According to WHO data, 15% of patients with COVID-19 develop severe disease, and 5% requires intensive care . The risk of severe COVID-19 increases with age. Therefore, adults aged 65 and higher were among the first groups of people who received the vaccination. Pfizer-BioNTech mRNA vaccine was the first COVID-19 vaccine registered for use in individuals 16 years of age and older . Currently, in Poland, the number of people fully vaccinated exceeded 19 million. 70% were people aged 60+ years . According to the data from clinical trials, the effectiveness of Pfizer-BioNTech mRNA vaccines in patients aged 65 years and older is over 95% . Another important aspect is the vaccine's safety, as many adverse effects (such as increased BP, pain, gastrointestinal disturbances) may be falsely interpreted as a symptom of a new disease of the patient and therefore cause the addition of new unnecessary pharmacotherapy.
Our results confirmed that adverse effects after vaccination affect a relatively small number of patients and are mild. It is consistent with results obtained in other studies [13–15]. Moreover, older people tend to have less frequent adverse effects than the younger population [13–15]. Our data indicated that such diversity could be observed even within the group of older patients: the group with no adverse effects was older than the group who developed adverse effects after the vaccine. It is known that biological ageing has a negative impact on the functioning of the immune system (immunosenescence) . Inflammation state, associated with immunosenescence, is a pathomechanism responsible for many age-related disorders (e.g. cardiovascular diseases, rheumatologic diseases, chronic pain) [17–19]. It can be characterized by redness, swelling, heat, pain, and loss of tissue function resulting from local immune, vascular and inflammatory cell response. Moreover, inflammation plays a significant role in severe COVID-19 course . Immunosenescence also leads to a significant reduction in naïve T cells that can respond to a vaccine, therefore decreasing the effectiveness of vaccination in older people .
Data from clinical trials indicated that adverse effects most commonly observed after the BoNTech mRNA COVID-19 vaccine are typical for acute and chronic inflammation . The results of our study confirm this observation. The elderly usually take a lot of drugs (for chronic disorders typical for this population: pain, cardiovascular diseases, CNS (central nervous system) disorders, diabetes), some of which have an anti-inflammatory effect [22–26]. Such ongoing pharmacotherapy may influence the risk of most common adverse effects associated with inflammation (pain, fever). Indeed, our data indicated that the use of drugs with anti-inflammatory effect was higher in the group of participants who did not report adverse effects after vaccination. Chronic anti-inflammatory therapy may affect the immune response to the vaccine . However, no recommendations suggest withholding NSAIDs (non-steroidal anti-inflammatory drugs) or other anti-inflammatories prior to receiving the COVID-19 vaccine .
Our study has some limitations concerning a relatively small number of participants and high disproportion between studied groups. Moreover, it would be worth considering the assessment of SARS-Cov-2 antibodies to estimate the immune response of the participants. Therefore, the research has been continued to provide more valuable data.