BACKGROUND:

Many hospitalized children are underimmunized, yet little is known about current systems supporting inpatient vaccination. We aim to describe national pediatric inpatient immunization practices and determine if variation exists among adolescent, childhood, and influenza vaccines.

METHODS:

An electronic survey regarding hospital vaccination practices was sent to physician, nurse, and pharmacy leaders via the Pediatric Research in Inpatient Settings Network in spring 2019. Hospitals reported the presence of various practices to support inpatient vaccination stratified by vaccine type: tetanus, diphtheria, and acellular pertussis, meningococcal, human papillomavirus, childhood series, and influenza. One-way analysis of variance testing compared differences in numbers of practices and χ2 tests compared proportions of sites reporting each practice between vaccine types. Qualitative responses were evaluated via content analysis.

RESULTS:

Fifty-one of 103 eligible hospitals completed the survey (50%). Standardized policies existed in 92% of hospitals for influenza, 41% for childhood, and 29% for adolescent vaccines. Hospitals identified an average of 5.1 practices to deliver influenza vaccines, compared with 1.5 for childhood; 0.9 for tetanus, diphtheria, and acellular pertussis; 0.7 for meningococcal; and 0.6 for human papillomavirus vaccines (P < .001). Standardized screening tools, visual prompts, standing orders, nurse- or pharmacy-driven screening or ordering, staff education, and quality improvement projects were reported more often for influenza vaccines than other vaccine types (P < .01 for all comparisons). Common barriers to delivery included communication difficulties, lack of systems optimization, and parent and provider discomfort with inpatient immunization.

CONCLUSIONS:

Existing hospital infrastructure supports influenza vaccine delivery over other vaccine types, potentially creating missed inpatient vaccination opportunities.

Nearly 2 million children are hospitalized annually, many of whom are due or overdue for vaccines.17  In the United States, between 27% and 84% of pediatric inpatients are not up to date on vaccines at the time of hospital admission, and hospitalization itself has been identified as a risk factor for underimmunization.16,8  Unfortunately, inpatient pediatric providers often do not identify patients in need of vaccines, and missed opportunities to immunize hospitalized children are common.2,5,6,9,10 

Pilot studies have revealed success in increasing inpatient vaccination rates, employing strategies such as visual prompts, staff education, construction of catch-up plans, standing orders, and nursing-driven protocols.1116  However, these studies have largely occurred at single centers, and many interventions have been limited to the influenza vaccine.11,12,15,16  Although using the inpatient setting to deliver vaccines is recommended by the Advisory Committee on Immunization Practices,17  there is currently a paucity of information regarding this practice. In an effort to close this knowledge gap, we aim to describe national inpatient immunization practices, and determine if variation in hospital practice exists among adolescent, childhood, and influenza vaccines.

We conducted a cross-sectional study of national inpatient immunization practices using the Pediatric Research in Inpatient Settings (PRIS) Network. The PRIS Network is a pediatric research network composed of 107 institutions across the United States and Canada, representing a range of practice settings from freestanding children’s hospitals to community sites. Each institution has a designated PRIS site lead physician.

An electronic Qualtrics (Qualtrics, Provo, UT) survey regarding hospital inpatient immunization policies and practices was sent to site lead physicians, nursing managers, and pharmacy directors from PRIS Network hospitals (Supplemental Fig 3). PRIS site lead physicians were contacted via the PRIS e-mail LISTSERV in April 2019 and asked to identify a nursing or pharmacy leader at their corresponding institution to also complete the survey. Given that the survey included questions pertaining to US vaccine policy, responses from Canadian institutions were excluded. Participants received an initial survey invitation and up to 2 e-mail reminders. Responses were collected over a 3-month period.

We developed a survey instrument that was used to examine hospital-level vaccination practices including (1) types of vaccines given to hospitalized patients (routine or catch-up, newborn, postexposure, live, and influenza vaccines); (2) primary care and electronic medical record (EMR) integration; (3) presence of standardized hospital immunization policies; (4) use of specific inpatient vaccine delivery practices; and (5) barriers to inpatient immunization. Survey items were chosen after review of previous literature regarding inpatient vaccination practices and barriers to hospital-based immunization programs.18 

Participants were asked to select whether their hospital used specific delivery practices for 5 vaccine types: the childhood series, influenza, and the adolescent vaccines of tetanus, diphtheria, and acellular pertussis (Tdap), meningococcal, and human papillomavirus (HPV). The childhood series was defined for participants as those vaccines traditionally delivered from birth to 6 years of age (hepatitis B; rotavirus; Tdap; Haemophilus influenzae type B; pneumococcal; poliovirus; measles, mumps, and rubella; varicella; and hepatitis A). Given well-documented differences in recommendation practices and provider hesitancy regarding HPV vaccines,1922  the authors hypothesized that inpatient practices for HPV may vary from Tdap and meningococcal vaccines; thus, the 3 adolescent vaccines were separated on the survey.

Twelve delivery practices were queried and included: (1) standardized vaccine screening tools; (2) visual prompts to screen or offer vaccines; (3) standing vaccine orders; (4) nurse- or pharmacist-driven vaccine screening; (5) nurse or pharmacist ability to order vaccines independently; (6) presence of a designated inpatient immunization coordinator; (7) vaccines incorporated into admission or discharge orders; (8) personalized catch-up plans for patients; (9) education sessions for staff; (10) quality improvement (QI) initiatives; (11) ability to offer vaccines to patients’ siblings or parents; and (12) Vaccines for Children (VFC) supplied vaccines for inpatients. Multiple spaces for free-text responses were included, and participants were asked to describe barriers to inpatient immunization programs at their institution.

The survey instrument was pilot tested and modified in January 2019 among physicians, nurse managers, and senior pharmacists at our institution to evaluate face validity, survey functionality, and readability. Participants in the pilot test did not include the PRIS site lead physician, nurse manager, or pharmacy leader eligible to complete the study survey at our institution.

Information on hospital- and state-level factors was collected from publicly available sources. Data regarding geographic region were obtained from US Census classifications,23  state school immunization exemption allowances from the National Conference of State Legislatures,24  state vaccine funding structure from the Association of Immunization Managers,25,26  hospital status as private or public from the Department of Homeland Security’s Homeland Infrastructure Foundation-Level Data,27  and presence of pediatric resident physician trainees from the Accreditation Council of Graduate Medical Education.28  Vaccine funding structure categories reflect whether states operate in a traditional VFC model (all recommended vaccines supplied free of charge to children meeting certain eligibility criteria) or through an augmented program.29 

The primary outcome was presence or absence of the 12 vaccine delivery practices for each vaccine type as indicated by survey responses. Secondary outcomes included variation in presence of standardized immunization policies (“Does your hospital give vaccines to inpatients?” and “Does your hospital have standardized policies regarding delivery of inpatient immunizations: childhood series, adolescent, or influenza vaccines?”) based on hospital and state-specific characteristics. To ensure accuracy of responses, physician and nurse and/or pharmacy surveys from each institution were compared with verify agreement, and respondents were contacted for clarification if disagreements occurred. If one respondent indicated “unknown” or left a question blank, the other respondent’s answer was selected as the valid response. In addition, if 3 respondents participated from a single institution, the majority response was selected. For sites in which discrepancies were unable to be resolved between participants, any respondent reporting the presence of a policy was considered the valid response. If all respondents from one site left the same question item unanswered, the institution was excluded from that item.

Characteristics of respondent and nonrespondent hospitals were compared by using χ2 and Fisher’s exact tests. Survey responses were then analyzed by using descriptive univariate analyses and reported as proportions. The mean number of practices present for each vaccine type was calculated, and the difference between means was analyzed by using 1-way analysis of variance. χ2 tests then were used to compare the proportions of sites reporting each of the 12 specific vaccine delivery practices among vaccine types. The association between state- and hospital-level factors and hospitals’ reported presence of standardized vaccination policies was evaluated by using χ2 and Fisher’s exact tests.

To ensure that the coding of responses for sites with unresolved discrepancies did not significantly impact results, a sensitivity analysis was performed. In the sensitivity analysis, any respondent reporting the absence of a policy was considered the valid response for discrepant question items. Statistical significance was set at a P value <.05. SAS version 9.4 (SAS Institute, Inc, Cary, NC) was used for all analyses.

Participant free-text responses were explored via content analysis and data were imported into Dedoose (SocioCultural Research Consultants, LLC, Los Angeles, CA) for review. Each qualitative response was coded independently by at least 2 team members. Coding assignments were then discussed and agreed on by 3 study team members in an iterative process until no further codes were generated and consensus was reached regarding all code applications. One team member reviewed all coded data further to identify major themes.

This study was approved by the Children’s Hospital Los Angeles Institutional Review Board.

Fifty-one of 103 (50%) eligible hospitals completed a survey, representing 19 states and all geographic regions (Table 1, Fig 1). Nearly all were private hospitals (96%) and had pediatric trainees (90%). The only significant difference between respondent and nonrespondent hospitals was that respondent hospitals were more likely to be in states only allowing medical vaccine exemptions and less likely to be in states with both religious and philosophical exemptions (P = .04).

TABLE 1

Hospital- and State-Level Characteristics of Survey Respondents and Nonrespondents

Respondents (n = 51), n (%)Nonrespondents (n = 52), n (%)P
Census region   .84a 
 Northwest 16 (31) 13 (25)  
 Midwest 14 (27) 14 (27)  
 South 13 (25) 17 (33)  
 West 8 (16) 8 (15)  
Pediatric resident trainees present   .11a 
 Yes 46 (90) 41 (79)  
 No 5 (10) 11 (21)  
Hospital type   .27b 
 Private 49 (96) 46 (88)  
 Public 2 (4) 6 (12)  
State exemption policy   .04b 
 No exemptions 8 (16) 1 (2)  
 Religious exemptions only 25 (49) 27 (52)  
 Religious and philosophical exemptions 18 (35) 24 (46)  
State VFC policyc   .21a 
 VFC only 34 (68) 29 (57)  
 VFC and underinsured 14 (28) 15 (29)  
 Universal select and universal purchase 2 (4) 7 (14)  
Respondents (n = 51), n (%)Nonrespondents (n = 52), n (%)P
Census region   .84a 
 Northwest 16 (31) 13 (25)  
 Midwest 14 (27) 14 (27)  
 South 13 (25) 17 (33)  
 West 8 (16) 8 (15)  
Pediatric resident trainees present   .11a 
 Yes 46 (90) 41 (79)  
 No 5 (10) 11 (21)  
Hospital type   .27b 
 Private 49 (96) 46 (88)  
 Public 2 (4) 6 (12)  
State exemption policy   .04b 
 No exemptions 8 (16) 1 (2)  
 Religious exemptions only 25 (49) 27 (52)  
 Religious and philosophical exemptions 18 (35) 24 (46)  
State VFC policyc   .21a 
 VFC only 34 (68) 29 (57)  
 VFC and underinsured 14 (28) 15 (29)  
 Universal select and universal purchase 2 (4) 7 (14)  
a

Statistical analysis was completed by using χ2 tests.

b

Statistical analysis was completed by using Fisher’s exact tests.

c

State VFC policy categorizations include VFC only (all recommended vaccines supplied to eligible children only); VFC and underinsured (all recommended vaccines supplied to eligible and underinsured children only); universal select (state supplies most but not all recommended vaccines to all children regardless of eligibility criteria); and universal purchase (state supplies all recommended vaccines to all children regardless of eligibility criteria). Hospitals residing in states categorized as other were excluded from analysis (1 respondent and 1 nonrespondent site).

FIGURE 1

Location of survey respondents and eligible sites. Figure was created by using mapchart.net, used under CC BY-SA 4.0.

FIGURE 1

Location of survey respondents and eligible sites. Figure was created by using mapchart.net, used under CC BY-SA 4.0.

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Survey respondents included 52 physicians, 12 nurse managers, and 19 pharmacy leaders, for a total of 83 survey responses; 176 individuals were invited to participate (47% response rate). These were aggregated to yield 1 unique response per institution (n = 51). Twenty-five hospitals had responses from both a physician and a nurse manager and/or pharmacy leader, and discrepancies were able to be resolved in 20 (80%) of these sites.

Hospitals reporting always or usually giving vaccines varied by category: for influenza and neonatal vaccinations, >80% of sites reported always or usually giving these, compared with 14% for routine or catch-up immunizations (Table 2).

TABLE 2

Hospitals’ Reported Inpatient Immunization Practices and Presence of Standardized Policies for Varying Vaccine Types

QuestionResponse, n (%)
Does your hospital give to inpatients… Always or usually Sometimes Rarely or never Unsure 
 Vaccines? 15 (29) 35 (69) 1 (2) 0 (0) 
 Routine or catch-up vaccines? 7 (14) 35 (69) 9 (18) 0 (0) 
 Vaccines to neonates, eg, hepatitis B vaccine? 45 (88) 3 (6) 1 (2) 2 (4) 
 Postexposure vaccines, eg, pertussis? 30 (59) 14 (27) 5 (10) 2 (4) 
 Influenza vaccine? 43 (84) 8 (16) 0 (0) 0 (0) 
 Live vaccines, eg, rotavirus, MMR, varicella? 7 (14) 23 (45)a 16 (31) 5 (10) 
Does your hospital have standardized policies regarding the delivery of inpatient immunizations? Yes No — Unsure 
 Childhood series vaccines 21 (41) 26 (51) — 4 (8) 
 Adolescent vaccines 15 (29) 32 (63) — 4 (8) 
 Influenza vaccines 47 (92) 3 (6) — 1 (2) 
QuestionResponse, n (%)
Does your hospital give to inpatients… Always or usually Sometimes Rarely or never Unsure 
 Vaccines? 15 (29) 35 (69) 1 (2) 0 (0) 
 Routine or catch-up vaccines? 7 (14) 35 (69) 9 (18) 0 (0) 
 Vaccines to neonates, eg, hepatitis B vaccine? 45 (88) 3 (6) 1 (2) 2 (4) 
 Postexposure vaccines, eg, pertussis? 30 (59) 14 (27) 5 (10) 2 (4) 
 Influenza vaccine? 43 (84) 8 (16) 0 (0) 0 (0) 
 Live vaccines, eg, rotavirus, MMR, varicella? 7 (14) 23 (45)a 16 (31) 5 (10) 
Does your hospital have standardized policies regarding the delivery of inpatient immunizations? Yes No — Unsure 
 Childhood series vaccines 21 (41) 26 (51) — 4 (8) 
 Adolescent vaccines 15 (29) 32 (63) — 4 (8) 
 Influenza vaccines 47 (92) 3 (6) — 1 (2) 

The total number of hospital respondents is 51 (N = 51). MMR, measles-mumps-rubella vaccine; —, not an option for this question.

a

Day of discharge only.

Two-thirds of hospitals (67%) reported having an integrated primary care network, and 59% had an on-site primary care clinic. Hospital EMRs were able to transmit to the state vaccine registry in 59% of institutions, and 37% were able to receive information from the state registry.

Of the 51 respondent hospitals, standardized policies were more likely to exist for the influenza vaccine (92%), compared with the childhood series (41%) or adolescent vaccines (29%). There was no association between geographic location, designation as a public or private institution, presence of pediatric trainees, state school entry vaccine exemption policy, or state VFC structure and standardized immunization policies.

There was significant variation in the number of delivery practices reported between vaccine types. Of the 12 vaccine delivery practices queried, hospitals had an average of 5.1 practices in place for inpatient influenza vaccine delivery, compared with 1.5 for childhood series, 0.9 for Tdap, 0.7 for meningococcal, and 0.6 for HPV vaccines (P < .001). A majority of practices were used most often for the influenza vaccine; in contrast, the adolescent vaccines had the lowest reported use for every practice (Fig 2, Supplemental Table 4). There was significant variation in use of standardized screening tools, visual prompts, standing orders, nurse- or pharmacy-driven screening or vaccine ordering, staff education, and QI projects among vaccine types (P < .01 for all comparisons). All results remained significant when sensitivity analysis was performed.

FIGURE 2

Percentage of hospitals reporting each vaccine delivery practice by vaccine type. χ2 tests compared the proportions of sites reporting each vaccine delivery practice among vaccine types.

FIGURE 2

Percentage of hospitals reporting each vaccine delivery practice by vaccine type. χ2 tests compared the proportions of sites reporting each vaccine delivery practice among vaccine types.

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Sixty-eight participants (82%) included free-text responses, and a total of 173 excerpts were reviewed. Major themes revolved around barriers to immunization delivery, specifically problems with communication, lack of systems optimization, and family or physician discomfort with inpatient vaccinations (Table 3). Providers noted that access to accurate vaccine histories and inability to communicate with patients’ primary care providers (PCPs) were major barriers to vaccination. One physician stated, “Our EMR is unwieldy and does not communicate with even our own outpatient system. Additionally, we do not require reporting to our state registry so it is difficult to communicate receipt of vaccines to PCPs.”

TABLE 3

Major Themes and Representative Quotes From Participant Survey Responses

Major ThemesSubthemesRepresentative Quotes
Communication Access to accurate vaccine histories “Many families do not know specifically which vaccines their child is missing and there is no centralized area for us to look up vaccination records.” 
  “We admit patients from multiple surrounding states, and coordinating with state registries can be difficult.” 
 Communication with PCP “Our EMR is unwieldy and does not communicate with even our own outpatient system. Additionally, we do not require reporting to our state registry so it is difficult to communicate receipt of vaccines to PCPs.” 
Systems not optimized Workflow “The inpatient ordering process is more cumbersome than outpatient ordering – we will often order vaccines days in advance so that a patient's discharge time is not prolonged while waiting for a vaccine.” 
  “It is not incorporated/standardized into our work flow. The EMR order pops up to remind you, but many of [us] place orders before seeing the patient … and therefore have not asked about vaccine status at the time of using the initial order set at admission.” 
 Vaccine orders and availability “Vaccine ordering is complicated since if you want to give catch-up or routine vaccines you have to order each individually including the appropriate vaccine generic name, strength and amount.” 
  “The order sets available also are not representative of what is actually stocked by the pharmacy … and therefore requires an additional phone call to the pharmacist.” 
Parental hesitancy Vaccine hesitancy “Same barriers as outpatient clinics regarding stigma and other hesitancy on vaccines like HPV.” 
 Preference for outpatient “Parents prefer/trust their PCP more than us, don't want the PCP to duplicate the vaccine.” 
 Acute illnesses “We find a lot of parental refusal. They feel that the patient is sick, therefore should wait to get the vaccines until later.” 
  “I would say that we always/usually offer catch up vaccines to families, but often they decline despite counselling that vaccinations are OK to be given even if a child is recovering from an illness.” 
Provider discomfort Fever and other side effects “Acutely ill or complex illnesses can influence team or family comfort with vaccination.” 
  “Some people worry the vaccines may cause fever, which could complicate the clinical picture for hospitalized children in some cases.” 
  “Issues with patients currently with fever and ‘confusing the picture’ by giving a vaccine that might cause fever.” 
 Nursing discomfort “Nurses belief that all immunization responsibilities belong to the physicians except for obtaining the ‘shot record.’ Nurses not willing to enter standing order.” 
Roles and responsibilities Role of PCP “Lack of physician buy-in that immunizations are everyone's responsibility. The providers believe it is the responsibility of the PCP.” 
  “Mostly, vaccination has been viewed as an outpatient practice.” 
 Not a priority “Hospitalist and subspecialists are not commonly think[ing] about providing catch up vaccines with the exception of influenza vaccine.” 
  “Lack of remembering to order vaccine, low on priority list for hospitalized patients.” 
Major ThemesSubthemesRepresentative Quotes
Communication Access to accurate vaccine histories “Many families do not know specifically which vaccines their child is missing and there is no centralized area for us to look up vaccination records.” 
  “We admit patients from multiple surrounding states, and coordinating with state registries can be difficult.” 
 Communication with PCP “Our EMR is unwieldy and does not communicate with even our own outpatient system. Additionally, we do not require reporting to our state registry so it is difficult to communicate receipt of vaccines to PCPs.” 
Systems not optimized Workflow “The inpatient ordering process is more cumbersome than outpatient ordering – we will often order vaccines days in advance so that a patient's discharge time is not prolonged while waiting for a vaccine.” 
  “It is not incorporated/standardized into our work flow. The EMR order pops up to remind you, but many of [us] place orders before seeing the patient … and therefore have not asked about vaccine status at the time of using the initial order set at admission.” 
 Vaccine orders and availability “Vaccine ordering is complicated since if you want to give catch-up or routine vaccines you have to order each individually including the appropriate vaccine generic name, strength and amount.” 
  “The order sets available also are not representative of what is actually stocked by the pharmacy … and therefore requires an additional phone call to the pharmacist.” 
Parental hesitancy Vaccine hesitancy “Same barriers as outpatient clinics regarding stigma and other hesitancy on vaccines like HPV.” 
 Preference for outpatient “Parents prefer/trust their PCP more than us, don't want the PCP to duplicate the vaccine.” 
 Acute illnesses “We find a lot of parental refusal. They feel that the patient is sick, therefore should wait to get the vaccines until later.” 
  “I would say that we always/usually offer catch up vaccines to families, but often they decline despite counselling that vaccinations are OK to be given even if a child is recovering from an illness.” 
Provider discomfort Fever and other side effects “Acutely ill or complex illnesses can influence team or family comfort with vaccination.” 
  “Some people worry the vaccines may cause fever, which could complicate the clinical picture for hospitalized children in some cases.” 
  “Issues with patients currently with fever and ‘confusing the picture’ by giving a vaccine that might cause fever.” 
 Nursing discomfort “Nurses belief that all immunization responsibilities belong to the physicians except for obtaining the ‘shot record.’ Nurses not willing to enter standing order.” 
Roles and responsibilities Role of PCP “Lack of physician buy-in that immunizations are everyone's responsibility. The providers believe it is the responsibility of the PCP.” 
  “Mostly, vaccination has been viewed as an outpatient practice.” 
 Not a priority “Hospitalist and subspecialists are not commonly think[ing] about providing catch up vaccines with the exception of influenza vaccine.” 
  “Lack of remembering to order vaccine, low on priority list for hospitalized patients.” 

In addition, even if systems were in place to facilitate vaccination, these were often not optimized. In free-text responses and correspondence, 1 in 4 sites indicated that vaccine practices only applied to certain units at their institution and were not hospital-wide. In line with this, another physician responded, “The inpatient ordering process is more cumbersome than outpatient ordering – we will often order vaccines days in advance so that a patient’s discharge time is not prolonged while waiting for a vaccine.”

Respondents also identified parental vaccine refusal, both from concerns that their child was too sick to receive vaccines and from vaccine hesitancy in general, as barriers. In addition to parental discomfort, physician and staff discomfort with inpatient vaccination was noted, including concerns that postvaccine fevers could complicate the clinical picture and the idea that vaccines should be given by the PCP only. One nurse found that a “physician or pharmacist discontinues standing order for vaccines based on [the] belief it is not their responsibility to give vaccines.” Of note, although providers did acknowledge that they may not remember to ask about inpatients’ vaccination status, they rarely voiced concerns regarding lack of time or immunization cost.

To our knowledge, this represents the first study used to describe national practices in pediatric inpatient immunization. We found that hospitals had significantly more practices in place to deliver influenza vaccines in comparison with primary childhood and adolescent vaccines. Common barriers to vaccinating hospitalized children, from lack of systems optimization to discomfort with inpatient immunization, were also identified.

Using every encounter with the health care setting as an opportunity to vaccinate is in line with national recommendations.17,30  However, although all of the vaccines included in our study are equally endorsed by the Advisory Committee on Immunization Practices, there were stark differences in hospital practices between vaccine types. These discrepancies appear to be independent of the number of undervaccinated patients on a population level; influenza and HPV vaccination rates are among the lowest of all pediatric immunizations3133  yet were drastically different in the number of practices supporting their delivery.

A number of factors may contribute to institutions’ differential treatment of certain vaccines, including bias toward diseases encountered more frequently, ability to obtain accurate vaccine histories, and provider perceptions. Increased hospital support of influenza vaccination likely is related to its substantial disease burden as well as its designation as a Joint Commission quality measure.34  Influenza accounted for 46 340 pediatric hospitalizations in the 2018–2019 season; in contrast, in 2019, there were only 128 hospitalizations for measles in the United States in both children and adults combined, and diagnosed cases of other vaccine-preventable illnesses, such as meningococcemia, tetanus, and diphtheria, were equally low.3537  In addition, although HPV is associated with significant morbidity, the consequences of this infection are rarely encountered by pediatricians; the median age of diagnosis of HPV-related cervical cancer is 49 years.38 

Influenza vaccines may also be easier to deliver in the hospital setting given suboptimal access to outpatient records. In our findings, only one-third of hospitals’ EMRs were able to receive information from state registries, and respondents identified the inability to accurately assess patients’ vaccination status as a barrier to immunization. Obtaining vaccination records for hospitalized children can be a time-intensive process and parental recall is often inaccurate.13,5,9  Whereas the influenza vaccine is delivered annually, a parent would need to correctly recall >20 vaccines separated over multiple medical encounters to identify a missed dose in an 18-month-old child or remember immunizations given years earlier in an older teenager.39  Increased confidence in parental recall may increase inpatient providers’ ability to identify patients requiring catch-up influenza vaccination and subsequent comfort with its administration.

Finally, provider hesitancy may also exist toward certain vaccines, such as the HPV vaccine, which had the lowest number of supporting practices in our findings. Physicians have been shown to recommend the HPV vaccine less strongly than other immunizations,19,20  and our institution previously found that pediatric residents were more likely to report rarely discussing or offering the HPV vaccine during hospitalization compared with primary childhood or influenza vaccines.22  In addition, our survey respondents identified concerns of parental refusal as a barrier to vaccination; however, providers may perceive an increased rate of parental hesitancy than is present. In one study, 35% of providers identified parental resistance as a barrier to inpatient vaccination, whereas only 5% of parents were concerned about receiving vaccines during hospitalization.40  Although previous literature has revealed that providers are overall supportive of inpatient immunization programs,40,41  physician discomfort with inpatient vaccinations, from postvaccination fevers to the belief that vaccines are the role of the PCP, was noted in our narrative responses. Whether providers’ personal views on inpatient immunizations or their perceptions of parental hesitancy toward certain vaccine types differentially impact physician behavior deserves further exploration.

By applying standardized strategies for only a subset of immunizations, missed vaccination opportunities are likely created. Expanding existing hospital infrastructure to deliver noninfluenza vaccines may be particularly beneficial for at-risk patient groups and those with difficulty accessing or who experience delayed outpatient care. Chronic medical conditions increase the risk of complications from multiple vaccine-preventable diseases, yet parents of children with chronic conditions have identified difficulty receiving timely outpatient vaccination because of frequent hospitalizations and illnesses.40,42  Vaccines delivered at all encounter types may also benefit patients who have recently moved or immigrated, children who have not yet established a medical home, and hospitalized adolescents, who have higher rates of undervaccination and see their PCP less frequently than other age groups.1,2,43  Finally, amid the current coronavirus disease 2019 pandemic and the resultant decline in childhood vaccine delivery, the ability to further understand and capitalize on all immunization opportunities appears to be more important than ever; indeed, in a study in Michigan, the one childhood vaccine that did not see decreased delivery was the birth dose of hepatitis B, which is traditionally given in the hospital setting.44,45 

Several limitations to this study exist. First, only 50% of sites responded to our survey request, which may introduce participant selection bias. Second, the survey was sent to pediatric hospitalists primarily; thus, participants may not be familiar with operations in all hospital areas. Third, although our survey respondents represented every geographic region in the country, a significant majority of sites were private institutions and teaching hospitals. In addition, surveys were sent to hospitals that voluntarily participate in the PRIS Network; thus, these results may not be generalizable across all centers. Finally, although we sought to understand current inpatient vaccination practices at institutions, we did not assess the number of vaccines given at each participant hospital; therefore, we are unable to comment on the efficacy of these strategies in delivery of vaccines.

Hospitals were most likely to report practices supporting inpatient influenza vaccination and least likely for adolescent vaccines. Further research is needed to elucidate whether existing hospital infrastructure for delivering influenza vaccines can be expanded to improve inpatient immunization efforts for all vaccine types. Multicenter studies used to evaluate the rates of inpatient vaccines delivered and whether specific policies lead to higher vaccine delivery could help inform best practices. In addition, qualitative studies of hospitals that have developed successful comprehensive immunization programs can help identify key strategies for overcoming barriers to inpatient vaccine delivery. Given the large number of undervaccinated pediatric inpatients, optimization of hospital-based immunization systems has potentially significant public health implications.

We acknowledge Dr Sunitha Kaiser and the PRIS Executive Council for their guidance and support in the construction of this study.

Dr Mihalek conceptualized and designed the study, coordinated and supervised data collection, participated in qualitative analysis, and drafted the initial manuscript; Dr Wu conceptualized the study, participated in data collection and qualitative analysis, and critically reviewed the manuscript; Dr Russell conceptualized the study, participated in data collection, and critically reviewed the manuscript; Mr Hassan participated in qualitative analysis and critically reviewed the manuscript; Ms Yeh conducted data analysis and critically reviewed the manuscript; and all authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

FUNDING: Supported by grants UL1TR001855 and UL1TR000130 from the National Center for Advancing Translational Science of the US National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The funder/sponsor did not participate in the work.

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Competing Interests

POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose.

FINANCIAL DISCLOSURE: Dr Wu holds stock in Eli Lilly; the other authors have indicated they have no financial relationships relevant to this article to disclose.

Supplementary data