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Plexision’s COVID-19 antibody immunity test
19, Mar 2021

Transplant recipients show impaired antibody responses to the first mRNA vaccine dose.

On March 15, 2021, Boyarski et al. reported results of antibody testing in 436 transplant recipients who had received the first dose of the Pfizer (BNT162b2) or Moderna (mRNA1273) vaccine. 

  • 52% of these patients received BNT162b2, and 48% received mRNA-1273
  • Antibodies were tested at a median of 20 days after the first vaccine dose.
  • 76 of 436 or 17% of patients had detectable antibodies to the S1 domain of the spike protein of SARS-CoV-2, or the receptor-binding protein component of the S1 domain. 
  • Antibodies were more likely to develop in individuals who were not receiving antimetabolite drugs, who were younger, or had received mRNA-1273. 
  • Antibodies were less likely to develop in patients receiving anti-metabolite anti-rejection drugs, patients who were older, and those who received the BNT162b2
  • Patients were vaccinated at a median interval of 6.2 years after transplantation.
  • Anti-rejection drugs used were Tacrolimus in 83%, Steroids in 54%, CellCept in 66%, Azathioprine in 9%, sirolimus in 4%, Everolimus in 2%. 

The authors acknowledged that these patients had not received the second dose, which led to antibody formation in most vaccinated subjects in the general population, and that non-transplant patients had not been tested at the same time for comparison. 

Thus, transplant patients may remain at risk for COVID-19 infection after the first vaccine dose. 

The authors concluded that antibody responses must be evaluated serially after the second dose. Further, COVID-19 vaccination may promote immunity in T- and B-cells in patients without strong antibody responses.  

Source: JAMA Network

About Plexision’s COVID-19 immunity tests, PlexCOVID-19 :

  • is a lab-developed blood test that measures T-cell-mediated immunity to the SARS-CoV-2 spike protein. 
  • The test is performed at Plexision’s reference laboratory is CLIA-approved and cGMP-compliant.  
  • Some caregivers have used this test to measure T-cell immunity to COVID-19 infection in patients who have not made antibodies after COVID-19 vaccination. 
  • The test predicts the likelihood of COVID-19 infection requiring hospitalization, whether increased or decreased. 


Plexision also performs antibody testing for COVID-19 infection. These tests measure IgG antibodies to the spike protein and its receptor-binding domain. To learn more, please call Plexision at 412-224-2507 or visit


Plexision develops cellular biomarkers for personalized diagnosis and drug development in solid organ transplantation and immunological disorders. We also pioneer in R&D projects centered on integrating biomarker targets in all phases of drug development, from preclinical to post-marketing. Plexision’s technology can be adapted to

  • - Assess disease risk for several immunological disorders.
  • - Predict the success of a drug for a specific patient.
  • - Develop dosing recommendations for new immunological drugs.

Our state-of-the-art laboratory is CLIA-certified and located in Pittsburgh, PA.