U.S. COVID-19 vaccine distribution strategies, systems, performance, and lessons learned, December 2020 - May 2023.

During December 2020 through May 2023, the Centers for Disease Control and Prevention's (CDC) Immunization Services Division supported and executed the largest vaccine distribution effort in U.S. history, delivering nearly one billion doses of COVID-19 vaccine to vaccine providers in all 50 states, District of Columbia, Puerto Rico, Virgin Islands, Guam, Federated States of Micronesia, American Samoa, Marshall Islands, Northern Mariana Islands, and Palau. While existing infrastructure, ordering, and distribution mechanisms were in place from the Vaccines for Children Program (VFC) and experience had been gained during the 2009 H1N1 pandemic and incorporated into influenza vaccination pandemic planning, the scale and complexity of the national mobilization against a novel coronavirus resulted in many previously unforeseen challenges, particularly related to transporting and storing the majority of the U.S. COVID-19 vaccine at frozen and ultra-cold temperatures. This article describes the infrastructure supporting the distribution of U.S. government-purchased COVID-19 vaccines that was in place pre-pandemic, and the infrastructure, processes, and communications efforts developed to support the heightened demands of the COVID-19 vaccination program, and describes lessons learned.

Effects of the COVID-19 Pandemic on Routine Pediatric Vaccine Ordering and Administration - United States, 2020.

On March 13, 2020, the president of the United States declared a national emergency in response to the coronavirus disease 2019 (COVID-19) pandemic (1). With reports of laboratory-confirmed cases in all 50 states by that time (2), disruptions were anticipated in the U.S. health care system's ability to continue providing routine preventive and other nonemergency care. In addition, many states and localities issued shelter-in-place or stay-at-home orders to reduce the spread of COVID-19, limiting movement outside the home to essential activities (3). On March 24, CDC posted guidance emphasizing the importance of routine well child care and immunization, particularly for children aged ≤24 months, when many childhood vaccines are recommended.

Gaps in vaccine financing for underinsured children in the United States.

CONTEXT: The number of new vaccines recommended for children and adolescents has nearly doubled during the past 5 years, and the cost of fully vaccinating a child has increased dramatically in the past decade. Anecdotal reports from state policy makers and clinicians suggest that new gaps have arisen in financial coverage of vaccines for children who are underinsured (ie, have private insurance that does not cover all recommended vaccines). In 2000, approximately 14% of children were underinsured for vaccines in the United States. OBJECTIVES: To describe variation among states in the provision of new vaccines to underinsured children and to identify barriers to state purchase and distribution of new vaccines. DESIGN, SETTING, AND PARTICIPANTS: A 2-phase mixed-methods study of state immunization program managers in the United States. The first phase included 1-hour qualitative telephone interviews conducted from November to December 2005 with 9 program managers chosen to represent different state vaccine financing policies. The second phase incorporated findings from phase 1 to develop a national telephone and paper-based survey of state immunization program managers that was conducted from January to June 2006. MAIN OUTCOME MEASURES: Percentage of states in which underinsured children are unable to receive publicly purchased vaccines in the private or public sectors. RESULTS: Immunization program managers from 48 states (96%) participated in the study. Underinsured children were not eligible to receive publicly purchased meningococcal conjugate or pneumococcal conjugate vaccines in the private sector in 70% and 50% of states, respectively, or in the public sector in 40% and 17% of states, respectively. Due to limited financing for new vaccines, 10 states changed their policies for provision of publicly purchased vaccines between 2004 and early 2006 to restrict access to selected new vaccines for underinsured children. The most commonly cited barriers to implementation in underinsured children were lack of sufficient federal and state funding to purchase vaccines. CONCLUSIONS: The current vaccine financing system has resulted in gaps for underinsured children in the United States, many of whom are now unable to receive publicly purchased vaccines in either the private or public sectors. Additional strategies are needed to ensure financial coverage for all vaccines, particularly new vaccines, among this vulnerable population.

Influenza vaccination coverage of children aged 6 to 23 months: the 2002-2003 and 2003-2004 influenza seasons.

BACKGROUND: Beginning in 2002 the Advisory Committee on Immunization Practices encouraged, when feasible, annual influenza vaccination of all children aged 6 to 23 months and household contacts and out-of-home caregivers of children < 2 years of age. OBJECTIVE: We sought to report influenza vaccination coverage for the 2002-2003 and 2003-2004 influenza seasons among children aged 6 to 23 months according to demographic and immunization-provider characteristics. METHODS: Data from the 2003 and 2004 National Immunization Survey were analyzed. Two measures of childhood influenza vaccination are reported: receipt of > or = 1 influenza vaccination and full vaccination (ie, receipt of the appropriate number of doses on the basis of previous vaccination history). chi2 tests and logistic-regression analyses to test for associations between influenza vaccination status and demographic characteristics were performed. RESULTS: In the 2002-2003 and 2003-2004 influenza seasons only 7.4% and 17.5%, respectively, of children aged 6 to 23 months received > or = 1 influenza vaccination, whereas only 4.4% and 8.4%, respectively, were fully vaccinated. In both seasons, adjusted influenza vaccination coverage was significantly lower among children living below the poverty level; non-Hispanic black children; older children; children with less-educated mothers; children vaccinated only at public clinics; and children not residing in a metropolitan statistical area. CONCLUSION: During the first 2 years of the Advisory Committee on Immunization Practices' encouragement for children aged 6 to 23 months to receive influenza vaccination, coverage was low, with significant demographic differences in receipt of vaccination. Beginning with the 2004-2005 influenza season, they replaced the encouragement with a recommendation that children aged 6 to 23 months receive annual influenza vaccination. Substantial work remains to fully and equitably implement this new recommendation and ensure vaccination with 2 doses for previously unvaccinated children.

Impact of state vaccine financing policy on uptake of heptavalent pneumococcal conjugate vaccine.

OBJECTIVE: We examined heptavalent pneumococcal conjugate vaccine (PCV7) uptake among children aged 19 to 35 months in the United States and determined how uptake rates differed by state vaccine financing policy. METHODS: We analyzed data from the 2001-2003 National Immunization Survey. States that changed their vaccine financing policy between 2001 and 2003 (n=17) were excluded from analysis. Logistic regression was performed to identify the association between state vaccine financing policy and receipt of 3 or more doses of PCV7 after control for demographic characteristics. RESULTS: The proportion of children receiving 3 or more doses increased from 6.7% in 2001 to 69.0% in 2003. After controlling for demographic characteristics, children residing in states that provided all vaccines except PCV7 to all children had lower odds of receiving 3 or more doses compared to children residing in states that provided PCV7 only to children eligible for the Vaccines for Children program (odds ratio=0.58; 95% confidence interval=0.51, 0.66). CONCLUSION: It is essential that we continue to monitor the effect that state vaccine financing policy has on the delivery of PCV7 and future vaccines, which are likely to be increasingly expensive.

Disparities between white and African-American children in immunization coverage.

INTRODUCTION: A recent study has shown that the national-scale difference in immunization coverage between non-Hispanic white (abbreviated "white") and non-Hispanic African-American (abbreviated "African-American") children aged 19-35 months in the United States has increased by about 1 percentage point annually. We examined how this widening gap differs with geography and income. METHODS: We used data from the National Immunization Survey, 1998-2003, a national telephone survey. We examined differences between white and African-American children in immunization coverage within income groups (at or above versus below the federal poverty level) for each census region (northeast, south, midwest and west). We tested the hypothesis of constant disparity over time. RESULTS: Among households at or above the federal poverty level in the northeast census region, disparity is widening (white coverage minus African-American coverage was -0.5 in 1998 but 15.5 in 2003). Among household at or above the federal poverty level in the midwest census region, disparity is narrowing (white coverage minus African-American coverage was 13.9 in 1998 but 2.5 in 2003). We found no significant evidence of a trend in other groups. CONCLUSIONS: Widening national-level disparity in immunization coverage is primarily attributable to trends in the northeast census region. Addressing the widening disparity in coverage requires new strategies that consider current social and economic contexts.

Vaccine shortages: history, impact, and prospects for the future.

Vaccine shortages can result from higher-than-expected demand, interruptions in production/supply, or a lack of resources to purchase vaccines. Each of these factors has played a role in vaccine shortages in the United States during the past 20 years. Since 2000, the United States has experienced an unprecedented series of shortages of vaccines recommended for widespread use against 9 diseases, after more than 15 years without vaccine supply problems. In developing countries, the major cause of vaccine shortages is lack of resources to purchase them. Although there are several steps that could reduce the likelihood of future vaccine shortages, many would take several years to implement. Consequently, we will probably continue to see occasional shortages of vaccines in the United States in the next few years.

Differential effects of the DTaP and MMR vaccine shortages on timeliness of childhood vaccination coverage.

OBJECTIVES: We determined the effect of diphtheria and tetanus toxoids and acellular pertussis vaccine (DTaP) and measles, mumps, rubella (MMR) vaccine shortages on timeliness of the third dose of DTaP (DTaP3), the fourth dose of DTaP (DTaP4), and the first dose of MMR (MMR1) among subgroups of preschool children. METHODS: Data from the 2001 and 2002 National Immunization Surveys were analyzed. Children age-eligible to receive DTaP3, DTaP4, or MMR1 during the shortages were considered subject to the shortage, and those not age-eligible were not subject to the shortage; timeliness of vaccinations was compared. RESULTS: Among children vaccinated only at public clinics, children residing outside metropolitan statistical areas, and children in the Southern Census Region, those age-eligible to receive DTaP4 during the shortage were less likely to be vaccinated by 19 months of age than children not subject to the shortage. CONCLUSIONS: There was notable disparity in the effects of the recent vaccine shortages; children vaccinated only in public clinics, in rural areas, or in the Southern United States were differentially affected by the shortages.

The United States pediatric vaccine stockpile program.

The initial goal of the national vaccine stockpile program was to establish a 6-month supply of all recommended childhood vaccines, to meet national demands if a manufacturing process was interrupted. When the first vaccine stockpiles were created in 1983, the childhood immunization schedule was much less complicated than it is today, and the first stockpiles included only measles-mumps-rubella, poliovirus, and pertussis vaccines, as well as diphtheria and tetanus toxoids. However, today's vaccine needs are much greater, and current stockpiles do not include all recommended childhood vaccines, partially because inclusion of vaccines that are universally recommended, fully implemented, and produced by a single manufacturer has been made a priority. Future planning must also consider substantially higher vaccine costs, the development of new combination vaccines, a wide range of production times, and changes in immunization recommendations. Expansion and strengthening of the national vaccine stockpile program are critical to protect against future disruptions in vaccine supply.

The association between having a medical home and vaccination coverage among children eligible for the vaccines for children program.

BACKGROUND: The Vaccines for Children (VFC) program is designed to reduce the cost of vaccines for vulnerable children, including Medicaid-eligible children, American Indian/Alaska Native children, uninsured children, and underinsured children whose health insurance does not cover the cost of vaccinations. A desired consequence of the program is to promote comprehensive continuous medical care within a medical home for these children. OBJECTIVES: To explore how having a medical home is associated with vaccination coverage among children eligible for the program. PARTICIPANTS: A total of 24514 children 19 to 35 months of age sampled by the National Immunization Survey. DESIGN: VFC eligibility was evaluated for 24514 children 19 to 35 months of age who were sampled by the National Immunization Survey. Children were considered to have a medical home if they had a doctor, nurse, or physician's assistant who provided them with ongoing routine care, including well-child care, preventive care, and sick care, according to their parents. Sampled children were determined to be 4:3:1:3:3 up-to-date (UTD) if their vaccination providers reported administering >or=4 doses of diphtheria-tetanus toxoids-acellular pertussis vaccine, >or=3 doses of polio vaccine, >or=1 dose of measles-mumps-rubella vaccine, >or=3 doses of Haemophilus influenzae type b vaccine, and >or=3 doses of hepatitis B vaccine. RESULTS: Nationally, 44.9% of all children were VFC eligible and 93.0% of the VFC-eligible children received all vaccine doses at a provider enrolled in the VFC program. Compared with children who were not VFC eligible, VFC-eligible children were less likely to be UTD (70.8% vs 77.7%) and less likely to have a medical home (82.1% vs 95.0%). However, among VFC-eligible children, children who had a medical home were significantly more likely to be UTD, compared with children who did not have a medical home (72.3% vs 63.5%). Also, among VFC-eligible children who had a medical home, children who used their medical home consistently to receive all of their vaccination doses were significantly more likely to be UTD, compared with children who did not receive all of their doses from their medical home (75.3% vs 65.7%). Finally, the 4:3:1:3:3 vaccination coverage rate among VFC-eligible children who received all of their vaccination doses from their medical home was not significantly different from that among non-VFC-eligible children, after controlling for significant differences in sociodemographic factors between these groups (adjusted difference: 2.8%; 95% confidence interval: -0.1% to 5.7%). CONCLUSIONS: Although the vaccination coverage rate among VFC-eligible children who had a medical home and received all vaccine doses from their medical home was essentially equivalent to that of non-VFC-eligible children, substantial percentages of VFC-eligible children either did not have a medical home or did not use their medical home to receive all of their recommended vaccinations. The vaccination coverage rate among these children was significantly lower. This suggests that there may be opportunities to increase vaccination coverage by removing barriers that prevent the adoption and consistent use of a medical home among these children.

Parental vaccine safety concerns: results from the National Immunization Survey, 2001-2002.

BACKGROUND: According to the 2002 National Immunization Survey (NIS), vaccination coverage with recommended vaccines among U.S. children aged 19 to 35 months remained near all-time highs. Sustaining this high coverage requires significant effort, including consideration of parental vaccine safety concerns that have led to decreasing coverage in other countries. METHODS: The Parental Knowledge and Experiences module was administered to a random subset of NIS respondents from July 2001 to December 2002. The module included questions regarding attitudes toward vaccine safety and side effects, simultaneous vaccine administration, and acceptance of new vaccines. Multivariate logistic regression analyses examined associations between attitudes and up-to-date (UTD) vaccination coverage (four or more doses of diphtheria and tetanus toxoids and pertussis vaccine, three or more doses of poliovirus vaccine, one or more doses of any measles-containing vaccine, three or more doses of Haemophilus influenzae type b vaccine, and three or more doses of hepatitis B vaccine), while controlling for demographics. RESULTS: Ninety-three percent of parents rated vaccines as safe, 6% as neither safe nor unsafe, and 1% as unsafe. After adjusting for demographics, parental safety belief was significantly associated with the child's vaccination status. For children whose parents believed vaccines are safe, the odds of being UTD were 2.9 times the odds of being UTD for children of parents who believed vaccines are unsafe (75% vs 53%, respectively). Children whose parents were neutral about the safety of vaccines had vaccination coverage similar to children whose parents believed vaccines are unsafe. CONCLUSIONS: A significant association with vaccine coverage was found for a small group of parents with high vaccine safety concerns. Strategies focused on safety concerns may yield better protection for these children.

Factors associated with underimmunization at 3 months of age in four medically underserved areas.

OBJECTIVE: Risk factors for underimmunization at 3 months of age are not well described. This study examines coverage rates and factors associated with under-immunization at 3 months of age in four medically underserved areas. METHODS: During 1997-1998, cross-sectional household surveys using a two-stage cluster sample design were conducted in four federally designated Health Professional Shortage Areas. Respondents were parents or caregivers of children ages 12-35 months: 847 from northern Manhattan, 843 from Detroit, 771 from San Diego, and 1,091 from rural Colorado. A child was considered up-to-date (UTD) with vaccinations at 3 months of age if documentation of receipt of diphtheria-tetanus-pertussis, polio, haemophilus influenzae type B, and hepatitis B vaccines was obtained from a provider or a hand-held vaccination card, or both. RESULTS: Household response rates ranged from 79% to 88% across sites. Vaccination coverage levels at 3 months of age varied across sites: 82.4% in northern Manhattan, 70.5% in Detroit, 82.3% in San Diego, and 75.8% in rural Colorado. Among children who were not UTD, the majority (65.7% to 71.5% per site) had missed vaccines due to missed opportunities. Factors associated with not being UTD varied by site and included having public or no insurance, >/=2 children living in the household, and the adult respondent being unmarried. At all sites, vaccination coverage among WIC enrollees was higher than coverage among children eligible for but not enrolled in WIC, but the association between UTD status and WIC enrollment was statistically significant for only one site and marginally significant for two other sites. CONCLUSIONS: Missed opportunities were a significant barrier to vaccinations, even at this early age. Practice-based strategies to reduce missed opportunities and prenatal WIC enrollment should be focused especially toward those at highest risk of underimmunization.

Pediatricians' self-reported clinical practices and adherence to national immunization guidelines after the introduction of pneumococcal conjugate vaccine.

BACKGROUND: Little is known about whether pneumococcal conjugate vaccine (PCV) has altered pediatricians' practices regarding well-child and acute care. OBJECTIVES: To (1) describe whether PCV caused pediatricians to move other routine infant vaccines and/or add routine visits; (2) characterize adherence to national immunization recommendations; and (3) determine whether PCV altered pediatricians' planned clinical approach to well-appearing febrile infants. DESIGN AND METHODS: One year after PCV was added to the pediatric immunization schedule, we mailed a 23-item survey to 691 randomly selected pediatricians in Massachusetts. The adjusted response rate was 77%. RESULTS: After PCV introduction, 39% of pediatricians moved other routine infant vaccines to different visits and 15% added routine visits to the infant schedule. The self-reported immunization schedules of 36% were nonadherent to national immunization guidelines for at least 1 vaccine. Nonadherence rates were significantly higher among pediatricians who had been in practice longer, moved another vaccine because of PCV introduction, and/or offered to give shots later when multiple injections were due. For a hypothetical febrile 8-month-old girl who had received 3 doses of PCV, pediatricians reported they were significantly less likely to (1) perform both blood and urine testing and (2) prescribe antibiotics than in the pre-PCV era. CONCLUSIONS: The introduction of PCV may have had unintended effects on pediatric primary care, including decreased adherence to national recommendations for the timing of immunizations and decreased urine testing for well-appearing febrile infants. Special efforts may be warranted to ensure that pediatricians remain current with changing recommendations.

Insurance status and vaccination coverage among US preschool children.

BACKGROUND: Insurance status has been shown to have an impact on children's use of preventive and acute health services. The objective of this study was to determine the relationship between insurance status and vaccination coverage among US preschool children aged 19 to 35 months. METHODS: We linked data from 2 national telephone surveys, the National Immunization Survey and the National Survey of Early Childhood Health, conducted during the first half of 2000. Children were considered up to date (UTD) when they had received at least 4 diphtheria-tetanus-acellular pertussis/diphtheria-tetanus-pertussis vaccines, 3 poliovirus vaccines, 1 MMR vaccine, 3 Haemophilus influenza vaccines, and 3 hepatitis B vaccines at the time the interview was conducted. RESULTS: Among the 735 children in our study sample, 72% were UTD. The vast majority (94%) reported some type of health insurance at the time of the survey. Children with private insurance were more likely to be UTD (80%) than those with public insurance (56%) or no insurance (64%). In a multivariate analysis that controlled for child's race/ethnicity; household income; maternal age/marital status/educational level; location of usual care; and Special Supplemental Nutrition Program for Women, Infants, and Children participation, insurance was no longer an independent predictor of vaccination. CONCLUSIONS: The disparity in vaccination coverage among publicly, privately, and uninsured children is dramatic, underscoring its importance as a marker for underimmunization, despite the multivariate findings. The Vaccines for Children Program, a partnership between public health and vaccination providers who serve uninsured children and those enrolled in Medicaid, is well suited to target and improve vaccination coverage among these vulnerable children.

Impact of vaccine shortages on immunization programs and providers.

BACKGROUND: During 2001 and the first half of 2002, the United States experienced severe shortages of five of the eight universally recommended vaccines for children. OBJECTIVES: To evaluate the impact of shortages of diphtheria-tetanus-acellular pertussis vaccine (DTaP), pneumococcal conjugate vaccine (PCV7), and tetanus and diphtheria vaccine (Td) shortages on state and urban area immunization programs and immunization providers between September 2001 and January 2002. METHODS: (1) Survey of state and urban area immunization program managers. Outcome measures included changes in vaccine distribution and suspension of daycare/Head Start and school entry immunization requirements for Td, DTaP, and PCV7. (2) Interviews with Vaccines for Children Program immunization providers scheduled to receive a routine site visit between January 21 and February 1, 2002. Outcome measures included problems experienced with vaccine orders, implementation of Advisory Committee on Immunization Practices (ACIP) interim recommendations for DTaP and PCV7, and length of time with no DTaP or PCV7 vaccines in stock. RESULTS: Over 85% of immunization programs changed the way they distributed PCV7, DTaP, and Td vaccines to providers, including limiting the amount of vaccine ordered or distributing partial orders. Additionally, 76% of programs experienced problems purchasing or receiving varicella vaccine. Sixty-eight percent of programs suspended school entry requirements for Td. Immunization providers reported problems with orders of Td (56%), PCV7 (45%), DTaP (30%), and varicella (29%). Approximately 16% and 29% of providers implemented the interim ACIP recommendations for DTaP and PCV7, respectively. However, 21% of providers suspended administration of all doses of PCV7 because they ran out of vaccine before learning of the shortage. CONCLUSIONS: From suspension of school entry requirements to delaying administration of vaccine, the recent vaccine shortages affected immunization programs' and providers' ability to administer vaccines in a timely manner.

Parental vaccine safety concerns. The experiences of pediatricians and family physicians.

OBJECTIVES: Recently several concerns regarding vaccine safety have received significant media attention. Primary care physicians are the most common interface for parents with the immunization delivery system and are likely to have the greatest opportunity for exposure and experience with parental vaccine safety concerns. METHODS: Mail survey study of a national random sample of 750 pediatricians (PDs) and 750 family physicians (FPs) was conducted in 2000. Outcome variables of primary interest included the number of parental vaccine refusals in the past year, frequency of specific parent vaccine safety concerns, and actions taken by physicians when parents refused a vaccine. Chi-square analysis was used to determine the significance of the association of each outcome variable of interest with physician specialty, frequency of vaccine refusal, and the demographic variables. Multivariate analysis explored the potential for independent predictors of physicians who experienced increases in vaccine refusal. RESULTS: The response rate was 70%. Overall, 93% of PDs and 60% of FPs reported at least one parental vaccine refusal in their practice in the past year. PDs also were more likely than FPs to report an increase in the number of vaccine refusals over the past year (18% v 8%, p =0.01), while FPs were more likely to report a decrease in vaccine refusals over the same time period (18% v 11%; p <0.5). PDs were more likely than FPs to provide additional information regarding vaccines to parents who refused vaccines and/or to discuss the issue at later visits. The most common concerns of parents were related to short-term reactions and pain from multiple injections. CONCLUSIONS: While almost all PDs and most FPs experienced at least one vaccine refusal from parents in the past year, far fewer physicians of both specialties observed an increase in their occurrence. Physicians must work to be consistently well informed of both the benefits of immunization as well as the issues of parental concern regarding vaccine safety.

Strengthening the supply of routinely recommended vaccines in the United States: recommendations from the National Vaccine Advisory Committee.

Between late 2000 and the spring of 2003, the United States experienced shortages of vaccines against 8 of 11 preventable diseases in children. In response, the Department of Health and Human Services requested that the National Vaccine Advisory Committee (NVAC) make recommendations on strengthening the supply of routinely recommended vaccines. The NVAC appointed a Working Group to identify potential causes of vaccine supply shortages, develop strategies to alleviate or prevent shortages, and enlist stakeholders to consider the applicability and feasibility of these strategies. The NVAC concluded that supply disruptions are likely to continue to occur. Strategies to be implemented in the immediate future include expansion of vaccine stockpiles, increased support for regulatory agencies, maintenance and strengthening of liability protections, improved communication among stakeholders, increased availability of public information, and a campaign to emphasize the benefits of vaccination. Strategies requiring further study include evaluation of appropriate financial incentives to manufacturers and streamlining the regulatory process without compromising safety or efficacy.