You will be presented with a collection of medical randomized controlled trial (RCT) reports addressing a shared clinical question -- for instance, the efficacy of a medical intervention on a disease or condition. Given the titles and abstracts of these reports, your task is to generate the conclusion of the systematic review article synthesizing the key findings. Your conclusion should be a few sentences long. In your response, include only the conclusion and no other text. The RCT reports are below.



Title 1:
A comparison of observation-level random effect and Beta-Binomial models for modelling overdispersion in Binomial data in ecology & evolution
Abstract 1:
Overdispersion is a common feature of models of biological data , but research ers often fail to model the excess variation driving the overdispersion , result ing in biased parameter estimates and st and ard errors . Quantifying and modeling overdispersion when it is present is therefore critical for robust biological inference . One means to account for overdispersion is to add an observation-level r and om effect ( OLRE ) to a model , where each data point receives a unique level of a r and om effect that can absorb the extra-parametric variation in the data . Although some studies have investigated the utility of OLRE to model overdispersion in Poisson count data , studies doing so for Binomial proportion data are scarce . Here I use a simulation approach to investigate the ability of both OLRE models and Beta-Binomial models to recover unbiased parameter estimates in mixed effects models of Binomial data under various degrees of overdispersion . In addition , as ecologists often fit r and om intercept terms to models when the r and om effect sample size is low ( < 5 levels ) , I investigate the performance of both model types under a range of r and om effect sample sizes when overdispersion is present . Simulation results revealed that the efficacy of OLRE depends on the process that generated the overdispersion ; OLRE failed to cope with overdispersion generated from a Beta-Binomial mixture model , leading to biased slope and intercept estimates , but performed well for overdispersion generated by adding r and om noise to the linear predictor . Comparison of parameter estimates from an OLRE model with those from its corresponding Beta-Binomial model readily identified when OLRE were performing poorly due to disagreement between effect sizes , and this strategy should be employed whenever OLRE are used for Binomial data to assess their reliability . Beta-Binomial models performed well across all context s , but showed a tendency to underestimate effect sizes when modelling non-Beta-Binomial data . Finally , both OLRE and Beta-Binomial models performed poorly when models contained < 5 levels of the r and om intercept term , especially for estimating variance components , and this effect appeared independent of total sample size . These results suggest that OLRE are a useful tool for modelling overdispersion in Binomial data , but that they do not perform well in all circumstances and research ers should take care to verify the robustness of parameter estimates of OLRE models


Title 2:
Baseline Meningococcal Carriage in Burkina Faso before the Introduction of a Meningococcal Serogroup A Conjugate Vaccine
Abstract 2:
ABSTRACT The serogroup A meningococcal conjugate vaccine MenAfriVac has the potential to confer herd immunity by reducing carriage prevalence of epidemic strains . To better underst and this phenomenon , we initiated a meningococcal carriage study to determine the baseline carriage rate and serogroup distribution before vaccine introduction in the 1- to 29-year old population in Burkina Faso , the group chosen for the first introduction of the vaccine . A multiple cross-sectional carriage study was conducted in one urban and two rural districts in Burkina Faso in 2009 . Every 3 months , oropharyngeal sample s were collected from > 5,000 r and omly selected individuals within a 4-week period . Isolation and identification of the meningococci from 20,326 sample s were performed by national laboratories in Burkina Faso . Confirmation and further strain characterization , including genogrouping , multilocus sequence typing , and porA-fetA sequencing , were performed in Norway . The overall carriage prevalence for meningococci was 3.98 % ; the highest prevalence was among the 15- to 19-year-olds for males and among the 10- to 14-year-olds for females . Serogroup Y dominated ( 2.28 % ) , followed by serogroups X ( 0.44 % ) , A ( 0.39 % ) , and W135 ( 0.34 % ) . Carriage prevalence was the highest in the rural districts and in the dry season , but serogroup distribution also varied by district . A total of 29 sequence types ( STs ) and 51 porA-fetA combinations were identified . The dominant clone was serogroup Y , ST-4375 , P1.5 - 1,2 - 2/F5 - 8 , belonging to the ST-23 complex ( 47 % ) . All serogroup A isolates were ST-2859 of the ST-5 complex with P1.20,9/F3 - 1 . This study forms a solid basis for evaluating the impact of MenAfriVac introduction on serogroup A carriage


Title 3:
Meningococcal carriage and immunity in western Burkina Faso, 2003.
Abstract 3:
A prospect i ve carriage and serological study was conducted in Burkina Faso during the 2003 meningitis season , which was characterized by hyperendemic Neisseria meningitidis serogroup W135 ( NmW135 ) and serogroup A ( NmA ) disease . Participants were evaluated five times at monthly intervals . In the presence of moderate NmW135 carriage , we found a low prevalence of putatively protective levels of specific immunoglobulin G ( IgG ) and serum bactericidal antibody ( SBA ) against NmW135 . Specific IgG concentrations and SBA titers against NmA were relatively high in this recently vaccinated population , while no NmA carriage was detected . NmW135 carriage infrequently induced protective immunity against reference or homologous strains , while natural immunity against NmW135 was frequently lost . A vaccine that is effective against W135 will be beneficial for sub-Saharan Africa


Title 4:
The effect of rifampicin on meningococcal carriage in family contacts in northern Nigeria.
Abstract 4:
Summary In a study of carriage of Neisseria meningitidis in family contacts of patients with group A meningococcal meningitis in the African meningitis belt an overall carrier rate of 17 per cent was observed . The rate was higher in the younger age groups ( 5–19 years ) .  No overall sex difference was observed . The carrier rate was significantly higher in the contacts who had been sleeping in the same room as the patient . Rifampicin  reduced the carrier rate from 20 per cent to five per cent within two weeks of treatment and a further drop of 2·5 per cent was observed four weeks later . The corresponding results for sulphadimidine were 14 , 14 and 10 per cent . More than 90 per cent of the strains isolated were resistant to 50 μg/ml of  sulphadiazine  in vitro . All of the strains initially isolated were sensitive to rifampicin  , but of the 11 strains isolated after treatment with this drug four were partially resistant


Title 5:
Failure of meningococcal vaccination to stop the transmission of meningococci in Nigerian schoolboys.
Abstract 5:
A combined group A and group C meningococcal polysaccharide vaccine was given to 438 Nigerian schoolboys shortly before an outbreak of group A meningococcal disease occurred in their school . Four months after vaccination the carriage rate of group A meningococci among vaccinated subjects ( 11 % ) was no different from that found among the controls ( 12 % ) , although a good antibody response to both components of the vaccine was observed . One case of group A meningococcal disease was recorded amongst 438 vaccinated subjects while five cases occurred among 874 controls
This is consistent with contact studies in Africa , which show that children 10–14 years have the highest frequency of contacts .
Targeting older children in Africa for conjugate vaccination may be effective in reducing meningococcal transmission