RESUMO
BackgroundImmunizations among vulnerable population, including solid organ transplant recipients (SOT), present suboptimal responses at vaccination and over time. We investigated safety and immunogenicity of the BNT162B2 mRNA COVID-19 vaccine in 34 SOT young adults as compared to 36 healthy controls (HC). Methodsimmunogenicity was measured through the analysis of anti SARS-CoV2 IgG Antibodies and antigen specific CD4 T cells (CD40L+), detected by flow cytometry before vaccination, 21 days after priming (T21), 7 days after booster dose (T28) and 2-4 months after priming (T120). Baseline T and B cell immune phenotype was deeply investigated. The safety profile was investigated by close monitoring and self-reported diary. ResultsAnti-S and anti-Trimeric Ab responses were significantly lower in SOT vs HC at T21 (p<0.0001) and at T28 (p<0.0001). Ten out of 34 SOT (29%) at T28 and 3 out of 33 (9%) at T120 had undetectable SARS-CoV-2 IgG. The analysis of SARS-CoV-2 specific CD4 T cells showed lower CD40L expression after in vitro stimulation in SOT compared to HC. Lower frequencies of memory B cells were found in patients not responding to vaccination. Lack of seroconversion was higher in patients treated with mycophenolate (p=0.0005). The vaccination was safe and well tolerated. Only short-term adverse events, were reported and no hospitalization or graft rejection were observed after vaccinations. ConclusionsThese data show that SOT have a suboptimal immune response following mRNA vaccinations as compared to HC. Alternative strategies should be investigated to improve the immunization against SARS-CoV-2 in these patients.
RESUMO
Many countries are currently facing high mortality caused by the circulation of SARS-CoV-2 among the elderly not yet vaccinated. Vaccine shortage poses relevant challenges to health authorities, called to act in a timely manner, and with scarcity of vaccine, and data. We have developed a model for estimating of the impact of vaccination on the mortality of the elderly following a schedule of mRNA SARS-CoV-2 vaccine that prioritize first dose administration, as alternative to the standard schedule of two doses administered 3 to 4 weeks apart. We studied the Italian scenario, considering it representative of other Countries facing similar conditions in terms of virus circulation, mortality, and vaccine shortage, in the period from February 10 to April 14 2021. Under different conditions of quantity of vaccine administration, the schedule prioritizing first doses showed always significant increase of protected individuals, and a decrease of deaths, up to 19.8% less than the standard schedule. These findings support the vaccination option of prioritizing first dose in the elderly until vaccine supplies are adequate.
