{'fraction_non_alphanumeric': 0.05377574370709382, 'fraction_numerical': 0.05091533180778032, 'mean_word_length': 4.4485981308411215, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Immunogenicity of the BNT162b2 mRNA Vaccine in Heart Transplanted Patients-A Prospective Cohort Study.

AIMS
To assess the short-term immunogenicity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccine in a population of heart transplanted (HTx) recipients.


METHODS
A prospective single-center cohort study of HTx recipients who received a 2-dose SARSCoV-2 mRNA vaccine (BNT162b2, Pfizer-BioNTech). Whole blood for anti-spike IgG (S-IgG) antibodies were drawn at days 21-26 and at days 35-40 after the first vaccine dose. Geometric mean titers (GMT) ≥50 AU/mL were interpreted positive.


RESULTS
Included were 42 HTx recipients at a median age of 61 (IQR 44, 69) years. Median time from HTx to the 1st vaccine dose was 9.1 (IQR 2.6, 14) years. Only 15% of HTx recipients demonstrated the presence of positive S-IgG antibody titers in response to the 1st vaccine dose (GMT 90 (IQR 54, 229) AU/mL). Forty-nine percent of HTx recipients induced S-IgG antibodies in response to either the 1st or the full 2-dose vaccine schedule (GMT 426 (IQR 106, 884) AU/mL). Older age (68 (IQR 59, 70) years vs. 46 (IQR 34, 63) years, p = 0.034) and anti-metabolites-based immunosuppression protocols (89% vs. 44%, p = 0.011) were associated with low immunogenicity. Importantly, 36% of HTx recipients who were non-responders to 1st vaccine dose became S-IgG seropositive in response to the 2nd vaccine dose.


DISCUSSION
Approximately a half of HTx recipients did not generate S-IgG antibodies following SARSCoV-2 2-dose vaccine. The generally achieved protection from SARSCoV-2 mRNA vaccination should be regarded with caution in the population of HTx recipients. The possible benefit of additive vaccine doses should be further studied.