Immunogenicity Characterization of COVID-19 Vaccines: A Systematic Review and Meta-analysis

Abstract

Introduction: Immunogenicity has emerged as a challenge in the development of vaccines against coronavirus disease of 2019 (COVID-19). Immunogenicity is a determinant of the efficacy and safety of vaccines. This systematic review and associated meta-analysis summarized and characterized the immunogenicity of COVID-19 vaccines in randomized controlled trials (RCTs). Methods: Relevant RCTs were systematically sourced from different medical databases in August 2021. The risk ratios and mean differences with 95% confidence intervals were calculated. Results: Of 2,310 papers, 16 RCTs were eligible for review. These RCTs involved a total of 26,698 participants (15,292 males and 11,231 females). The pooled results showed a significant difference in the geometric mean titer between the vaccinated and control groups in favor of the vaccine group after 1 and 2 months of follow-up, for the young age group (18 - < 55y), and with different doses (P < 0.001). The difference in the older age group (>55y) was insignificant (P = 0.24). The seroconversion rate of spike neutralizing antibodies favored the vaccine groups 1 or 2 months after vaccination (P < 0.001). The seroconversion rate of the vaccine group was significantly different (P < 0.001) from that of the control group. Conclusions: Vaccination elicits immunogenicity in the follow-up period for all age groups and at low and large doses. Therefore, people should be encouraged to receive vaccines currently being offered. A boost dose has been asserted for the elderly.

Evaluation of CoronaVac and CoviShield Vaccines on SARS-CoV-2 Infection in Healthcare Workers in Salvador, Brazil

“…CoronaVac and Covishield vaccines have previously demonstrated their ability to induce an immune response rapidly, intensely, and effectively against SARS-CoV-2. They showed high efficacy against the alpha variant for up to 20 weeks, leading to a significant reduction in deaths, hospitalizations, and severe cases of COVID-19 [16,[21][22][23][24]. These data underscore the critical role of vaccination for the general population.…”

“…Such mutations have been linked to the emergence of new variants associated with increased rates of COVID-19 transmission. These developments have led to inquiries regarding the effectiveness of vaccines in reducing transmission risk and curbing the spread of various SARS-CoV-2 variants [16]. This study was conducted to evaluate the effect of the CoviShield and CoronaVac vaccines on the Ct value, which serves as an indicator of viral load, and the development and severity of symptoms among healthcare workers with primary SARS-CoV-2 infections.…”

COVID-19 Vaccines over Three Years after the Outbreak of the COVID-19 Epidemic

“…Protein subunit vaccines are developed with the use of the protein components of viral particles. In addition, the combination of various antigens can be used as a conjugate vaccine [ 24 , 25 , 26 , 27 ]. Due to the fact that the antigenic composition is well-defined and tested, and there is no risk of incomplete virus inactivation or reversion to virulence, the risk of side effects is minimized, and such vaccines are considered very safe.…”

“…Due to the fact that the antigenic composition is well-defined and tested, and there is no risk of incomplete virus inactivation or reversion to virulence, the risk of side effects is minimized, and such vaccines are considered very safe. However, subunit vaccines have low immunogenicity and require adjuvants to enhance the immunogenicity and, very often, booster doses [ 24 , 26 , 28 ]. Unlike a live attenuated vaccine, the immune response to a subunit vaccine is mostly antibody production with little or no cellular immunity results, whereas the immune response to a live attenuated vaccine is virtually identical to that produced by a natural infection (CDC, The Pink Book).…”

COVID-19 vaccination atlas: an integrative systems vaccinology approach

“…Particularly, ChAd and BNT were the most used vaccines during the first years of vaccination and 2 and 3-dose heterologous regimens were widely used and assessed 7,8 . The combination of different vaccines and platforms shows how classical and new-generation vaccines can help control epidemics and potentially trigger complementary systemic immune responses that individual vaccine technologies are intrinsically incapable of [8][9][10][11] . The complete homologous vaccination regimen showed high efficacy in clinical trials against COVID-19, as high as 95.0%, 94.1%, and 90% for new-generation vaccines, such as BNT, MO, and ChAd, respectively [11][12][13] .…”