Abstract
BACKGROUND: Rotavirus vaccines (RVVs) were included in the US immunization program in 2006 and are coadministered with the diphtheria-tetanus-acellular pertussis (DTaP) vaccine, yet their coverage lags behind DTaP. We assessed timing, initiation, and completion of the RVV series among children enrolled in active gastroenteritis surveillance at 7 US medical institutions during 2014–2016.
METHODS: We compared coverage and timing of each vaccine series and analyzed characteristics associated with RVV initiation and completion. We report odds ratios (ORs) and 95% confidence intervals (CIs) from multivariable logistic regression models.
RESULTS: We enrolled 10 603 children. In 2015, ≥1 dose coverage was 91% for RVV and 97% for DTaP. Seven percent of children received their first DTaP vaccine at age ≥15 weeks versus 4% for RVV (P ≤ .001). Recent birth years (2013–2016) were associated with higher odds of RVV initiation (OR = 5.72; 95% CI 4.43–7.39), whereas preterm birth (OR = 0.32; 95% CI 0.24–0.41), older age at DTaP initiation (OR 0.85; 95% CI 0.80–0.91), income between $50 000 and $100 000 (OR = 0.56; 95% CI 0.40–0.78), and higher maternal education (OR = 0.52; 95% CI 0.36–0.74) were associated with lower odds. Once RVV was initiated, recent birth years (2013–2016; OR = 1.57 [95% CI 1.32–1.88]) and higher maternal education (OR = 1.31; 95% CI 1.07–1.60) were associated with higher odds of RVV completion, whereas preterm birth (OR = 0.76; 95% CI 0.62–0.94), African American race (OR = 0.82; 95% CI 0.70–0.97) and public or no insurance (OR = 0.75; 95% CI 0.60–0.93) were associated with lower odds. Regional differences existed.
CONCLUSIONS: RVV coverage remains lower than that for the DTaP vaccine. Timely DTaP administration may help improve RVV coverage.
- ACIP —
- Advisory Committee on Immunization Practices
- AGE —
- acute gastroenteritis
- CI —
- confidence interval
- DTaP —
- diphtheria-tetanus-acellular pertussis
- IIS —
- Immunization Information System
- NVSN —
- New Vaccine Surveillance Network
- OR —
- odds ratio
- RVV —
- rotavirus vaccine
What’s Known on This Subject:
Rotavirus vaccine coverage in US children lags behind diphtheria-tetanus-acellular pertussis vaccine. The Advisory Committee on Immunization Practices recommended that age restrictions for the rotavirus vaccine likely play a role; other factors associated with low uptake have not fully been described.
What This Study Adds:
We identify preterm birth and older age at diphtheria-tetanus-acellular pertussis vaccine initiation as factors leading to missed opportunities for rotavirus vaccination (in addition to region-specific socioeconomic factors). We identify interventions to improve coverage and special populations for further study.
The introduction of rotavirus vaccines (RVVs) in the United States in 2006 heralded dramatic declines in rotavirus disease burden.1–3 Two RVVs are licensed by the US Food and Drug Administration and recommended by the Advisory Committee on Immunization Practices (ACIP) for universal infant immunization.4 Rotarix (RV1; GlaxoSmithKline Biologicals, Rixensart, Belgium) is a 2-dose monovalent RVV recommended by the ACIP to be given at 2 and 4 months of age, and RotaTeq (RV5; Merck and Company, Kenilworth, NJ) is a 3-dose pentavalent RVV recommended to be given at 2, 4, and 6 months of age. RVVs are coadministered with other vaccines, including the diphtheria-tetanus-acellular pertussis (DTaP) vaccine.5 ACIP recommendations for RVV include maximum ages for the first dose (14 weeks, 6 days) and last dose (8 months, 0 days)6 with no catchup; these restrictions are based on the absence of safety and efficacy data on RVV given outside these ages and do not exist for the DTaP vaccine.
RVV coverage in US children lags behind that for the DTaP vaccine. Among children aged 19 to 35 months, the National Immunization Survey (NIS) has consistently reported at least a 21 percentage point lower RVV coverage compared with that of the DTaP vaccine since 2009.7–12 In 2015, the estimated 3-dose DTaP vaccine coverage was 95% (95% confidence interval [CI] 94%–96%), whereas full-series RVV coverage (2-dose RV1 or 3-dose RV5) was 73% (95% CI 72%–75%).12 Two other studies, from state immunization registries (Immunization Information System [IIS] sentinel sites) and a large commercial data set, also revealed lower RVV coverage compared with that of the DTaP vaccine. The former revealed a 6 to 8 percentage point discrepancy between the DTaP vaccine and RVV for ≥1 dose coverage among children 5 months of age during 2012–2013,13 whereas the latter revealed that full-course RVV coverage among children 13 months of age born in 2011–2012 trailed 3-dose DTaP vaccine coverage by 10 percentage points.14 Reasons for these differences are not clear, but the child’s age at vaccination, birth year, ethnicity, and race; provider type; and urban versus rural residence have been implicated.14–17
To better understand why RVV coverage continues to be lower than that of the DTaP vaccine despite the recommendation to administer both vaccines at the same age-defined health care visits, we analyzed data from a large active acute gastroenteritis (AGE) surveillance system at 7 US medical institutions with large catchment areas. Our objectives were the following: (1) to determine the proportion of children who initiated RVV and the DTaP vaccine, (2) to examine timeliness of RVV and DTaP vaccine administration, (3) to determine risk factors for missed opportunities to initiate RVV, and (4) to examine factors associated with RVV series completion.
Methods
Patients
We analyzed data for children enrolled in the New Vaccine Surveillance Network (NVSN) during December 2014–June 2016. The NVSN is a previously described active prospective AGE surveillance network18 in 7 sentinel sites: Nashville, Rochester, Cincinnati, Seattle, Houston, Kansas City, and Oakland. We included children born after January 1, 2007, because RVV became available in the United States during 2006. Children with AGE (≥3 episodes of diarrhea and 24 hours and/or ≥1 episode of vomiting) were enrolled and tested for rotavirus by using Rotaclone enzyme immunoassay; children who were immunocompromised were excluded. In 6 sites, children aged 14 days to 10 years with AGE were enrolled from inpatient and emergency wards. In Nashville, outpatients with AGE were also enrolled. Healthy controls in this age range with no AGE symptoms for the previous 14 days were enrolled at well-child visits from all sites. Epidemiological and clinical data were collected from structured caregiver interviews, medical chart reviews, and verified rotavirus and DTaP immunization data from immunization registries and provider records. Approval for the study was obtained from the institutional review board at each site and from the Centers for Disease Control and Prevention.
Analysis
We examined different subsets of enrolled patients with AGE and healthy controls for each objective.
To determine coverage with ≥1 dose of RVV or the DTaP vaccine, using previously described NVSN methods, we examined data from children aged 6 to 35 months with rotavirus-negative AGE (from inpatient and/or emergency department setting) during January 2015–June 2015.
All remaining analysis groups combined children with AGE (rotavirus-positive or rotavirus-negative) and healthy controls. Timeliness of DTaP vaccine and RVV receipt was assessed for those with verified immunization records. Among all children who received 1, 2, or 3 RVV doses, the cumulative proportion that received each dose was calculated by age; similar calculations were made for the first 3 DTaP vaccine doses. The cumulative proportion of children vaccinated with specific dose numbers of RVV was compared with that of the DTaP vaccine. To determine if age restrictions contributed to lower reported RVV coverage, the proportion initiating RVV at ≥15 weeks of age, (ie, after the ACIP-recommended maximum age for the first RVV dose) was compared with the proportion initiating the DTaP vaccine at ≥15 weeks of age. Similar analyses were completed for the last dose of RVV and the third dose of the DTaP vaccine at ≥8 months of age.
To study missed opportunities for RVV initiation (defined as receipt of ≥1 RVV dose), we restricted the study population to those aged ≥15 weeks at enrollment who had received the first DTaP vaccine dose within the recommended ACIP schedule for the first RVV dose (between 6 and 14 weeks, 6 days of age). This window reflects the recommended ACIP schedule shared for both the DTaP vaccine and RVV, and by enrolling those aged ≥15 weeks, we ensured that children had an opportunity to receive a first RVV dose. The outcome was RVV initiation. Covariates included birth year, preterm birth, age at DTaP vaccine initiation, race, ethnicity, household income, insurance status, mother’s age, and mother’s educational status. Given that the Food and Drug Administration temporarily recommended suspension of monovalent RVV from March 22, 2010, to May 16, 2010,19 we performed a sensitivity analysis to determine if exclusion of infants born during January 2010–June 2010 altered findings.
To study factors associated with RVV series completion, we restricted the study population to children enrolled at age ≥8 months who had initiated RVV. This ensured that children had the opportunity to finish either the 2- or 3-dose RVV series by the ACIP-recommended time of 8 months. The outcome was RVV completion, with receipt of either 2-dose monovalent RVV or 3 doses of either RVV series classified as complete. A partial series (1 dose of either RVV or 2 doses of pentavalent RVV or 2 doses of mixed monovalent and pentavalent RVV) was categorized as an incomplete RVV series.
Descriptive data are reported by using proportions and χ2 testing for categorical variables and medians and nonparametric Wilcoxon tests for continuous variables. An unconditional logistic regression was used to compare potential factors associated with RVV receipt, and odds ratios (ORs) with 95% CIs are reported. Statistically significant characteristics from bivariate analyses were included in the multivariable model by using backward elimination to keep significant variables in the final model. Similar methods were used for the RVV completion analysis. Both analyses were stratified by site, and the same methods were used to obtain the most parsimonious multivariable models. Models yielding unstable results are not shown (α = .05).
Results
A total of 10 603 children born after January 1, 2007, were enrolled during December 2014–June 2016. Different subsets of this population were analyzed for timeliness and missed opportunities for RVV initiation and completion (Fig 1). Of the enrolled children, 10 101 had verified DTaP vaccine and RVV information and were included in the timeliness analysis. Of these, 8386 (83%) received the DTaP vaccine within age 6 to 15 weeks and were ≥15 weeks of age at enrollment. And of these DTaP vaccine recipients, 7968 (95%) had also initiated RVV, whereas 418 (5%) had not; these children were included in the missed opportunities for RVV initiation analysis. Among the 10 101 enrollees with vaccine data available, 7281 (72%) initiated RVV and were aged ≥8 months at enrollment. Of these, 6101 (84%) completed the RVV series, whereas 1180 (16%) did not; these children were included in the missed opportunities for RVV completion analysis.
Flowchart of children included in analyses of timeliness, missed opportunities, and series completion (NVSN, December 2014–June 2016). a Includes rotavirus-positive and rotavirus-negative cases.
Coverage With ≥1 Dose of RVV Versus DTaP Vaccine
In 2015, 91% of enrollees in the coverage cohort who were rotavirus negative initiated RVV, and 97% initiated DTaP vaccine (Fig 2). One-dose RVV coverage was lower than that of DTaP vaccine at all sites, with significant differences in Cincinnati, Seattle, Kansas City, and Oakland.
Proportion of children aged 6 to 35 months old who received ≥1 dose of RVV or the DTaP vaccine by site (NVSN, 2015). Coverage for these vaccines was calculated from enrolled children with AGE who tested negative for rotavirus between January 2015 and June 2015. For RVV, the proportions by site include the following: Nashville, 116 of 125; Rochester, 78 of 92; Cincinnati, 116 of 128; Seattle, 65 of 74; Houston, 111 of 116; Kansas City, 148 of 166; and Oakland, 161 of 173. For the DTaP vaccine, the proportions by site include the following: Nashville, 119 of 125; Rochester, 82 of 90; Cincinnati, 124 of 128; Seattle, 71 of 73; Houston, 111 of 116; Kansas City, 148 of 166; and Oakland, 161 of 173. a Indicates P < .05 for comparison of the proportion who initiated RVV and the proportion who initiated the DTaP vaccine.
Timing of Vaccine Initiation
Of the 10 101 children with vaccine data available analyzed, 1666 never initiated RVV, and 460 never initiated the DTaP vaccine, whereas 439 did not initiate either vaccine. Among children who initiated either vaccine, 3.9% (341 of 8798) received the first RVV dose at age ≥15 weeks, compared with 7.2% (695/9641) for the DTaP vaccine (P ≤ .001; Fig 3). The proportions that received the doses at age ≥8 months was 1.5% (65 of 4454) for last-dose RVV versus 16.2% (1308 of 8076) for third-dose DTaP vaccine (P ≤ .001).
Timing of DTaP vaccines and RVV doses among children who received the indicated dose (NVSN, December 2014–June 2016). ACIP-recommended RVV series age schedules include the following: 2 doses, 2 and 4 months; and 3 doses, 2, 4, and 6 months. The x-axis has been truncated at 102 weeks; 99.9% of children who had received RVV3 did so by 102 weeks, whereas 98.2% of children who had received DTaP3 did so by that time point.
Missed Opportunities for RVV Initiation
Unconditional multivariable logistic regression models revealed that children born in 2013–2016 had 5.72 times (95% CI 4.43–7.39) the odds of RVV initiation versus those born in 2007–2009 (Table 1). Additionally, for each 1-week increase in infant age at DTaP vaccine initiation, the child’s odds of initiating RVV dropped by 15% each week (OR = 0.85; 95% CI 0.80–0.91). Other factors associated with lower odds of receiving RVV included preterm birth (OR = 0.32; 95% CI 0.24–0.41), household income ($50 001–$100 000: OR = 0.56 [95% CI 0.40–0.78]; $100 000–$150 000: OR = 0.68 [95% CI 0.47–0.99]), and higher maternal education (OR = 0.52; 95% CI 0.36–0.74). The exclusion of 288 children born during January 2010–June 2010 did not appreciably change estimates (data not shown).
Description of the Cohort and Factors Associated With RVV Series Initiation (NVSN, December 2014–June 2016)
When stratified by site, children born in 2013–2016 had 4.18 to 12.95 higher odds of initiating RVV compared with those born in 2007–2009 (Table 2). African American infants had higher odds of receiving RVV than white infants in Cincinnati (OR = 1.97; 95% CI 1.05–3.71) and Oakland (OR = 4.20; 95% CI 1.58–11.17). Hispanic infants had twice the odds of initiating RVV versus non-Hispanic infants in Seattle (OR = 2.23; 95% CI 1.19–4.17) and Houston (OR = 2.45; 95% CI 1.32–4.58) but less than half the odds of non-Hispanic infants in Kansas City (OR = 0.45; 95% CI 0.26–0.78). Increasing age at DTaP vaccine administration was associated with 15% to 25% lower odds of initiating RVV in Cincinnati, Houston, and Kansas City. Mothers with higher education in Oakland had less than half the odds of RVV initiation versus those with no formal degree (OR = 0.40; 95% CI 0.17–0.94).
Multivariable Models Used to Assess the Factors Associated With RVV Initiation Among Children Enrolled in NVSN by Site (December 2014–June 2016)
Factors Associated With RVV Completion
Among the 1180 children who did not complete the RVV series, 173 (19%) had initiated the RVV series when aged ≥15 weeks. Factors associated with higher odds of RVV completion included recent birth years (OR = 1.57 [95% CI 1.32–1.88]) and higher maternal education (OR = 1.31 [95% CI 1.07–1.60]; Table 3). Conversely, preterm birth (OR = 0.76; 95% CI 0.62–0.94), greater age at DTaP vaccine initiation (OR = 0.94; 95% CI 0.93–0.96), African American race (OR = 0.82; 95% CI 0.70–0.97), and public or no insurance (OR = 0.75; 95% CI 0.60–0.93) were associated with lower odds of RVV completion. When stratified by site, notable differences included that Hispanic children had more than half the odds of RVV completion versus non-Hispanic children in Rochester (OR = 0.53; 95% CI 0.29–0.97), whereas African American infants in Houston had less than half the odds of RVV completion versus white infants (OR = 0.44 [95% CI 0.26–0.74]; Table 4). Mothers with higher education in Oakland had higher odds of RVV series completion versus those without high school degrees (OR = 2.06; 95% CI 1.31–3.25).
Factors Associated With RVV Series Completion (NVSN, December 2014–June 2016)
Factors Associated With RVV Series Completion Among Children Enrolled in NVSN by Site (December 2014–June 2016)
Discussion
Among children enrolled in AGE surveillance at 7 large US pediatric medical institutions, RVV initiation lagged behind DTaP vaccine initiation by 6 percentage points nearly a decade after RVV’s approval for routine infant vaccination4 in concordance with the 4% to 10% lag reported by IIS sites and in insurance claims studies.13,14
Concerns previously reported to contribute to lagging RVV coverage have included vaccine safety concerns related to intussusception, which resulted in the development of age restrictions for RVV administration4; concerns with vaccinating infants hospitalized in the NICU with live-attenuated virus vaccines, including RVV; detection of porcine circovirus genetic material in RVV; and RVV-derived reassortant strains.20 Our findings reveal that RVV age restrictions and lower NICU RVV vaccination practices are factors contributing to the lower odds of uptake for RVV compared with the DTaP vaccine.
Given the overlapping recommended immunization schedules for RVV and the DTaP vaccine, children presenting to a health care provider to initiate DTaP vaccination within 6 to 14 weeks, 6 days of age theoretically have the same opportunity to initiate RVV, barring contraindications or vaccine unavailability.15,17 However, children outside this age window should not initiate RVV per ACIP recommendations, and we found 15% lower odds of RVV initiation with each week of increasing age at DTaP vaccine initiation. We also found that ∼4% and 2% of children received their first and final RVV doses after the maximum ACIP-recommended ages, respectively, and that this occurred less often than receiving the DTaP vaccine outside these ages (7% and 16%, respectively), highlighting the rigidity of RVV recommendations. The proportion of children receiving the first RVV dose outside the recommended age is similar to that reported by the Vaccine Safety Datalink (1.4%) and the Centers for Disease Control and Prevention IIS (5.0%)21 in studies conducted soon after RVV introduction. Insurance claims data have revealed that coverage for RVV, the DTaP vaccine, and the pneumococcal conjugate vaccine, which are coadministered, diverges at 8 months.14 In that study of infants born between 2009 and 2012, coverage for these 3 vaccines was similar in the first 7 months of life; RVV coverage increased only from 69% to 73% between 7 and 13 months, whereas DTaP vaccine coverage increased from 73% to 83%, and pneumococcal conjugate vaccine coverage increased from 69% to 84%. In Australia, although RVV age restrictions may have improved the timeliness of vaccines coadministered with RVV, they have also been associated with a 7 percentage point lower coverage for RVV compared with these other vaccines.22 Although the World Health Organization issued recommendations for loosening this age restriction in developing countries with a higher rotavirus disease burden, no easing of the age restriction is recommended for lower-burden settings.23 Urging earlier DTaP vaccine receipt for infants may be 1 potential way of remediating a missed opportunity for RVV receipt arising from these age restrictions.
NICU and hospital nursery vaccination practices involving live-attenuated virus vaccines, such as RVV, also appear to have played a role in lower RVV uptake in our cohort. Children born before 37 weeks’ gestation had 68% lower odds of RVV initiation compared with those born at 37 weeks or later. Many of these preterm children may have had prolonged stays in a NICU or hospital nurseries and missed vaccination opportunities. A previous study revealed that 63% of infants with very low birth weight failed to receive RVV at the time of NICU discharge often because they exceeded the upper age limit for vaccine receipt.24 A study of a more recent cohort of infants discharged from a NICU revealed that RVV coverage at discharge was 33% vs 83% for other vaccines, with 43% of children without the RVV discharged after the age cutoff.25 The shedding of RVV strains has been raised as a potential concern in these settings, but real-world NICU observations have not revealed vaccine-type rotavirus to be detected in infants who are unvaccinated, including those whose NICU stays overlapped by time and location with those of patients who were vaccinated.25,26
Children born in the years shortly after introduction of RVV had a higher risk of missed RVV initiation. Many reasons may have played a role in this finding, including variations in insurance adoption and reimbursement rates,27 caregiver lack of knowledge regarding rotavirus disease,28 or hesitancy regarding RVV safety given that the first licensed RVV (RotaShield; Wyeth Laboratories, Marietta, PA) was withdrawn because of concerns regarding intussusception.27,29
Socioeconomic and educational factors differed for RVV initiation versus completion. Children from households with an income of $50 000 to $100 000 had 44% lower odds of initiating RVV compared with children from households with an income of <$25 000. Mothers with some college education were half as likely to initiate RVV for their child compared with those who had no high school degree. Interestingly, these findings stand in contrast to those of an earlier study of factors associated with RotaShield, which revealed that infants who were from households with a higher economic status, who had mothers with higher education, who were of white race, and who were of non-Hispanic ethnicity were more likely to have initiated RotaShield.30
Our data revealed that once RVV was initiated, income was not significantly associated with RVV completion, and mothers with higher educational attainment were more likely to have their children complete the RVV series. Additionally, African American children and those with public or no insurance had lower odds of series completion compared with white children and those with private insurance, respectively. Whether decreased RVV initiation among wealthier parents with higher education is due to vaccine hesitancy,31 and whether some wealthier families with greater educational attainment (if they do initiate RVV) are more likely to complete the series because of greater access to medical care, requires further study.
Geographical variation may have played a role in these discrepancies in RVV initiation and completion. Stratified by geographic location, income remained a significant predictor of RVV initiation in Kansas City, and maternal educational status remained a significant predictor in Oakland. Ethnicity was not associated with RVV initiation in our full sample, as reported elsewhere16; however, site-specific analyses revealed that Hispanic ethnicity doubled the odds of RVV initiation in Seattle and Houston, whereas it halved the odds in Kansas City. For series completion, examples from the literature reveal a mixed picture. An insurance claims–based study of a commercially insured cohort revealed that DTaP vaccine initiation, visits with a pediatrician versus a family physician, and living in a large urban area versus smaller urban and rural areas predicted RVV completion.17 The authors of a case-control study in Georgia assessed factors associated with RVV series completion and found that non-Hispanic children had a higher odds of an incomplete RVV series, as did children born in earlier birth years and those who did not complete the DTaP vaccine series.16 Additional research is needed to further explore these findings.
Our study had several limitations. First, the population used for most analyses included children with rotavirus disease, and although these analyses should not be interpreted as providing standard estimates of vaccine coverage, they are appropriate for comparing RVV and DTaP vaccine initiation and completion patterns. Additionally, our subjects were enrolled in surveillance at 7 medical institutions and may not be representative of all US children. Next, we did not collect DTaP vaccine data before 2015, resulting in 1 comparison year. However, the proportions vaccinated in our assessment are similar to discrepancies between DTaP vaccine and RVV uptake observed elsewhere. RVVs were available at different times in the states where NSVN sites are located and early after vaccine introduction; this likely played a role in coverage. Next, we were unable to separately analyze the group of children with public insurance or no insurance because the sample size was too small; as such, we were unable to evaluate factors associated with RVV receipt among this specific subgroup. Also, we did not have detailed information on premature children and were unable to assess age at hospital discharge or whether they were in a NICU. Finally, we were unable to assess direct caregiver- or provider-related information regarding missed opportunities. As such, we were unable to further explore vaccine hesitancy, which was reported as a possible factor impacting the implementation of rotavirus immunization in the United States.32
Conclusions
For both the initiation and completion of the ACIP-recommended RVV series, age restrictions and preterm birth were at least partially responsible for lower RVV coverage when compared with that of the DTaP vaccine. Sociodemographic factors played a role, including household income, maternal educational, insurance status, and demographics, all with geographic variation. Timely DTaP vaccine administration may help improve RVV coverage, and further exploration of preterm children and socioeconomic factors may aid in developing public health efforts to improve RVV coverage in the United States.
Acknowledgments
We thank Samantha H. Johnston for her assistance and the enrollment staff and data managers at each study site.
Footnotes
- Accepted November 19, 2018.
- Address correspondence to Negar Aliabadi, MD, MS, Global Immunization Division, Center for Global Health, US Centers for Disease Control and Prevention, 1600 Clifton Rd NE, Mailstop H24-2, Atlanta, GA 30329. E-mail: ydh6{at}cdc.gov
The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the US Centers for Disease Control and Prevention.
FINANCIAL DISCLOSURE: Dr Bernstein received a patent on the GlaxoSmithKline rotavirus vaccine; the other authors have indicated they have no financial relationships relevant to this article to disclose.
FUNDING: This article was prepared without any specific financial support. The New Vaccine Surveillance System is supported through a cooperative agreement with the Centers for Disease Control and Prevention.
POTENTIAL CONFLICT OF INTEREST: Dr Halasa received vaccines from Sanofi Pasteur for 1 of her studies and was a consultant for GlaxoSmithKline and Moderna; Dr Englund reports research support to her institution for clinical studies by GlaxoSmithKline and Merck; Dr Bernstein has received research funding from GlaxoSmithKline, Merck, and Wyeth Laboratories; Dr Harrison was an investigator on research projects for which his institution received grant funds from Merck, Pfizer, Cubist, Allergan, Regeneron, Janssen, and GlaxoSmithKline; he also received travel funds and an honorarium to present scientific data to Pfizer’s research team at their corporate headquarters; the other authors have indicated they have no potential conflicts of interest to disclose.
References
- Copyright © 2019 by the American Academy of Pediatrics
