Interim Clinical Treatment Considerations for Severe Manifestations of Mpox — United States, February 2023

Monkeypox (mpox) is a disease caused by infection with Monkeypox virus (MPXV), an Orthopoxvirus (OPXV) in the same genus as Variola virus, which causes smallpox. During 2022, a global outbreak involving mpox clade IIb was recognized, primarily among gay, bisexual, and other men who have sex with men.* Most affected patients have been immunocompetent and experienced ≤10 rash lesions (1). CDC has recommended supportive care including pain control.† However, some patients have experienced severe mpox manifestations, including ocular lesions, neurologic complications, myopericarditis, complications associated with mucosal (oral, rectal, genital, and urethral) lesions, and uncontrolled viral spread due to moderate or severe immunocompromise, particularly advanced HIV infection (2). Therapeutic medical countermeasures (MCMs) are Food and Drug Administration (FDA)-regulated drugs and biologics that are predominantly stockpiled by the U.S. government; MCMs developed for smallpox preparedness or shown to be effective against other OPXVs (i.e., tecovirimat, brincidofovir, cidofovir, trifluridine ophthalmic solution, and vaccinia immune globulin intravenous [VIGIV]) have been used to treat severe mpox. During May 2022-January 2023, CDC provided more than 250 U.S. mpox consultations. This report synthesizes data from animal models, MCM use for human cases of related OPXV, unpublished data, input from clinician experts, and experience during consultations (including follow-up) to provide interim clinical treatment considerations. Randomized controlled trials and other carefully controlled research studies are needed to evaluate the effectiveness of MCMs for treating human mpox. Until data gaps are filled, the information presented in this report represents the best available information concerning the effective use of MCMs and should be used to guide decisions about MCM use for mpox patients.

clinicians caring for patients with mpox, developing guidance and other online clinical resources for health care providers, and issuing health alerts ¶ when emerging clinical concerns (e.g., severe infections in patients with advanced HIV infection) were detected. Before the 2022 outbreak, CDC experts in poxviruses and associated MCMs had evaluated efficacy data from animal models and reports of MCM use for a few human cases of related OPXV infections (e.g., vaccinia virus and cowpox virus). This information and unpublished data shared by intergovernmental partners guided initial clinical consultations; as more knowledge was acquired through clinical consultations, many of which involved repeated consultations and regular follow-up, CDC's approach to mpox cases was refined. Recurrent questions that would benefit from expert input were identified (e.g., management of ocular infections); input was solicited from external experts in infectious diseases (including HIV), immunology, neurology, ophthalmology, dermatology, and public health emergency response. Identified experts included leaders of professional societies and physicians experienced in treating mpox during the current outbreak. Partners from the Public Health Emergency Medical Countermeasures Enterprise,** a U.S. intragovernmental committee that optimizes preparedness for public health emergencies (e.g., through developing and stockpiling available MCMs), were also consulted. This report is a comprehensive synthesis of the compiled evidence and is intended to foster strategic decision-making rather than serve as a prescriptive treatment guideline. Clinical considerations were developed in the context of limited data about MCM effectiveness during the current outbreak, finite supplies of some MCMs (e.g., VIGIV and intravenous [IV] tecovirimat), and a need to incorporate evolving data and clinical observations into guidance that can be used to manage cases, including in future months if case counts increase. The rationale for specific guidance is included.

MCMs Being Used to Treat Mpox and Indications for Use
MCMs for OPXV infections include antivirals (i.e., tecovirimat, brincidofovir, cidofovir, and trifluridine ophthalmic solution) and VIGIV. Tecovirimat, brincidofovir, and VIGIV are recommended based on efficacy data from experimental animal models involving exposure to diverse OPXVs (i.e., variola, mpox, vaccinia, ectromelia, and rabbitpox viruses), albeit via the respiratory route, which is different from the close skin and mucosal contact associated with the ongoing mpox outbreak. Cidofovir and trifluridine ophthalmic solution are recommended because of their successful use treating other viral infections; cidofovir is also recommended based on data on the effectiveness of brincidofovir. All four antivirals were sporadically used to treat severe manifestations of human OPXV infections before the 2022 global outbreak (3)(4)(5)(6)(7); VIGIV has been used to treat adverse events from live, replicating vaccinia virus vaccines that are licensed to prevent smallpox (e.g., progressive vaccinia after receipt of Dryvax § § or ACAM2000 ¶ ¶ ), and was used to treat smallpox disease before its 1980 worldwide eradication (8)(9)(10)(11). Despite this real-world use, it is not known how often MCMs were associated with favorable outcomes and whether clinical improvements were due to MCMs, natural resolution of illness, or a combination of these.
MCMs have been widely used during the 2022 outbreak. As of February 2023, tecovirimat and VIGIV continue to be available through CDC-sponsored expanded access Investigational New Drug (IND) protocols; brincidofovir through an FDAauthorized single-patient emergency use IND; and cidofovir and trifluridine, commercially. To date, no data have shown whether MCMs are beneficial, including for pain control (irrespective of severity). Most persons recover with supportive care alone (including pain control***). MCMs (particularly tecovorimat) used without close monitoring could result in suboptimal drug levels and promote drug resistance, † † † thereby reducing its effectiveness for the individual patient and others. In addition, the effectiveness of MCMs for the treatment of mpox has not been systematically evaluated. For these reasons, CDC strongly encourages enrollment in clinical trials (e.g., the National Institutes of Health ( Severe mpox might manifest as hemorrhagic disease, many confluent or necrotic lesions, severe necrotizing or obstructive lymphadenopathy (e.g., of the upper airway), obstructive edema (e.g., of the gastrointestinal tract), extradermatologic manifestation (e.g., pulmonary nodules, encephalitis, myopericarditis, and ocular infections), and sepsis (12). Some patients might not have severe mpox at the time of first health care interaction but are at risk for severe mpox because of underlying medical condition (e.g., severe or moderate immunocompromise) ¶ ¶ ¶ or presence of lesions on certain surfaces (e.g., penile foreskin, urethral meatus, or vulva). These might predispose patients to complications such as strictures or edema which could require procedures including urethral catheterization, colostomy, or surgical debridement. MCMs should be considered in these cases irrespective of patient immune status. Children and adolescents aged <18 years and pregnant persons have accounted for a small percentage (<0.3%) of total U.S. cases during the current outbreak, and when affected, have experienced mild illness (13,14); however, because these populations (particularly children aged <8 years) have historically experienced more severe clade I mpox infections, and because outcomes in pregnant women and neonates during the current outbreak might not be known for several months, case-by-case consideration of MCMs should be undertaken after weighing the potential benefits and harms.**** Other populations might also benefit from case-by-case consideration of MCM use. Persons with a history of atopic dermatitis and eczema (both well-controlled and not) might experience uncontrolled viral spread, possibly as a result of associated defects in the innate or adaptive immune response (15). Persons with extensive breaks in the dermal barrier (e.g., from burns, impetigo, varicella zoster virus infections, herpes simplex virus infection, severe acne, severe diaper dermatitis with extensive denuded skin, psoriasis, and Darier disease [keratosis follicularis]) might also be at risk for severe manifestations of uncontrolled viral spread depending on the severity of the underlying condition (16).

Approach to Using MCMs to Treat Mpox
Through iterative consultations, a management algorithm outlining the approach to patients with suspected, probable, or confirmed mpox has been developed to aid in decision-making regarding the earliest use of effective MCMs when indicated ( Figure). Coinfections (e.g., with syphilis, herpes simplex, varicella zoster, or molluscum contagiosum) should be considered. All patients with suspected mpox should be evaluated for preexisting immunocompromising conditions and be tested for ¶ ¶ ¶ https://www.cdc.gov/poxvirus/monkeypox/clinicians/people-with-HIV.html **** https://www.  * Treatment includes MCMs (i.e., tecovirimat, brincidofovir, cidofovir, VIGIV, and trifluridine) and supportive therapies, including pain management. https://www. cdc.gov/poxvirus/monkeypox/clinicians/pain-management.html † Most immunocompetent patients should display signs of clinical improvement within 4 days of antiviral initiation (i.e., tecovirimat, brincidofovir, cidofovir, and trifluridine). Tecovirimat is expected to reach steady state concentrations by day 6 of dosing in healthy volunteers; therefore, worsening clinical illness after 7 days of treatment in patients with severe illness could prompt additional evaluations. § Concern for altered drug absorption includes the inability to tolerate or take oral therapy (e.g., nothing by mouth), or possibility that the oral drug absorption might be altered because of inability to consume a high-fat meal, severity of symptoms (e.g., systemic illness), comorbidities (e.g., history of gastric bypass or underlying GI disease), or other factors that might alter oral drug absorption. ¶ Hemorrhagic disease, a large number of confluent or necrotic lesions, severe lymphadenopathy that is necrotizing or obstructing (e.g., of the upper airway causing airway compromise or of the GI tract necessitating parenteral feeding), edema that is obstructing (e.g., of the lower GI tract), extradermatologic manifestations (e.g., pulmonary nodules, encephalitis, myopericarditis, or ocular infections), and sepsis. Detailed characteristics of severe disease are available at https://www.cdc. gov/poxvirus/monkeypox/clinicians/treatment.html#anchor_1655488137245. ** Persons with underlying medical conditions (e.g., severe or moderate immunocompromise [https://www.cdc.gov/poxvirus/monkeypox/clinicians/people-with-HIV. html]); bacterial superinfections; or complications including strictures, edema, and infections of the penile foreskin, vulva, urethral meatus, or anorectum, which could require procedural intervention (e.g., urethral catheterization, colostomy, or surgical debridement). This also includes those with or at risk for ocular lesions (i.e., presence of eyelid lesions, facial lesions near the eyes, or finger or hand lesions in patients unable to avoid touching their eyes [for whom autoinoculation is a concern]). Detailed characteristics of persons at risk for severe disease are available at https://www.cdc.gov/poxvirus/monkeypox/clinicians/treatment.html#anchor_1655488137245. † † https://www.cdc.gov/poxvirus/monkeypox/clinicians/case-definition.html § § This figure is a comprehensive synthesis of heterogeneous evidence and is intended to foster strategic decision-making rather than serve as a prescriptive treatment guideline.
HIV. No antiviral MCMs for use against OPXVs are virucidal, and optimal immune function is essential to recovery, irrespective of whether multiple MCMs are administered. Antiviral MCMs might complement the immune response by reducing replication, maturation, or spread of OPXVs. VIGIV might provide some level of passive immunity to certain patients with moderate or severe immunocompromise until a patient's immune system is able to clear the virus. However, earliest optimization of immune function (e.g., by temporarily delaying or decreasing doses of chemotherapy and immunomodulatory therapies and by promptly initiating effective antiretroviral medications [ARVs] for treatment of HIV) is critical to favorable outcomes. Since August 2022, consultations with CDC have involved a large proportion of immunocompromised persons, particularly those with HIV and low CD4 cell counts (12). Comprehensive information about each MCM, including mechanism of action, safety, efficacy, and dosing should be reviewed along with the management algorithm when deciding about administration or cessation of MCMs (Table).
Interactions with other medications including ARVs should also be considered (17). Tecovirimat. Tecovirimat is administered two to three times daily (depending upon patient's weight), typically for 2 weeks. Based on the favorable safety and efficacy profile of tecovirimat compared with other MCMs, if only one MCM is administered, it should be tecovirimat, unless there is a contraindication such as a previous adverse event after receiving the drug. The pharmacokinetics of orally administered tecovirimat taken with a fatty meal compare favorably with those of IV tecovirimat. IV tecovirimat (which is currently available in limited supply) should be prioritized for patients who are unable to take oral medications or fatty meals with each dose, have gastrointestinal disease that might impair absorption (e.g., new or chronic diarrhea), or have diffuse and disseminated infection. † † † † For patients for whom IV tecovirimat is indicated, prepositioned oral tecovirimat should be administered until the IV formulation is obtained.
Patients with severe immunocompromise might benefit from extended treatment (i.e., >14 days) if new confirmed OPXV lesions occur or existing lesions worsen despite treatment. Data from animal studies suggest it might be safe to extend tecovirimat treatment (18). Clinicians should carefully consider the risks and benefits of extending treatment, and extensions of short, defined intervals should be used (e.g., an additional 3-7 days) with close monitoring for safety signals and clinical response. Tecovirimat resistance has been detected in a small number of patients with advanced HIV who received tecovirimat for periods of weeks to months (19). Resistance can also develop as the result of subtherapeutic levels of tecovirimat (e.g., because of medication noncompliance or because fatty meals are not taken with the oral formulation). Testing for tecovirimat resistance and pharmacokinetics § § § § for public health surveillance purposes is encouraged when any new lesions form after ≥7 days of treatment.
Brincidofovir and cidofovir. One of these drugs can be added to tecovirimat treatment for patients with (or at risk for) severe mpox. They are usually administered once weekly for 2 weeks. One animal study suggests that combined treatment (tecovirimat and brincidofovir, the prodrug of cidofovir) might have synergistic efficacy (20). Brincidofovir or cidofovir without tecovirimat should typically only be administered to patients in whom tecovirimat is contraindicated. Brincidofovir and cidofovir should not be used simultaneously or within 1 week of one another, because they form the same active metabolite (cidofovir diphosphate), which has a prolonged duration of action. Both drugs have FDA black box warnings and other safety considerations that require close monitoring. Diarrhea has been commonly reported in patients who receive brincidofovir ¶ ¶ ¶ ¶ ; diarrhea of any etiology might impair absorption of orally administered tecovirimat and indicate a need for IV tecovirimat. In vitro studies suggest that brincidofovir might have superior antiviral activity to that of cidofovir against variola virus, likely because of better cellular uptake (21,22); however, because data are limited, side effect profiles should be prioritized when choosing between the two drugs. Development of resistance to brincidofovir or cidofovir is less likely to occur than is resistance to tecovirimat (23,24).
VIGIV. VIGIV administered as a single dose provides passive immunoglobulin (Ig) G antibodies against vaccinia virus, which might provide some cross-protection across the OPXV genus, including for MPXV. During the current outbreak, it has been recommended for mpox patients unable to mount a sufficiently robust immune response to clear the virus (e.g., because of HIV-related CD4 count <350 or after solid organ transplantation). Although its effectiveness for mpox is unknown, the safety profile is believed to be favorable; however, caution should be exercised when administering VIGIV to patients with ocular mpox involving the cornea because of a report of an animal study of vaccinia keratitis in which VIGIV was associated with persistent corneal scarring (25,26). VIGIV is available in limited supply. Subsequent dosing (i.e., § § § § https://www.cdc.gov/poxvirus/monkeypox/pdf/attachment-5-optional-pksample-testing.pdf ¶ ¶ ¶ ¶ https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/214460s000, 214461s000lbl.pdf   * This table is a comprehensive synthesis of the heterogeneous evidence and is intended to foster strategic decision-making rather than serve as a prescriptive treatment guideline. † Dosing for persons <40 kg and children is available at https://www.cdc.gov/poxvirus/monkeypox/pdf/tecovirimat-ind-protocol-cdc-irb.pdf. § Dosing for persons <48 kg and children is available at https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/214460s000,214461s000lbl.pdf. ¶ Data suggest that an aggressive early dosing regimen for patients with severe immunocompromise might be most beneficial; for this reason, a dose in the higher range (9,000 units/kg) early in the clinical course, potentially followed by an additional dose 3-4 days later, might help saturate viral antigens and halt viremia and viral replication. ** IV administration requires a syringe pump, a device that might not be easily accessible in all health care settings and has a slow infusion longer than 6 hours, irrespective of total infusion volume. † † Per EA-IND the standard duration of tecovirimat treatment is 14 days, with clinical data being limited to a 14-day course. Based on individual patient risk-benefit assessment and disease progression, tecovirimat and cidofovir may be extended beyond 14 days, or shortened because of lack of virologic or clinical response or adverse event occurrence. Extension of brincidofovir currently requires FDA authorization on an individual patient basis through an emergency IND request secondary to concerns related to the BBW stated within the table. § § Secondary to potential accumulating of hydroxypropyl-β-cyclodextrin, an excipient in the IV tecovirimat formulation which is eliminated through glomerular filtration. Intravenous tecovirimat may be used with caution in patients with renal impairment (creatine clearance <30 mL/min) only if drug absorption via enteral administration is not anticipated to be dependable or feasible, and based on the risk-benefit assessment by the treating clinician that determines IV tecovirimat clinically necessary. ¶ ¶ Other animal studies examine the use of these agents; the studies noted within the table were used to gain FDA approval or provide evidence of efficacy for its offlabel use. *** https://www.cdc.gov/mmwr/volumes/71/wr/mm7137e1.htm?s_cid=mm7137e1_w † † † CNS penetration was determined based on available animal and human data. Well: data suggested that an MCM was able to cross the blood-brain barrier and enter intrathecal space at concentrations known to be effective; Uncertain: data suggested that an MCM can cross the blood-brain barrier, but unclear if at sufficient concentrations to be effective; Limited: evidence suggested that an MCM does not or would not cross the blood-brain barrier. The theoretical utility of any medical countermeasure in clearing MPXV from the central nervous system is unknown. § § § To date, <0.5% specimens (out of >5,000 specimens) sent to CDC for testing have been found to develop resistance within the current outbreak.

TABLE. (Continued) Summarized mechanisms of action, administration recommendations, adverse events, clinical considerations, and supporting data about medical countermeasures that can be used to treat mpox*-United States, January 2023
including vaccinia virus (27) and has demonstrated efficacy against ocular vaccinia virus infections in animal models (25,28) and humans (28,29). Continuous administration beyond the recommended 4-week duration of treatment should be avoided because of the risk for corneal epithelial toxicity (30).

Considerations in the Management of Severe Mpox Cases
Severe mpox (including ocular infections, neurologic complications, myopericarditis, mucosal lesion complications, and uncontrolled viral spread) have been reported. Manifestations of these complications, recommended MCMs, and other clinical considerations for each type of infection (e.g., involvement of specific clinical subspecialists) are summarized (Box). US Department of Health and Human Services/Centers for Disease Control and Prevention Ocular infections. These can manifest as blepharitis, conjunctivitis, conjunctival lesions, keratitis, and vision loss. Ocular infections have occurred when MPXV infects the eye or periorbital area, usually via autoinoculation or local spread from nearby lesions (31).
Neurologic complications. Encephalitis and myelitis have been reported in some mpox patients (32). Whether these result from direct viral invasion of the central nervous system or autoimmune disease from antigenic stimulus is not known. Cases involving neurologic complications have rarely been reported to CDC, but have occurred in immunocompetent persons, despite resolving mpox skin lesions.
Myopericarditis. Myopericarditis cases have been reported among immunocompetent patients (1,32,33). The pathogenic mechanism is uncertain but might result from direct viral invasion or lymphocytic infiltration of the myocardium or pericardium, its sequelae (e.g., myonecrosis or myocardial fibrosis), or an autoimmune process.
Complications associated with some mucosal (oral, rectal, genital, and urethral) lesions. Certain mucosal surface lesions can cause strictures and other complications that impair activities of daily living (e.g., reduced oral intake, painful bowel movements, impaired urination, and airway obstruction).
Complications from uncontrolled viral spread in immunocompromised patients. Moderately or severely immunocompromised patients (e.g., advanced HIV and organ transplant recipients) have sometimes developed diffuse and disseminated lesions that have involved multiple organ systems, possibly because of persistent viremia or uncontrolled viral growth (12). Overwhelming systemic illness has resulted in death.

Other Clinical Considerations
Immune dysregulation. Earliest optimization of immune function is critical to favorable outcomes. Mpox patients with advanced HIV who have recently started ARVs and who then experience persistent or progressive lesions might manifest features commonly associated with immune reconstitution inflammatory syndrome; whether immune dysregulation is the cause of illness or the immune system is unable to effectively clear MPXV from infected cells is not known. Until definitive data are available, administration of systemic immunomodulators (including steroids) to patients with mpox should be undertaken with caution; models suggest that steroids are associated with severe illness and even death in OPXV-infected animals (34).
Lesions that persistently test positive. Positive OPXV and MPXV polymerase chain reaction (PCR) test results are expected until lesions resolve; therefore, serial testing of lesion specimens is not informative unless new lesions appear or lesions progress despite tecovirimat treatment. Test results do not guide duration of infection control policies because patients are considered infectious until all lesions have scabbed, the scabs have fallen off, and healthy tissue is visible underneath.
Prolonged occurrence of new lesions despite appropriate MCMs. If progressive lesions are noted, particularly after reversal of immunocompromise, diagnostic evaluation should include testing new lesions for OPXV and other infections, and evaluation for superinfections, noninfectious processes such as erythema multiforme, and immunologic function. Laboratories, such as CDC's poxvirus laboratory,***** can test for presence of viable virus from lesion specimens using culture techniques that might guide patient care. If viral culture is unavailable, evaluating trends in PCR cycle threshold values might be informative.

Knowledge Gaps and Next Steps
Knowledge gaps regarding optimal treatment of severe mpox are best addressed through data collected during randomized controlled trials and other carefully controlled research studies. Patients enrolled in well-designed studies might benefit from the close monitoring provided by these studies (e.g., effective adjustments of tecovirimat doses are made as part of the STOMP trial based on serially monitored pharmacokinetic parameters). Understanding the role of immune dysregulation in the clinical course of severely immunocompromised HIV patients started on ARVs was frequently recognized as a knowledge gap: CDC has partnered with NIH to study this (Virologic and Immunologic Characteristics of Severe Mpox Among Persons with Advanced HIV [VIRISMAP] study). † † † † † Clinicians and health departments are encouraged to contact CDC when treating mpox in a patient recently started on ARVs. Controlled studies focused on understanding the impact of monotherapy or combination therapy on virus shedding, duration of illness, and clinical outcomes are needed, particularly for patients with severe immunocompromise. Public health laboratories, academic laboratories, and CDC continue to sequence the F13L gene (the tecovirimat target) to assess F13L viral mutations that might be associated with resistance. Phenotypic testing to evaluate resistance is also occurring at CDC. §

Complications from uncontrolled viral spread in moderately to severely immunocompromised patients
• Clinical manifestations: Numerous, large, coalescing, or necrotic lesions of the skin can occur in patients with severe immunocompromise. Other organ systems (e.g., gastrointestinal tract, liver, lungs, brain, or adrenal glands) can be involved, resulting in signs and symptoms of organ dysfunction irrespective of severity of cutaneous lesions.
Overwhelming systemic illness including sepsis can occur and might progress to death. • Diagnostic findings: Uncontrolled viral spread can manifest as the appearance of new skin lesions or worsening of existing lesions. Involvement of other organ systems can result in a range of findings on physical exam and laboratory investigations (e.g., gastrointestinal obstruction, severe pneumonia, empyema, encephalitis, intractable hypotension, or transaminitis). Alternate or coinciding causes of severe illness should be investigated. • Treatment: Immune function should be optimized through interventions such as effective HIV antiretrovirals and reduced immunomodulatory therapy as feasible. Prompt initiation of tecovirimat (potentially the intravenous formulation), and possible combination with either cidofovir or brincidofovir, and VIGIV, should be considered. Wound care is critical to ensure healing and prevent superinfection and autoinoculation. § Diffuse skin lesions might cause insensible fluid losses requiring intensive fluid management. • Other considerations: Consider consultation with experts in infectious diseases, critical care, dermatology, wound care, gastroenterology, and surgery (e.g., general surgery, plastic surgery, and burn experts) as indicated. Administration of MCMs for extended durations (>14 days) might be reasonable if clinically indicated (e.g., new or progressive mpox lesions occur). The role of immune dysregulation in severe mpox illness is not known; there is no high-quality evidence to support or refute the use of steroids and other immunomodulators, and clinicians should weigh the risks and benefits of such therapies because optimal immune function aids recovery from mpox. Supportive care and close clinical monitoring for occurrence of complications such as secondary bacterial infections and sepsis can be critical in patients with severe mpox illness.

Summary
What is already known about this topic?
During the 2022 global monkeypox (mpox) outbreak, some patients have experienced severe clinical manifestations. Medical countermeasures (MCMs) developed to treat smallpox have been used to treat mpox.
What is added by this report?
Data relevant to the use of tecovirimat, brincidofovir, cidofovir, trifluridine ophthalmic solution, and vaccinia immune globulin intravenous were reviewed. Animal models, MCM use for human cases of related orthopoxviruses, unpublished data, input from clinician experts, and experience during CDC mpox consultations were also evaluated to develop interim clinical treatment considerations.
What are the implications for public health practice?
Until data from controlled studies are available, these interim clinical considerations facilitate strategic decision-making about the use of MCMs to manage specific severe manifestations of mpox.
because immune response is crucial to viral clearance, and this data might facilitate development of improved clinical guidance (35). Until data from controlled studies are available, observational data from patients treated under IND might provide insights into clinical outcomes. Providers administering MCMs under IND programs should complete and submit optional data collection forms to facilitate improved understanding of the role of MCMs. CDC will update guidance, as appropriate, as new data emerge.