The Importance of Vaccination and Its Role in Health
Vaccines play an invaluable role in protecting humanity from numerous infectious diseases, preventing severe conditions and mortality [1, 5, 7]. Their principle of action is to stimulate the immune system to produce a robust and long-term response to the pathogens contained in the vaccine [1]. Thanks to this, the body becomes prepared to encounter a real infection.
However, unlike most medications prescribed to sick individuals, vaccines are administered to healthy people. This circumstance significantly increases attention to potential side reactions and complications that may arise after vaccination [5].
Classification of Side Effects: From Mild to Severe
Side effects associated with vaccination can range from minor to potentially serious. Most of them are mild, acute, and temporary [5]. These include local reactions at the injection site, such as pain, redness, or swelling, which, although causing discomfort, do not pose a significant threat to health [1].
Nevertheless, in rare cases, more serious reactions can occur, including acute hypersensitivity reactions, infection induction, or autoimmune processes. These rare complications can be severe and even fatal [5]. It is important to understand that the occurrence of side effects is not unexpected, since vaccines are essentially chemical compounds that stimulate the immune system [8].
Allergic Reactions to Vaccines: What You Need to Know
Allergic reactions are one type of side effect that can occur after vaccination. They can manifest as acute hypersensitivity reactions to vaccine components [1]. The most serious, albeit extremely rare, form of an allergic reaction is anaphylaxis [1, 5].
During the mass COVID-19 vaccination campaign, data were obtained on the frequency of anaphylactic reactions. Thus, for the mRNA vaccines BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna), these rates were estimated at 11.1 and 2.5 cases per million doses administered, respectively [4]. These are quite low rates, but they become significant in the context of vaccinating a huge number of people worldwide [4].
It is known that certain vaccine components, such as gelatin and egg white, can be a source of allergic reactions [7]. Regulatory health authorities recommend that individuals with a known allergy to specific vaccine components or other medications refrain from vaccination [4]. However, there is some misunderstanding between general allergies and specific allergies to vaccine components [4]. It is important to note that immediate systemic allergic reactions after the administration of widely used vaccines are extremely rare [7].
Vaccination and Autoimmune Processes: A Complex Interrelationship
The stimulation of the immune system necessary for forming protection can in some cases be excessive and potentially associated with the development of autoimmune conditions, especially in individuals with genetic predisposition [1]. Autoimmune reactions after vaccination are rare events, and their cause-and-effect relationship is often difficult to establish due to the rarity of cases and the possible long latent period, which can range from several days to several years [5].
The concept of autoimmune/inflammatory syndrome induced by adjuvants (ASIA syndrome) combines various autoimmune side effects of vaccines, especially those containing adjuvants. This concept helps systematize research and improve the understanding of the mechanisms underlying such reactions [8].
In the context of COVID-19 vaccines, cases of autoimmune reactions, including vasculitis and hypersensitivity reactions, have also been reported [6]. For example, alopecia areata (patchy hair loss) has been recorded in some patients after COVID-19 vaccination, especially in those with a personal or family history of this disease [6]. However, large retrospective analyses show that the overall incidence of alopecia areata does not increase after COVID-19 vaccination [6].
Rare and Specific Side Effects of COVID-19 Vaccines
The COVID-19 pandemic led to the unprecedentedly rapid development and mass deployment of various vaccines, including mRNA vaccines (Pfizer-BioNTech BNT162b2, Moderna mRNA-1273) and adenovirus-vectored vaccines (AstraZeneca ChAdOx1-S, Janssen Ad26.COV2.S, Sputnik V) [2, 3]. These vaccines have proven effective in preventing severe COVID-19 and reducing mortality [2].
Nevertheless, as data accumulated, rare and previously unknown side effects were reported. For example, a case of gastric ulcer development was described after the administration of the second dose of the Sputnik V vaccine (Gam-COVID-Vac), which is a vectored vaccine containing recombinant adenoviruses [3]. In addition, COVID-19 vaccines have been associated with a new set of cutaneous side effects, including hypersensitivity reactions and vasculitis [6]. Ongoing monitoring and reporting of such cases provide valuable information for further studying vaccine safety [3].
Conclusion and Recommendations
Vaccination remains one of the most effective public health tools. Although most vaccine side effects are mild and temporary, it is important to be aware of the possibility of rare but more serious reactions, such as allergies and autoimmune conditions [5, 8]. It is crucial to report any adverse events following vaccination to promote a better understanding of their mechanisms, early diagnosis, and appropriate treatment [8].
If there is a history of severe allergic reactions or autoimmune diseases, it is necessary to discuss the risks and benefits of vaccination with a healthcare provider. Only a qualified specialist can assess the individual characteristics of the patient and give adequate recommendations.
Sources
- 1. Adverse reactions to vaccination: from anaphylaxis to autoimmunity. (The Veterinary clinics of North America. Small animal practice, 2018)
- 2. Ambivalence of human reactions after COVID-19 vaccination. (Biomolecules, 2024)
- 3. Development of peptic ulcer disease after the second injection of Sputnik V vaccine: A case report and literature review on rare side effects of Sputnik V vaccine. (Case reports in infectious diseases, 2023)
- 4. Allergy to COVID-19 vaccines: Current status. (Allergology international : official journal of the Japanese Society of Allergology, 2021)
- 5. Vaccines and autoimmunity. (Nature reviews. Rheumatology, 2009)
- 6. A review of alopecia areata and its association with COVID-19 vaccination. (Archives of dermatological research, 2024)
- 7. Vaccination and allergy. (Current opinion in otolaryngology & head and neck surgery, 2004)
- 8. Vaccines and autoimmunity – from side effects to ASIA syndrome. (Medicina (Kaunas, Lithuania), 2023)
Disclaimer: The information provided in this article is for reference purposes only and cannot replace professional medical advice, diagnosis, or treatment. Always consult your healthcare provider regarding any questions related to your health and vaccination.