ABSTRACT
BACKGROUND: 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 to assess the effects of anti-SARS-CoV-2 vaccines on solid organ transplant recipients (SOTR) were performed using mRNA-based vaccines. OBJECTIVE: This study aims to assess the seroconversion rate in a cohort of liver and liver- intestinal transplant patients after vaccination with the non-replicative vector-based vaccines after transplantation used in our country, Argentina (rAd26-rAd5 (Sputnik V) and ChAdOx11 nCoV-19 (AZD1222) (Astra Zeneca-Oxford). METHODS: One hundred and three (103) liver and liver-intestinal transplant recipients were enrolled. Patients with previous PCR-confirmed COVID19 were excluded, therefore 77 were finally included for analysis; 75 were liver transplant recipients, 1 was a combined liver-intestine and 1 a multivisceral transplant. All received their first vaccine dose between March and June 2021; 66,2% males, and the mean age was 56,3 years. All patients have a post-transplant follow up longer than 1 year (mean 6.6 years, median 5 years, range 1-23 years). Immune response after first, second and third doses were determined using three different spike (S)-S commercial ELISA kits and an in-house made anti nucleocapsid-protein (N) ELISA. RESULTS: Following the three doses, 57.1 % (44/77) of the patients seroconverted, while 33/77 (42.9 %) did not present anti-SARS-CoV-2 antibodies. The seroconversion rate was different for each dose. We found that 5/27 (18.5 %) of transplant patients seroconverted after a single dose; 18/29 pts (62.0 %) had anti-SARS-Cov-2 antibodies after the second doses; and 18/21 pts (85.7 %) reached the seroconversion after the third doses. The proportion of seroconversion was significantly increased in the second doses regardless the response observed after the first doses (p = 0.012, Fisher's exact test), particularly when two doses of ChAdOx11 vaccine was administrated (p = 0.040, Chi-square). However, the comparisons of seroconversion rate between Sputnik V and ChAdOx11 vaccines showed no differences after the different vaccination doses. No significant statistical difference in patientÌs gender, age, comorbidities, type of vaccine, post-transplant, or maintenance immunosuppressive therapy was found between responders and non-responders. 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. This analysis provides further support to safety and efficacy of viral-vector vaccines in liver and liver-intestine transplant patients.
ABSTRACT
Heterologous vaccination against coronavirus disease 2019 (COVID-19) provides a rational strategy to rapidly increase vaccination coverage in many regions of the world. Although data regarding messenger RNA (mRNA) and ChAdOx1 vaccine combinations are available, there is limited information about the combination of these platforms with other vaccines widely used in developing countries, such as BBIBP-CorV and Sputnik V. Here, we assess the immunogenicity and reactogenicity of 15 vaccine combinations in 1,314 participants. We evaluate immunoglobulin G (IgG) anti-spike response and virus neutralizing titers and observe that a number of heterologous vaccine combinations are equivalent or superior to homologous schemes. For all cohorts in this study, the highest antibody response is induced by mRNA-1273 as the second dose. No serious adverse events are detected in any of the schedules analyzed. Our observations provide rational support for the use of different vaccine combinations to achieve wide vaccine coverage in the shortest possible time.