PHWR Public Health Weekly Report

Vaccination is the most effective and vital means of preventing infectious diseases, as evidenced by our response to coronavirus disease 2019 (COVID-19) over the past 3 years. Through vaccination, several diseases have been managed, and timely vaccination has prevented severe illness, long-term aftereffects, and death. Therefore, it is crucial to consider the life cycle when planning vaccination schedules.

As vaccine development technology has advanced, the range of vaccine-preventable diseases (VPD) has expanded, and improved vaccines have been created for more effective disease prevention. In November 2023, the world’s first Chikungunya vaccine was approved by the U.S. Food and Drug Administration. In addition, vaccines that address the ongoing mutations of the coronavirus (SARS-CoV-2) have been developed annually for COVID-19.

In response to social demands, such as the development of effective and safe new vaccines and the expansion of mandatory vaccinations for high-risk groups, the Korea Disease Control and Prevention Agency (KDCA) has continuously broadened the scope of support for mandatory vaccinations through careful review.

In the Republic of Korea (ROK), state-led vaccination began with the smallpox vaccination in 1882. The foundation for the current vaccination program was laid with the enactment of the Infectious Disease Prevention Act in 1954, originally known as the Infectious Disease Control and Prevention Act. This established the legal framework for vaccination in the ROK. Since the designation of seven infectious diseases, including smallpox and diphtheria, as mandatory vaccinations in 1954, the scope of mandatory vaccinations has expanded over the past 70 years to include diseases with a high and urgent need for immunization. As of 2023, with the introduction of mandatory vaccination against rotavirus, a total of 19 types of vaccines are supported (Table 1).

Table 1 Mandatory vaccination

Target	Vaccine type
Children	Tuberculosis (BCG, intradermal use), Hepatitis B (HepB), Diphtheria/Tetanus/Pertussis (DTaP), Tetanus/Diphteria (Td), Tetanus/Diphtheria/Pertussis (Tdap), Polio (IPV), Diphteria/Tetanus/Pertussis/Polio (DTaP-IPV), Diphtheria/Tetanus/Pertussis/Polio/Type B haemophilus influenza (DTaP-IPV/Hib), Type B haemophilus influenza (Hib), Pneumococcal infection (Pneumococcal Conjugate Vaccine, PCV), Measles/Mumps/Rubella (MMR), Varicella (VAR), Japanese encephalitis inactivated vaccine (IJEV), Japanese encephalitis live attenuated vaccine (LJEV), Hepatitis A (HepA), Human papillomavirus infection (HPV), Influenza (IIV), Rotavirus infection (RV)
Teenager	Influenza (IIV), Human papillomavirus infection (HPV)
Pregnant women	Influenza (IIV)
The eldery	Influenza (IIV), Pneumococcal infection (pneuococcal polysaccharides vaccine, PPSV23)

With the support of mandatory vaccinations, infectious diseases such as smallpox, polio, and diphtheria have been eradicated, and the incidence of diseases such as Japanese encephalitis and whooping cough has decreased significantly compared to the past (Table 2) [1]. For instance, following the implementation of the National Measles Eradication 5-Year Project, which included a vaccination verification project for school-aged children, measles cases dropped from approximately 56,000 in 2000–2001, leading to the declaration of measles eradication in the ROK by 2006 [2]. Similarly, rubella incidence has steadily decreased since mandatory vaccination began in 1979, and ROK received eradication certification from the World Health Organization (WHO) in 2017. The hepatitis B perinatal prevention project, initiated in 2002, achieved WHO certification within 6 years. In 2023 alone, the introduction of mandatory vaccination against rotavirus infection reduced household costs by approximately KRW 48.8 billions, protecting the health of infants and young children and alleviating household financial burdens.

Table 2 Rate of decrease since the most outbreak by infectious disease

Infectious disease	Highest number of occurrences (year of occurrence)	No. of patients in 2023	Reduction rate (%)
Diphtheria	1,281 (1966)	0	100.0
Pertussis	16,887 (1961)	293	98.2
Polio	2,003 (1961)	0	100.0
Measles	32,647 (2000)	8	99.9
Rubella	128 (2001)	0	100.0
Japanese encephalitis	3,563 (1966)	17	99.5

Reused from https://dportal.kdca.go.kr/pot/is/summary.do [1]..

The high vaccination rate in the ROK has been crucial in the prevention and eradication of infectious diseases. According to the results of comparing the vaccination rate of children vaccinated in the same age group (36 months old) by country as of 2022, the vaccination rate of children in the ROK is 97.0%, which is about 2 to 10 percentage points higher on average than other countries (Figure 1) [3,,-6].

Figure 1. Vaccination rates by country and vaccine (based on children aged 2 years)

In the ROK, the special self-governing city mayor, special self-governing province governor, or head of Si, Gun, or Gu has provided vaccinations for diseases subject to vaccination to the public by dividing them into mandatory vaccination and temporary vaccination based on Articles 24 and 25 of the Infectious Disease Prevention Act (Table 3).

Table 3 Infectious diseases subject to vaccination under the Korean Infectious Disease Prevention Act

Vaccination	Infectious disease
Mandatory vaccination (Article 24)	Diphtheria, Polio, Pertussis, Measles, Tetanus, Tuberculosis, hepatitis B, Mumps, Rubella, Varicella, Japanese encephalitis, Type B haemophilus influenza, Pneumococcal infection, Influenza, Hepatitis A, Human papillomavirus infection, Rotavirus infection, Typhoid, Hemorrhagic fever with renal syndrome
Temporary vaccination (Article 25)	In addition to coronavirus disease 2019 and MPOX, infectious diseases, etc. deemed necessary for vaccination by the mayor, the governor of a special self-governing province, or the head of a Si/Gun/Gu

To ensure the safe and effective use of vaccines, vaccination guidelines must be established based on the characteristics of infectious diseases in each country. After review by the Korea Expert Committee on Immunization Practices, the KDCA periodically revises and publishes standard vaccination guidelines on implementation standards and methods for infectious diseases (Supplementary Figure 1; available online).

The government determines the scope of infectious diseases subject to mandatory vaccination by considering the characteristics of the diseases, the scale of the disease burden, vaccine effectiveness and safety, cost-effectiveness analysis, vaccine introduction priorities, and vaccination demand.

Among the 20 infectious diseases for which the WHO counts and publishes the inclusion of mandatory vaccinations, ROK has introduced mandatory vaccination for all except malaria, meningococci, and yellow fever, due to the low incidence or rarity of these diseases in the ROK.

Even after the introduction of mandatory vaccinations, it is crucial to continuously monitor the incidence of infectious diseases and the reduction in severity and mortality rates to evaluate the performance of vaccination programs and guide future projects.

An effectiveness evaluation system appropriate for the target disease and vaccine characteristics should be regularly implemented. The KDCA aims to establish evaluation methods for each disease and vaccine, set standards and procedures for feedback and policy reflection, and prepare an evaluation manual for effectiveness. Using evaluation results, vaccination policies can be adjusted to improve safety and effectiveness, including changes in the number of vaccinations, recipients, and types of vaccines used.

The rotavirus vaccine, recently introduced as a mandatory vaccination, aims to prevent rotavirus infection, which causes severe diarrhea, dehydration, and electrolyte imbalance in infants and young children. Vaccines selected as mandatory vaccinations have significant health and financial impacts, as many people are vaccinated annually and large budgets are continuously invested. Therefore, careful review is required before and after expanding support. Accordingly, the KDCA regularly evaluates the priorities and effectiveness of vaccines requiring support, establishes an evidence-based national vaccination policy, and expands the number of vaccines eligible for support.

Ethics Statement: Not applicable.

Funding Source: None.

Acknowledgments: None.

Conflict of Interest: The authors have no conflicts of interest to declare.

Author Contributions: Conceptualization: HML, YRK. Data curation: YRK, MJK. Investigation: YRK, MJK. Resources: YRK, MJK. Supervision: HML. Writing – original draft: YRK. Writing – review & editing: YRK, MJK.

Supplementary data are available online.