Declines in Routine Adult and Teen Vaccinations Continued in 2021

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Updated Avalere analysis shows that routine immunization continued to lag in 2021 below pre-pandemic levels, highlighting the continuing effect of COVID-19 on routine vaccination.

The COVID-19 pandemic continues to impact healthcare delivery, including the utilization of routine preventive services like vaccines. In February and June 2021, Avalere released a series of analyses that found persistent and sometimes steep declines in vaccination claims for Advisory Committee on Immunization Practices (ACIP)-recommended adolescent and adult vaccines since the start of the pandemic.

The previously reported analyses compared claims submissions for ACIP-recommended vaccines from January–November 2020 to the same months in 2019 across commercial, Managed Medicaid, Medicare Advantage, and Medicare Fee-for-Service (FFS) Part B markets. The analyses found that declines in ACIP-recommended adolescent and adult vaccine claims across this timeframe translated into an estimated 26 million missed doses of recommended vaccines.

To assess the pandemic’s continued impact on routine immunizations, Avalere conducted a follow-up analysis comparing vaccine claims from December 2020–July 2021 to claims from the same months in 2019 (e.g., comparing May 2019 to May 2020 and comparing June 2019 to June 2021). In this analysis, 2019 vaccine claims continue to represent baseline pre-pandemic vaccination levels.

Key Findings

  • Building on the previous analyses, from January 2020–July 2021, monthly vaccine claims decreased on average 32% for adults and 36% for adolescents when compared to the same months in 2019.
  • Declines in ACIP-recommended adolescent and adult vaccinations persisted across all markets from December 2020–July 2021; across markets, total vaccine claims in this timeframe were between 7%–64% lower than 2019 claims in adolescents and 15%–62% lower than 2019 claims in adults.
  • From December 2020–July 2021, adolescents and adults in the studied markets potentially missed approximately 11.1 million doses of recommended vaccines compared to 2019.
  • Cumulatively, from January 2020–July 2021, adolescents and adults across the studied markets may have missed an estimated 37.1 million doses of recommended vaccines compared to 2019.

Adolescent and Adult Vaccine Claims Continue to Lag Behind Pre-Pandemic Levels

Across both adolescent and adult populations, total routine vaccine administration and product claims from January 2020–July 2021 were below 2019 levels. At the end of 2020, a surge in early flu vaccinations drove claims above 2019 levels during the same timeframe. This most recent analysis, however, found that routine vaccination levels for adults experienced a notable drop in January 2021, ranging 28%–55% lower than January 2019 levels depending on the source of insurance coverage, with the steepest declines occurring among commercially insured adults. Adult vaccination levels remained lower than 2019 levels throughout the first half of 2021 but stayed relatively steady. Adolescent routine vaccinations similarly remained below 2019 levels from December 2020–July 2021 but experienced a brief increase across both commercial and Managed Medicaid markets around March 2021, with claims in Managed Medicaid rising to 5% below March 2019 levels. This coincided with phased school reopening and the restart of activities, such as school sports, in some states. These improvements were temporary, however, as vaccination levels fell again in April and continued to decline through July.

Figure 1. Changes in Claims for All ACIP-Recommended Adolescent and Adult Vaccines Across Markets January 2020–July 2021 Compared to the Same Months in 2019
Figure 1. Changes in Claims for All ACIP-Recommended Adolescent and Adult Vaccines Across Markets January 2020–July 2021 Compared to the Same Months in 2019

Avalere used national enrollment data to extrapolate the difference between observed monthly vaccine claims from January 2020–July 2021 and monthly claims in 2019 to estimate the potential number of “missed doses” on a national level. The methody employed is consistent with the previously reported analysis.

The analysis found that from January 2020–July 2021, adolescents and adults across the included insurance markets missed a potential 37.1 million doses of recommended vaccines, with an additional 11.1 million missed doses since November 2020. As with the previous analysis, “missed doses” refers to the decrease in doses of recommended adolescent and adult vaccines from 2019 to 2020 and 2019 to 2021. Adults enrolled in commercial plans continue to experience the largest volume of missed doses, followed by adolescents in commercial plans and adults in Medicare FFS. Notably, missed doses in both Medicare FFS and Medicare Advantage markets more than doubled since November 2020.

Figure 2. Estimated Missed Doses for All Vaccine Claims Across Markets, January 2020–July 2021
Figure 2. Estimated Missed Doses for All Vaccine Claims Across Markets, January 2020–July 2021


As noted in the previously published analysis, adolescent and adult vaccination levels increased moderately in the second half of 2020, particularly as COVID-19 cases temporarily declined, flu vaccinations became available, and some schools made plans to reopen. These gains leveled off or steadily declined through the end of 2020 and into 2021 as new cases of COVID-19 surged. During this time, COVID-19 vaccines became available, initially for older adolescents and adults and then for younger adolescents. In May 2021, the Center for Disease Control updated guidance to allow coadministration of COVID-19 vaccines with other routine vaccines, in part to encourage uptake of other ACIP-recommended vaccines, though the impact of those recommendations is unclear.

The COVID-19 landscape continues to evolve and impact routine preventive care in the US, particularly regarding uptake of routine vaccinations, which was sub-optimal prior to the start of the pandemic for adult and some adolescent vaccines. When considered in the context of broader cultural shifts like heightened vaccine hesitancy in some communities, the ongoing pandemic may continue to challenge efforts to both recover from and exceed pre-pandemic routine vaccine coverage levels to meet national vaccination goals.

Funding for this research was provided by GlaxoSmithKline. Avalere Health retains full editorial control.

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Updated Analysis

Avalere analyzed changes in administration of ACIP-recommended adult (≥19 years of age) and adolescent (7–18 years of age) vaccines using pre-adjudicated medical benefit Medicare FFS claims from a provider clearinghouse dataset maintained by Inovalon, Avalere’s parent company, as well as from the Inovalon MORE2 Registry®, a large scale, real-world multi-payer dataset consisting of medical, pharmacy, and lab claims and clinical data on more than 338 million de-identified patients. The provider clearinghouse dataset contains Medicare FFS Parts A and B data. The MORE2 Registry® contains medical and pharmaceutical claims across commercial markets (group, individual, and exchanges), Medicaid managed care, and Medicare Advantage.

Specifically, vaccines were identified using Current Procedural Terminology (CPT) and Healthcare Common Procedure Coding System (HCPCS) codes for vaccine products, National Drug Codes (NDCs) when product codes were not available,1 and general vaccine administration HCPCS codes when neither product nor administrative codes were included on a claim. Avalere compared vaccine claims in 2020 and 2021 to vaccine claims in 2019. The claims comparison was calculated as the percentage change between the months of 2019 and the corresponding months of subsequent years (e.g., between May 2019 and May 2020 and between June 2019 and June 2021). Avalere adjusted the analysis to account for any changes in claim sources within the data by employing a “same store” analysis that requires the same providers and health plans to have submitted claims in 2019 and 2020, and then 2019 and 2021, to ensure that reported vaccine utilization changes are not driven by the addition or subtraction of claim sources over time.

Missed Doses

Avalere used a market-specific, rate-based method to extrapolate the number of vaccine claims to a national population. As specified above, vaccines were identified using product specific CPT and HCPCS codes, general vaccine administration HCPCS codes, and NDCs (when available), and a “same store” method was used across years. In addition to vaccine claims, the vaccination rate was based on the number of unique enrollees in each dataset, by market and age group, for each month in 2019 and 2020, and for January–July 2021.

A market-specific, claims-based vaccination rate was calculated as the sum of all the vaccine claims for each month of the year divided by the number of unique enrollees in the MORERegistry® and provider clearinghouse data sets by market. The annual vaccination rate was then applied to 2019 national population estimates in each insurance market as reported in the American Community Survey from the US Census Bureau. The 2019 claims-based vaccination rate applied to the national sample was considered the baseline for vaccination volumes, and missed doses were estimated as a difference between the baseline and the 2020 and 2021 claims-based rate applied to the 2020 and 2021 national population estimates.


The vaccine utilization analysis used 2 different data sources, reflecting different claim types and different sample sizes across payer markets. For Medicare FFS, Avalere leveraged a provider clearinghouse dataset that captures pre-adjudicated claims submitted by institutional and noninstitutional providers for payment and represents 5%–7% of Medicare FFS claims volume nationally. Not all the submitted claims volume result in full adjudication and reimbursement from Medicare FFS. The provider clearinghouse is limited to claims submitted through Medicare Part A (inpatient and hospital coverage) and Part B (outpatient/medical coverage) and does not include Part D (drug coverage). Claims for nearly all vaccines covered in this analysis are observed in the Medicare Part B data. While Part D claims were not included in the analysis of FFS Medicare claims, some claims for Part D vaccines that were administered in the provider setting may have been captured.

For all other markets, Avalere used the Inovalon MORE2 Registry®, which includes roughly a 42% sample of the national commercially insured population, a 69% sample of the national Medicaid managed care population, and a 25% sample of the national Medicare Advantage population. Due to variability across states in billing requirements for vaccines provided through the Vaccines for Children program, this analysis may not fully capture adolescent vaccine utilization in the Managed Medicaid market.

While both data sources are nationally representative, different geographies are likely reflected in the analysis of each market. Further, Avalere did not control for the cross-payer population shifts between 2019 and 2021 due to the insurance coverage changes. While payers captured in the analysis were the same in all 3 years, changes in the vaccine utilization may be driven by underlying volume of patients enrolled in a given plan or program, in addition to access and clinical practice patterns.

Definitive vaccine administration cannot be observed within claims data because it would require long-term longitudinal data over the full range of years for which the vaccine is recommended. However, this analysis uses year-over-year comparisons to estimate the impact of COVID-19 based on the volume of claims submitted by payers over 3 years.

Vaccines Included in the Analysis

  • Influenza
  • Haemophilus influenzae (Hib)
  • Hepatitis A
  • Hepatitis B
  • Human Papillomavirus (HPV)
  • Meningococcal ACWY
  • Meningococcal B
  • Measles, Mumps, and Rubella (MMR)
  • Pneumococcal
  • Tetanus, Diphtheria, and Pertussis (Tdap)
  • Varicella Zoster (Chickenpox)
  • Herpes Zoster (Shingles)


  1. Pharmaceutical claims were not available for in the provider clearinghouse data, so NDC codes were not used in the FFS market.

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