International Journal of Clinical Case Reports 2024, Vol.14, No.3, 117-131 http://medscipublisher.com/index.php/ijccr 123 However, mRNA vaccines also have some disadvantages. They are associated with a higher incidence of certain adverse events, such as serious vessel disorders, compared to traditional vaccines (Fan et al., 2021). Additionally, mRNA vaccines require stringent cold chain storage conditions, which can pose logistical challenges, particularly in low-resource settings (Alberer et al., 2017). In contrast, traditional vaccines, such as inactivated and live attenuated vaccines, often have more established safety profiles and less demanding storage requirements, making them more accessible in various settings (Ma et al., 2016; Wang et al., 2021). 6 Case Study 6.1 Case study 1: pfizer-BioNTech (BNT162b2) vaccine The Pfizer-BioNTech (BNT162b2) vaccine has demonstrated significant efficacy and safety in various clinical trials and real-world studies. In a pivotal efficacy trial involving 43,448 participants, the BNT162b2 vaccine showed a 95% efficacy in preventing COVID-19 among individuals aged 16 years and older. The trial reported that the vaccine was effective across different subgroups defined by age, sex, race, ethnicity, baseline body-mass index, and the presence of coexisting conditions. The safety profile was characterized by mild-to-moderate pain at the injection site, fatigue, and headache, with a low incidence of serious adverse events (Figure 3) (Polack et al., 2020). Further studies extended the follow-up period to six months, confirming the vaccine's continued efficacy at 91.3% and a favorable safety profile, although a gradual decline in efficacy was noted over time (Thomas et al., 2021). Figure 3 Local and Systemic Reactions After BNT162b2 Vaccination in Different Age Groups (Adapted from Polack et al., 2020) Real-world data also support the vaccine's effectiveness. For instance, a study conducted by the VISION Network across 10 states in the U.S. found that the vaccine was highly effective in preventing COVID-19-associated emergency department and urgent care encounters and hospitalizations among children and adolescents aged 5-17 years. The vaccine efficacy (VE) was particularly high among adolescents aged 12-17 years, with VE increasing to 86% after a third booster dose during the Omicron predominant period (Klein et al., 2022). Additionally, the vaccine was shown to be 93% effective in preventing COVID-19 hospitalization among adolescents aged 12-18 years during the Delta variant predominance (Olson et al, 2021). These findings underscore the importance of vaccination in controlling the pandemic and protecting various age groups from severe outcomes.
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