A machine learning-based approach to determine infection status in recipients of BBV152 (Covaxin) whole-virion inactivated SARS-CoV-2 vaccine for serological surveys.

Data science has been an invaluable part of the COVID-19 pandemic response with multiple applications, ranging from tracking viral evolution to understanding the vaccine effectiveness. Asymptomatic breakthrough infections have been a major problem in assessing vaccine effectiveness in populations globally. Serological discrimination of vaccine response from infection has so far been limited to Spike protein vaccines since whole virion vaccines generate antibodies against all the viral proteins. Here, we show how a statistical and machine learning (ML) based approach can be used to discriminate between SARS-CoV-2 infection and immune response to an inactivated whole virion vaccine (BBV152, Covaxin). For this, we assessed serial data on antibodies against Spike and Nucleocapsid antigens, along with age, sex, number of doses taken, and days since last dose, for 1823 Covaxin recipients. An ensemble ML model, incorporating a consensus clustering approach alongside the support vector machine model, was built on 1063 samples where reliable qualifying data existed, and then applied to the entire dataset. Of 1448 self-reported negative subjects, our ensemble ML model classified 724 to be infected. For method validation, we determined the relative ability of a random subset of samples to neutralize Delta versus wild-type strain using a surrogate neutralization assay. We worked on the premise that antibodies generated by a whole virion vaccine would neutralize wild type more efficiently than delta strain. In 100 of 156 samples, where ML prediction differed from self-reported uninfected status, neutralization against Delta strain was more effective, indicating infection. We found 71.8% subjects predicted to be infected during the surge, which is concordant with the percentage of sequences classified as Delta (75.6%-80.2%) over the same period. Our approach will help in real-world vaccine effectiveness assessments where whole virion vaccines are commonly used.

Extent of surgery in the management of phyllodes tumor of the breast: a retrospective multicenter study from India.

INTRODUCTION: Phyllodes tumor (PT) is a rare tumor of the breast. Usually, difficulty in making preoperative diagnoses and unpredictable clinical outcome of this disease leads to inappropriate management. Till date, no definite conclusion regarding the appropriate surgical procedure can be drawn. OBJECTIVES: The objective of this retrospective study is to study the clinicopathological correlation of phyllodes tumors in North-Central part of the India and also to evaluate efficacy of the various surgical options available for the management of phyllodes tumors of the breast. MATERIALS AND METHODS: A retrospective study of 24 cases from the archives of department of surgery of three tertiary institutes of North-Central part of India. We reviewed the clinical, pathological features of this disease entity with a view to highlight relevant features. We also analyzed various surgical options done for primary as well as recurrent PT. RESULTS: The breast masses in our study were particularly large. The mean size of the lump was 9.5 +/- 5.5 cm (range was 4.0-23 cm). Histopathological report was benign, borderline, and malignant PT in 62.4%, 20.8%, and 16.8% of the cases, respectively. Overall, 31 surgical procedures (24 in primary and 7 in recurrent) were performed. Simple lumpectomy, wide local excision and simple mastectomy were done in 25%, 27.4% and 27.4% of primary (non-recurrent) cases of PT, respectively. Modified radical mastectomy and simple mastectomy with LD flap reconstruction was done in 7.2% and 2.4% in primary cases, respectively in recurrent cases, simple mastectomy was done in four cases and modified radical mastectomy was done in one case. Overall, recurrence was seen in 29.2% of the cases. The median time for recurrence was 6 months (range 5.0-36 months). 90% (6/7) of recurrence occurred in lumpectomy patients. CONCLUSION: The unpredictable behavior of histological types and the disputable results of particular surgical procedures have contributed to the controversies. The therapeutic issue is further compounded by an imprecise preoperative diagnosis. This study shows that wide local excision for benign and borderline and simple mastectomy with or without reconstruction for the malignant PT of the breast are acceptable best surgical options.