Stem cell transplant recipients respond well to COVID-19 vaccination, study finds
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Hematopoietic stem cell transplant recipients responded well to the Pfizer-BioNTech COVID-19 vaccine in a single-center study, with 83% having an antibody response after two doses, researchers reported in JAMA Network Open.
For their study, Amandine LeBourgeois, MD, a physician in the hematology department at Nantes University Hospital in Nantes, France, and colleagues enrolled 121 hematopoietic stem cell transplant (HSCT) recipients with no clinical history of COVID-19 and no active graft-versus-host disease more than 3 months after transplant.
Vaccination occurred from Jan. 20 through Aug. 17. The researchers tested antibody responses twice at the time of the second dose and then 1 month later. They considered titers greater than or equal to 0.8 U/mL to be positive, with the highest value being greater than 250 U/mL.
Of the 121 patients enrolled, for had asymptomatic COVID-19 and were excluded from the study. The 117 remaining patients had a mean age of 57 years (interquartile range [IQR] = 20-75 years), and 60% were male (n = 70). The median time between vaccine doses was 22 days (IQR = 16-37 days).
At the time of the second dose, 54% of patients (n = 63) had a positive anti-spike antibody response, LeBourgeois and colleagues reported. IgG titers among those with responses were 15.8 U/mL and ranged from 0.9 U/mL to more than 250 U/mL, they said. Four patients (3%) exceeded the 250 U/mL value.
The next antibody test came a median of 35 days (IQR = 18-77 days) after the second dose and was positive in 97 patients (83%). Of the 97 patients, 72 (62%) reached the highest antibody titer.
According to the researcher, the absence of an antibody response was associated with haplotransplants, HSCT procedure occurring within the last year, lymphopenia, and recent immunosuppressive treatment or chemotherapy at the time of vaccination.
“This is much more than the 54% rate of seroconversion that has been reported after two doses in solid-organ transplant recipients and compares favorably with data obtained in patients treated for solid tumors, for whom a 95% of response rate was obtained after the second dose,” the authors wrote. “This humoral response is, however, only one marker of immunity, and allogeneic HSCT recipients will likely have differences in T cell reactivity that should be explored.”
In a related editorial, Joshua A. Hill, MD, a physician in the vaccine and infectious disease division at the Fred Hutchinson Cancer Research Center in Seattle, said that available data demonstrate that administration of COVID-19 vaccines should be a priority after allogeneic HSCT recipients. However, vaccines are just one aspect of a broader strategy.
“For now, patients who are in the first year after HCT or remain otherwise immunosuppressed should regard SARS-CoV-2 as a serious threat despite vaccination and follow behaviors with which they are already familiar: avoiding high-risk exposures, masking, hand hygiene, and ensuring that their close contacts are vaccinated,” Hill wrote. “Strategies to better protect [HSCT] recipients from SARS-CoV-2 infection remain a high priority for the medical community.”
References:
LeBourgeois A, et al. JAMA Netw Open. 2021;doi:10.1001/jamanetworkopen.2021.26344.
Hill JA, et al. JAMA Netw Open. 2021;doi:10.1001/jamanetworkopen.2021.27454.
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