***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objective The objective of this trial was to determine the effectiveness of 1.0 % C31 G ( SAVVY ) in preventing male-to-female vaginal transmission of HIV infection among women at high risk . Methodology /Principal Findings This was a Phase 3 , double-blind , r and omized , placebo-controlled trial . Participants made up to 12 monthly visits for HIV testing , adverse event reporting , and study product supply . The study was conducted between March 2004 and February 2006 in Accra and Kumasi , Ghana . We enrolled 2142 HIV-negative women at high risk of HIV infection , and r and omized them to SAVVY or placebo gel . Main outcome measures were the incidence of HIV-1 and HIV-2 infection as determined by detection of HIV antibodies from oral mucosal transu date specimens and adverse events . We accrued 790 person-years of follow-up in the SAVVY group and 772 person-years in the placebo group . No clinical ly significant differences in the overall frequency of adverse events , abnormal pelvic examination findings , or abnormal laboratory results were seen between treatment groups . However , more participants in the SAVVY group reported reproductive tract adverse events than in the placebo group ( 13.0 % versus 9.4 % ) . Seventeen HIV seroconversions occurred ; eight in participants r and omized to SAVVY and nine in participants receiving placebo . The Kaplan-Meier estimates of the cumulative probability of HIV infection through 12 months were 0.010 in the SAVVY group and 0.011 in the placebo group ( p = 0.731 ) , with a hazard ratio ( SAVVY versus placebo ) of 0.88 ( 95 % confidence interval 0.33 , 2.27 ) . Because of a lower-than-expected HIV incidence , we were unable to achieve the required number of HIV infections ( 66 ) to obtain the desired study power . Conclusions / Significance SAVVY was not associated with increased adverse events overall , but was associated with higher reporting of reproductive adverse events . Our data are insufficient to conclude whether SAVVY is effective at preventing HIV infection relative to placebo . Trial Registration Clinical Trials.gov BACKGROUND Female-initiated HIV-prevention options , such as microbicides , are urgently needed . We assessed Carraguard , a carrageenan-based compound developed by the Population Council , for its efficacy and long-term safety in prevention of HIV infection in women . METHODS We undertook a r and omised , placebo-controlled , double-blind trial in three South African sites in sexually-active , HIV-negative women , aged 16 years and older . 6202 participants , who were r and omly assigned by a block r and omisation scheme to Carraguard ( n=3103 ) or placebo ( methylcellulose [ n=3099 ] ) , were instructed to use one applicator of gel plus a condom during each vaginal sex act . Participants were followed up for up to 2 years . Visits every 3 months included testing for HIV presence and pregnancy , pelvic examinations , risk reduction counselling , and treatment for curable sexually transmitted infections and symptomatic vaginal infections . The primary outcome was time to HIV seroconversion . Analysis was in the efficacy population ( a subset of the intention-to-treat population , excluding participants for whom efficacy could not be assessed ) . This study is registered with Clinical Trials.gov , number NCT00213083 . FINDINGS For the primary outcome ( time to HIV seroconversion ) we analysed 3011 women in the Carraguard group and 2994 in the placebo group .  HIV incidence was 3.3 per 100 woman-years ( 95 % CI 2.8 - 3.9 ) in the Carraguard group ( 134 events ) and 3.8 per 100 woman-years ( 95 % CI 3.2 - 4.4 ) in the placebo group ( 151 events ) , with no significant difference in the distribution of time to seroconversion ( p=0.30 ) . The covariate-adjusted hazard ratio was 0.87 ( 95 % CI 0.69 - 1.09 ) . Rates of self-reported gel use ( 96.2 % Carraguard , 95.9 % placebo ) and condom use ( 64.1 % in both groups ) at last sex acts were similar in both groups . On the basis of applicator testing , however , gel was estimated to have been used in only 42.1 % of sex acts , on average ( 41.1 % Carraguard , 43.1 % placebo ) . 1420 ( 23 % ) women in the intention-to-treat population had adverse events ( 713 Carraguard , 707 placebo ) , and 95 ( 2 % ) women had adverse events that were related to gel use ( 48 Carraguard , 47 placebo ) . Serious adverse events occurred in 72 ( 2 % ) women in the Carraguard group and 78 ( 3 % ) in the placebo group , only one of which was considered possibly related to gel use ( placebo group ) . INTERPRETATION This study did not show Carraguard 's efficacy in prevention of vaginal transmission of HIV . No safety concerns were recorded BACKGROUND Observational data and non-human primate challenge studies suggest that cell-mediated immune responses might provide control of HIV replication . The Step Study directly assessed the efficacy of a cell-mediated immunity vaccine to protect against  HIV-1 infection or change in early plasma HIV-1 levels . METHODS We undertook a double-blind , phase II , test-of-concept study at 34 sites in North America , the Caribbean , South America , and Australia . We r and omly assigned 3000 HIV-1-seronegative participants by computer-generated assignments to receive three injections of MRKAd5 HIV-1 gag/pol/nef vaccine  ( n=1494 ) or placebo  ( n=1506 ) . R and omisation was prestratified by sex , adenovirus type 5 ( Ad5 ) antibody titre at baseline , and study site . Primary objective was a reduction in HIV-1 acquisition rates ( tested every 6 months ) or a decrease in HIV-1 viral-load setpoint ( early plasma HIV-1 RNA measured 3 months after HIV-1 diagnosis ) . Analyses were per protocol and modified intention to treat . The study was stopped early because it unexpectedly met the prespecified futility boundaries at the first interim analysis . This study is registered with Clinical Trials.gov , number NCT00095576 . FINDINGS In a prespecified interim analysis in participants with baseline Ad5 antibody titre 200 or less , 24 ( 3 % ) of 741 vaccine recipients became HIV-1 infected versus 21 ( 3 % ) of 762 placebo recipients ( hazard ratio [ HR ] 1.2 [ 95 % CI 0.6 - 2.2 ] ) . All but one infection occurred in men . The corresponding geometric mean plasma HIV-1 RNA was comparable in infected male vaccine and placebo recipients ( 4.61 vs 4.41 log(10 ) copies per mL , one tailed p value for potential benefit 0.66 ) . The vaccine elicited interferon-gamma ELISPOT responses in 75 % ( 267 ) of the 25 % r and om sample of all vaccine recipients ( including both low and high Ad5 antibody titres ) on whose specimens this testing was done ( n=354 ) . In exploratory analyses of all study volunteers , irrespective of baseline Ad5 antibody titre , the HR of HIV-1 infection between vaccine and placebo recipients was higher in Ad5 seropositive men ( HR 2.3 [ 95 % CI 1.2 - 4.3 ] ) and uncircumcised men ( 3.8 [ 1.5 - 9.3 ] ) , but was not increased in Ad5 seronegative ( 1.0 [ 0.5 - 1.9 ] ) or circumcised ( 1.0 [ 0.6 - 1.7 ] ) men . INTERPRETATION This cell-mediated immunity vaccine did not prevent HIV-1 infection or reduce early viral level . Mechanisms for insufficient efficacy of the vaccine and the increased HIV-1 infection rates in subgroups of vaccine recipients are being explored Background This trial evaluated the safety and effectiveness of 6 % cellulose sulfate vaginal gel in preventing male-to-female vaginal transmission of HIV , gonorrhea and chlamydial infection . Methods This Phase III , double-blind , r and omized , placebo-controlled trial was conducted between November 2004 and March 2007 in Lagos and Port Harcourt , Nigeria . We enrolled 1644 HIV-antibody negative women at high risk of HIV acquisition . Study participants were r and omized 1∶1 to cellulose sulfate or placebo  and asked to use gel plus a condom for each act of vaginal intercourse over one year of follow-up . The participants were evaluated monthly for HIV , gonorrhea and chlamydial infection , and for adverse events . Results The trial was stopped prematurely after the data safety monitoring board of a parallel trial concluded that cellulose sulfate might be increasing the risk of HIV . In contrast , we observed fewer infections in the active arm ( 10 ) than on placebo ( 13 ) , a difference that was nonetheless not statistically significant ( HR = 0.8 , 95 % CI 0.3–1.8 ; p = 0.56 ) . Rates of gonorrhea and chlamydial infection were lower in the CS group but the difference was likewise not statistically significant ( HR = 0.8 , 95 % CI 0.5–1.1 ; p = 0.19 for the combined STI outcome ) . Rates of adverse events were similar across study arms . No serious adverse events related to cellulose sulfate use were reported . Conclusions Cellulose sulfate gel appeared to be safe in the evaluated study population but we found insufficient evidence that it prevented male-to-female vaginal transmission of HIV , gonorrhea or chlamydial infection . The early closure of the trial compromised the ability to draw definitive conclusions about the effectiveness of cellulose sulfate against HIV . Trial Registration Clinical Trials.gov Background Observational studies suggest that male circumcision may provide protection against HIV-1 infection .  A r and omized , controlled intervention trial was conducted in a general population of South Africa to test this hypothesis . Methods and Findings A total of 3,274 uncircumcised men , aged 18–24 y , were r and omized to a control or an intervention group with follow-up visits at months 3 , 12 , and 21 . Male circumcision was offered to the intervention group immediately after r and omization and to the control group at the end of the follow-up . The grouped censored data were analyzed in intention-to-treat , univariate and multivariate , analyses , using piecewise exponential , proportional hazards models . Rate ratios ( RR ) of HIV incidence were determined with 95 % CI . Protection against HIV infection was calculated as 1 − RR . The trial was stopped at the interim analysis , and the mean ( interquartile range ) follow-up was 18.1 mo ( 13.0–21.0 ) when the data were analyzed . There were 20 HIV infections ( incidence rate = 0.85 per 100 person-years ) in the intervention group and 49 ( 2.1 per 100 person-years ) in the control group , corresponding to an RR of 0.40 ( 95 % CI : 0.24%–0.68 % ; p < 0.001 ) . This RR corresponds to a protection of 60 % ( 95 % CI : 32%–76 % ) . When controlling for behavioural factors , including sexual behaviour that increased slightly in the intervention group , condom use , and health-seeking behaviour , the protection was of 61 % ( 95 % CI : 34%–77 % ) . Conclusion Male circumcision provides a degree of protection against acquiring HIV infection , equivalent to what a vaccine of high efficacy would have achieved . Male circumcision may provide an important way of reducing the spread of HIV infection in sub-Saharan Africa . ( Preliminary and partial results were presented at the International AIDS Society 2005 Conference , on 26 July 2005 , in Rio de Janeiro , Brazil . OBJECTIVE To determine the efficacy of the nonoxynol 9 contraceptive sponge in preventing  sexual acquisition of the human immunodeficiency virus ( HIV ) .  DESIGN Prospect i ve , r and omized placebo-controlled trial . SETTING Research clinic for prostitutes in Nairobi , Kenya . PATIENTS AND INTERVENTIONS One hundred thirty-eight HIV-seronegative women were enrolled , of whom 74 were assigned to  nonoxynol 9 sponge use and 64 to  placebo  use . These two groups did not significantly differ with respect to demographic characteristics , sexual practice s , or prevalence of genital infections at enrollment , except for a lower number of sex partners per week and a higher initial prevalence of genital ulcers among women assigned to nonoxynol 9 sponge use . Among the  
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Conclusion : Reporting of trials of biomedical HIV prevention interventions has improved over time .