Impact of timing and combination of different BNT162b2 and ChAdOx1-S COVID-19 basic and booster vaccinations on humoral immunogenicity and reactogenicity in adults.

In this single-center observational study with 1,206 participants, we prospectively evaluated SARS-CoV-2-antibodies (anti-S RBD) and vaccine-related adverse drug reactions (ADR) after basic and booster immunization with BNT162b2- and ChAdOx1-S-vaccines in four vaccination protocols: Homologous BNT162b2-schedule with second vaccination at either three or six weeks, homologous ChAdOx1-S-vaccination or heterologous ChAdOx1-S/BNT162b2-schedule, each at 12 weeks. All participants received a BNT162b2 booster. Blood samples for anti-S RBD analysis were obtained multiple times over a period of four weeks to six months after basic vaccination, immediately before, and up to three months after booster vaccination. After basic vaccination, the homologous ChAdOx1-S-group showed the lowest anti-S RBD levels over six months, while the heterologous BNT162b2-ChAdOx1-S-group demonstrated the highest anti-S levels, but failed to reach level of significance compared with the homologous BNT162b2-groups. Antibody levels were higher after an extended vaccination interval with BNT162b2. A BNT162b2 booster increased anti-S-levels 11- to 91-fold in all groups, with the homologous ChAdOx1-S-cohort demonstrated the highest increase in antibody levels. No severe or serious ADR were observed. The findings suggest that a heterologous vaccination schedule or prolonged vaccination interval induces robust humoral immunogenicity with good tolerability. Extending the time to boost-immunization is key to both improving antibody induction and reducing ADR rate.

Shortening of freezing cycles provides equal outcome to standard ablation procedure using second-generation 28 mm cryoballoon after 15-month follow-up.

AIMS: Complications such as thermal oesophageal lesions, phrenic nerve injury, and pulmonary haemorrhage were found in cryoballoon (CB) ablation. Whether shortening of freezing times translates into equal efficacy rate and outcome is unknown. The aim of this study was to test the hypothesis that a single freeze cycle per pulmonary vein (PV) without dormant conduction during adenosine infusion is equally effective to standard CB procedure with a bonus freeze after documented PV isolation (PVI). METHODS AND RESULTS: In 53 patients with drug-refractory atrial fibrillation (AF) demonstrating PVI after a single 240 s freeze cycle without PV activity during adenosine no additional bonus freeze was applied (study group). In 139 patients, PVI was performed using a bonus freeze (240 s) after documented PVI (control group). Primary endpoint was recurrence of AF. Secondary endpoint was the assessment of quality of life (QoL-score from 1 to 6, being 1 the best and 6 the worst). Follow-up (FU) was performed at 3, 6, and 12 months. Freedom from symptomatic AF during a mean FU of 458 ± 107 days was achieved in 43 (81%) patients in the study group and in 110 (79%) control patients (P = ns). The QoL-score improved equally in both groups (4.8 ± 0.9 to 2.1 ± 0.7, P < 0.05 and 4.7 ± 0.6 to 2.2 ± 0.6, P < 0.05). Procedure duration (79 ± 14 vs. 98 ± 16 min, P < 0.01) was shorter in the study group. Complication rate was similar in both groups. CONCLUSION: Shortening of freezing times to 4 min per PV without residual dormant PV conduction after adenosine provocation is equally effective to the standard CB ablation protocol using a bonus freeze.