The Side Effects and Adverse Clinical Cases Reported after COVID-19 Immunization

COVID-19 remains a deadly disease that poses a serious threat to humanity. COVID-19 vaccines protect the public and limit viral spread. However, public acceptance is significantly dependent on the efficacy and side effects (SEs) of the vaccinations being produced. Four important mechanisms have been examined for COVID-19 vaccines: DNA-based, mRNA-based, protein-based, and inactivated viruses. Vaccination safety research was formerly limited to manufacturer-sponsored studies, but numerous additional cross-sectional survey-based studies conducted globally have contributed to the generation of vaccine-related safety data reports. Twenty-seven studies and twenty-four case reports published-up till 2021 were overviewed for the presentation of SEs and their severity. Injection site pain remained the most dominant localized SE, while headache and fatigue were the most prevalent systemic SEs. Most studies reported that all vaccinations were safe, with very little or no adverse effects, but the nature of SEs was reported to be more persistent in DNA- and mRNA-based vaccines, while inactivated viral vaccines were associated with longer-duration SEs. Overall, SEs were found to be more dominant in women and youngsters. Case reports of adverse reactions have also been documented, but there is still a need to find out their pathological linkage with the COVID-19 vaccination.