Many Solid Organ Transplant Patients Make No Antibodies to SARS-CoV-2 After mRNA Vaccination

(Reuters Health) – Solid organ transplant patients may not mount an immune response to SARS-CoV-2 mRNA vaccines, a new study in France suggests.

Data from 367 solid organ patients who received two shots of the Pfizer-BioNTech or Moderna mRNA vaccines revealed that the vaccine was well-tolerated but in two out of three patients followed for four weeks, vaccination did not lead to production of antibodies to the SARS-CoV-2 spike protein, according to the report published in the Annals of Internal Medicine.

“Our study included a large number of patients from a single center,” said study coauthor Dr. Nassim Kamar, a professor at Toulouse Purpan University Hospital, Paul Sabatier University and INSERM UMR 1291. We found “a weak humoral response to mRNA-based anti-SARS-CoV-2 vaccine in solid-organ-transplant patients.”

That doesn’t mean the vaccine is useless in solid organ transplant (SOT) patients, Dr. Kamar said in an email. “These patients should be vaccinated,” he added. But also, “barrier measures should be maintained in this population. In France, a third dose of the vaccine is now recommended in SOT patients.”

Dr. Kamar and his colleagues explored the effectiveness of mRNA vaccines in 895 SOT patients who received at least one vaccine shot and had an antibody screen before vaccination, when 19 (2.1%) were found to be seropositive. Only 5 of the 19 had experienced symptomatic COVID-19.

A total of 576 patients had a second vaccine dose by day 28. Before that second dose, 37 of these patients (6.4%) had anti-SARS-CoV-2 antibodies on day 28. In the 367 patients who had follow-up four weeks after the second dose, 124 (33.8%) had produced antibodies by that point.

Tolerance of the mRNA vaccines was “excellent” with only one serious adverse event, a paresthesia of the lower limb in a liver transplant patient, Dr. Kamar and his colleagues report. Kidney function and liver enzymes remained stable in kidney and liver transplant patients before, and 28 days after, the first dose. One kidney transplant patient presented three weeks after the first dose with a 50% increase in serum creatinine level related to drug-induced dehydration. That patient recovered after rehydration and reduction of diuretics. Liver transplant patients showed a better humoral response than patients whose transplants involved other organs.

The researchers suggested that since the vaccine was so well tolerated a better response might be achieved if patients are given an increased antigen dose or a third dose of the vaccine. Further studies “are required to assess both cellular and humoral responses to the vaccines and to determine their long-term protective capacity,” they write.

The researchers recommend that SOT patients use enhanced barrier measures to protect themselves, and that household members and close contacts be vaccinated.

“This larger study confirms a prior, smaller study showing that the majority of organ transplant recipients do not develop antibodies after two doses of mRNA vaccine,” said Dr. John Mellors, chief of the Division of Infectious Diseases at UPMC and the University of Pittsburgh School of Medicine. “The antibody titers were not determined so it is difficult to know how well the ‘responders’ did respond to vaccinations,” he noted

“T cell responses were not measured,” Dr. Mellors said in an email. “It’s not clear whether antibody non-responders won’t be protected (probably not, but if they developed T cell responses they may have some protection), or whether antibody responders will be protected (since) no information was given on antibody titers or whether the antibodies that were elicited do neutralize virus. Overall, other than being a larger study, it does not provide much in the way of new insights.”

SOURCE: Annals of Internal Medicine, online May 24, 2021.

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