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Interpreting vaccine efficacy trial results for infection and transmission.

ABSTRACT: Randomized controlled trials (RCTs) have shown high efficacy of multiple vaccines against SARS-CoV-2 disease (COVID-19), but evidence remains scarce about vaccines' efficacy against infection with, and ability to transmit, the virus. We describe an approach to estimate these vaccines' effects on viral positivity, a prevalence measure which under reasonable assumptions forms a lower bound on efficacy against transmission. Specifically, we recommend separate analysis of positive tests triggered by symptoms (usually the primary outcome) and cross-sectional prevalence of positive tests obtained regardless of symptoms. The odds ratio of carriage for vaccine vs. placebo provides an unbiased estimate of vaccine effectiveness against viral positivity, under certain assumptions, and we show through simulations that likely departures from these assumptions will only modestly bias this estimate. Applying this approach to published data from the RCT of the Moderna vaccine, we estimate that one dose of vaccine reduces the potential for transmission by at least 61%, possibly considerably more. We describe how these approaches can be translated into observational studies of vaccine effectiveness.

Highlights

SARS-CoV-2 vaccine trials did not directly estimate vaccine efficacy against transmission.We describe an approach to estimate a lower bound of vaccine efficacy against transmission.We estimate one dose of the Moderna vaccine reduces the potential for transmission by at least 61%.We recommend approaches for analyzing data from trials and observational studies.

SUBMITTER: Lipsitch M

PROVIDER: S-EPMC7924301 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:PURPOSE: Validated biomarkers predictive of response/resistance to anthracyclines in breast cancer are currently lacking. The neoadjuvant TOP trial, in which patients with estrogen receptor (ER)-negative tumors were treated with anthracycline (epirubicin) monotherapy, was specifically designed to evaluate the predictive value of topoisomerase IIα (TOP2A) and to develop a gene expression signature to identify those patients who do not benefit from anthracyclines. METHODS: The TOP trial included 149 patients, of which 141 were evaluable for response prediction analyses. The primary endpoint was pathological complete response (pCR). TOP2A and gene expression profiles were evaluated using pre-epirubicin biopsies. Gene expression data from ER-negative samples of the EORTC 10994/BIG 00-01 and MDACC 2003-0321 neoadjuvant trials were used for validation purposes. RESULTS: A pCR was obtained in 14% of the evaluable TOP patients. TOP2A amplification, but not protein overexpression, was significantly associated with pCR (p=0.001 and 0.22). We developed an “anthracycline-based score (A-Score)” that combines three signatures: a TOP2A gene signature and two previously published signatures related to tumor invasion and immune response. The A-Score was characterized by a high negative predictive value (NPV=0.98 [95% CI: 0.90-1.00]) overall, and in the HER2-negative and HER2-positive subpopulations. Its performance was independently confirmed in the anthracycline-based (FAC/FEC) arms of the two validation trials (BIG 00-01: 0.80 [0.61-0.92] and MDACC 2003-0321: 1.00 [0.80-1.00]). CONCLUSION: Given its high NPV, the A-Score could become, if further validated, a useful clinical tool to identify those patients who do not benefit from anthracyclines and could therefore be spared the non-negligible side effects. Predicting the efficacy of anthracyclines (epirubicin) in breast cancer (BC) patients (TOP trial) 120 microarray experiments from primary ER-negative breast tumors of anthracycline-treated patients. No replicate, no reference sample.

Project description:BackgroundTyphoid fever is a major public health problem in low-resource settings. Vaccination can help curb the disease and might reduce transmission. We have previously reported an interim analysis of the efficacy of typhoid conjugate vaccine (TCV) in Nepali children. Here we report the final results after 2 years of follow-up.MethodsWe did a participant-masked and observer-masked individually randomised trial in Lalitpur, Nepal, in which 20 019 children aged 9 months to younger than 16 years were randomly assigned in a 1:1 ratio to receive a single dose of TCV (Typbar TCV, Bharat Biotech International, India) or capsular group A meningococcal conjugate vaccine (MenA). Participants were followed up until April 9, 2020. The primary outcome was blood culture-confirmed typhoid fever. Cases were captured via passive surveillance and active telephone surveillance followed by medical record review. The trial is registered at ISRCTN registry, ISRCTN43385161 and is ongoing.FindingsFrom Nov 20, 2017, to April 9, 2018, of 20 119 children screened, 20 019 participants were randomly assigned to receive TCV or MenA vaccine. There were 75 cases of blood culture-confirmed typhoid fever included in the analysis (13 in the TCV group and 62 in the MenA group) over the 2-year period. The protective efficacy of TCV against blood culture-confirmed typhoid fever at 2 years was 79·0% (95% CI 61·9-88·5; p<0·0001). The incidence of typhoid fever was 72 (95% CI 38-123) cases per 100 000 person-years in the TCV group and 342 (95% CI 262-438) cases per 100 000 person-years in the MenA group. Adverse events occurring within the first 7 days post-vaccination were reported previously.InterpretationThe final results of this randomised, controlled trial are in keeping with the results of our published interim analysis. There is no evidence of waning protection over a 2-year period. These findings add further support for the WHO recommendations on control of enteric fever.FundingBill & Melinda Gates Foundation.

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Interpreting vaccine efficacy trial results for infection and transmission.

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