Everyday aches, pains, and fevers are your body’s way of signaling that something needs attention-whether it is rest, hydration, or assessment for an infection or another condition. While these symptoms often improve, noticing their duration, how strong they are, and any warning signs helps you decide when to seek medical care instead of trying to diagnose yourself. Talking with a doctor or other healthcare provider when you are unsure or symptoms persist is a safe way to understand what your body is telling you and to receive appropriate guidance.

Body ache, muscle pain, and fever are among the most common health complaints people experience.¹ These symptoms often arise due to stress, overuse, or underlying infection.^2,3 While many cases improve with rest and self-care, understanding what triggers these discomforts can help you decide when to seek medical help rather than trying to diagnose yourself.

Your body speaks to you through aches, pains, and fevers-but what exactly is it trying to say?

What Causes Everyday Aches and Pains
The most common reasons for muscle pain include tension, stress, overuse, and minor injuries.⁴ When you exercise too hard, lift heavy objects, or maintain poor posture for hours at your desk, your muscles work harder than usual. This creates tiny amounts of strain in muscle fibers, resulting in the soreness you feel afterward.⁴
Sometimes your whole body hurts, and that is different from localized muscle pain.³ When aches spread throughout your body, this can be caused by an infection, such as the flu.³ Viral infections like the common cold, influenza, and other respiratory illnesses trigger your immune system to release chemicals that help fight infection, and these can also cause widespread muscle pain and tiredness.⁵

Understanding Fever
A fever is your body’s temporary rise in temperature, usually as part of your immune system’s response to infection.² For most adults, normal body temperature is around 37 °C, with a typical range of about 36.1-37.2 °C.² A temperature of about ≥38 °C (measured in the mouth, rectum, ear, or temporal artery) or ≥37.2 °C (measured in the armpit) is generally considered a fever.^2,6

Usually, most fevers are harmless and don’t need treatment.² You may experience sweating, chills, and shivering along with aches in muscles and joints.⁷ Fevers related to common infections are a part of the body’s way of fighting germs, but can still make you feel unwell, so medical advice is important if symptoms are severe or do not settle.^2,7

Common Triggers to Know
Beyond infections, several everyday factors can be linked with body aches and pains. Dehydration disrupts the balance of salts in your body, which can lead to muscle cramps and soreness.^3,4 Low levels of certain vitamins, such as Vitamin D, can also be a reason for your muscle pain.^3,4 Chronic stress can cause your muscles to remain tense for extended periods, resulting in ongoing discomfort in areas such as the neck, shoulders, or back.⁸
Fever can happen for many reasons. It is often caused by infections such as bacteria or viruses, but it can also occur after vaccinations, as a reaction to certain medicines, or due to inflammation in the body. In some cases, fever may be related to cancer.⁹

When to See a Doctor
Many everyday aches and milder fevers improve within a few days with rest, fluids, and avoiding overexertion, but they should not be used to self-diagnose.^4,7 For children under three months old with a temperature of 38 °C or higher, contact a doctor immediately.⁷ Seek medical attention if your temperature reaches about 38.9°C or you have warning signs that require prompt medical care, including severe headache, unusual skin rash, stiff neck, mental confusion, persistent vomiting, difficulty breathing, chest pain, or seizures with your fever.^2,8 If aches, pains, or fever keep coming back, get worse, or worry you, it is safer to speak to a doctor or other qualified healthcare professional rather than trying to work out the cause on your own.

FAQ

Q: How long should body aches and fever last before I worry?
A: Fevers and body aches often improve within a few days, but you should contact a doctor if your temperature is about 38.9 °C or higher, lasts more than about three days, or if you feel very unwell.^4,9

Q: Can stress really cause physical body aches?
A: Yes, ongoing stress can cause muscles to stay tight and can lower the body’s ability to recover, which may lead to pain in areas such as the neck, shoulders, back, and head.⁸

Q: Why do I get body aches when I have a cold or flu?
A: When viral infections like colds and flu enter your body, your immune system releases chemicals that help fight infection but can also cause inflammation and widespread muscle pain, which is why you may feel achy all over.⁵

Q: Should I exercise when I have body aches?
A: If your aches clearly follow mild overuse or a minor strain, gentle movement and light stretching may help, but if you are unsure about the cause of your pain—or if you also have a fever or feel unwell-it is safer to avoid exercise and check with a healthcare professional first.⁴

Flu season occurs predictably each year, typically peaking between December and March in the Northern Hemisphere.1 Influenza accounted for 140,000 to 810,000 hospitalizations and 12,000 to 61,000 deaths annually, during the flu seasons from 2010 to 2020, in the United States alone.² Understanding when flu season occurs, who faces the highest risk, how the virus spreads, and recognizing symptoms early helps you protect yourself and your family during this challenging time.

Every year, flu season arrives with predictable timing but unpredictable severity, affecting millions of people and overwhelming healthcare systems worldwide._^3,4 Understanding what makes this annual occurrence so impactful helps you prepare and respond appropriately when flu comes to your community.

When flu season occurs

For countries in the Northern Hemisphere, the typical timing of the flu epidemic peak falls during the winter season, with the vast majority occurring in February and the first half of March.¹ This seasonal pattern reflects how influenza viruses thrive in specific environmental conditions, particularly cold and dry weather that favors virus survival and transmission.³ The increased time people spend indoors during cold weather, often in close quarters with others, facilitates spread.³

Interestingly, flu seasonality varies considerably around the world. While temperate regions experience distinct winter epidemics, tropical countries show much more variability, with flu activity potentially occurring at any time of the year depending on local climate patterns, latitude, and rainfall.¹ This global variation in timing underscores how environmental factors influence when and where flu viruses circulate most actively.¹

The burden of the flu season

The numbers associated with flu season reveal its substantial impact on public health. The Centers for Disease Control and Prevention estimates that influenza accounted for 4.3 to 21 million medical visits, 140,000 to 810,000 hospitalizations, and 12,000 to 61,000 deaths annually in the United States during flu seasons from 2010-11 through 2019-20.² This wide range reflects variability in flu season severity from year to year, depending on which virus strains circulate and how well they match available preventive measures.²

Beyond the immediate health burden, influenza significantly impacts healthcare resources and economic productivity. Studies show that influenza infection is associated with prolonged hospital stays, with patients experiencing hospital stays that are twice as long or more compared to patients without flu.⁴ The ripple effects include work absences, school closures, and strain on emergency departments and hospitals during peak activity periods.

Who faces the highest risk?

While anyone can get flu, certain groups face substantially higher risk of serious complications and hospitalizations. The elderly population and those with specific chronic conditions are particularly vulnerable.² Research examining high-risk groups found that elderly flu patients with conditions like congestive heart failure, chronic obstructive pulmonary disease, coronary artery disease, or chronic kidney disease had 3 to 7 times higher 30-day hospitalization rates compared to similar patients without flu.² This elevated risk has been consistently attributed to age-related changes in immune defenses.²

Children also play a crucial role in flu season dynamics. Studies examining household transmission found that children, particularly preschool and school-age children, are more susceptible to flu infection and more likely to transmit the virus to household members.⁵ Research shows that 40% to 48% of secondary household cases are attributable to transmission from a sick child, with preschool children posing the highest transmission risk.⁵ This makes understanding flu season especially important for families with young children.

Recognizing the pattern

Flu typically begins suddenly, with symptoms such as fever, chills, severe body aches, headache, sore throat, and a dry cough. Some people – especially children – may also experience vomiting or diarrhea. This abrupt onset of symptoms helps distinguish flu from the common cold, which usually develops more gradually. While most individuals recover within 3 to 7 days, flu can lead to serious complications in some cases, particularly among children, older adults, and people with underlying chronic conditions.⁶

FAQs

Q 1: When exactly does flu season start and end each year?
A: In the Northern Hemisphere, including the United States, flu season typically begins in the fall and peaks between December and March, with the majority of peak activity occurring in February and early March. However, flu viruses can circulate year-round in tropical regions, and the period of influenza activity varies even between neighbouring countries.¹ The timing relates to environmental conditions, including cold, dry weather that favors flu virus survival and increased indoor crowding during winter months.²

Q 2: What causes the seasonality in flu infection?
A: Flu tends to be seasonal due to a combination of factors. During certain times of the year, the body’s ability to fight infections may be lower, possibly influenced by changes in sunlight and vitamin levels. The flu virus also survives and spreads more easily in cold, dry air. In addition, people, especially children, spend more time indoors or in close contact at schools, which helps the virus spread from person to person. Together, these factors explain why flu infections rise at specific times each year.^3,6

Q 3: Why are children such a concern during flu season?
A: Children, particularly preschool and school-age children, play a major role in flu transmission for several reasons. They’re more susceptible to infection, shed virus at higher levels and for longer periods, have more frequent close contact with others in school settings, and practice less effective hygiene habits. Research shows that 40% to 48% of secondary household flu cases are attributable to transmission from sick children. When a child brings flu home, household contacts face significantly elevated infection risk compared to exposure from sick adults. This makes protecting children especially important for protecting entire families.⁵

Q 4: Who should be most concerned about getting the flu this season?
A: While anyone can get flu, certain groups face a substantially higher risk of serious complications. Elderly individuals, particularly those with chronic conditions like heart failure, COPD, coronary artery disease, or kidney disease, have 3 to 7 times higher hospitalization rates when infected compared to those without flu.³ Young children, especially under age 5, face elevated risk. Pregnant women, people with weakened immune systems, and those with chronic medical conditions also experience higher complication rates. If you’re in any high-risk group, be especially vigilant about recognizing symptoms early and seeking prompt medical evaluation.⁶

Advancing cancer care by expanding access to science‑based solutions

This World Cancer Day, Abbott honors every unique cancer story and the hope that grows when everyone can reach the care they need.

Cancer remains one of the defining health challenges of our time

Cancer affects millions of people every year and continues to place a growing burden on families, healthcare systems and societies¹. While scientific progress has transformed cancer care in recent decades², access to timely diagnosis and effective treatment remains uneven, particularly in emerging countries, which account for over half of new patients and cancer deaths worldwide³.

In emerging countries, 11.4M people are diagnosed with cancer each year, corresponding to nearly 60% of all new cancer cases each year⁴.

At Abbott, we recognize cancer as a pressing global health challenge and are committed to helping expand access to meaningful, science‑based healthcare solutions. Earlier diagnosis⁵ and innovative treatment^6,7, including biologics for hard-to-treat cancers, are improving the outlook for many people struggling with cancer, giving families more time together.

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A comprehensive approach to oncology

Abbott’s approach to oncology is grounded in addressing real‑world needs across the cancer continuum.

Be support people in living healthier as they battle with cancer by :

• Supporting earlier and more accurate diagnosis through advanced diagnostic technologies
• Expanding access to high‑quality medicines in emerging markets, where our medicines business is focused
• Helping healthcare systems adopt advanced therapies by addressing barriers such as affordability, education and supply reliability
• Supporting people beyond treatment through nutritional and care solutions tailored to the needs of patients living with cancer

By looking at cancer care holistically, we aim to contribute to better outcomes for more people, wherever they live.

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Expanding access to advanced cancer treatments

Many of today’s advances in oncology are built on biologic medicines — therapies that have reshaped how cancer is treated⁷. Yet access to these treatments remains limited in large parts of the world⁸.

Abbott works to broaden access to advanced cancer therapies by bringing both established and next‑generation treatment options to emerging countries. This includes supporting the responsible adoption of high‑quality biologics and biosimilars, helping healthcare systems treat more people while maintaining rigorous standards of safety, quality and effectiveness.

For Abbott, access is not an abstract concept. A healthcare solution only fulfills its purpose if it reaches the people who need it.

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Building a future for oncology through partnerships and quality

Progress in cancer care depends on collaboration. Abbott works with healthcare professionals, policymakers, scientific partners and local institutions to help strengthen oncology ecosystems and address access barriers at the country level. This can include debunking myths and misconceptions on therapies, or supporting patients in their cancer journey,

Quality is foundational to this effort. Across our medicines business, we apply robust, internationally aligned standards to ensure reliability, consistency and trust, because people facing cancer deserve therapies they can depend on.

By combining scientific expertise, local insight and long‑term commitment, Abbott aims to contribute to more resilient cancer care systems and better health outcomes over time.

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On World Cancer Day

On World Cancer Day, we stand with patients, caregivers and healthcare professionals around the world. We recognize both the progress that has been achieved and the work that still lies ahead.

At Abbott, we work relentlessly to help people live healthier, fuller lives as they navigate cancer and other health challenges. For many, that support means more moments—and more time—with the people they love.

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This content is intended for general information only and does not promote any specific medicine or treatment.

FAQs

1. What are biologic medicines?

According to the World Health Organization, biologic therapeutics, also referred to as Biologicals, are those class of medicines which are grown and then purified from large-scale cell cultures of bacteria or yeast, or plant or animal cells.
 
Biologicals are a diverse group of medicines which includes vaccines, growth factors, immune modulators, monoclonal antibodies, as well as products derived from human blood and plasma.
 
What distinguishes biologicals from other medicines is that these are generally proteins purified from living culture systems or from blood, whereas other medicines are considered as ‘small molecules’ and are either made synthetically or purified from plants⁹.

2. How have biologic medicines changed cancer care?

According to the Americal Cancer Society, biologic therapies play an important role in cancer treatment, in part because of their ability to target specific aspects of cancer cells.
 
Many biologics work by using a patient’s own immune system, directly or indirectly, to fight cancer.
 
For example, monoclonal antibodies (antibodies), some of the most complex biologics, can be used to target cancer cells and flag them for destruction by the immune system.  In many cases, these biologics may not kill as many healthy cells as other drug treatments, may be less toxic, and may have fewer or more manageable side effects¹⁰. 

3. Are biologic medicines the same as chemotherapy?

No. Traditional chemotherapy uses chemical substances to treat cancer. Biological therapy, by contrast, uses living organisms, substances derived from organisms, or laboratory-made versions of those substances to act against cancer cells¹¹.

4. Are these treatments available to everyone with cancer?

Access to biologics varies by region and healthcare system. Their high costs have limited accessibility for many patients globally. Biosimilar versions of biologic medicines are now helping to change this landscape by providing more affordable treatment options, particularly in low- and middle-income countries (LMICs) where the burden of disease is high, and healthcare budgets are constrained​⁸.

This article was written with the assistance of generative AI technology and reviewed for accuracy.

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The term ‘biosimilar’ is recognised and designated by both the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA).^2,3 Regulatory bodies require a robust and comprehensive collation of data for a biosimilar to be approved.

This review of comparability focuses on demonstrating that the biosimilar is highly similar to the reference medicine. It includes a step-wise evaluation that begins with extensive comparative analytical and functional studies. Clinical data, typically including a comparative clinical pharmacology study and often a comparative clinical efficacy and safety study, is also required to address any residual uncertainties from earlier analyses.^2,3

CONCEPTS OF BIOSIMILARS^1,2,4

A table of definitions for some key terms related to biosimilars. A clear understanding of this terminology is essential for navigating the topic of biosimilar medicines.

Biologic	Biologics are complex, large-molecule medicines derived from living cells or produced through biological processes.
Biosimilar	A biological medicine that is highly similar to an already approved reference medicine in terms of structure, biological activity, efficacy, safety and immunogenicity.
Extrapolation	Extension of the efficacy and safety data from a therapeutic indication for which the biosimilar has been clinically tested to another therapeutic indication approved for the reference medicine.
Generic	A medicine that is developed to be the same as a medicine that has already been authorised. Its authorisation is based on efficacy and safety data from studies on the authorised medicine. A company can only market a generic medicine once the 10-year exclusivity period for the original medicine has expired.
Interchangeability	The ability to exchange one medicine for another medicine that is expected to have the same clinical effect.
Microheterogeneity	Minor molecular variability among biological substances due to natural biological variability and slight alterations to production methods.
Substitution	Practice of dispensing one medicine instead of another equivalent and interchangeable medicine at pharmacy level without consulting the prescriber.
Switching	When the prescriber decides to exchange one medicine for another medicine with the same therapeutic intent.

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Below are some of the EMA’s specific considerations when assessing extrapolation:¹

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REFERENCES

1. European Medicines Agency. Biosimilars in the EU: Information Guide for Healthcare Professionals. Published 2017. Accessed October 2025. Available at: https://www.ema.europa.eu/en/documents/leaflet/biosimilars-eu-information-guide-healthcare-professionals_en.pdf.
2. European Medicines Agency. Reflection paper on a tailored clinical approach in biosimilar development. Published 2014. Accessed October 2025. Available at: https://www.ema.europa.eu/en/documents/other/reflection-paper-tailored-clinical-approach-biosimilar-development_en.pdf.
3. U.S. Food and Drug Administration. Biosimilar Development Process. Published 2017. Accessed October 2025. Available at: https://www.fda.gov/files/drugs/published/Biosimilar-Development-Process.pdf

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Interchangeability refers to the exchange of one medicine for another medicine that is expected to have the same clinical effect.¹ In the context of biosimilars, this means an approved biosimilar can be used instead of its reference product (or vice versa), or one biosimilar can be replaced with another biosimilar of the same reference product.¹

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REFERENCES

Abbreviations: EMA, European Medicines Agency; FDA, Food and Drug Administration; HMA, Human Medicines Agency.

1. European Medicines Agency. Biosimilars in the EU: Information Guide for Healthcare Professionals. Published 2017. Accessed October 2025. Available at: https://www.ema.europa.eu/en/documents/leaflet/biosimilars-eu-information-guide-healthcare-professionals_en.pdf.
2. Afzali A, et al. The automatic substitution of biosimilars: definitions of interchangeability are not interchangeable. Adv Ther. 2021;38(5):2077–2093.
3. Knox RP, et al. Biosimilar approval pathways: comparing the roles of five medicines regulators. J Law Biosci. 2024;11(2):1-27.
4. European Medicines Agency. Statement on the scientific rationale supporting the interchangeability of biosimilar medicines in the EU. Published September 19, 2022. Accessed October 2025. Available at: https://www.ema.europa.eu/en/documents/public-statement/statement-scientific-rationale-supporting-interchangeability-biosimilar-medicines-eu_en.pdf.
5. U.S. Food and Drug Administration. Biosimilar and interchangeable biologics: more treatment choices. Published July 28, 2021. Accessed October 2025. Available at: https://www.fda.gov/consumers/consumer-updates/biosimilar-and-interchangeable-biologics-more-treatment-choices.

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While small molecule development typically requires an investment of $2–3 million and takes 2–3 years, developing a biosimilar can demand $100–200 million and span 8–10 years.¹ A comparative, step-wise approach to biosimilar approval is adopted by regulatory bodies such as the European Medicines Agency (EMA) and the U.S. Food and Drug Administration (FDA) to ensure that the drug maintains safety and efficacy to the reference biologic.

THE BIOSIMILAR DEVELOPMENT AND APPROVAL PROCESS

Adapted from Rugo et al. 2016.²

COMPARISON OF DATA REQUIREMENTS FOR APPROVAL OF A BIOSIMILAR VERSUS THE REFERENCE MEDICINE4

European Medicines Agency⁴

Once approved, biosimilars can be prescribed in place of their reference products, offering patients proven treatment alternatives that could broaden access, reduce costs, and support more sustainable healthcare systems.

REFERENCES

Abbreviations: PD, pharmacodynamic; PK, pharmacokinetic.

1. GaBI Online. Comparison of the cost of development of biologicals and biosimilars. Generics and Biosimilars Initiative Journal. Published March 11, 2022. Accessed October 2025. Available at: https://gabionline.net/reports/comparison-of-the-cost-of-development-of-biologicals-and-biosimilars.
2. Rugo HS, Rifkin RM, Declerck P, Bair AH, Morgan G, Woollett G, et al. A clinician’s guide to biosimilars in oncology. Cancer Treat Rev. 2016;46:73–9. Accessed October 2025. Available at: https://www.sciencedirect.com/science/article/pii/S0305737216300172.
3. Nupur N, Singh SK, Rathore AS. Analytical similarity assessment of biosimilars: global regulatory landscape, recent studies and major advancements in orthogonal platforms. Front Bioeng Biotechnol. 2022;10:832059.
4. European Medicines Agency. Biosimilars in the EU: Information Guide for Healthcare Professionals. Published 2017. Accessed October 2025. Available at: https://www.ema.europa.eu/en/documents/leaflet/biosimilars-eu-information-guide-healthcare-professionals_en.pdf.

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It is estimated that biosimilars will generate savings of up to $290 billion globally by 2027, freeing up healthcare systems to support more people.¹ They are also improving affordability.² For instance, where an originator biologic medicine can require an $800 million investment and 8­­–10 years of development, biosimilars can markedly reduce this investment by as much as eightfold.² These scientifically developed alternatives to originator biologics can offer substantial cost savings that could be reinvested into healthcare systems, unlocking broader access to life-changing therapies.

PRICE DIFFERENCES PER COUNTRY BETWEEN BIOSIMILARS AND REFERENCE BIOLOGIC.³

In a cross-national study of biosimilar pricing across Argentina, Brazil, Italy, and Australia; Brazil showed the highest median price reduction at 36.3%, with nearly half of its biosimilars priced over 40% below the originator.³

GLOBAL OVERVIEW OF AVAILABILITY OF GENERAL AND INSULIN-SPECIFIC BIOSIMILAR GUIDELINES.⁵

However, the global picture is still uneven. In some countries, biosimilar regulatory guidelines have yet to be established, or their status remains unknown, which could slow patient access.⁵ Addressing these gaps is essential to ensuring that the benefits of biosimilars reach patients everywhere, not just in markets with established frameworks.

Biosimilars play a critical role in addressing this imbalance. By fostering constructive market competition, they help lower costs and expand access to life-changing treatments.⁷ In fact, as of July 2024, the cumulative savings at list prices from the impact of biosimilar competition in Europe reached €56 billion.⁷

As more biosimilars reach the market (with 40 FDA-approved and over 100 in development^*) they offer a scalable solution to rising healthcare costs. When biosimilars are adopted, both biosimilars and their reference biologics become more affordable, freeing up resources that can be reinvested in other areas of care.⁸

REFERENCE

As of 2023.

1. IQVIA. The Global Use of Medicines 2023. Accessed October 2025. Available at: https://www.iqvia.com/insights/the-iqvia-institute/reports/the-global-use-of-medicines-2023.
2. GaBI Online. Comparison of the cost of development of biologicals and biosimilars. Generics and Biosimilars Initiative Journal. Published March 11, 2022. Accessed October 2025. Available at: https://gabionline.net/reports/comparison-of-the-cost-of-development-of-biologicals-and-biosimilars.
3. Machado FLS, Cañás M, Urtasun MA, Marín GH, Albuquerque FC, Pont L, et al. A cross-national comparison of biosimilars pricing in Argentina, Australia, Brazil, and Italy. Ther Innov Regul Sci. 2024;58:549–56.
4. World Health Organization. Biosimilars: Expanding Access to Essential Biologic Therapies. Published February 13, 2025. Accessed October 2025. Available at: https://www.who.int/news/item/13-02-2025-biosimilars–expanding-access-to-essential-biologic-therapies.
5. Heinemann L, Khatami H, McKinnon R, Home PD. An overview of current regulatory requirements for approval of biosimilar insulins. Diabetes Technol Ther. 2015;17(7):510–6.
6. U.S. Food and Drug Administration. FDA and FTC Collaborate to Advance Competition in the Biologic Marketplace. Published March 2, 2023. Accessed October 2025. Available at: https://www.fda.gov/news-events/fda-voices/fda-and-ftc-collaborate-advance-competition-biologic-marketplace.
7. IQVIA. The Impact of Biosimilar Competition in Europe 2024. Accessed October 2025. Available at: https://www.iqvia.com/-/media/iqvia/pdfs/library/white-papers/the-impact-of-biosimilar-competition-in-europe-2024.pdf.
8. Kvien TK, Patel K, Strand V. The cost savings of biosimilars can help increase patient access and lift the financial burden of health care systems. Semin Arthritis Rheum. 2022;52:151941.

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This section serves as a dedicated hub for a curated selection of scientific articles and studies that explore the efficacy and real-world effectiveness of biosimilars.

Here, you will find links to foundational research and real-world evidence demonstrating how biosimilars expand treatment choices for patients. Explore the articles linked below to delve deeper into the science behind biosimilars.

What Are Biosimilars, and How Can They Help You? | Abbott Newsroom

What are Biologic Medicines and Biosimilars? | Abbott Newsroom

Our biosimilars in women’s health – Abbott | Medicines GLOBAL

Our biosimilars in oncology – Abbott | Medicines GLOBAL

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