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P16.16 Seroconversion in liver and intestine transplant patients after one, two or three doses of adenoviral vector vaccines against SARS-CoV-2. Single center experience in Argentina

Abstract

Seroconversion in liver and intestine transplant patients after one, two or three doses of adenoviral vector vaccines against SARS-CoV-2. Single center experience in Argentina

Silvina Yantorno2, Virginia Gentilini2, Renata Curciarello1, Gaston Rizzo1, Malena Ferreyra Compagnucci1, Lorena Tau3, Laura Delaplace3, Victoria Atencio2, Valeria Descalzi2, Gabriel Gondolesi2, Guillermo Docena1, Martin Rumbo1.

1Instituto de Estudios Inmunológicos y Fisiopatológicos, Universidad Nacional de La Plata, La Plata, Argentina; 2Hospital Universitario Fundación Favaloro. Instituto de Medicina Traslacional, Trasplante y Bioin, Fundacion Favaloro, Buenos Aires, Argentina; 3Laboratorio de Salud Publica, Universidad Nacional de La Plata, La Plata, Argentina

Introduction: The capacity of different anti-SARS-CoV-2 vaccines to elicit immune response is not equivalent in the healthy population compared to chronically immunosuppressed patients. Most of the reports available so far to assess the effects of anti-SARS-CoV-2 vaccines on solid organ transplant recipients (SOTR) were performed using mRNA-based vaccines. The majority of the vaccines used so far in our country are adenovirus-vector vaccines (Sputnik V and Covishield/AstraZeneca-Oxford).  Goal:  to assess the seroconversion after vaccination with the non-replicative vector-based vaccines after transplantation.

Methods: Seventy-nine patients of liver transplant (79), combined liver-intestine transplant (1) or intestinal/multivisceral transplant (4) receiving their first vaccine dose between March and June 2021 were included, mean age of was 55,6 years old (range 18-75,9; 71% males). All patients have a post-transplant follow up longer than 1 year (median 6 years, range 1-25 years). Samples after second and third doses were also analyzed, in all cases obtained at least three weeks after last vaccination. Patients serological status was evaluated using three different anti-S commercial ELISA kits and an in-house made anti-N ELISA. Patients with previous PCR-confirmed COVID19 were excluded.

Results: We found that 28,1% of patients (9 out of 32) seroconverted after a single dose of Sputnik V (8 out of 21) or Covishield (1 out of 11), whereas 18 out of 27 (66,7%)  seroconverted after second dose of Sputnik V (7 out of 10) or Covishield (11 out of 17) and 12 out of 13 seroconverted after a third dose (92%), most of them have received two doses of Sputnik V and receiving Moderna, Pfizer or Covishield as third dose. There is a significant difference in the proportion of seroconversion between the groups that received one dose or two doses of vaccine (p<0.005, Chi square test) whereas the difference is not significant between groups receiving two and three doses (p=0.08, Chi square test). The comparison between responder’s and non-responders to the single dose vaccine showed no differences in either patient age, post-transplant time, days after vaccination, presence of comorbidities and maintenance immunosuppressive therapy.

Conclusion: Despite having a lower seroconversion rate compared to the general population, viral-vector vaccines benefit SOTR patients increasing the seroconversion rate using at least two doses of vaccine. These results support the concept of developing tailor-made vaccination guidelines for this specific population.

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