The administration of the human papillomavirus (HPV) vaccination is becoming increasingly widespread, not only in South Korea but also abroad. [1] Particularly, the number of foreigners receiving this vaccine in Korea is growing. [2] This includes short-term residents who are here for study or business, tourists visiting the country, and those who incorporate vaccination into their travel itinerary. The COVID-19 pandemic is likely to have not only shrunk domestic vaccination activities, but also greatly reduced overseas travel for vaccination. [3,4] However, no research exists to confirm whether and to what extent this trend has recovered, or to explore the demographic changes among the vaccine recipients post-COVID-19.

The aim of this study is to compare the trends of the HPV vaccination among domestic and foreign populations in South Korea and to forecast trends following the impact of COVID-19. Especially, I aimed to understand how the balance point of cost-benefit for vaccine tourism has changed by comparing the age and sex characteristics of domestic and foreign vaccine recipients.

This study examined patients who received the HPV vaccine at Seoul National University Hospital. I analyzed data from a total of 30,216 individuals from January 2017 to June 2023. The variables included in the study were nationality (domestic or foreign), sex, age, and the date of vaccination. The domestic and foreign groups were compared, and the difference between the two groups was assessed using the chi-square test, with a significance level defined as a P-value <0.05. Statistical analysis was performed using STATA 18.0 (StataCorp.). This study was approved by the institutional review board (E-2308-082-1458).

Out of the study participants, 22,610 (74.8%) were domestic patients and 7,606 (25.2%) were foreign patients (Table 1). The average age of domestic patients was 27.2±12.3 years, while that of foreign patients was 25.6±4.5 years. Notably, the proportion of male participants was higher in the domestic group (13.7%) than in the foreign group (2.3%) (P-value <0.05). While the age distribution was relatively even among the domestic patients, a significant 77.9% of the foreign patients were in their 20s (Fig. 1).

The trend in HPV vaccination reveals an increase among both domestic and foreign patients. Notably, the number of foreign patients dramatically declined in 2020 due to COVID-19, but is gradually recovering (Fig. 2). The number of Korean recipients of the HPV vaccine experienced an upward trend from 2017, peaking in 2021, and subsequently exhibiting a gradual decline. On the other hand, foreign recipients showed a steady increase up until 2019, followed by a sharp decline in 2020, which we attribute to the impacts of COVID-19. Since then, the trend has gradually been rebounding. The proportion of foreign patients reached its highest in 2019 at 41%, dropped to 9% in 2020 due to the pandemic, and is projected to gradually recover to 30% by 2023.

The trends in HPV vaccine recipients, segmented by sex, reveal distinctly different patterns. Particularly, from 2017 to 2020, the proportions of domestic male recipients were maintained at about 8% to 10%, after which it began to increase and reached 24% by 2023. In contrast, the foreign male recipients have remained under 5% (Fig. 3).

The age-related differences between domestic and foreign HPV vaccine recipients were also quite clear. Among domestic recipients, over 40% were 30 years of age or older, a proportion that has remained fairly constant. However, among foreign recipients, the upward trend in the proportion aged 30 or older significantly dipped after the outbreak of COVID-19, with the proportion remaining under 10% since then (Fig. 4).

It's worth noting that a considerable number of foreigners are visiting Seoul National University Hospital for HPV vaccination. The proportion of foreign patients receiving the vaccine had reached 41% by 2019, just before COVID-19, but this figure significantly decreased during the pandemic. From 2022, it began to recover, reaching 30%, and it is expected that this rate may further increase in the future.

Meanwhile, it’s important to highlight that the proportion of foreign males visiting medical institutions for HPV vaccination remains below 5%. There could be several reasons for this, including a lack of perceived necessity for the vaccine among foreign male patients, or perhaps the costs associated with visiting overseas medical institutions are seen as outweighing the benefits [5-7].

While domestic patients receiving the HPV vaccine ranged evenly from 0 to over 50 years old, only 0.6% of foreign vaccine recipients were over 40 years, and only 18% were in their 30s. The fact that foreign pediatric and adolescent patients aged 0 to 19 years find it difficult to visit overseas medical institutions is somewhat understandable. It's particularly noteworthy that most foreign HPV vaccine recipients are in their 20s. These individuals seem willing to seek medical services overseas for the sake of their health.

The impact of COVID-19 has affected foreigners more heavily than domestic individuals. The number of foreign patients visiting this institution for the HPV vaccine dropped to about one-fifth due to COVID-19, but after three years, it seems to be recovering almost to its previous level. Especially for foreigners over 30, there was a significant decrease due to the pandemic, and recovery has not been observed.

This study’s limitations include the fact that it's based on patients from a single institution, limiting its generalizability. Additionally, I classified foreigners only by nationality, not by their place of residence, meaning some foreign residents of Korea might have been included. Despite these limitations, this study holds great significance as it's the first to compare the status of domestic and foreign individuals visiting Korean medical institutions for HPV vaccination and analyze the impact of COVID-19 and subsequent trends.

The behavior and trends related to HPV vaccination differ significantly between domestic individuals and foreigners, likely influenced by various factors. The willingness to bear the cost of overseas travel for the benefits and necessity of vaccination seems to be a key consideration. Additional incentives or cost-saving measures may be necessary to encourage foreign males and individuals over 30 to visit overseas medical institutions for HPV prevention. Further ongoing research is needed, and multi-institutional studies are recommended.

No potential conflict of interest relevant to this article was reported. Juwon Lim has been the editor-in-chief since 2022 and had no role in the decision to publish this article.

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