International Journal of Clinical Case Reports 2024, Vol.14, No.3, 117-129 http://medscipublisher.com/index.php/ijccr 121 found that the vaccine was generally safe, although the rate of seroconversion was substantially lower than in healthy controls. The study highlighted the need for additional vaccine doses in certain immunocompromised patient groups to improve immunity (Bergman et al., 2021). Another study on the mRNA-1273 vaccine included participants at high risk for SARS-CoV-2 infection or its complications. The vaccine showed 94.1% efficacy at preventing COVID-19 illness, including severe disease, with no safety concerns identified (Baden et al., 2020). Bergman et al. (2021) studied the seroconversion and antibody titers in different immunocompromised patient groups and healthy controls. The study indicated that the seroconversion rate and antibody titers post-vaccination were significantly higher in the healthy control group compared to the immunocompromised groups. Among the immunocompromised patients, those in the HIV and HSCT/CAR-T groups showed more notable antibody responses, while the SOT and CLL groups exhibited weaker responses. These results highlight the differential responses to vaccination among immunocompromised patients, suggesting the need for personalized vaccination strategies to enhance protection in these high-risk populations. In children aged 5 to 11 years, a systematic study and meta-analysis found that mRNA COVID-19 vaccines were associated with lower risks of SARS-CoV-2 infections and severe COVID-19-related illnesses. Most vaccinated children experienced at least one local adverse event, but severe adverse events were rare and resolved within several days (Watanabe et al., 2023). These findings indicate that mRNA vaccines are generally safe in special populations, although additional doses or tailored vaccination strategies may be necessary for optimal protection. 5 Comparative Analysis 5.1 mRNA vaccines vs. traditional vaccines mRNA vaccines, such as those developed for COVID-19, represent a novel approach compared to traditional vaccines like inactivated or live attenuated vaccines. Traditional vaccines, such as the inactivated hepatitis A vaccine (HA-I) and live attenuated hepatitis A vaccine (HA-L), have been shown to provide robust immunogenicity and safety profiles in various populations. For instance, a study comparing HA-I and HA-L in Chinese children demonstrated high seroconversion rates and acceptable safety profiles for both vaccines, with HA-I showing slightly higher geometric mean concentrations of antibodies after a booster dose (Ma et al., 2016). Similarly, inactivated influenza vaccines have been shown to provide broad protection against circulating influenza viruses with minimal adverse reactions (Wang et al., 2021). In contrast, mRNA vaccines have shown a higher efficacy in preventing SARS-CoV-2 infection compared to traditional vaccines. A systematic study and meta-analysis indicated that mRNA vaccines conferred a significantly lower risk of SARS-CoV-2 infection compared to viral vector and inactivated vaccines (Fan et al., 2021). However, mRNA vaccines were also associated with a higher incidence of certain adverse events, such as serious vessel disorders, compared to traditional vaccines (Fan et al., 2021). Despite these differences, both mRNA and traditional vaccines have demonstrated the ability to induce strong immune responses and provide protection against their respective target pathogens. 5.2 Comparison with other COVID-19 vaccines When comparing mRNA vaccines to other COVID-19 vaccines, such as inactivated and viral vector vaccines, several key differences emerge. Inactivated vaccines like CoronaVac and BBIBP-CorV have shown good safety profiles and moderate efficacy in preventing symptomatic COVID-19. For example, the CoronaVac vaccine demonstrated an efficacy of 83.5% in preventing PCR-confirmed symptomatic COVID-19 in a phase 3 trial in Turkey, with a good safety profile (Tanriover et al., 2021). Similarly, the BBIBP-CorV vaccine was found to be safe and well-tolerated, inducing strong humoral responses in both younger and older adults (Xia et al., 2020; Wu et al., 2021).
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