Document text
Advisory Committee on Immunization Practices (ACIP)
Centers for Disease Control and Prevention (CDC)
Respiratory Syncytial Virus (R SV) Immunization Workgroup, Materna l, Infant, Adult
Terms of Reference
UPDATED: December 18, 2025
PURPOSE
This document defines the activities, membership, and administrative requirements associated
with the establishment of a Respirat ory Sync ytial Virus (RSV) Immunization Workgroup for
patients of all ages under the Advisory Committee on Immunization Practices, Centers for
Disease Control and Prevention (ACIP, CDC). ACIP utilizes subgroups of the Committee, known
as Workgroups (WGs), to review relevant published and unpublished data, and clinical and
scientific knowledge, and develop options for presentation to the full ACIP parent committee during its public meetings to facilitate discussion, deliberation and development of
recommendations. ACIP WGs are intend ed to enhance the effectiveness of ACIP. The direction,
focus and pace of both ACIP and the individual WG’s are guided by CDC and HHS priorities, and by the need for expert advice to inform development of immunization policy. ACIP WGs
serve a key scientific role in support of immunization recommendations.
The RSV Immunization WG has been established to review data as well as scientific and clinical knowledge on RSV vaccine products and monoclonal antibodies currently in use or under
consideration for the prevention of severe RSV infection in both the infant and at -risk adult
population. These findings will be presented to the full ACIP parent committee in a public forum
and will be considered in the formulation of recommendations regarding the use of these
products to the Director of the CDC.
BACKGROUND
RSV is a viral illness primarily affecting infants , but older children and adults with certain co -
morbidities or of older age are also at risk of serious disease. Infants who get RSV almost always
have symptomatic disease. While the majority of RSV infections are mild —70% -- and localized
to the upper airway , RSV can also cause severe illness such as bronchiolitis (inflammation of the
small airways in the lungs) and pneumonia (infection of the lungs). Before the introduction of universal RSV immunization recommendations for infants in 2023, RSV was the leading cause of hospitalization among U.S. infants (aged <12 months): an estimated one ( 1)%–three ( 3)% of
infants w ere hospitalized for RSV each year , accounting for the largest non- birth hospital ization
health care expenditures in the US for children under five (5 ). Adults, unlike infants, may not
always show symptoms after infection with RSV . However, some adults , including those with
certain medical conditions, especially those associated with respiratory compromise and immune compromise, are at risk of severe disease including pneumonia, exacerbation of underlying chronic conditions such as heart failure and chro nic obstructive pulmonary disease (COPD), and
death. Older adults are also at increased risk of severe RSV disease and at increased risk of
declining functional status after RSV infection.
CDC recommends several U.S. Food and Drug Administration (FDA) -approved products to
provide active or passive immunity to the at -risk populations . One such product is a recombinant
protein subunit vaccine with ASO1E adjuvant approved by FDA on May 3, 2023 for adults 60
years of age and older for the prevention of lower respiratory tract disease (LRTD) caused by
RSV. In July 2025 FDA announced the agency also accepted an application to review use of this
same product for adults aged 18-49 years at increased risk of LRTD caused by RSV .
A second product is a bivalent recombinant protein subunit vaccine with no adjuvant, approved
by FDA on:
• May 31,2023 for adults 60 years of age and older for the prevention of LRTD ;
• August 21, 2023 for maternal vaccination at 32- 36 weeks ’ gestation for prevention of
LRTD in infants through 6 months of age ; and approved
• October 22, 2024 for adults ages 18 -59 with risk factors for the prevention of LRTD .
Both protein subunit vaccines target sites on the pre- fusion F (preF) protein on the surface of the
RSV virus .
A third product is an mRNA -based vaccine approved by FDA on May 31, 2024, fo r adults 60
years of age and older for the prevention of LRTD caused by RSV , and approved by FDA on
June 12, 2025 for those age d 18- 59 years at increased risk of LRTD caused by RSV . This
product also targets the preF protein.
For the indication of protection of adults, two of the products have shown significant efficacy in
randomized clinical trials against preventing lower respiratory tract illness (LRTI) and
effectiveness in post -licensure observational studies against hospitalization. For the indication of
maternal use of RSV vaccine to protect infants after birth, randomized clinical trials for one of
these products have also demonstrated efficacy and a postmarketing real world effectiveness
study also showed the vaccine to be effective .
Two of the available products have been associated with rare but significant adverse reactions in
older adults , notably Guilla in-Barrè Syndrome . There was also an imbalance of atrial fibrillation
in the clinical trials for the use of these vaccines in adults 60 and older, but no signal has emerged in post -marketing studies to date, though safety surveillance is ongoing. No cases of
Guillain -Barrè Syndrome have been reported in pregnant women after RSV vaccination.
One product has also shown significant efficacy in preventing L RTI in randomized clinical trials .
Because approval of this product was more recent than for other available products and uptake of
this product has been lower, there are not yet post -licensure observational studies of vaccine
effectiveness available.
In addition to vaccines there are three monoclonal antibody products now available for newborn
infants and some older children, each providing long- term passive immunity (One product was
approved by FDA in 2023 for use in infants born during or entering their first RSV season and
children up to 24 months of age who remain vulnerable to severe RSV disease through their
second RSV season . A second product clesrovimab was approved by FDA in June 2025 for
infants born during or entering their first RSV season. CDC recommends e ither product for
infants younger than 8 months born during or entering their first RSV season; for children ages 8 through 19 months who are at increased risk of severe RSV disease and entering their second
RSV season, only one is recommended. A third product, was first approved in the United States
on June 19, 1998 and will be available until the end of December, 2025. Two of the products
have both shown significant efficacy in randomized clinical trials against preventing RSV -
associated medically attended lower respiratory tract illness (RSV MA -LRTI) and RSV MA -
LRTI with hospitalization. P ost-licensure observational studies have demonstrated that one
product is effective in preventing RSV -associated hospitalization .
The WG will engage external subject matter experts, as needed, to support presentations to the WG members and development of materials for presentation to the parent committee for its
deliberations.
TOPICS FOR 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 a nd 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 o ngoing 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 monoclona l 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 RS V 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 a ny 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 o n-going review s
of post -marketing surveillance of the immunization products?
MEMBERSHIP AND LEADERSHIP
Workgroup Leadership: The RSV Immunization WG is chaired by one of the ACIP, CDC parent
committee members. The Workgroup Lead (WGL) is a federal employee, identified by the
Immediate Office of the Director in consultation with the appropriate CDC program. The WG Chair, in consultation with the WGL, and ACIP CDC Designated F ederal O fficial (DFO),
determines the WG’s membership and work priorities and deliverables to the full committee. The DFO may further assign some of the DFO -related roles and responsibilities , as
appropriate, to the WGL.
Workgroup Membership: The RSV Immunization WG is composed of experts who are appointed
based on their professional, scientific, technical, or other expertise. They are experts who are
regarded as an authority or a practitioner of unique competence and skill by other persons i n their
profession, or occupation. Upon request, HHS federal agencies named in the ACIP charter may
also appoint members to serve on WGs. The RSV Immunization WG will be composed of members from a variety of disciplines. The WG will en gage with the following disciplines on
WG activities:
• Public health science and practice;
• Public health policy development, analysis, and implementation, including development and execution of immunization programs for children and adults;
• Clinical and medical practice, and patient- care experience;
• Epidemiology;
• Molecular biology;
• Immunology;
• Virology;
• Diagnostics and correlates of protection;
• Drug and vaccine safety;
• Bioethics; and
• Consumer perspectives and/or social and community aspects of immunization programs
Due to the complexity and variability of the information to be gathered, additional external subject matter experts may also be invited to provide data and presentations to the WG and answer questions during RSV Immunization WG meetings on an a d-hoc basis. Such additional
external subject matter experts will not be members of the WG and will not participate in any
deliberations or WG discussions.
MEETINGS, ADMINISTRATION, and TIMELINES
1. Administrative Oversight: The WGL will work with the WG Chair to arrange meetings,
document meeting proceedings, and report to the ACIP on the RSV Immunization WG’s
activities and findings.
2. Meeting frequency and location : The RSV Immunization WG will meet on an as needed
basis as determined by the WG Chair and WGL. All RSV Immunization WG meetings
are convened virtually via teleconference.
3. Meeting structure : In addition to the WGL, at least two ACIP parent committee members
(one of whom serves as the RSV Immunization WG Chair) must be present at each
meeting for a quorum. An agenda, relevant publications, and background documents will
be circulated as read -ahead material before each meeting.
4. Conflicts of Interest : WG members will complete an ACIP WG Agreement and Conflict
of Interest Certification process before participation on the WG. The WGL will screen
for conflict -of-interest declarations and share any conflicts that need to be elevated to the
DFO/ACIP Secretariat . The ACIP Secretariat and DFO , in collaboration with the WGL
will work with Ethics office within the Office of Strategy Business Initiatives (OSBI) and
the Office of General Counsel (OGC), as needed, to resolve any conflicts th at the WGL
identifie d. WG members will consent to abide by guiding principles and disclose
interests (e.g., employment, special interests, grants, or contracts) that a reasonable
person could view as conflicts or potential conflicts of interest with their RSV
Immunization WG participation. Members will also disclose any potential conflicts of
interest before each meeting. If an RSV Immunization WG member indicates a potential
or actual conflict of interest to the WGL, the WGL or a delegate will forward any
conflicts to the DFO to determine whether the individual must recuse themselves from participating in WG discussions that implicate such a conflict -of-interest concern. If
needed, the DFO will engage OSBI and OGC to assist with making COI determination.
5. Confidentiality : The discussions by the RSV Immunization WG may include information
that is unpublished, protected, privileged, or confidential. WG deliberations, including policy options under consideration by the WG, are also considered confidential. Information of this nature must not b e disseminated, distributed, or copied
to persons not authorized to receive such information. When these types of information
are distributed, the person presenting will identify the information as such, so all
members a re duly informed; and written materials shall be clearly marked as
such. Unlike ACIP parent committee meetings, which are open to the public, RSV
Immunization WG teleconferences are not subject to the open meeting requirements of the Federal Advisory Committee Act or the GSA Final Rule; data presented during these meetings/teleconferences are often proprietary and should not be distributed to peopl e
other than approved RSV Immunization WG members.
6. CDC Staff Involvement: CDC staff do not serve as members of the RSV Immunization
WG but may provide administrative support and technical expertise to ACIP WGs, as appropriate, bringing subject matter expertise and current professional focus in areas
relevant to the goals of the RSV Immunization WG. Consultation or informational
presentations by CDC staff will be transparent and evident to minimize the risk of, or the
appearance of, undue influence that would compromise the independence of the
WG. The DFO a nd WGL of the RSV Immunization WG, in consultation with the Chair
of the RSV Immunization WG, will monitor the interaction between the WG and the agency staff to ensure that the WG activities and work products are appropriate and that there is no undue influence by the CDC or by any special interest group on the activities or work products of the WG.
7. Timelines : ACIP WGs are established when needed and terminated once the activities
and work products stated in the terms of reference have been completed and the WG’s charge has been fulfilled.
8. Workgroup Meeting Summaries: Meeting minutes will be created to capture the
information gathered during each RSV Immunization WG meeting and teleconference.
9. Workgroup findings : The RSV Immunization WG will present findings (briefing
documents, background materials, and presentations) to the ACIP parent committee for
consideration and deliberation in a public meeting. Final versions of all slides presented at the ACIP parent committee meeting will be posted on the ACIP website following the
meeting and included in the committee’s official records.
10. Workgroup Record Keeping: All CDC FACA committees, subcommittees, and WGs are
subject to the Federal Records Act. All records will be uploaded to the Federal Advisory
Committee Management Portal. The summary report of WG meeting activities and other
WG documents will become part of the ACIP’s official records as required by GENERAL RECORDS SCHEDULE 6.2: Federal Advisory Committee Records .
RECORDKEEPING and REPORTING
The WG Chair and WGL will present findings/outcomes/observations/recommendations to the
ACIP parent committee for discussion, deliberations, further development of recommendations, and vote in an open public forum. Approved ACIP recommendations adopted by the CDC Director will be posted on CDC’s ACIP website and al so published in the Morbidity and
Mortality Weekly Report (MMWR). In addition, approved ACIP recommendations will be included in the ACIP meeting minutes and annual report.