Side Effects After Vaccination Using the Pzer-Biontech (Bnt162b2) Against Sars-Cov-2 in the Young Adults

Background: In order to limit the spread of the SARS-CoV-2 virus, national immunization programs have started in many countries. Vaccinations are effective in preventing infection and severe clinical form of COVID-19, which affects 15% of patients. Despite the high ecacy of The Pzer-BioNTech (BNT162b2) vaccine, the characterization of side effects in age-stratied populations is still not exhaustive in the literature. Aim: The aim of our study is to determine what side effects affect the population of young adults following vaccination with the Pzer-BioNTech vaccine (BNT162b2). Material and methods: An anonymous survey was conducted. People vaccinated with two doses of the SARS-CoV-2 vaccine (BNT162b2) were qualied for the study. The Paired Wilcoxon and Fisher's exact tests were used for statistical analysis. Results: The main side effects after the rst dose were increased pain, pain and swelling at the injection site. After the 2nd dose, the dominant side effects were weakness, fever and headache. In the case of the 2nd dose, no difference in side effects was observed between those who suffered of COVID-19 and those who had no symptoms of COVID-19 in their past medical history. million doses of vaccines. Vaccinations show clinically signicant ecacy against contracting COVID-19 and a severe course of illness. At the moment, the literature does not exhaust the incidence and characteristics of adverse effects in stratied populations due to age. As of October 23, 2021, 38.6M doses have been administered to the Polish population and 19.8 M are fully vaccinated, which is 52.3% of the population. 3 . The aim of our study is to characterize side effects after the rst and second dose. As well as their frequency and duration in the young adults. And also how the time interval beetwen doses, previous symptoms of COVID-19, positive antigen/RT-PCR results and the presence of Anti-SARS-CoV-2 antibodies affects duration and occurance of side effects. 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

Introduction SARS-CoV-2 (primarily 2019-nCoV) infection causing the COVID-19 disease, only three months after the diagnosis of the rst case, was declared as a pandemic by the World Health Organization on March 11, 2020 1 .
Due to the lack of effective and cheap treatment of COVID-19, the main goal was prevention by using vaccines. Since December 2020 national vaccination programs have started in many countries in order to limit the transmission of the virus 2 . As of December 12, 2020, the European Commission has signed six advance purchase agreements with: Astra Zeneca, Sano -GSK, Janssen Pharmaceutica NV / Johnson & Johnson, P zer / BioNTech, CureVac and Moderna for a total of 62.06 million doses of vaccines. Vaccinations show clinically signi cant e cacy against contracting COVID-19 and a severe course of illness. At the moment, the literature does not exhaust the incidence and characteristics of adverse effects in strati ed populations due to age. As of October 23, 2021, 38.6M doses have been administered to the Polish population and 19.8 M are fully vaccinated, which is 52.3% of the population. 3 .
The aim of our study is to characterize side effects after the rst and second dose. As well as their frequency and duration in the young adults.
And also how the time interval beetwen doses, previous symptoms of COVID-19, positive antigen/RT-PCR results and the presence of Anti-SARS-CoV-2 antibodies affects duration and occurance of side effects.

Materials
Research procedure An anonymous survey was conducted.
The questions concerned local side effects (NRS (numeric rating scale), shoulder pain, duration of arm pain, redness or swelling, lymphadenopathy) and systemic side effects (weakness, headache, fever, chills, weakness). In addition, a general medical history of the last 16 months was collected.
Before the survey had been made available on students forums, it was validated on 38 people. In numerical questions, Cronbach's Alpha was 0.891. The average time to complete the questionnaire was 4 min 39 seconds.
The time interval between vaccination and completion of the questionnaire did not show a normal distribution. It showed the features of a linear increasing function in proportion to the time interval of lling. The median was 76 days and the mod was 37.

Studied group
The survey was completed by 175 people. 123 people were included in the study. The study excluded people who did not meet the age criteria, who were vaccinated with only one dose, and who were vaccinated with a vaccine other than the P zer-BioNTech vaccine (BNT162b2).
The subjects included in the study were between 18-30 years old and were vaccinated with two doses of The P zer-BioNTech vaccine (BNT162b2) ( Table 1).

Results
To comprare quantitive side-effect after 1st and 2nd dose, we used Wilcoxon paired test, that demonstrated that the Severity of Pain (NRS) and duration of pain or swelling at the injection site were signi cantly greater after the srt dose.
The duration of muscle or joint pain, weakness and headache was signi cantly longer after the second dose (Table 2), ( Figure 1).
Qualitative Comparison of side-effect after 1st and 2nd dose with The Fisher's exact test showed that pain or swelling at the injection site was more common after dose 1. Feeling of weakness, chills, fever and headache were more common after dose 2. (Figure 2), (Table 3). Dyspnoea 6 (4,88%) 6 (4,88%) p=1 Problems with memory 6 (4,88%) 6 (4,88%) p=1 Comparison side effects after 1st dose with and without positive RT-PCR. Based on the qualitative comparisons made using Fisher's exact test after the rst dose among people who were positive for RT-PCR compared to those who were negative "fever" occurred more often in the group Analogical calculations performed using Fisher's exact test showed no statistically signi cant differences after the second dose.
A qualitative comparison of the occurrence of side effects depending on the difference in the time interval between doses intake (below and above 25 days) was also performed, showed no statistically signi cant difference.
To compare quantitative side-effect after 1st dose with and without positive RT-PCR, P -Mann-Whitney test showed that the duration of pain or swelling at the injection site, feelings of weakness, fever and headache was signi cantly greater in the group with positive RT-PCR results, after the rst dose (Table 4), (Figure. 3).  To compare person after second dose with Positive RT-PCR or serological test to person without, we performed P -Mann-Whitney test that showed no statistically signi cant difference. (Table 5)  The duration of the feeling of weakness after 2nd dose was signi cantly greater in the group that took the second dose up to 25 days after the rst dose (Table 5).

Disscusion
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 de ned 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.

Limitatations
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 signi cant 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. 2. The most common side effects after the rst dose were the increase in pain, pain duration and swelling at the injection site, local side effects are more common, in case of the second dose, the most common side effects were weakness, fever and headache (generalized side effects).
3. In people who suffered from COVID-19, systemic symptoms dominated after the 1st dose; they resembled side effects after the 2nd dose in people who were not ill. 4. The duration of the feeling of weakness was signi cantly longer in the group of people vaccined with the second dose up to 25 days after the rst. Figure 2 Comparison of side-effect after 1st and 2nd dose, p-chi-squared or sher's exact test (Tabel. 3) Figure 3 Comparison of side-effect after 1st dose with and without positive RT-PCR, p-Mann-Whitney test (Tabel. 4) Figure 4 Comparison of side effects after the 1st dose between people with positive RT-PCR or serology versus people who did not have positive tests, p -mann-whitney test (Tabel. 4)