US Military Deployments
In 2016, approximately 1.3 million US military members were on active duty, and approximately 800,000 were in the reserve forces. The US military, as a matter of policy, follows most of the recommendations in the CDC Yellow Book. However, certain situations apply only to the US military, and some policies or recommendations differ from what is recommended in the Yellow Book for civilian travel. Active-duty military physicians generally manage predeployment medicine, but civilian physicians may interact with people who are on reserve status, home on leave, recently discharged from active duty, or veterans. Providers can find predeployment and postdeployment information, policies, and guidelines for clinicians, service members and their families, and veterans on the Deployment Health Clinical Center website (www.pdhealth.mil).
Force Health Protection
Force health protection (FHP) is an important concept in military medicine. FHP is defined as all measures taken by commanders, supervisors, individual service members, and the military health system to promote, protect, improve, conserve, and restore the mental and physical well-being of service members across the range of military activities and operations. Delivery of vaccines and the use of malaria chemoprophylaxis agents are 2 aspects of FHP.
Medical interventions for FHP are the responsibility of the unit commander, with advice from the unit medical officer. When predeployment vaccines or malaria chemoprophylaxis are indicated, the commander includes such requirements in the mission plan. Service members are then required to receive these interventions under proper medical supervision. If a particular vaccine or drug is medically contraindicated, alternative agents may be employed if they are available. The unit medical officer documents which military personnel have not received standard preventive measures, so these people may receive additional monitoring or treatment if they become ill.
FHP policy positions in the Department of Defense (DoD) are issued as directives and instructions. All directives and instructions can be found online at www.dtic.mil/whs/directives. The Policy and Program for Immunizations to Protect the Health of Service Members and Military Beneficiaries is found in directive 6205.02E (September 19, 2006) at www.esd.whs.mil/Portals/54/Documents/DD/issuances/dodd/620502p.pdf.
Although policy may be made at higher levels in Washington, DC, the final decision to use vaccines or malaria chemoprophylaxis under FHP is made by commanders in the field, guided by their medical staff. In certain circumstances, individual service members may be exempt from vaccination. There are 2 types of exemptions from immunization: medical and administrative. Granting medical exemptions is a medical function that can be validated only by a health care professional. Granting administrative exemptions is a nonmedical function, usually controlled by the person’s unit commander.
Routine and Travel-Related Immunization
Department of Defense (DoD) policy states that the recommendations for immunization from CDC and the Advisory Committee for Immunization Practices shall generally be followed, consistent with requirements and guidance of the Food and Drug Administration (FDA) and with consideration for the unique needs of military settings and exposure risks. The specific vaccines given prior to deployment are dependent on the assignment and are summarized at the Military Health System website (https://health.mil/Military-Health-Topics/Health-Readiness/Immunization-He...). The Defense Health Agency (DHA) Immunization Healthcare Branch (IHB) [formerly the Military Vaccine Agency (MILVAX)] enhances military medical readiness by coordinating DoD immunization (vaccination) programs worldwide. A valuable source of service-specific information on immunizations for all branches of the US Armed Services is found at the DHA IHB website (www.health.mil/vaccines).
Preventing malaria in military units deployed to endemic areas is essential. Medical commanders must designate trained staff to provide comprehensive malaria prevention counseling to military and civilian personnel considered at risk of contracting malaria.
Several features of malaria prophylaxis are unique to the US military because of the activities and stressors of military deployments. When antimalarial drugs are used, the military can only use FDA-approved agents in accordance with the specific FDA-approved indications. Off-label use of drugs is not allowed. If off-label use is felt to be in the best interest of the person or unit, trained and knowledgeable clinicians must provide one-on-one medical evaluations, document in the medical record the rationale for such use, and provide a prescription for the drug or vaccine to each person.
Atovaquone-proguanil (Malarone) is the recommended malaria prophylaxis option for all personnel for both short- and long-term deployments in high-transmission areas of Africa. For practical purposes, this includes most of sub-Saharan Africa. For people who are unable to receive atovaquone-proguanil because of intolerance or contraindication, doxycycline is the preferred second-line therapy. Use of mefloquine as prophylaxis is a third-line recommendation for those unable to receive either atovaquone-proguanil or doxycycline. Before prescribing mefloquine for prophylaxis, absolute and relative contraindications as described in the approved product label must be considered.
Atovaquone-proguanil and doxycycline are both first-line choices in areas other than sub-Saharan Africa. Mefloquine should be reserved for people with intolerance or contraindications to both first-line medications.
As a matter of policy, the US military routinely uses primaquine for presumptive antirelapse treatment (PART) in returning military populations to prevent the late relapse of P. vivax malaria or P. ovale malaria. PART is also referred to as “terminal prophylaxis.” In PART, primaquine is given to otherwise healthy people on their departure from an endemic area. Primaquine is used for this indication much more frequently in the military than in most civilian travelers.
The FDA-approved regimen for PART is 15 mg (base) given daily for 14 days. In 2003, CDC recommended 30 mg (base) of primaquine daily for 14 days for PART based on available evidence, but the FDA-approved regimen remains the lower dose. Adherence to the daily 14-day regimen is poor unless primaquine is given under directly observed therapy, which is rarely done. As a result of noncompliance and subtherapeutic dosing with the 15-mg/day regimen, periodic outbreaks of relapsed P. vivax malaria continue to occur in returning military personnel. Use of the higher-dose primaquine regimen for PART is now recommended for military personnel.
Although primaquine is included as an acceptable alternative by CDC for primary prophylaxis in some countries where the risk of malaria is exclusively or mostly P. vivax malaria, primaquine is not FDA-approved for primary prophylaxis. Because use of primaquine for primary prophylaxis constitutes off-label use, it cannot be prescribed for a deploying group, but it can be prescribed by a licensed medical provider on an individual basis as part of medical practice.
The most important risk of using primaquine is hemolytic anemia in those who are deficient in G6PD. Current policy is for all US military personnel to be screened for G6PD deficiency on entry into military service. However, some people, such as reservists, may have deployed without testing, or clinicians may not be able to confirm results for all people in a unit requiring PART. Clinicians should be aware that hemolytic reactions to primaquine may occur in those with unrecognized G6PD deficiency.
A recurrent issue for military medicine is the correct timing of primaquine when given as PART in conjunction with the standard prescribed prophylaxis. Primaquine can be given at any time after personnel leave an endemic area. For convenience and for enhancing adherence to the 14-day regimen, it is often best for military units to prescribe primaquine in the immediate 2 weeks after return. During this time, units are often still at their home base completing in-processing before block leave. Once personnel depart on leave, adherence and monitoring for side effects are more difficult.
In 2018, the US Food and Drug Administration approved tafenoquine for malaria prophylaxis and treatment, including PART for P. vivax and P. ovale malaria. As with primaquine, the most important risk of tafenoquine is hemolytic anemia in people who are G6PD deficient. As of press time, it is unclear whether and how the US military will adopt the use of tafenoquine. More information on tafenoquine is available in Chapter 4, Malaria.
Unique Needs for the Military
US military personnel may encounter threats, such as biological warfare agents, that are not usually considered for civilian travelers. Vaccines, immunoglobulins, drug prophylaxis, and drug treatment regimens can be given only in accordance with FDA-licensed products and regimens and for FDA-approved indications.
Products not approved by the FDA are given to soldiers only with voluntary informed consent under an institutional review board-approved protocol and in accordance with a current and FDA-approved investigational new drug application.
Only under exceptional circumstances would products not approved by the FDA be given to soldiers without informed consent. The FDA commissioner can authorize the use of an unapproved medical product or an unapproved use of an approved medical product during a declared emergency involving a heightened risk of attack on the public or US military forces or when national security may be affected.
The Returning Service Member with Health Concerns
Symptoms and health concerns after a deployment may be similar to health issues reported from nonmilitary returning travelers. However, deployment presents a different set of circumstances from the civilian traveler such as differential vaccination recommendations, physical and psychological stress and trauma of combat, environmental exposures, and infections that may cause unique health concerns. The Post-Deployment Health Clinical Practice Guideline (PDH-CPG) is designed to help clinicians implement specific approaches to address these distinctive experiences and exposures and includes clinical tools and resources to evaluate and manage patients with the full spectrum of deployment-related concerns.
Drs. Forgione and Riddle are employees of the Department of Defense. The views expressed in this section are those of the authors and do not necessarily reflect the official policy or position of the Departments of the Air Force, Army, or Navy, nor the Department of Defense.
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Gregory A. Raczniak, Mark S. Riddle, Michael Forgione