Author(s): Sherry Gracey, Alexander Keller, Gary Montgomery, Gregory Raczniak, Bryan Schumacher, Nicholas Studer

In 2021, ≈1.4 million Americans served on active duty in the military, and approximately 800,000 were in the reserve forces. The United States Armed Forces follow most of the recommendations in the Centers for Disease Control and Prevention (CDC) Yellow Book as a matter of policy. Certain situations apply only to military personnel, however, and some policies or recommendations differ from what is recommended for civilian travel in this text.

Military physicians generally manage military- unique aspects of medical care for service members, but civilian physicians might interact with people on reserve status, on leave from duty, recently discharged from active duty, or veterans. Less commonly, active-duty service members not stationed near military hospitals or clinics must use civilian physicians for their care. Deployments can vary depending on the service branch, so understanding the type of deployment or work travel the service member participated in is essential because not all deployments or work travel are alike.

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 conserve, improve, promote, protect, and restore the mental and physical well-being of service members across the range of military activities and operations. Delivery of vaccines, use of malaria chemoprophylaxis agents, and mental health screening are examples of the many measures employed under the umbrella of FHP and are likely the most common scenarios that civilian providers will encounter. Medical and mental health screenings, both pre- and postdeployment, also support FHP to identify, track, and treat concerns.

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 might be used if available. The unit medical officer documents which military personnel have not received standard preventive measures so these people can 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. The Policy and Program for the Department of Defense Immunization Program [PDF] is found in directive 6205.02 (July 23, 2019).

Although policy is 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 might be exempt from vaccination. The 2 types of exemptions from immunization are administrative and medical. Granting administrative exemptions is a nonmedical function, usually controlled by the unit commander with input from other sources (e.g., religious counsel). Granting medical exemptions is a medical function that can be validated only by a health care professional.

Immunizations

DoD policy states that the recommendations for immunization from CDC and the Advisory Committee on Immunization Practices generally shall be followed, consistent with requirements and guidance developed by the US Food and Drug Administration (FDA) and with consideration for the unique needs of military settings and exposure risks. Specific assignment-dependent vaccines given prior to deployment are summarized at the Military Health System website.

The Defense Health Agency (DHA) Immunization Healthcare Branch (IHB) enhances military medical readiness by coordinating DoD vaccination programs worldwide. A valuable source of service-specific information on immunizations for all branches of the United States Armed Forces is available on the DHA IHB website.

Malaria Prophylaxis

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 specific to the US military because of the unique 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 for population-based approaches. 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 service member.

Primary Prophylaxis

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 unable to receive atovaquone-proguanil because of intolerance or contraindication, doxycycline is the preferred second-line therapy.

Use of mefloquine prophylaxis is a third-line recommendation for those unable to receive either atovaquone-proguanil or doxycycline. Before prescribing mefloquine for prophylaxis, consider the absolute and relative contraindications as described in the approved product label.

Atovaquone-proguanil and doxycycline are both first-line choices in areas other than sub-Saharan Africa. Reserve the use of mefloquine for people with intolerance or contraindications to first-line medications.

Although primaquine is included as an acceptable alternative by CDC for primary prophylaxis in some countries where the risk for malaria is exclusively or mostly due to Plasmodium vivax, 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. It can, however, be prescribed by a licensed medical provider on an individual basis as part of medical practice.

Terminal Prophylaxis (Presumptive Antirelapse Therapy)

Primaquine

To prevent the late relapse of P. vivax or P. ovale malaria in returning military populations, the United States Armed Forces routinely use primaquine for terminal prophylaxis (also referred to as presumptive antirelapse therapy [PART]). As a matter of policy, 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. For more information on terminal prophylaxis, see Sec. 5, Part 3, Ch. 16, Malaria.

Dosing

The FDA-approved regimen for terminal prophylaxis is 15 mg (base) given daily for 14 days. In 2003, CDC recommended 30 mg (base) of primaquine daily for 14 days for terminal prophylaxis 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 terminal prophylaxis is now recommended for military personnel.

Timing

A recurrent issue for military medicine is the correct timing of primaquine when given as terminal prophylaxis in conjunction with the standard prescribed primary 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 becomes more challenging, and civilian physicians might encounter service members who were prescribed terminal prophylaxis.

Hemolytic Anemia

The most crucial risk of primaquine use is the potential for hemolytic anemia in people who are glucose-6-phosphate-dehydrogenase (G6PD)–deficient. Current policy is for all US military personnel to be screened for G6PD deficiency on entry into military service. Some (e.g., reservists) might have deployed without testing, however, or clinicians might not be able to confirm results for all people in a unit requiring terminal prophylaxis. Hemolytic reactions to primaquine can occur in people with an unrecognized G6PD deficiency.

Tafenoquine

In 2018, the FDA approved tafenoquine for malaria prophylaxis and treatment, including terminal prophylaxis 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 2019, tafenoquine is considered a second-line drug for both chemoprophylaxis of chloroquine-resistant malaria and terminal prophylaxis in military populations. This guidance for tafenoquine use in members of the US military differs from recommendations for use in civilian populations; see Sec. 5, Part 3, Ch. 16, Malaria, for CDC guidance regarding civilian use of tafenoquine.

Unique Military Needs

US military personnel can encounter threats (e.g., biological warfare agents) that are not usually considered for civilian travelers. Drug prophylaxis, drug treatment, immunoglobulins, and vaccines 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 service members 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 military personnel without their 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 could be affected.

Returning Service Members With Health Concerns

Although symptoms and health concerns after a deployment can be similar to health issues reported from nonmilitary returning travelers, deployments present a different set of circumstances for service members than does civilian travel. These circumstances include differential vaccination recommendations, physical and psychological impact from deployment experiences, environmental exposures, and infections that create distinct health concerns. Civilian providers can help members of the United States Armed Forces access medical services, but providers should reference service-specific standards to help ensure that the treatments and medications they offer are appropriate.

The authors of this chapter are all uniformed service members of the United States Government (USG). The views expressed in this section are those of the authors and do not necessarily reflect the official policy or position of any USG Department.