Effectiveness of COVID-19 Vaccines against Delta Variant (B.1.617.2): A Meta-Analysis

Objectives: The highly transmissible COVID-19 Delta variant (DV) has contributed to a surge in cases and exacerbated the worldwide public health crisis. Several COVID-19 vaccines play a significant role in a high degree of protection against the DV. The primary purpose of this meta-analysis is to estimate the pooled effectiveness of the COVID-19 vaccines against the DV in terms of risk ratio (RR) among fully vaccinated, compared to unvaccinated populations. Methods: We carried out a systematic review, with meta-analysis of original studies focused on COVID-19 vaccines effectiveness against a DV clinical perspective among fully COVID-19 vaccinated populations, compared to placebo (unvaccinated populations), published between 1 May 2021 and 30 September 2021. Eleven studies containing the data of 17.2 million participants were identified and included in our study. Pooled estimates of COVID-19 vaccines effectiveness (i.e., risk ratio, RR) against the DV with 95% confidence intervals were assessed using random-effect models. Publication bias was assessed using Egger’s regression test and funnel plot to investigate potential sources of heterogeneity and identify any differences in study design. Results: A total population of 17.2 million (17,200,341 people) were screened for the COVID-19 vaccines’ effectiveness against the DV. We found that 61.13% of the study population were fully vaccinated with two doses of COVID-19 vaccines. The weighted pooled incidence of COVID-19 infection was more than double (20.07%) among the unvaccinated population, compared to the fully vaccinated population (8.16%). Overall, the effectiveness of the COVID-19 vaccine against the DV was 85% (RR = 0.15, 95% CI: 0.07–0.31). The effectiveness of COVID-19 vaccines varied slidably by study designs, 87% (RR = 0.13, 95% CI: 0.06–0.30) and 84% (RR = 0.16, 95% CI: 0.02, 1.64) for cohort and case-control studies, respectively. Conclusions: The effectiveness of COVID-19 vaccines were noted to offer higher protection against the DV among populations who received two vaccine doses compared with the unvaccinated population. This finding would help efforts to maximise vaccine coverage (i.e., at least 60% to 70% of the population), with two doses among vulnerable populations, in order to have herd immunity to break the chain of transmission and gain greater overall population protection more rapidly

The global and regional burden of sexual behaviors and food insecurity and their combined association on the magnitude of suicidal behaviors among 121,248 adolescent girls: An international observational study in 67 low- and middle-income and high-income countries

Background: Food insecurity and early sexual behaviors increase the risk of suicidal behavior, however their combined association on social behaviors receive little attention. Therefore, this study estimated the magnitude of adolescent global suicidal burden, it correlates with food insecurity and sexual behaviors, and assessed the combined association of food insecurity and sexual behaviors on the burden of suicidal behaviors (SBs) among school-going adolescent girls aged between 11 and 17 years. Methods: The study design is multi-county, and pooled cross-sectional in nature. Data for 67 countries from the Global School-based Student Health Survey (GSHS) were used. A random-effects meta-analysis was used to generate national and overall pooled estimates of suicidal behaviors. Multinomial logistic regression analyses were employed to estimate the adjusted effect of independent factors and the combined associations of sexual behaviors and food insecurity on adolescent SBs in the context of global, regional, and country income groups and adjusted by a set of explanatory factors. Results: The study included 121,248 girls aged 11–17 years. The population-weighted prevalence of high-level (SBs) was 40.65% among school-going girls who experienced sexual intercourse and 7.41% among those who reported severe food insecurity. However, the burden of SBs varied according to type of sexual behaviors and the age. The burden of SB among girls who had sexual intercourse with 1–2 sex partners, 3–4 sex partners, or >4 sex partners was 11.49%, 13.28%, or 18.43%, respectively. The high-level SB was double (23.08%) among adolescent girls who had first sexual intercourse aged 11–13 years old compared to adolescent girls aged 14–17 years (11.49%). The burden of SBs (for at least one SB, for two SBs, or for three SBs) were significantly associated with adolescent girls who experienced sexual intercourse (relative risk ratio, RRR = 2.04, 95% confidence interval, CI:1.83–2.28; RRR = 2.24, 1.99–2.52; RRR = 1.86, 1.59–2.18), sexual intercourse with four or more sex partners (RRR = 1.44, 1.15–1.79; RRR = 1.65, 1.33–2.06; RRR = 2.47, 1.94–3.16), first sexual intercourse aged 11–13 years (RRR = 1.22, 1.02–1.46; RRR = 1.51, 1.26–1.82; RRR = 2.26, 1.81–2.83), compared to adolescents who had no experience of SBs. Compared to adolescent girls who did neither experience food insecurity nor sexual intercourse, the overall burden of SBs (for at least one SB, for two SBs or for three SBs) were significantly higher among girls reporting to have experienced both food insecurity and sexual intercourse (RRR = 1.55, 1.29–1.86; RRR = 1.70, 1.42–2.04; RRR = 1.54, 1.26–1.88); and those reporting having experienced food insecurity but have never had sexual intercourse (RRR = 1.66, 1.48–1.87; RRR = 1.45, 1.26–1.67; RRR = 1.62, 1.36–1.92). However, it was significantly lower among girls reporting to have had sexual intercourse but never experienced food insecurity. This association was extended among adolescents in the context of regional and country income groups. Conclusion: The high burden of suicidal behaviors among adolescents calls for an urgent policy interventions to address food insecurity as a means to keep adolescents in school. The interventions should also aim to integrate safeguards that dissuade youngsters from early sex and protect them from sexual victimisation, and the associated adverse outcomes that that hamstring the attainment of SDG 3.4.2