Understanding COVID-19 Vaccine Response in Transplant Patients

Lung and heart transplant patients display delayed and defective responses to the first two COVID-19 vaccine doses but significantly augmented response to a third dose, according to a study published in the journal published in Open Forum Infectious Diseases. The human coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19. For immunocompromised individuals, data on the immune responses to vaccines against COVID-19 infection including messenger RNA (mRNA) vaccines, are limited.

Transplant recipients must take life-long immunosuppressive medications to prevent rejection, but these drugs can compromise the effectiveness of vaccines (1^✔ ✔Trusted Source
Update on Covid-19: vaccines, timing of transplant after COVID-19 infection and use of positive donors

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To assess the strength, durability, and changes in responses among transplant recipients, researchers conducted a study to compare the immune response to the COVID-19 vaccine among healthy individuals and transplant patients.

It included 18 lung transplant recipients, 17 heart transplant recipients, 7 non–lung-transplanted patients with cystic fibrosis, and 12 healthy individuals (all without SARS-CoV-2 infection).

Extra COVID-19 Vaccine Dose May Help Protect Transplant Patients

Researchers measured blood levels of antibodies against different variants of SARS-CoV-2 at various time points after a primary mRNA COVID-19 vaccination series. Among healthy controls, strong antibody responses to the SARS-CoV-2 spike protein arose immediately following vaccination and displayed cross-neutralization against all variants (2^✔ ✔Trusted Source
Delayed and Attenuated Antibody Responses to Coronavirus Disease 2019 Vaccination With Poor Cross-Variant Neutralization in Solid-Organ Transplant Recipients—A Prospective Longitudinal Study

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Among heart and lung transplant recipients, increases in antibody concentrations occurred only gradually following the first two vaccine doses, and cross-neutralization was less than 10% against variants (and completely absent against the Omicron variant).

Most (73%) transplant recipients developed a significant response after the third vaccine dose, however, reaching levels comparable to those of healthy controls, with improved but lower level responses against Beta, Gamma, and Omicron variants. Responses of non–lung-transplanted cystic fibrosis patients paralleled those of healthy controls.

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These findings highlight that effective protection of most transplant recipients is achievable but requires the recommended additional doses of vaccine. However, for most individuals, cross-protection of their responses to currently circulating immune-evasive SARS-CoV-2 variants is attenuated (3^✔ ✔Trusted Source
Immune responses following 3rd and 4th doses of heterologous and homologous COVID-19 vaccines in kidney transplant recipients

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The multiple subsequent vaccine doses recommended for transplant recipients are likely critical for maintaining immunity. The next steps are to analyze the cellular immune responses of solid organ transplant recipients over the same longitudinal time frame.

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References:

1. Update on Covid-19: vaccines, timing of transplant after COVID-19 infection and use of positive donors - (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9992272/)
2. Delayed and Attenuated Antibody Responses to Coronavirus Disease 2019 Vaccination With Poor Cross-Variant Neutralization in Solid-Organ Transplant Recipients—A Prospective Longitudinal Study - (https://academic.oup.com/ofid/article/10/8/ofad369/7239317)
3. Immune responses following 3rd and 4th doses of heterologous and homologous COVID-19 vaccines in kidney transplant recipients - (https://www.thelancet.com/journals/eclinm/article/PIIS2589-5370(22)00372-8/fulltext)

Source-Eurekalert