# Why Do Some People Experience More COVID-19 Vaccine Side Effects Than Others? Implications for Nursing Practice - Savonia AMK

> Younger adults and females appear to report COVID-19 vaccine side effects more frequently than older adults and males.

## Introduction
The COVID-19 pandemic affected millions of people worldwide and highlighted the importance of vaccination in preventing severe disease and reducing mortality. Although COVID-19 vaccines have been proven safe and effective, concerns about side effects have remained one of the most common reasons for vaccine hesitancy. As a registered nurse, I have often met patients who were worried about possible vaccine reactions and asked whether side effects differ between individuals. These questions inspired my interest in exploring age- and gender-related differences in COVID-19 vaccine side effects and their implications for nursing practice.

## Immune Response and Side Effects
Vaccines work by stimulating the immune system to recognize and respond to infectious diseases. COVID-19 vaccines activate immune responses that help the body develop protection against the SARS-CoV-2 virus. This immune activation may cause temporary side effects such as pain at the injection site, fatigue, headache, fever, chills, and muscle pain (World Health Organization 2024).

Most vaccine side effects are mild and disappear within a few days. According to previous research, age and biological sex may influence the frequency and intensity of vaccine reactions because immune responses vary between different population groups (Klein & Flanagan 2016). Younger individuals often have stronger immune responses than older adults, while females generally develop stronger immune reactions than males. These biological differences may affect how side effects are experienced following vaccination.

## Age and Gender Differences in Reported Reactions
The reviewed studies showed that younger adults more frequently reported local and systemic reactions such as fatigue, headache, fever, and muscle pain, whereas older adults generally experienced fewer and milder side effects. Similarly, females reported side effects more frequently and with greater intensity than males. 

Key findings from the literature include:
* **Age-related differences:** Younger adults reported local and systemic side effects more frequently than older adults (Polack et al. 2020; Baden et al. 2021).
* **Gender-related differences:** Females reported side effects more frequently than males (Menni et al. 2021), with women commonly reporting injection-site reactions, fatigue, and headache.

These findings suggest that biological and hormonal differences contribute to these variations (Klein & Flanagan 2016). Despite these differences, the studies consistently demonstrated that most side effects were temporary and self-limiting.

## Risk Perception and Public Health
An important aspect highlighted by the COVID-19 vaccination campaign was the difference between actual risk and perceived risk. While most side effects were mild, individuals often perceived rare events as more dangerous due to extensive media attention. Conversely, many underestimated the risks associated with the COVID-19 infection itself. Understanding this gap between perceived and actual risk is essential for healthcare professionals to address public anxiety and uncertainty.

## Implications for Nursing Practice
The findings of this review are highly relevant to nursing practice. Nurses are often the primary point of contact for patients with questions about vaccines. Key implications include:

* **Individualized Education:** Nurses should provide evidence-based counseling and reassurance about expected vaccine reactions to support informed decision-making.
* **Addressing Concerns:** Effective communication requires listening to patients' fears and acknowledging their concerns respectfully.
* **Building Trust:** By providing clear, accurate information, nurses can improve health literacy, increase vaccine confidence, and contribute to better public health outcomes.

## Conclusion
Younger adults and females appear to report COVID-19 vaccine side effects more frequently than older adults and males. However, most reactions are mild, temporary, and a normal part of the body’s immune response. Understanding these differences can help nurses improve patient education, reduce anxiety, and strengthen public confidence in vaccination programmes.

**Authors:**
* Zahedeh Khanlari, Master’s Degree Programme in Public Global Health, Savonia University of Applied Sciences
* Maria Luojus, Principal lecturer, Savonia University of Applied Sciences

## References
* Baden, L.R., El Sahly, H.M., Essink, B., Kotloff, K., Frey, S., Novak, R. et al. 2021. Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine. New England Journal of Medicine, 384(5), 403–416.
* Klein, S.L. & Flanagan, K.L. 2016. Sex Differences in Immune Responses. Nature Reviews Immunology, 16(10), 626–638.
* Menni, C., Klaser, K., May, A., Polidori, L., Capdevila, J., Louca, P. et al. 2021. Vaccine Side-Effects and SARS-CoV-2 Infection After Vaccination. The Lancet Infectious Diseases, 21(7), 939–949.
* Polack, F.P., Thomas, S.J., Kitchin, N., Absalon, J., Gurtman, A. et al. 2020. Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine. New England Journal of Medicine, 383(27), 2603–2615.
* World Health Organization. 2024. COVID-19 Vaccines: Safety and Effectiveness.