Results presented by Fernando P. Polack et al. also showed a trend towards more systemic symptoms after the 2nd dose. The prevalence of local side effects in our work defined the occurrence of pain after the 1st dose at 91% and 73% after the 2nd dose (in the study mentioned above 87% and 66%, respectively.
Tendencies to increase in systemic symptoms in articles "Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine", "A randomized, cross-sectional study with detailed self-reported symptoms from healthcare workers", "Side effects after COVID-19 vaccinations among residents of Poland" are similar as in our results.
Results presented by Fernando P. Polack et al. in “Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine” a randomized trial was made included results related to local side effects (pain, redness, swelling) and systematic side effects (fever, fatigue, headache, chills, vomiting, diarrhea, muscle pain and joint pain). In the age group of 16-55 after the first dose 83% reported pain, 5% redness, and 7% swelling. Systemic symptoms: fever 4%, fatigue 47%, headache 42%, chills 14%, vomiting 1%, diarrhea 11%, muscle pain 21% and joint pain 11%. In the age group of 16-55 after second dose reported local side effects were as follows: pain 66%, 7% redness, 7% swelling
Systemic side effects: fever 16%, fatigue 59%, headache 52%, chills 35%, vomiting 2%, diarrhea 10%, muscle pain 37% and joint pain 22%
The data in the study was classified qualitatively and categorically (scales of severity of various symptoms) 4.
Results presented by Kadali et.al in “A randomized, cross-sectional study with detailed self-reported symptoms from healthcare workers”. In a randomized cross sectional study in which HCWs (medical workers) were included in the study, the side effects were obtained after the 1st or 2nd dose. Local symptoms: Approximately 88.04% (707/803) of HCWs reported a sore arm or pain at the injection site as their primary localized side effect, followed by localized swelling at the injection site (5.48%, 44/803), lymphadenopathy (axillary or regional) (3.36%, 27/803). Systemic symptoms: Myalgia (muscle pain) (45.7%, 367/803), arthritis or joint pain (16.56%, 133), weakness or fatigue (58.9%, 473/803), headache (44.83%, 360/803), chills (35.99%, 289/803), fever (22.04%, 177/ 803) decrease in memory (0.75%, 6/803), decreased sleep quality (5.35%, 43/803)5
In the publication “Side effects after COVID-19 vaccinations among residents of Poland” Among 196 people vaccinated with the first dose of Pfizer, 124 (63.3%) reported pain at the injection site, 143 (73%) reported shoulder pain, 21 (10.7%) reported muscle aches, 31 (15.8%) reported headaches, 13 (6.6%) reported fever, 13 (6.6%) reported chills, and 47 (24%) reported weakness.
After the second dose of the Pfizer vaccine among 177 individuals who had received the second dose, 101 (57.1%) reported injection site pain, 30 (16.9%) reported shoulder pain, 62 (35%) reported muscle aches, 60 (33.9%) reported headaches, 50 (28%) reported fever, 57 (32.2%) reported chills, and 89 (50.3%) reported weakness6.
The limitations of the study resulted mainly from the anonymous, not guarded questionnaires. The research group was only 123 but there were enough number of people to show statistically significant data. Another limitation was the time between vaccination and the completed questionnaire. However, it was assumed that due to the young age and the relatively low incidence of memory disorders, these data would not be able to distort the results and conclusions.