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.
ABSTRACT
Objectives: To compare the number of deaths that occurred in the state of Amazonas and in Brazil, from March 16th to August 20th 2020, using the variables skin color, sex, place of death, age group and association with COVID-19, and secondly, to verify whether between 2019 and 2020, in the period from March 16th to August 20th, there was a significant change in the number of deaths from diseases not associated with COVID-19. Methods: We searched the databases of the Brazilian public agency "Transparency Portal" for the data on deaths that occurred in the state of Amazonas and Brazil in the period from March 16th to August 20th, 2019 and 2020. The absolute frequencies and percentages of the variables studied were used for statistical analysis. Results: COVID-19 was responsible for an 11.01% increase in deaths in Brazil;however, this rate quadrupled in the state of Amazonas. In relation to age group, there was a similar percentage between Amazonas and the national average. The stratified analysis showed significant differences between genders and races, with higher death rates in men and people of brown/black skin. The number of deaths at home increased significantly, especially those from causes not associated with COVID-19. Conclusions: The national drop in deaths from diseases not associated with COVID between March and August 2020 in Brazil is misleading and may be due to the result of misreported causes of death.