1 Introduction

Human papillomavirus (HPV) vaccine provides protection against more than 90% of HPV-attributable cancers [1, 2]. HPV vaccine is recommended for routine vaccination at age 11 or 12 years, with a second dose given 6–12 months after the first dose [3]. It can be given to children as young as 9 years [3]. Despite its benefits, HPV vaccination coverage in the United States lags behind that of other recommended adolescent vaccines and is below the Healthy People 2030 target of 80% [4].

Following the declaration of the COVID-19 public health emergency (PHE), model-based analyses predicted that the pandemic would lead to significant declines in HPV vaccine administration in the United States [5, 6] and that substantial catch-up efforts in the next 2 to 10 years would be required [6]. A study using state immunization data from 10 jurisdictions found a decrease in HPV vaccination for children and adolescents from March to September 2020 compared to the same time periods in 2018 and 2019 [7]. Data from the National Immunization Survey-Teen show that overall HPV vaccination rates for adolescents aged 13 to 17 in 2022 and 2023 were similar to pre-pandemic periods, with the exception of certain groups (e.g., those insured by Medicaid or Vaccines for Children-eligible children) [8, 9]. A study of a predominantly Hispanic community in the border region of Texas observed a decrease in HPV vaccine initiation rates among children and adults during the pandemic (2020–2021), which improved slightly in the post-pandemic period (2022–2023), though they did not return to the pre-pandemic (2016–2019) levels [10]. Studies using electronic medical charts from health systems have shown mixed evidence regarding the impact of the pandemic. One study reports a decrease in adolescent HPV vaccination in the pandemic period compared to the pre-pandemic period [11]. Meanwhile, others found that administered HPV vaccine doses have returned to pre-pandemic levels [12] or that the percentage of patients receiving HPV vaccination was higher in 2021 compared to 2019 [13].

Different restrictions and non-pharmacological measures of pandemic control also likely impacted HPV vaccination. Structural changes in healthcare delivery, such as the shift to telehealth visits, as well as patient concerns about exposure to COVID-19, may have reduced the number of visits to healthcare facilities and limited opportunities for vaccination [14]. Many U.S. primary care clinics also operated at reduced capacity during the pandemic to accommodate social distancing measures and implement stricter cleaning protocols, which may have affected their ability to provide routine vaccination [15, 16]. Moreover, although no studies have directly examined how the introduction of COVID-19 vaccination influenced clinics' prioritization of HPV vaccination, research has documented an increase in HPV vaccine hesitancy during the COVID-19 pandemic [17].

Little is known on whether the effects of the pandemic on HPV vaccination differed by sociodemographic characteristic, particularly in privately insured populations. This focus is important, as more than half of children under the age of 18 in the United States are covered by private insurance [18] and some research has shown that adolescents with private insurance also have lower HPV vaccine uptake compared to those covered by Medicaid [19, 20]. A better understanding of how the COVID-19 pandemic affected HPV vaccination may inform targeted outreach and messaging efforts for this substantial population. In this study, we used nationwide medical claims data for privately insured populations to investigate HPV vaccine administration before and during the PHE. We examined whether these rates differed by age group, sex, and urbanicity.

2 Methods

3 Results

Our sample denominator varied over the years, consisting of n = 4,819,881 in 2019; n = 4,589,165 in 2020; n = 4,212,520 in 2021; and n = 3,987,173 in 2022 (Table 1), representing about 5.8% of the total U.S. population aged 9 to 26 per the 2020 U.S. Census data (5.7% for 9–12, 5.6 for 13–17, and 6.0% for 18–26) [25]. In 2019, the yearly HPV vaccine administration (proportion) was 24.0%, 12.8%, and 2.8% for children, adolescents, and young adults, respectively, with variations by sex and urbanicity (Table 1). Monthly HPV vaccine administration (proportion) dropped sharply during the months following March 2020 when the PHE was declared, across all age groups, compared with those in the corresponding months in 2019. Overall, we found that the HPV vaccine administration during the PHE in 2020, 2021, and 2022 was lower than prior to the PHE in 2019 and continued to decline (Figure 1). The relative percent change in the overall yearly rate in 2022 relative to 2019 was −6.0% (95% CI [−6.5, −5.4]) among children, −38.3% (95% CI [−38.9, −37.7]) among adolescents, and −42.5% (95% CI [−43.4, −41.5]) among young adults. Among the demographic subgroups defined by sex or urbanicity, the highest percent decreases in each age group were −13.5% (95% CI [−15.3, −11.6]) among children living in rural areas, −39.8% (95% CI [−40.6, −39.0]) among male adolescents, and −46.0% (95% CI [−49.3, −42.8]) among young adults living in rural areas.

The most prominent percent declines were in April 2020 when many healthcare practices suggested delaying non-urgent visits (such as for vaccination) to reduce COVID-19 transmission: −72.0% (95% CI [−73.7, −70.3]) among children (Appendix A), −76.8% (95% CI: [−78.8, −74.9]) among adolescents (Appendix B), and −71.8% (95% CI [−74.4, −69.2]) among young adults (Appendix C). Thereafter, monthly administration started to recover gradually among all age groups. In the summer of 2021, when the Delta variant of COVID-19 was dominant in the Unites States, the trend of recovery was disrupted for adolescents and young adults. In 2022, when the Omicron variant of COVID-19 was widespread, vaccination dropped again across all age groups compared to 2019, with 6.0% (95% CI [5.4, 6.5]) lower administration among children, 38.3% (95% CI: [37.7, 38.9]) lower for adolescents, and 42.5% (95% CI [41.5, 43.4]) lower for young adults (Figure 1).

Greater initial declines and slower recovery in HPV vaccine administration, relative to the baselines in 2019, were observed among male compared to female young adults (Figure 1). For example, HPV vaccine administration in 2021 and 2022 among female young adults was 30.7% (95% CI [29.5, 31.9]) and 40.8% (95% CI [39.6, 42.1]) lower than administration in 2019, while the administration among male young adults in 2021 and 2022 was 32.3% (95% CI [30.7, 33.8]) and 44.8% (95% CI [43.4, 46.3]) lower, respectively (Figure 1). A different pattern was observed for children: compared to 2019, administration among female and male children was 2.2% (95% CI [1.4, 2.9]) and 2.2% (95% CI [1.5, 3.0]) lower in 2021, respectively, and 5.5% (95% CI [4.8, 6.2]) and 6.4% (95% CI [5.7, 7.1]) lower in 2022, respectively (Figure 1).

The impact of urbanicity varied by age group. In April 2020, HPV vaccine administration between rural and non-rural residents decreased with a modest gap among children (69.0% [95% CI [62.8, 75.1]] vs. 72.2% [95% CI [70.5, 73.9]]), with larger gaps between rural and non-rural residents among adolescents (71.1% [63.9, 78.3] vs. 77.3% [75.3, 79.3]) and young adults (67.4% [58.3, 76.5] vs. 72.2% [69.4, 74.9]) compared to April 2019 (Appendix D). For children and young adults, those in rural areas experienced slower recovery thereafter compared to non-rural residents. 2022 administration was 13.5% (95% CI [11.6, 15.3]) and 5.4% (95% CI [4.9, 5.9]) lower among rural and non-rural children compared to 2019, and 46.0% (95% CI [42.8, 49.3]) and 42.2% (95% CI [41.2, 43.2]) lower among rural and non-rural young adults. The trend is different among adolescents, with 37.3% (95% CI [35.1, 39.5]) lower administration in 2022 compared to 2019 among those in rural areas and 38.4% (95% CI [37.8, 39.1]) lower among those in non-rural areas (Figure 1).

4 Discussion

Our findings add important insights to the limited literature on HPV vaccine administration trends during the pandemic. To our knowledge, this study was the first to analyze data from a nationwide sample of privately insured populations and provide estimates by sex, age groups, and urbanicity. The monthly administration of HPV vaccine doses dropped after the declaration of the PHE across all age groups. While administration was comparable to or even higher during some months of the PHE among children following an initial decline, these trends were not observed among adolescents and young adults. In 2022, HPV vaccine administration did not exceed the 2019 level for any age group. In addition, older males, rural children, and rural young adults, despite small samples from rural areas, consistently experienced large declines (or slow recoveries) in administration from 2021 to 2022 compared to their counterparts in the same age group.

Our findings align with studies documenting the declines in HPV vaccination following the PHE declaration. For example, one found a decrease in HPV vaccination for children and adolescents from March to September 2020 compared to the same time periods in 2018 and 2019 [7]. Meanwhile, another study using data from children aged 9 to 14 at pediatric practices found that a smaller percentage of children were vaccinated during the pandemic (March 2020 to April 2022) compared to the pre-pandemic period (March 2018 to February 2020) and that when COVID-19 positivity rates peaked, HPV vaccination also declined [11]. However, it should also be noted that these studies did not include young adults. They also provided neither estimates by age group, sex, or urbanicity nor focused exclusively on privately insured populations. Differences in the timeframes used to define pandemic or post-pandemic periods also complicate comparisons across studies.

Data from the National Immunization Survey–Teen highlight additional trends among adolescents aged 13 to 17 [8]. Between 2015 and 2021, coverage with ≥ 1 HPV vaccine dose was lower among those with private insurance compared to those covered by Medicaid [8]. However, in 2022, because coverage declined among Medicaid beneficiaries while remaining stable among those with private insurance, this change resulted in similar coverage between the two groups during this year [8]. In addition, in contrast to our findings, a study of children aged 9 to 12.9 years in California found that, following an initial decrease in March to April 2020, the number of HPV vaccine doses administered in 2020 and 2021 has returned to levels seen in 2019 [12]. However, these studies relied on either nationally representative survey data or electronic medical records from a single health system and focused on narrower age ranges compared to our study, which used medical claims data and included individuals aged 9 to 26. These methodological and population differences provide important context for understanding the variation in findings across studies.

Declines in HPV vaccine administration, as documented in our study, could hamper long-term efforts that have been made toward improving HPV vaccination coverage and pose critical challenges to population-level reductions of HPV-related cancers [15]. Communication efforts and other evidence-based strategies that focus on adolescents/parents of adolescents and young adults (particularly males for both groups), including standing orders and reminders/recalls, may help reverse the observed decline in HPV vaccination [26, 27]. Moreover, rural areas have historically experienced lower HPV vaccination coverage [8, 28]. The pandemic has compounded challenges for rural clinics in implementing interventions to increase HPV vaccination [14]. HPV vaccine ordering has recovered post-pandemic but still showed cumulative deficits, with rural counties experiencing greater shortfalls compared to urban areas [29]. Continued monitoring of uptake based on geographic residence could inform policies or interventions to promote HPV vaccination.

5 Conclusion

Using nationwide medical claims data for privately insured populations, we provide critical insights into HPV vaccination before and during the COVID-19 pandemic by age, sex, and urbanicity. As of the end of 2022, the yearly vaccine administration did not exceed pre-pandemic levels, with larger declines seen among adolescents and young adults. Findings underscore the need for targeted communication and intervention strategies, especially in rural areas and among older males, to counteract the declines and ultimately improve HPV vaccination coverage and reduce HPV-related cancers.

Author Contributions

M.V. as the corresponding and submitting author, contributed to the writing of the original draft, funding acquisition, project administration, visualization, and reviewing and editing of the manuscript. J.L. contributed to validation and writing review and editing. K.H. contributed to the methodology, visualization, validation, writing review and editing, software development, formal analysis, and data curation. J.W.K. contributed to writing review and editing. B.-H.C. contributed to writing review and editing. Y.K. contributed to project administration, writing review and editing.

Conflicts of Interest

The authors declare no conflicts of interest.