Performance comparison between heterologous and homologous COVID19 vaccine schedules on Omicron variant incidence: A real-world retrospective cohort study in Southern Italy

As the COVID19 pandemic progresses, there is an increasing need to evaluate the performance of vaccine strategies. This study investigated the vaccine schedule performance of heterologous vaccination compared to homologous vaccination in preventing Omicron SARS-CoV2 infection in the adult population. This retrospective cohort study utilized data from the Infections Regional Information System and the Apulia Regional Vaccine Registry to identify individuals who received a booster dose of one of 14 different COVID19 vaccination schedules between September 2021 and August 2022 in the province of Lecce, Southern Italy. The standardized cumulative incidence of SARS-CoV2 infection after the booster dose was assessed and the risk of infection between subgroups of heterologous and homologous vaccination schedules was compared using the Cochran-Mantel-Haenszel test. A total of 469,069 subjects were included in the study. The standardized incidence of SARS-CoV2 infection varied greatly among different vaccine schedules, with the highest and lowest being AZ-AZ-BNT (34.7 %) and MOD-MOD-BNT (18.9 %), respectively, and some heterologous schedules performing better than homologous ones. The risk of SARS-CoV2 infection was significantly lower in individuals who received specific heterologous vaccination schedules compared to homologous vaccination schedules, the best performing being MOD-MOD-BNT with a common odd ratio of 0.661 (IC. 95 % [0.620-0.704]). This study provides evidence that heterologous vaccination schedules may be more effective in preventing Omicron SARS-CoV2 infection compared to homologous vaccination schedules, highlighting how the vaccine product, rather than the platform, is involved in the different protection provided by heterologous vaccination.

Visual Results Following Implantation of a Refractive Multifocal Intraocular Lens in One Eye and a Diffractive in the Contralateral Eye

Objectives

To assess the visual outcomes in patients who underwent cataract surgery with multifocal intraocular lens (IOL) implantation using a “mix and match” approach.

Materials and Methods

Twenty patients (40 eyes) were involved in this prospective, nonrandomized study. Refractive multifocal IOLs (ReZoom NXG1) were implanted in patients’ dominant eyes and diffractive multifocal IOLs (Tecnis ZMA00) were implanted in their non-dominant eyes. Monocular and binocular uncorrected distance, intermediate and near visual acuity (logMAR), and contrast sensitivity levels were measured at 1, 3, and 6 months after cataract surgery. Defocus curves, reading speeds, patient satisfaction, spectacle dependence, and halo and glare symptoms were also evaluated at 6 months after the surgery. Postoperative quality of life was assessed with the Turkish version of National Eye Institute Visual Function Questionnaire-25.

Results

The study group comprised 8 females and 12 males with a mean age of 69.45±10.76 years (range, 31-86 years). The uncorrected distance and intermediate visual acuity levels were significantly better in the ReZoom-implanted eyes at postoperative 6 months (p=0.026 and p=0.037, respectively). There was no statistically significant difference in uncorrected near visual acuity (p>0.05). There was no statistically significant difference in contrast sensitivity, reading speed, halos, or glare between the groups (p<0.05). Mild glare/halo was reported by 40% of the subjects. The mean patient satisfaction was 95% and all patients were spectacle independent.

Conclusion

Mixing and matching multifocal IOLs in selected cataract patients provides excellent visual outcome, a high level of patient satisfaction, and spectacle independency.

Stem taper mismatch has a critical effect on ceramic head fracture risk in modular hip arthroplasty

BACKGROUND

Modular total hip prostheses with ceramic heads are well established in orthopedic surgery and widely used. With the variety of different manufacturers and available designs, components are at risk for mismatch. Several case studies show the potentially devastating effects of mismatch.

METHODS

The aim of this study was to investigate the outcome of one arbitrary component mismatch with commercially available components that appear to provide a stable fixation during assembly. A biomechanical in-vitro analysis of fracture strength (n=5) was carried out in accordance with ISO 7206-10. "Type1" Bi-Metric®-stems were mismatched with "V40" Al₂O₃ ceramic heads.

FINDINGS

Mean fracture strength was reduced to about 50% of the recommended FDA minimum by the mismatch (Mean 23.68kN, SD 2.35kN). A small contact area between head and stem taper was identified as a potential key parameter.

INTERPRETATION

Mixing and matching components can put a patient at greater risk for ceramic head fracture and must be avoided.