About Us
Our Story, Our Team, and How We Can Help You
Our Story: The Journey of Pioneer Valley Allergy
Before Pioneer Valley Allergy: A Decade of Collaboration
Long before our doors officially opened, our team shared a deep-rooted history. For over ten years, we worked side by side, serving patients across the Pioneer Valley. Together, we built not just professional experience, but lasting relationships within our community.
Grounded in Experience and Compassion
Each of our providers brings specialized training and credentials in asthma and allergy care. But what truly sets us apart is our shared commitment to understanding the unique needs of Pioneer Valley families — because it’s our home, too.
2025 — The Vision Takes Shape
Dr. Vanessa Van Stee, an allergy and immunology specialist with a passion for patient-centered care, founded Pioneer Valley Allergy with one clear goal: to bring modern, dedicated allergy and asthma care to the heart of our community.
July 2025 — Our Digital Home Launches
In July 2025, the launch of our website marked a major milestone for our new practice — our first step into introducing Pioneer Valley Allergy to the region. It was the beginning of something special: a place where people could learn, connect, and find care they could trust.
Today — Thriving and Growing Together
Since our launch, Pioneer Valley Allergy has grown alongside our patients. We continue to expand our reach, offering advanced treatments while keeping our focus on the people and community that make our work meaningful.
Our Founder
Vanessa Van Stee, M.D.
Allergy & Immunology/Board Certified
Dr. Vanessa Van Stee brings over sixteen years of experience in Allergy and Immunology to the Pioneer Valley community. Before founding Pioneer Valley Allergy, she provided dedicated care to patients throughout western Massachusetts, including many years serving the communities of Westfield and Greenfield.
Dr. Van Stee’s educational path reflects her deep commitment to both science and patient care. She earned her Bachelor of Science in Bioengineering from Walla Walla College, followed by a Master of Science in Biomedical Engineering from the University of Memphis. She went on to obtain her Doctor of Medicine from Loma Linda University School of Medicine, completed her Internal Medicine internship and residency at Baystate Medical Center in Springfield, Massachusetts, and pursued advanced training through a Fellowship in Allergy and Immunology at the University of Medicine and Dentistry of New Jersey.
Throughout her career, Dr. Van Stee has been known for her thoughtful, evidence-based approach to managing allergies, asthma, and immune disorders. She believes effective care begins with listening — taking time to understand each patient’s story and providing solutions that fit their life.
Outside of her practice, Dr. Van Stee enjoys exploring the scenic beauty of western Massachusetts and staying involved in the community she’s proud to call home. Learn more about Dr. Van Stee here.
Our Team
Margaret Sharron, NP
Board-Certified Family Nurse Practitioner
Margaret Sharron, NP, is a Board-Certified Family Nurse Practitioner with over two decades of experience providing compassionate, patient-centered care. Since 2017, she has specialized in Allergy, bringing both clinical expertise and a collaborative approach to helping patients manage and improve their health.
Margaret earned her Bachelor of Science and Master of Science in Nursing from the University of Massachusetts and has been board certified as a Family Nurse Practitioner since 2000. Her career spans primary care, internal medicine, endocrinology, and more - giving her a broad foundation to support patients with diverse needs.
Margaret focuses on patient-centered care. She believes in empowering individuals to take an active role in their health journey, ensuring that each treatment plan reflects both medical best practices and the patient’s personal goals.
Outside of medicine, Margaret embraces adventure as an amateur race car driver - a hobby that reflects her energy, focus, and drive both on and off the track. Learn more about Margaret here.
Casey Erelli, PA-C
Physician Assistant
Casey is a Physician Assistant with a strong background in emergency medicine and a deep passion for allergy and immunology. She is committed to patient‑centered care and enjoys helping patients better understand and manage their allergic conditions.
Casey earned her Bachelor’s in Biology from UMass Amherst and her Master’s in Physician Assistant Studies from Bay Path University. She is BLS CPR certified and trained extensively in allergy testing, immunotherapy, and chronic disease management. Casey began her medical career as an EMT in 2015, later serving as a field supervisor and CPR instructor. She worked for 3.5 years at Cooley Dickinson Urgent Care before transitioning into allergy and immunology 4 years ago. She is experienced in skin testing, immunotherapy injections, desensitization therapies, and the full process of biologics, IVIg, and allergen extract preparation.
Outside of work, Casey enjoys golfing, skiing, DIY crafts, and spending time at her family’s Lake Winnipesaukee home. She loves being with her husband Brett, their daughter Alessandra, and their pets Benny, Leo, and Bella.
Casey’s warm, approachable style helps patients feel supported and understood, reflecting Pioneer Valley Allergy’s commitment to compassionate, patient‑centered care. She values the opportunity to partner with individuals and families throughout their allergy journey. Learn more about Casey here.
Adrianna Carriere
Patient Care Coordinator
Adrianna, Patient Care Coordinator, joins Pioneer Valley Allergy with eight years of experience in the allergy field and a strong commitment to the communities she calls home. Having grown up in Southwick and Granby, Connecticut, and now residing in Westfield, she is deeply connected to the Pioneer Valley region and the people who live here.
Throughout her career, Adrianna has worked in a variety of roles—including front desk reception, billing, and management—giving her a well‑rounded understanding of practice operations and the patient experience. This versatility allows her to support both patients and providers with ease, empathy, and professionalism. She believes that healthcare is strongest when it reflects the community it serves, and she is excited to contribute to a practice that shares those values.
A married mother of two, Adrianna’s family is at the heart of everything she does. Much of her free time is spent cheering on her children at their school sports and activities, something she treasures as part of her connection to the local community. She brings that same sense of care into her work each day, offering patience, organization, and compassion to every interaction.
Adrianna is dedicated to ensuring that every patient who walks through our doors feels welcomed, supported, and truly cared for—reflecting the values of the community she proudly serves.
Chelsea Yothers
Clinical Coordinator
Chelsea is a Registered Medical Assistant with over eight years of experience in allergy and immunology care. She has spent her career working closely with patients and providers, building strong relationships, and developing a deep understanding of individual patient needs.
As Clinical Coordinator, Chelsea guides patients through biologic and IVIG therapies, prior authorizations, and specialty medications. She is committed to making each step of the process clear, organized, and supportive, helping patients feel informed and confident throughout their care journey.
Living and working in the Pioneer Valley, Chelsea values being part of a close-knit community and takes pride in caring for the people and families within it. She brings a steady, approachable presence to her work and believes that small moments of kindness and reassurance can make a meaningful difference in a patient’s experience.
Outside of work, Chelsea enjoys spending time with her family and appreciating the simple, meaningful moments of everyday life.
Kate Zucco
Practice Manager
Kate was hired in 2009 as Dr. Van Stee’s receptionist - and has been working alongside her ever since. With 16 years in healthcare and over 10 years in healthcare management, she has grown into a role that allows her to support both the operational side of the practice and the people who make it thrive.
As Practice Manager, Kate is deeply committed to making sure our office runs smoothly and effectively. She takes pride in creating an environment where staff and patients feel respected, heard, and genuinely cared for. Her management style is inclusive and collaborative; she believes in hands-on leadership and meets challenges with empathy and accountability. She also finds great joy in mentoring our team - encouraging each person to develop their skills and confidence, which enriches all of us. She’s always eager to learn and excited to keep expanding her knowledge in medical practice management. She loves the challenge of keeping things organized and responsive to our providers and patients.
Kate was born and raised in Westfield and truly loves her community. Her deep roots in the area shape her belief in kindness, connection, and showing up for others - values she carries into every aspect of her life and work. Outside of work, she enjoys spending time with her 20-year-old son and gathering with family. Whether at home or in the office, Kate is committed to growth, kindness, and creating spaces where people feel truly seen and supported.
Kate feels incredibly fortunate to be involved in the development and launch of something so meaningful to Dr. Van Stee.
How We Can Help You
Become A New Patient
Starting your care with Pioneer Valley Allergy is simple. Learn how to schedule your first visit and begin a personalized plan to manage your allergies or asthma with confidence.
call if you have questions
Our team is here to help. Whether you’re unsure about symptoms, treatment options, or appointment details, we’re happy to answer your questions and guide you every step of the way.