ACIP Work Groups

About

ACIP uses subgroups of the committee, known as work groups, to review relevant published and unpublished data and develop recommendation options for presentation to the ACIP.

Work groups are typically task oriented and convene in response to specific policy needs. Each work group operates under specific terms of reference and disband when current work group activities are completed.

The following work groups are currently active: (Updated 10/9/2025)

• Chikungunya Vaccines

• Childhood and Adolescent Immunization Schedule

• COVID-19 Immunizations

• Cytomegalovirus Vaccines

• Human Papillomavirus Vaccine

• Immunization Schedule Documentation Maintenance

• Influenza Vaccines

• Meningococcal Vaccines
  

• Mpox Vaccines

• Pneumococcal Vaccines

• Respiratory Syncytial Virus (RSV) Immunization Workgroup, Maternal, Infant, Adult

Chikungunya Vaccines

• Work group purpose: The Chikungunya Vaccines Work Group reviews and evaluates data on chikungunya disease, epidemiology, and vaccines and develops policy options for ACIP’s consideration.

• Topics under discussion by the work group:
  • Use of chikungunya vaccines in U.S. persons at risk of chikungunya, including those who travel abroad, laboratory workers, and residents of U.S. territories and states with, or at risk of, transmission.

• Work group activities:
  • Review information on chikungunya disease, including outcomes.
  • Review data on chikungunya epidemiology and burden among U.S. residents, including travelers and persons living in areas at risk for local transmission.
  • Review data on safety, immunogenicity, and effectiveness of chikungunya vaccines.
  • Provide evidence-based recommendation options for ACIP.
  • Identify areas in need of further research for informing potential future vaccine recommendations.
  • Publish chikungunya vaccine MMWR Recommendations and Reports document.

Childhood and Adolescent Immunization Schedule

TOPICS UNDER DISCUSSION BY THE WORKGROUP

In accordance with the ACIP Charter and in a multi-year effort, the Childhood and Adolescent Immunization Schedule WG members will work with expert consultants as appropriate and in accordance with FACA statutory requirements and policies, to prepare information for the ACIP members to enable them to make recommendations on:

• The timing and order of different vaccines. For example, should the last toddler dose of the non-live DTaP vaccine be given before, on the same day, or after the MMR vaccine?
• The concurrent administration of various vaccines and other immunizing products such as monoclonal antibodies. For example, does the risk of post-vaccination febrile seizures increase or decrease with concomitant administration?
• The safety of ingredients that are present in multiple different vaccines. For example, do either of the two different aluminum adjuvants increase the risk of asthma?
• The efficacy and safety of different vaccine schedules used in different countries. For example, are there differences in efficacy or safety between the U.S. and Danish childhood vaccine schedules?

DESCRIPTION OF WORKGROUP ACTIVITIES

The following activities provide a framework for the Childhood and Adolescent Immunization Schedule WG multi-year efforts, which may involve data requests from other Federal and non-Federal entities: Review and summarize existing knowledge from published and unpublished research and safety surveillance systems. This work may include the following three multi-faceted tasks, which may be completed in sequence or in parallel:

• Identify gaps in and collaborate accordingly to address new research studies that ascertain important aspects of the vaccine schedule, particularly from CDC's Vaccine Safety Datalink (VSD), from Food and Drug Administration's Biologics Efficacy and Safety System (BEST), and the National Institutes of Health through their extramural grant awards program.
• Based on the highest quality studies, determine whether a change in the vaccine schedule may be warranted, outline various options, and vote on which option to recommend to the full ACIP for consideration.
• Communicate the deliberations and recommendations to the full ACIP, for them to review and vote on. Together with the WG majority views, minority views will also be communicated to the full ACIP, with rationales for the different opinions.

Childhood and Adolescent Immunization Schedule Workgroup Terms of Reference

COVID-19 Immunizations

TOPICS UNDER DISCUSSION BY THE WORKGROUP

The following topics relevant to COVID-19 immunization for effective control of COVID-19 disease in the civilian population of the United States will be under discussion in the WG in multi-year efforts.

• Risk-benefit and cost-benefit analyses of existing and newly FDA-authorized mRNA and other COVID-19 immunizations, and immunization schedules as it relates to COVID-19 immunization to inform use recommendations, personalized per age-group, major risk factors and health status.
• To identify critical gaps in the existing scientific and clinical knowledge and methodologies related to the safety and efficacy of the COVID-19 immunizations, to inform the development of policy recommendations and further analyses and research by the CDC, other related federal agencies, and the scientific community.
• To review and summarize data, clinical and scientific knowledge related to adverse events associated with COVID-19 immunizations to inform immunization recommendations in terms of precautions and contraindications to receipt of immunization.

DESCRIPTION OF WORKGROUP ACTIVITIES

The following activities provide a framework for the COVID-19 immunization WG multi-year efforts which may involve data requests from other Federal and private partners:

• Review and summarize existing data and published and unpublished research and clinical knowledge related to the safety, effectiveness, and immunogenicity of COVID-19 immunizations authorized or approved in the United States.
• Summarize literature reviews of the epidemiology of COVID-19 disease and SARS-CoV-2 virus.
• Assess the benefit-risk balance for administration of COVID-19 immunization products at the same time as other immunizations.
• Identify areas where additional data and research are needed to inform COVID-19 immunization recommendations.
• Develop COVID-19 immunization recommendations.
• Review and summarize the existing clinical and scientific information available; and gaps in the existing knowledge, including from other federal agencies like the FDA, where appropriate relating to bio distribution, pharmacokinetics and persistence of the spike protein, mRNA, and lipid nanoparticles to inform immunization recommendations.
• Review and summarize the existing clinical and scientific information (including from federal agencies like the FDA, where appropriate); gaps in the existing knowledge regarding potential impurities (e.g., DNA contamination and endotoxins) in existing immunization products and their health impacts to inform immunization recommendations.
• Review and summarize the existing scientific knowledge, and gaps, regarding the cumulative short- and long-term impact of repeated boosting immunization including non-specific effects (e.g., IgG4 class switching, immune imprinting, viral evolution under leaky immunizations) to help inform immunization recommendations.
• Examine the impact of COVID-19 immunization on COVID-19 and all cause deaths, hospitalizations, and disability to inform immunization recommendations.
• Analyze existing data and scientific knowledge regarding cardiovascular, thrombotic, neurological, immunological and other serious adverse events potentially caused by COVID-19 immunization.
• Review and summarize available data, information, and gaps regarding long-term Covid effects from scientific literature and clinical experience associated with COVID-19 immunization products and COVID-19 infection to inform policy recommendations.
• Map existing COVID-19 immunization policies in countries around the world and how they compared to the US.
• Analyze existing data and scientific knowledge related to the safety of COVID-19 immunization during pregnancy.

COVID-19 Immunizations Workgroup Terms of Reference

Cytomegalovirus Vaccines

• Work group purpose: Cytomegalovirus, or CMV, is the most common infectious cause of birth defects in the United States. About 1 out of 200 babies is born with congenital CMV infection. One out of 5 babies with congenital CMV infection will have symptoms or long-term health problems, such as hearing loss. CMV is also an important cause of morbidity and mortality among people with immunocompromising conditions. Multiple candidate CMV vaccines are currently under development. The purpose of the ACIP CMV Vaccines Work Group is to review data on CMV vaccines and develop CMV vaccine policy options for ACIP consideration.

• Topics under discussion by the work group: Future use of CMV vaccines in the U.S.

• Work group activities:
  • Review safety, immunogenicity, and efficacy data for CMV vaccine candidates from Phase I-III clinical trials.
  • Review the epidemiology of CMV and congenital CMV infection and identify potential target populations for vaccination.
  • Identify areas where additional data are needed to inform CMV vaccine policy recommendations.
  • Develop CMV vaccine policy options that ACIP may consider for recommendation.

Human Papillomavirus Vaccine

TOPICS UNDER DISCUSSION BY THE WORKGROUP

The following topics relevant to a comprehensive review of the efficacy, effectiveness and safety of the HPV vaccine, as well as to specific vaccination policies regarding the use of HPV vaccine and effective control of HPV infection and related disease in the population of the United States will be under discussion in the HPV Vaccine WG in multi-year efforts and include, for presentation to the parent committee for its deliberation and development of recommendations to CDC, evaluation of:

• HPV vaccination schedules with fewer doses;
• Wording of the age for routine HPV vaccination; and
• Draft policy recommendations following a comprehensive review of the cumulative scientific and clinical data, knowledge, and evidence regarding the efficacy, effectiveness, and the safety of the HPV vaccine. This includes assessment of the long term effects of HPV vaccination programs on population level incidence (per subtype), morbidity and mortality of cervical cancer.

DESCRIPTION OF WORKGROUP ACTIVITIES

The following activities provide a framework for the HPV Vaccine WG multi-year efforts, which may involve data requests from other Federal and private partners, for development of presentations to the parent ACIP for its deliberations as it develops recommendations to the CDC Director:

• Summarize and review the cumulative data on temporal trends in the U.S. and other countries of HPV infection, precancers, cervical cancer incidence; other HPV attributable outcomes; and mortality per different age groups and how they potentially correlate with evolving vaccination rates and screening policies.
• Summarize and review, using existing systematic reviews, where possible, the cumulative data and knowledge regarding vaccine efficacy and effectiveness in relation to cervical cancer and surrogate outcomes, including a meta-analysis of clinical trials and observational studies.
• Summarize and review the cumulative data and knowledge regarding vaccine safety and related adverse events, including VAERS source and other safety data and meta-analysis of clinical trials and observational studies.
• Characterize the nature of the safety reports in men and women and timing of the report post vaccination with the first and second dose.
• Summarize and review existing data and knowledge regarding the potential toxicity of HPV vaccine, adjuvants, and potential contaminants and/or impurities.
• Summarize and review existing knowledge related to the efficacy, effectiveness and safety of HPV vaccination when given to individuals with prior exposure to HPV infections.
• Summarize and review the existing data on potential HPV type replacement (i.e., increase in oncogenic types not targeted by HPV vaccine, after introduction of HPV vaccination programs, as well as data and knowledge related to the potential impact of vaccination rates.
• Review and summarize existing data, including published and as available and appropriate, unpublished research, as well as clinical knowledge, related to the efficacy, effectiveness, and immunogenicity of HPV vaccination with fewer than two doses in individuals aged 9 through 14 years.
• Review and summarize existing data including published and, as available and appropriate, unpublished research, as well as clinical knowledge related to the efficacy, effectiveness, and immunogenicity of HPV vaccination with fewer than three doses in individuals to inform vaccination recommendations for persons aged 15 years and older.
• Review programmatic data on age at vaccination in the United States.
• Develop HPV vaccination policy options for presentation to and deliberation by, the ACIP parent committee.

Overall, the HPV Vaccine WG will prepare information for the ACIP members to enable them to:

• Advise on population groups and/or circumstances in which a vaccine or related agent is recommended.
• Provide recommendations on contraindications and precautions for use of the vaccine and related agents and provide information on recognized adverse events.
• Provide recommendations that address the general use of vaccines and if applicable, immune globulin preparations as a class of biologic agents, use of specific antibody products for prevention of infectious diseases, and special situations or populations that may warrant modification of the routine recommendations.
• Support committee deliberations on use of immunization to control disease including consideration of disease epidemiology and burden of disease, immunization safety, immunization efficacy and effectiveness, the quality of evidence reviewed, economic analyses, medical ethics, and implementation issues including informed consent language.
• Revise or withdraw their recommendation(s) regarding a particular immunization should new information on disease epidemiology, immunization effectiveness or safety, economic considerations, or other data become available.

HPV Vaccines Workgroup Terms of Reference

Immunization Schedule Documentation Maintenance

• Work group purpose: The Immunization Schedule Documentation Maintenance Work Group edits and maintains the child/adolescent and adult immunization schedule documents. The child/adolescent immunization schedule summarizes the ACIP vaccination recommendations for persons 18 years of age and younger, and the adult immunization schedule summarizes the ACIP vaccination recommendations for persons 19 years of age and older.

• Topics under discussion by the work group: The products of this work group do not establish new vaccine recommendations; the work group documents reflect existing ACIP recommendations.

• Work group activities:
  • Publication of the child/adolescent and adult immunization schedules.

Influenza Vaccines

TOPICS UNDER DISCUSSION BY THE WORKGROUP

In accordance with the ACIP Charter and in a multi-year effort, the Influenza Immunization WG members will work with expert consultants as appropriate and in accordance with FACA statutory requirements and policies, to prepare information for presentation to and deliberation by the parent ACIP committee in developing their recommendations. In particular, the following topics and related activities relevant to influenza immunization for effective control of influenza A and/or B-related disease in the civilian population of the United States will be considered as a framework for and/or undertaken by the Influenza WG in multi-year efforts:

• Conduct and/or review risk-benefit and cost-benefit data for, and/or analyses of, existing and newly-licensed influenza vaccines, and their administration schedules, to inform the parent committee’s deliberations on vaccine use recommendations according to age-group, major risk factors, and health status.
• Identify critical gaps in existing scientific and clinical knowledge and CDC monitoring methods related to the safety, efficacy/effectiveness, immunogenicity, and long-term immune system impacts of influenza vaccines to inform the parent committee’s deliberations on development of policy recommendations and to identify further analyses and research to be recommended to CDC for its consideration and CDC potential advice to other federal agencies and the scientific community to conduct.
• Review and summarize data, clinical and scientific knowledge related to short and long-term adverse events associated with influenza vaccines to present to the parent committee for its deliberations in identifying precautions and contraindications recommendations.
• Review and summarize data for presentation to the parent committee on the long-term immunological effects of repeated annual influenza vaccination as a function of risk group and strain variability or type (drift/shift).

DESCRIPTION OF WORKGROUP ACTIVITIES

The following activities provide a framework for the Influenza Immunization WG multi-year efforts, which may involve data requests from the FDA and other federal agencies and private partners, for development of presentations to the parent ACIP for its deliberations as it develops recommendations to the CDC Director:

• Review and summarize existing data including published and unpublished research and clinical knowledge related to the safety, effectiveness, and immunogenicity of influenza vaccines authorized or approved in the United States.
• Summarize literature reviews of the epidemiology of influenza disease and infection.
• Assess the benefit-risk balance for administration of influenza immunization products co[1]administered with other vaccinations.
• Identify areas where additional data and research are needed to inform influenza immunization recommendations to be developed by ACIP.
• Annually review and develop updates of U.S. seasonal influenza immunization policy recommendations.
• Review and summarize the existing clinical and scientific information concerning the role of innate, adaptive innate, adaptive cellular, and adaptive humoral immune responses associated with different influenza vaccines, adjuvants, and correlates of protection associated with influenza vaccination.
• Review and summarize the existing clinical and scientific information, and gaps in the existing knowledge, including from the FDA and other federal agencies, as well as academic studies, concerning the impact of repeated influenza vaccination including immunological effects such as immune imprinting, “original antigenic sin,” and related phenomena.
• Review and summarize the existing clinical and scientific information, and identify and address gaps in the existing knowledge regarding both antigenic sequence mismatch, as well as glycosylation mismatch, in existing immunization products and their health impacts to inform immunization recommendations.
• Review and summarize the existing scientific knowledge and gaps, regarding the cumulative short- and long-term impact of repeated annual seasonal influenza vaccination (including boosting in young children’s first season), including non-specific effects (e.g., IgG4 class switching, immune imprinting, viral evolution under leaky immunizations) to help inform immunization recommendations.
• Examine the impact of Influenza A and B immunization on influenza and all-cause deaths, hospitalizations, and disability to inform immunization recommendations.
• Analyze existing data and scientific knowledge regarding cardiovascular, thrombotic, neurological, immunological, and other serious adverse events potentially caused and averted by influenza immunization.
• Review, analyze, and summarize available data concerning the safety and effectiveness of influenza immunization of the elderly, including the interaction between influenza vaccines and immunosenescence, and both innate and adaptive immunity.
• Review and summarize available data, information, and gaps regarding long-term repeated Influenza vaccination effects from scientific literature and clinical experience associated with influenza immunization products and influenza infection to inform policy recommendations.
• Map existing influenza immunization policies in countries around the world and how they compare to U.S. vaccine policy.
• Analyze existing data and scientific knowledge related to the safety of influenza immunization during pregnancy, including both potential teratogenic effects and potential beneficial effects for the newborn.

Influenza Vaccines Workgroup Terms of Reference

Meningococcal Vaccines

• Work group purpose: The Meningococcal Vaccines Work Group discusses meningococcal vaccine recommendations and develops policy options for ACIP’s consideration.

• Topics under discussion by the work group:
  • The adolescent meningococcal vaccine schedule is being revisited to ensure vaccines are administered at a time to optimize protection for higher risk ages (e.g., re-consideration of the 11-12 year-old dose for MenACWY, higher meningitis B risk during first year of college) and reflect implementation considerations (e.g., routine vs. risk-based vs. shared clinical decision-making recommendations, harmonization with existing adolescent platform).
  • Guidance for use of GSK’s pentavalent meningococcal vaccine will be developed. It is anticipated that this vaccine will be licensed as a 2-dose series (doses separated by 6 months) for the prevention of Neisseria meningitidis infections in persons ages 10 through 25 years.

• Work group activities:
  • Review the epidemiology of invasive meningococcal disease in the U.S., including burden in adolescents (including race/ethnicity) and breakthrough infections.
  • Review immunogenicity and safety clinical trial data for GSK’s pentavalent vaccine.
  • Perform economic analyses (including burden of disease averted by vaccination).
  • Develop draft policy recommendations based on grading of recommendations, assessment, development and evaluation (GRADE) and the evidence to recommendations (EtR) framework.

Mpox Vaccines

• Work group purpose: The Mpox Vaccine Work Group discusses the data about use of JYNNEOS vaccine in children 12-17 years of age and develops policy options for use of the 2-dose JYNNEOS vaccine series for this population. The Work Group reviews data and literature related to mpox vaccine effectiveness, and safety and also considers other domains in the Evidence to Recommendations framework in anticipation of presenting the data to ACIP for consideration.

• Topics under discussion by the work group:
  • Use of JYNNEOS (MVA-BN) in adolescents aged 12-17 years at risk for mpox during 1) an mpox outbreak* and 2) because of the ongoing clade IIb global mpox outbreak.

• Work group activities
  • Review the epidemiology of mpox in children 12-17 years of age, including the burden among persons in the United States.
  • Discuss safety, effectiveness, and immunogenicity of the vaccine in persons aged 12-17 years.
  • Propose evidence-based recommendation options for ACIP.
  • Identify areas in need of further research for informing future vaccine recommendations, including use of JYNNEOS in children under 12 years of age.

* Public health authorities determine whether there is an mpox outbreak; a single case may be considered an mpox outbreak at the discretion of public health authorities. Other circumstances in which a public health response may be indicated include ongoing risk of introduction of mpox into a community due to disease activity in another geographic area.

Pneumococcal Vaccines

• Work group purpose: Each year in the United States, pneumococcal disease causes thousands of infections, such as meningitis, bloodstream infections, pneumonia, and ear infections. The Pneumococcal Vaccines Work Group:
  • Reviews current data on pneumococcal disease epidemiology;
  • Reviews current data on pneumococcal vaccines and assesses the strength of the evidence;
  • Assesses cost-effectiveness and public health impact of new and current vaccine policy options; and
  • Develops revised or updated policy options for pneumococcal vaccines as needed.

• Topics under discussion by the work group:
  • Use of new pneumococcal conjugate vaccines in U.S. adults and children.

• Work group activities
  • Reviews new evidence on pneumococcal disease epidemiology and pneumococcal vaccine coverage in the United States.
  • Reviews new evidence on pneumococcal vaccines that are currently recommended in the United States.
  • Reviews evidence on new pneumococcal vaccines in advanced stages of development.
  • Summarize evidence relevant to the policy questions considered by the ACIP using Evidence to Recommendations framework and GRADE.
  • Update MMWR Policy Note and MMWR Recommendation and Report, as needed.

Respiratory Syncytial Virus (RSV) Immunization Workgroup, Maternal, Infant, Adult

TOPICS UNDER DISCUSSION BY THE WORKGROUP

The topics for discussion by the RSV immunization workgroup can be most efficiently described by breaking them into two groups: 1) adult populations (18-49 with risk factors, 50 and older with risk factors, and those 75 and above); and 2) the maternal-infant group (for which there is currently a recommendation for all newborns), as well as use of a monoclonal antibody product in the second RSV season for young children susceptible to serious RSV disease, including groups such as all American Indian/Alaska Native infants. The WG will work on questions and topics described below and prepare deliverables for the ACIP parent committee to consider.

Adults:

Ages 18-49 years. The CDC is being asked to consider a recommendation for vaccination of persons in this age cohort with 'risk factors' making them susceptible to severe RSV infection. This raises several questions for the WG, for example:

• What is the scope of the problem? How many patients in this cohort are admitted to the hospital annually for RSV LRTI. What are the outcomes data? What is the total number of hospitalizations for LRTI of all causes in this group?
• What are the specific risk factors that have been identified as being significant?
• How are these risk-factors measured for severity?
• What are the critical values, (i.e. FEV1 in the case of obstructive airway disease, cardiac output for those with congestive heart failure, A1C for diabetics, Creatinine levels for chronic renal failure patients, psychiatric assessments for patients with psychoses, etc.).
• What congenital or other anatomic abnormalities are of concern?
• What living situations, in addition to a nursing home environment, are considered to be high risk? This information is essential for both patients and for the physicians caring for them responsible for providing adequate education for informed consent (noting that informed consent is a matter under state law).
• Will boosters be necessary, and if so, how often?
• What are the results of ongoing monitoring of post-licensure safety and adverse events?

Age 50 and older with risk factors:

• What is the scope of the problem?
• What are the defined risk factors, how they are measured, and the critical values?
• Will boosters be needed? The duration of immunity in this cohort is currently unknown.

Age 75 and older:

• Currently this is a universal recommendation. The WG should provide updates on hospitalization rates of those vaccinated and unvaccinated, outcomes, and deaths attributed to RSV infection. How many admissions for LRTI for any etiology are there in this cohort?
• The WG should provide updates on the incidence of serious adverse events for all who have been vaccinated, broken down by specific vaccine. This cohort is particularly susceptible.

Maternal-Infant and young children with risk factors:

• What is the uptake of the maternal vaccine and how does it compare with administration of monoclonal antibodies to newborns?
• The WG should provide updates on rates of RSV-associated hospitalization in infants who do not receive protection from either maternal vaccination or a monoclonal antibody, in infants born to mothers that received maternal vaccination, and in infants that have received monoclonal antibodies only.
• What is the number needed to treat to prevent a hospital admission, an ICU admission, or death? How does that compare with the number needed to vaccinate to see a significant adverse event for each product?
• The WG should provide a thorough review of the data presented at the last ACIP meeting in June 2025 regarding the safety of relevant RSV products. This would include the study design, the original description of the study groups. and a reanalysis of the safety data using more sophisticated methodologies.
• The WG should review all raw data on the RCTs including data from the ongoing trials of RSV products.
• The WG should address any significant aberration or discrepancy between what was presented in June and what is found on re-analysis that may trigger a review of the ACIP recommendation regarding other RSV products?
• What are the results of on-going reviews of post-marketing surveillance of the immunization products?

RSV Immunizations Workgroup Terms of Reference