Gaps in Immunizing Children During Hospitalization: How Can We Close Them?

In the Author’s own words:

Children are often under-vaccinated at the time of hospitalization. Hospitalized children experience many barriers to vaccination, including challenges accessing vaccines and caregiver concerns about vaccines, both for routine childhood vaccines and coronavirus disease 2019 (COVID-19) vaccines.

In this issue of Hospital Pediatrics, 2 studies explored inpatient immunization and barriers to vaccine delivery during hospitalization.^1,2  Lissinna et al assessed the immunization status of hospitalized children at their institution in Canada and explored caregiver barriers to and concerns about vaccination via the Searching for Hardships and Obstacles to Shots (SHOTS) survey.¹  Orbea et al examined attitudes, behaviors, and beliefs about COVID-19 vaccines in caregivers of hospitalized children and general vaccine hesitancy using the Parent Attitudes about Childhood Vaccines (PACV) Survey over 3 seasons during the COVID-19 pandemic.²  Both studies identified a notable gap in immunization coverage for hospitalized children. In Lissinna et al, only 58.2% of hospitalized patients were up-to-date on all immunizations, well below population-based provincial vaccine coverage rates; in Orbea et al, only 17% of hospitalized children had received the COVID-19 vaccine, consistent with low national coverage of COVID-19 vaccines in children.^1,2  Improving vaccine delivery during hospitalization has the potential for significant public health impact by increasing childhood vaccine coverage if the barriers to inpatient vaccine delivery can be identified and overcome.

The hospital setting is a missed opportunity to provide vaccines to children. In prior studies, 27% to 84% of pediatric inpatients were missing ≥ 1 recommended childhood vaccine,³  and these numbers may be even larger now as pediatric vaccination rates have declined in the aftermath of the health care systems disruptions caused by the COVID-19 pandemic.⁴  Lissina et al identified that pediatric inpatients were less likely to be up-to-date than their same age cohorts in the surrounding province, suggesting immunization efforts may be even more critical for the hospitalized population.¹  Although a majority of caregivers are supportive of inpatient vaccination,⁵  vaccines are delivered in <2% of hospitalizations at children’s hospitals nationally.⁶  This mismatch is in line with a key finding in Orbea et al – most caregivers who intended to vaccinate their child with the COVID-19 vaccine were willing to vaccinate during hospitalization, yet few were offered vaccines during hospitalization.² 

Multiple barriers exist to inpatient vaccine delivery, from suboptimal hospital workflows to caregiver concerns about vaccines; both Orbea et al and Lissinna et al explored the latter. Lissinna et al administered the SHOTS survey to caregivers of hospitalized children.¹  The SHOTS survey includes items along 3 subscales, access to shots, concerns about shots, and importance of shots.⁷  Although overall median scores were low, they identified that caregivers of under-immunized children scored higher on all 3 subscales than those whose children were up-to-date on vaccines. Although they did not specifically measure vaccine hesitancy, the concerns about shots subscale was higher in children who were behind on their vaccines, reflecting the need to address parental concerns when considering inpatient vaccination.¹  Orbea et al administered the PACV to caregivers of hospitalized children, and identified that 19% of caregivers were vaccine hesitant (defined as a score > 50 on the PACV).²  The PACV has been validated as a measure of parent vaccine hesitancy across different clinical settings, including caregivers of hospitalized children.^8,9  Similarly, Orbea et al identified that general caregiver vaccine hesitancy was strongly associated with the child not receiving the COVID-19 vaccine before or during hospitalization.² 

A prior inpatient study conducted by Hofstetter et al and an outpatient state-wide sample by Higgins et al identified a similar proportion of caregivers (20% to 24%) to be vaccine hesitant.^8,10  Of note, despite the sociopolitical climate surrounding the COVID-19 vaccine, Higgins et al surveyed a state-wide sample of caregivers before and during the COVID-19 pandemic on vaccine hesitancy using the PACV and, importantly, the proportion of vaccine-hesitant caregivers remained stable.¹⁰  However, both Orbea and Higgins did identify changes in trust of vaccine information over the course of their study, which is an important finding.^2,10  Incorporating this information into how to best address vaccine hesitancy and promote vaccination during hospitalization is an important next step in vaccine communication efforts.

Although vaccine hesitancy is a problem in the United States and contributes to under-immunization, ultimately most parents are willing to accept routine childhood vaccines; only ∼1% of children receive no vaccines, and there had been improved timeliness of child vaccine receipt over the decade before the COVID-19 pandemic.^11,12  In addition, in inpatient studies of influenza and COVID-19 vaccines, caregivers who were hesitant were still willing to accept vaccines after having a discussion with their inpatient provider.^8,13  Orbea et al identified that a large proportion of caregivers had never spoken with their child’s health care provider about the COVID-19 vaccine (39% of overall participants, including 33% of children during the 2022–2023 season), which highlights vaccine communication as a missed opportunity during hospitalization.²  An area that has yet to be fully explored that may improve vaccine uptake during hospitalization is to translate primary care strategies on vaccine communication to the inpatient setting for all recommended childhood vaccines. Importantly, in qualitative interviews and surveys, unique facilitators to vaccine delivery have been identified from caregivers during hospitalization, such as hospital staff as experts in caring for children with vaccine-preventable disease, the ability to observe children after receiving vaccines, and reducing the number of additional visits for medically complex children.^5,14  Incorporating these factors into hospital-based vaccination strategies may be effective at improving vaccine acceptance and uptake in hospitalized children, in particular those with vaccine-hesitant caregivers.

Finally, Lissinna et al identified that caregivers of under-immunized children reported significantly more barriers to vaccination, scoring higher on the access to shots subscale, compared with hospitalized children who are up-to-date on vaccines.¹  Unfortunately, a recent study by Newcomer et al identified widening disparities in on-time pediatric vaccine coverage, with lower coverage in children living below the federal poverty line and nonprivately insured children.¹²  These disparities add to the evidence that vaccine access is a key barrier to on-time vaccine delivery¹¹  and strengthen the need to vaccinate during hospitalization, as hospitals are an important location of clinical care for children in these groups.¹⁵  Similarly, patients without a medical home or those with difficulty accessing the health care system have these barriers largely eliminated while hospitalized; thus providing vaccines in the inpatient setting may have an impact on health equity if missed immunization opportunities could be reduced.

The first key step in decreasing missed opportunities to vaccinate in hospitalized children is to systematically identify children as under-immunized and offer them necessary vaccines. In the primary care setting, this process has been effectively done using strategies such as standing orders, prompts, and audit and feedback.¹⁶  Similarly, in the inpatient setting, allocating additional staff for opportunistic immunization programs, staff education, audit and feedback, and prompts have also been successful in improving hospital-based vaccine delivery.¹⁷  Influenza vaccine programs during hospitalization are the main model for inpatient vaccine programs; there has been moderate success with nurse-screening programs and automated screening embedded within the electronic health record (EHR) for influenza vaccines.¹⁷  One advantage to providing influenza and COVID-19 vaccines during hospitalization is that they are seasonal, thus it is easier to identify whether a child is up-to-date and has received this season’s vaccine. Furthermore, hospitalization may also be the first opportunity during a given season when a child is in a health care setting and is eligible for the influenza and/or COVID-19 vaccine. Using all available opportunities to vaccinate is particularly important in hospitalized children and children with medical complexity, who are at higher risk of having a missed opportunity for vaccination during hospitalization and at higher risk of subsequent hospitalization with influenza.¹⁸ 

Another advantage when considering vaccinating during hospitalization in the current epoch is the availability of population-based immunization information systems (IIS) and the growing integration of IISs into hospital EHRs. Vaccine schedules are complicated, and parent-reported vaccine status is often inaccurate.¹⁹  Having bidirectional data exchange with hospital-based EHRs and population-based IISs is a valuable and underused tool to identify hospitalized children as up-to-date.²⁰  Furthermore, it provides an effective mechanism in many cases to convey vaccine doses given during hospitalization back to the primary care practice and medical home, which should be a major aspect of any inpatient immunization program.

When the COVID-19 pandemic brought to the forefront the need to rapidly deliver vaccines to a large population, many hospitals developed additional infrastructure to provide COVID-19 vaccines in response to this need, such as mobile vaccine teams, vaccine clinics for children, caregivers and families, and additional screening tools to accurately identify children as not up-to-date on COVID-19 vaccines. However, despite these efforts, hospitals were and continue to be insufficiently used as vaccination sites for under-vaccinated children. Orbea et al and Lissinna et al’s work highlights that hospitalized children remain a population at high risk of under-vaccination.^1,2  There continue to be major challenges to inpatient vaccine delivery, including caregiver vaccine hesitancy and a lack of effective systems to deliver vaccines when caregivers are willing to accept vaccines.