodies after the first shot - and around 35 days after getting the second jab.

The team found that after the first shot, 54 percent of participants - 63 of the 117 - had developed appropriate antibody responses.

After two shots, 83 percent, or 97 out of 117, were discovered to have developed high antibody responses.

Only 62 percent of those who received both shots reached the highest classification of antibody levels, though, which as the levels the general population reaches after both shots. 

The results are promising, and could mean that many of those with stem cell transplants could be just as protected against the virus as against the general population.

Blood cancer patients are significantly more likely to die from Covid, and previous studies found that they are less likely to develop antibodies from the vaccine.

While scientists have yet to develop a tangible connection between higher antibody levels and more protection against the virus, though they do believe there is a link. 

Despite the potential of receiving little protection, cancer patients are still recommended to get the COVID-19 vaccine as soon as they can.

Currently in the U.S., more than 63 percent of the total population has received at least one shot of a vaccine and 54 percent of people are fully vaccinated.