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Read the GEIS Strategy to learn how the section will support infectious disease surveillance and outbreak response to enhance FHP decision making in the future operating environment. The focus of these efforts is rapid detection and advanced characterization of endemic or emerging threats to military forces, including vectors and reservoirs of infectious disease transmission.

Supported activities also include the study of clinical and epidemiological characteristics of infectious disease and associated risk factors to provide timely and actionable findings to DoD stakeholders. The Data to Decision Initiative, started in August , formalizes a process for timely and consistent reporting of surveillance information for immediate FHP decision making and longer term analysis.

The Consortium brings GEIS partners together to share information on capabilities, standard operating procedures, and expertise, to enhance coordination and collaboration in NGS and its associated BI challenges. GEIS provides direct technical support to GCC-led international scientific coalitions and strategic engagement efforts that focus on infectious disease prevention, detection, and response.

GEIS funding supports a global network of highly qualified DoD Service laboratories positioned in key locations to provide on-the-ground infectious disease surveillance and outbreak response.

GEIS partners have built surveillance networks and relationships with the U. This Strategy describes how GEIS will support infectious disease surveillance and outbreak response to enhance FHP decision making in the future operating environment. GEIS will achieve this end state through direct support to the six Geographic Combatant Commands GCC and the global DoD laboratory network that operates in all of their areas of operation to provide early detection, prevention and response to infectious disease threats of military relevance.

AFHSB recently released new, web-based interactive disease surveillance maps. To reduce the impact of respiratory pathogens on service members, the Armed Forces Health Surveillance Branch coordinates a global respiratory surveillance program for the military. Learn how the program detects dangerous pathogens to keep armed forces healthy. PLoS Med 15 8 : e This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. In outbreaks of emerging infectious diseases for which no proven efficacious vaccines exist but investigational vaccines have been developed, it is important both to rapidly test the investigational vaccines and, if effective, to deploy them.


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Following the — Ebola epidemic, the World Health Organization WHO , the Coalition for Epidemic Preparedness Innovations, and other bodies committed to developing investigational vaccines for emerging infectious diseases [ 1 , 2 ]. They aim to evaluate them for immunogenicity and safety, so that promising candidates will be available for efficacy testing and possible deployment when an epidemic occurs.

In the Ebola epidemic, various strategies were used for the design of efficacy i.

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Some investigators argued for individually randomized controlled trials iRCTs , while others argued for forms of cluster-randomized controlled trials cRCTs [ 4 , 5 ]. Later in the epidemic, rapidly declining disease incidence required changes to some trial designs. Ideally, principles and protocols based on scientific, ethical, and feasibility considerations should be drawn up in advance of an epidemic, facilitating expediency and trust for rapid, early implementation once an epidemic occurs. Here, we summarize key scientific, ethical, and feasibility considerations relevant to the design of Phase 3 vaccine trials in epidemic situations.

Trial design choices are discussed, highlighting the benefits and drawbacks of each in given contexts. When designing and implementing randomized efficacy trials for investigational vaccines after safety and immunogenicity data have been collected in Phase 1 and 2 trials , some key choices must be made. In the current regulatory system, randomized trials are considered the gold standard and, except in rare circumstances, have been required for vaccine licensure [ 6 , 7 ]. We restrict our scope to randomized trials of a single vaccine against an emerging infectious disease for which no effective vaccine exists.

We assume that all participants, whether in the intervention or control group if any , will have access to the best currently available other preventative measures e. We discuss four key elements of trial design: randomization unit, trial population, comparator intervention, and trial implementation.

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We weave into that discussion three important ethical considerations: the social and scientific value of the trial, its risk—benefit profile, and the fairness of participant selection [ 8 , 9 ]. These aspects are, in our views, key to trial design in these settings. Table 1 summarizes the major designs that have been used or proposed for vaccine trials.

Some have not been employed in epidemic settings. The table does not provide an exhaustive list, and not all designs have been used for evaluating vaccines against emerging infectious diseases. Table 2 summarizes key features of iRCTs, in which vaccination is randomized between individuals in the same population, and cRCTs, in which groups of individuals are randomized.

In cRCTs, population-level protective effects are measured i. Either approach depends on the fact that, if the investigational vaccine is effective, the control group will be at greater risk of infection; the difference is simply how the membership of the control group is assigned [ 21 ]. When testing an investigational vaccine during an epidemic, it is important to establish an efficacy estimate as rapidly as possible so that, if efficacious, the vaccine may still be deployed in the same epidemic.

Also, in a declining epidemic, cases may become so rare that a trial is no longer feasible. The fact that an iRCT measures the direct effect of a vaccine, whereas a cRCT measures the combined direct plus indirect effect, may favor either design. By including indirect effects, cRCTs provide a measure of protection closer to what might be obtained in widespread rollout of a vaccine. The combined effect may thus be of specific interest to decision-makers. However, indirect effects are more difficult to extrapolate to other settings than direct effects, the former depending on setting, population, network structure, and vaccine coverage [ 28 — 31 ].

A cRCT measures the protective effect that is highly relevant to the context in which the trial is conducted but may be less relevant at a later time in the same population, or in a different population. The direct vaccine effect, as measured in iRCTs, is likely to be less variable in different settings and, with assumptions about transmission dynamics, can be used to model indirect effects in different coverage and epidemic settings.

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Deriving an estimate of the direct effect from a cRCT is more complex and assumption dependent. Thus, we posit that the most valuable parameter to estimate in trials of unproven vaccines is the direct effect, as measured in an iRCT. Importantly, also, direct effects are generally the basis for regulatory decisions on the licensure of vaccines. For all these reasons, we believe that iRCTs should be the default design for evaluating investigational vaccines during epidemics.

Nonetheless, particular circumstances may weigh in favor of a cRCT. Recent work has shown that despite the larger sample size typically required in cRCTs compared to iRCTs because of the design effect see glossary , in some settings, the difference in sample size may be modest, because the larger effect measured indirect plus direct in a cRCT partly offsets this effect [ 33 ]. In the Ebola epidemic, many considered a cRCT as the most feasible and acceptable design.

However, with extensive community engagement, it was possible to launch an iRCT of an investigational Ebola vaccine in Liberia [ 12 ]. Trial participants may be selected either from the general population or from a group at high risk of exposure to infection. When a vaccine is intended for widespread use in the general population, conducting the trial in the general population will enhance the generalizability of trial results.

However, such trials will be feasible only if the incidence of the disease under study is high enough for a trial of manageable size. A vaccine trial conducted in persons at high risk of exposure, such as serodiscordant couples for a sexually transmitted infection [ 13 ] or healthcare workers for a disease transmitted by direct contact [ 14 ], is likely to reduce the required sample size and have greater statistical efficiency.

Efforts to enhance the risk—benefit profile of a trial may lead to performing a trial in a group that is especially likely to benefit if the investigational vaccine proves effective, such as those with occupational, familial, or household exposure to infection. However, if such individuals would be in the eventual target population for a vaccination program, there are compelling arguments for including them in a trial.

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Complexities ensue when these considerations conflict. Consider, for example, pregnant women and investigational vaccine trials against Zika virus infection. Concern about adverse effects on the fetus might argue for excluding all pregnant women. However, pregnant women and their fetuses are likely to benefit the most if an investigational Zika vaccine proves effective.

A systematic precautionary approach has led to the previous exclusion of pregnant women from vaccine trials, even when they are an important target population for the vaccine [ 35 , 36 ]. The default should therefore be to include pregnant women and other so-called vulnerable groups in investigational vaccine trials during epidemics, provided that the risks of participation are judged acceptable [ 8 , 37 ].

For naturally immunizing infections, investigators sometimes restrict enrollment in a trial to those who have not previously been infected to ensure that trial participants are truly at risk of becoming infected; this is especially relevant when selecting individuals thought to be at high risk for infection.

However, selecting participants who both have risk factors for infection and are uninfected at enrollment may be problematic.


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  • First, it means that all potential participants must be tested for evidence of prior infection. Second, individuals who have remained uninfected despite many opportunities for exposure may be more resistant to infection or have lower-risk exposures than is typical in the general population [ 38 ]. Serodiscordant couples, for example, may tend to be those who practice safer sex or for whom the infected partner is less infectious than in other couples.