Effectiveness of Covid-19 vaccines against SARS-CoV-2 Omicron variant (B.1.1.529): A systematic review with meta-analysis and meta-regression

BackgroundThere is a need for evaluation regarding vaccine effectiveness (VE) and the urgency of booster vaccination against Covid-19 B.1.1.529 (Omicron) variant. MethodsSystematic search was conducted on April 6th, 2022, on databases (PubMed, ScienceDirect, CENTRAL, Web of Science, Scopus). VE difference (VED) estimates were assessed using random-effects model and DerSimonian-Laird tau estimators. Two models result, i.e., within 3 months and within 3 months or more, are compared. VE versus time meta-regression analysis was evaluated using mixed-effects model with Restricted-Maximum Likelihood tau estimators and Hartung-Knapp adjustments. FindingsAd26.COV2.S, BNT162b2, ChAdOx1 nCov-19, and mRNA-1273 vaccines were included in the analyses. Compared to full dose, booster dose of overall vaccines provided better protection against any (VED=22% (95%CI 15%-29%), p<0.001), severe (VED=20% (95%CI 8%-32%), p=0.001) and symptomatic (VED=22% (95%CI 11%-34%), p<0.001) Omicron infections within 3 months, as well as within 3 months or more (VED=30% (95%CI 24%-37%), p<0.001 for any, VED=18% (95%CI 13%-23%), p<0.001 for severe and VED=37% (95%CI 29%-46%), p<0.001 for symptomatic infections). The meta-regression analysis of overall vaccines revealed that the full dose VE against any and symptomatic Omicron infections were significantly reduced each month by 3.0% (95%CI 0.9%-4.8%, p=0.004) and 5.2% (95%CI 3.3%-7.1%, p=0.006), respectively; whereas booster dose effectiveness against severe and symptomatic Omicron infections were decreased by 3.7% (95%CI 5.1%-12.6%, p=0.030) and 3.9% (95%CI 1.2%-6.5%, p=0.006), respectively. InterpretationCompared to full dose only, a booster dose addition provides better protection against B.1.1.529 infection. Although the VE estimates of Ad26.COV2.S, BNT162b2, ChAdOx1 nCov-19, and mRNA-1273 vaccines against B.1.1.529 infection after both full and booster doses are generally moderate, and the booster dose provides excellent protection against severe infection, it is important to note that the VE estimates decline over time, suggesting the need for a regular Covid-19 booster injection after certain period of time to maintain VE.

Covid-19 Vaccination in Pregnancy: A Systematic Review

ObjectivePregnancy is a risk factor for severe Covid-19. Looking for safe vaccines that evoke protective maternal and fetal antibody response is important. MethodsWe searched from registries (ClinicalTrials.gov, the WHO Clinical Trial Registry, and the EU Clinical Trial Registry) and databases (MEDLINE, ScienceDirect, Cochrane Library, Proquest, and Springer) up until June 20, 2021. Articles were selected based on inclusion and exclusion criteria after duplicates were removed. Infection rate, maternal antibody response, placental antibody transfer, and adverse events were described. This systematic review was performed with quality assessment and semi-quantitative synthesis according to PRISMA guidelines. ResultsTwelve observational studies with a total of 40.509 pregnant women included. The mRNA based vaccines (Pfizer-BioNTech and Moderna) can prevent future SARS-CoV-2 infections (p=0.0004). Both vaccines did not affect pregnancy, delivery, and neonatal outcomes. The most commonly encountered adverse reactions are injection-site pain, fatigue, and headache but only transient. Antibody responses were rapid after the prime dose of vaccines. After booster, antibody responses were higher and associated with better placental antibody transfer. Longer intervals between first vaccination dose and delivery were also associated with higher antibody fetal IgG and better antibody transfer ratio. ConclusionsThe Pfizer-BioNTech and Moderna vaccines are efficacious for preventing future SARS-CoV-2 infections. These vaccines can be considered as a safe option for pregnancy and their fetus. Two doses of vaccines were recommended for more robust maternal and fetal antibody responses. Longer latency was associated with higher fetal antibody responses. Systematic Review RegistrationPROSPERO (CRD42021261684)

The efficacy and safety of monoclonal antibody treatments against COVID-19: A systematic review and meta-analysis of randomized clinical trials

ObjectivesThe use of monoclonal antibody for COVID-19 showed conflicting results in prior studies and its efficacy remains unclear. We aimed to comprehensively determine the efficacy and safety profile of monoclonal antibodies in COVID-19 patients. MethodsSixteen RCTs were analyzed using RevMan 5.4 to measure the pooled estimates of risk ratios (RRs) and standardized mean differences (SMDs) with 95% CIs. ResultsThe pooled effect of monoclonal antibodies demonstrated mortality risk reduction (RR=0.89 (95%CI 0.82-0.96), I2=13%, fixed-effect). Individually, tocilizumab reduced mortality risk in severe to critical disease (RR=0.90 (95%CI 0.83-0.97), I2=12%, fixed-effect)) and lowered mechanical ventilation requirements (RR=0.76 (95%CI 0.62-0.94), I2=42%, random-effects). Moreover, it facilitated hospital discharge (RR=1.07 (95%CI 1.00-1.14), I2=60%, random-effects). Meanwhile, bamlanivimab-etesevimab and REGN-COV2 decrease viral load ((SMD=-0.33 (95%CI -0.59 to -0.08); (SMD=-3.39 (95%CI -3.82 to -2.97)). Interestingly, monoclonal antibodies did not improve hospital discharge at day 28-30 (RR=1.05 (95%CI 0.99-1.12), I2=71%, random-effects) and they displayed similar safety profile with placebo/standard therapy (RR=1.04 (95%CI 0.76-1.43), I2=54%, random-effects). ConclusionTocilizumab improved hospital discharge and reduced mortality as well as the need for mechanical ventilation, while bamlanivimab-etesevimab and REGN-COV2 reduced viral load in mild to moderate outpatients. In general, monoclonal antibodies are safe and should be considered in severe to critical COVID-19 patients. RegistrationPROSPERO (CRD42021235112)