Report from the World Health Organization's immunization and vaccines related implementation research advisory committee (IVIR-AC) meeting, Geneva, 11-13 September 2023

Evaluating vaccine-related research is critical to maximize the potential of vaccination programmes. The WHO Immunization and Vaccine-related Implementation Research Advisory Committee (IVIR-AC) provides an independent review of research that estimates the performance, impact and value of vaccines, with a particular focus on transmission and economic modelling. On 11-13 September 2023, IVIR-AC was convened for a bi-annual meeting where the committee reviewed research and presentations across eight different sessions. This report summarizes the background information, proceedings and recommendations from that meeting. Sessions ranged in topic from timing of measles supplementary immunization activities, analyses of conditions necessary to meet measles elimination in the South-East Asia region, translating modelled evidence into policy, a risk-benefit analysis of dengue vaccine, COVID-19 scenario modelling in the African region, therapeutic vaccination against human papilloma virus, the Vaccine Impact Modelling Consortium, and the Immunization Agenda 2030 vaccine impact estimates.

Considerations for unblinding individual study participants during vaccine trials

Premature unblinding of individual participants is rarely reported in publications, but such unblinding can disrupt vaccine trials by causing worry and drop-out of other participants or "pseudo unblinding," in which participants or investigators over-interpret certain symptoms as being related to receiving an investigational product. This review summarizes appropriate reasons for unblinding in vaccine trials. Regulatory guidance could be improved by distinguishing guidance for vaccine trials from drug trials, with the recognition that unblinding individual participants in vaccine studies is rarely needed for management of adverse events following immunization.

Ensuring Equitable Access To COVID-19 Vaccines In The US: Current System Challenges And Opportunities

There has been a worldwide effort to accelerate the development of safe and effective vaccines for severe acute respiratory syndrome coronavirus-2. When vaccines become licensed and available broadly to the public, the final hurdle is equitable distribution and access for all who are recommended for vaccination. Frameworks and existing systems for allocation, distribution, vaccination, and monitoring for safety and effectiveness are assets of the current immunization delivery system that should be leveraged to ensure the equitable distribution and broad uptake of licensed vaccines. The system should be strengthened to address gaps in access to immunization services and to modernize the public health infrastructure. We offer five recommendations as guideposts to ensure that policies and practices at the federal, state, local, and tribal levels support equity, transparency, accountability, availability, and access to coronavirus disease 2019 vaccines.

Achieving an Optimal Childhood Vaccine Policy

Policies to remove parents' ability to opt-out from school immunization requirements on the basis of religious or personal beliefs (ie, nonmedical exemptions) may be a useful strategy to increase immunization rates and prevent outbreaks of vaccine-preventable disease. However, there is uncertainty about the effectiveness of this strategy and the range of possible outcomes. We advocate for a more deliberative process through which a broad range of outcomes is scrutinized and the balance of values underlying the policy decision to eliminate nonmedical exemptions is clearly articulated. We identify 3 outcomes that require particular consideration before policies to eliminate nonmedical exemptions are implemented widely and outline a process for making the values underlying such policies more explicit.

Polio endgame: the global introduction of inactivated polio vaccine

In 2013, the World Health Assembly endorsed a plan that calls for the ultimate withdrawal of oral polio vaccines (OPV) from all immunization programs globally. The withdrawal would begin in a phased manner with removal of the type 2 component of OPV in 2016 through a global switch from trivalent OPV to bivalent OPV (containing only types 1 and 3). To mitigate risks associated with immunity gaps after OPV type 2 withdrawal, the WHO Strategic Advisory Group of Experts has recommended that all 126 OPV-only using countries introduce at least one dose of inactivated polio vaccine into routine immunization programs by end-2015, before the trivalent OPV-bivalent OPV switch. The introduction of inactivated polio vaccine would reduce risks of reintroduction of type 2 poliovirus by providing some level of seroprotection, facilitating interruption of transmission if outbreaks occur, and accelerating eradication by boosting immunity to types 1 and 3 polioviruses.

Quality standards for immunization. Guidelines from the Infectious Diseases Society of America

This is the third in a series of guidelines commissioned by the Infectious Diseases Society of America through its Practice Guidelines Committee. It is presented as a standard of care rather than a practice guideline because the case for following these recommendations is very strong and it should be followed with rare exceptions. The purpose of this guideline is to provide assistance to clinicians when making decisions on providing immunizations to healthy infants, children, and adults. The document is a summary of guidelines already developed by national organizations. The targeted providers are pediatricians, family practitioners, internists, and other physicians who provide immunizations. The IDSA provided the funding. Panel members represent experts in adult and pediatric infectious diseases. The guidelines are evidence-based. A standard ranking system is used for the strength of the recommendations and the quality of the evidence cited in the literature reviewed. The document has been subjected to external review by peer reviewers as well as by the Practice Guidelines Committee and was approved by the IDSA Council. An executive summary and tables highlight the major recommendations. Indicators for measuring compliance with the standards are included.

Live virus vaccines in human immunodeficiency virus-infected children: a retrospective survey

Live virus vaccines can cause serious adverse reactions when administered to immunocompromised patients. Because children infected with human immunodeficiency virus (HIV) may be immunosuppressed, immunization of these children with live virus vaccines is a potential problem. A retrospective survey was conducted by the New York City Department of Health, with consultation from the Centers for Disease Control, to evaluate the frequency of serious adverse events following receipt of live vaccines among children with HIV infection receiving pediatric care in New York City and New Jersey. Outpatient records of 319 children being cared for by 16 participating physicians were reviewed. Of the 319 charts, 221 (69%) contained vaccination histories. Perinatal transmission of HIV infection was suspected for 208 (94%) of the 221 cases and infection via transfusion for the remaining 13 (6%). Of the 221 for whom immunization histories were available, 180 (81%) had received at least one dose of live oral polio vaccine and 70 (32%) had received measles, mumps, and rubella vaccine. There were 120 children for whom a temporal relationship between immunization and onset of symptoms of immunodeficiency could be seen; 46/120 had received at least one dose of oral polio vaccine and 23/45 had received measles, mumps, and rubella vaccine after onset of symptoms. Although follow-up of this population has been limited, there were no reports of serious adverse events such as typical or atypical measles, paralytic poliomyelitis, or aseptic meningitis in the month following vaccination.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical mumps vaccine efficacy

From February 5 through April 23, 1982, 110 cases of mumps were reported among 357 students in a middle school in Ashtabula County, Ohio, an overall attack rate of 31%. Vaccine efficacy was calculated using a variety of case definitions, case surveillance systems, and vaccination-status ascertainment methods to evaluate their effects on the estimated vaccine efficacy. From data collected at the school for case ascertainment and vaccination status, clinical vaccine efficacy was initially estimated at 37%. By means of a uniform case definition (parotitis lasting two days or more) and only cases and vaccination status ascertained from parental questionnaires, estimated vaccine efficacy increased to 70%. From secondary attack rates in household members with provider-verified vaccination status, the vaccine efficacy further increased to 85%. This outbreak investigation confirms that the methods used to ascertain cases and determine vaccination status greatly affect estimates of vaccine efficacy. Studies relying solely on school records for case finding and determination of immunization status may provide misleadingly low estimates of vaccine efficacy for mumps vaccine as well as for other vaccines. Appropriate methods demonstrate that mumps vaccine is highly effective and support recommendations for its continued use.

Legionnaires' disease: description of an epidemic of pneumonia

An explosive, common-source outbreak of pneumonia caused by a previously unrecognized bacterium affected primarily persons attending an American Legion convention in Philadelphia in July, 1976. Twenty-nine of 182 cases were fatal. Spread of the bacterium appeared to be air borne. The source of the bacterium was not found, but epidemiologic analysis suggested that exposure may have occurred in the lobby of the headquarters hotel or in the area immediately surrounding the hotel. Person-to-person spread seemed not to have occurred. Many hotel employees appeared to be immune, suggesting that the agent may have been present in the vicinity, perhaps intermittently, for two or more years.