Although a second COVID-19 vaccine dose significantly increased the rate of seroconversion in most patients with immunocompromised conditions, seroconversion rates remained decreased and significantly differed among solid organ transplant (SOT) recipients. These findings were published in BMJ.
In this systemic review and meta-analysis, researchers pooled data studies published between December 2020 and November 2021 that assessed the efficacy of COVID-19 vaccination among patients who were immunocompromised. The primary outcomes were the rates of seroconversion after receipt of the first and second doses of a COVID-19 vaccine, which were calculated via frequentist random effects meta-analysis.
Among a total of 82 studies included in the analysis, 77 (94%) used mRNA COVID-19 vaccines, 16 (20%) used viral vector vaccines, and 4 (5%) used inactivated whole virus vaccines. Of the included studies, the risk of bias was decreased in 63 and moderate in 19.
The researchers reviewed 73 studies that assessed seroconversion after a second COVID-19 vaccine dose in patients (n=9974) who were immunocompromised. The pooled risk ratio (RR) was most decreased among those who were SOT recipients (RR, 0.39; 95% CI, 0.32-0.46; I2=92%), followed by those with hematologic cancers (RR, 0.63; 95% CI, 0.57-0.69; I2=88%). Compared with these patients, seroconversion was increased among those with immune mediated inflammatory disorders (RR, 0.75; 95% CI, 0.69-0.82; I2=92%), with the greatest increase observed in those with HIV infection (RR, 1.00; 95% CI, 0.98-1.01; I2=0%). Of note, the rate of seroconversion increased significantly by 1.64-fold between receipt of the first (RR, 0.55; 95% CI, 0.65-0.90) and second (RR, 0.90; 95% CI, 0.88-0.93) COVID-19 vaccine doses among patients with solid cancer.
In regard to patients who were SOT recipients, the researchers found that seroconversion rates significantly differed between the first and second vaccine doses. In SOT recipients, seroconversion rates were most increased among those with SOTs involving the liver (RR, 0.66; 95% CI, 0.55-0.80), followed by kidney (RR, 0.34; 95% CI, 0.26-0.45), lung (RR, 0.25; 95% CI, 0.17-0.37), and heart (RR, 0.16; 0.11-0.25). Of these patients, the subgroup effect was statistically significant (P <.001).
There was significant variation in seroconversion rates observed after a second vaccine dose in patients with hematologic cancer and SOT recipients. Owing to these findings, the researchers suggested that these patents may benefit from a third COVID-19 vaccine dose.
Limitations included the observational design of the included studies, as well as inconsistencies in regard to the definition of immunocompromised and type of immunoassays used in each study.
According to the researchers, “additional strategies, such as the administration of a third vaccine dose to the conventional [2-dose] regimen for mRNA COVID-19 vaccines would be warranted to confer [increased] seroprotection for patients [with immunocompromised conditions].”
Lee ARYB, Wong SY, Chai LYA, et al. Efficacy of COVID-19 vaccines in immunocompromised patients: Systemic review and meta-analysis. BMJ. Published online March 2, 2022. doi.10.1136/bmj-2021-068632