Recent Trends in Cytomegalovirus IgG Seropositivity in the Adult Population of Korea: A Cross-Sectional Study and Literature Review

Abstract

Background

Cytomegalovirus (CMV) infection is prevalent worldwide. Although Korea has historically shown high CMV IgG seropositivity (>95%), declines have been reported recently. We assessed current CMV IgG seropositivity and analyzed prevailing trends in the Korean population.

Methods

Residual samples from individuals undergoing regular health checkups were analyzed. We assessed 1,978 samples (from 937 men and 1,041 women) where the age group distribution was relatively balanced. CMV IgG levels were measured at two institutions using a commercial immunoassay (Alinity i CMV IgG Reagent Kit, Abbott) following the manufacturer’s instructions. Results were interpreted as “reactive” when the CMV IgG concentration was ≥6.0 arbitrary units (AU)/mL or “nonreactive” when the CMV IgG concentration was <6.0 AU/mL. Seropositivity was compared by sex and across age groups (20–29, 30–39, 40–49, and 50–59 yrs).

Results

The overall CMV IgG seropositivity was 89.9% (1,778/1,978) and was significantly higher in men (91.7%, 859/937) than in women (88.3%, 919/1,041) (difference 3.4%; 95% confidence interval 0.8%–6.0%; P=0.012, chi-square test). No significant differences with regard to sex were found within each age group. Seropositivity increased with age, from 76.3% (347/455, 20–29 yrs) to 99.8% (448/449, 50–59 yrs) (P for trend <0.001), consistently in both sexes.

Conclusions

Our findings provide the most up-to-date estimate of CMV IgG seropositivity in the Korean adult population. Because of lower seropositivity in younger adults, continued monitoring and further education are essential for CMV control and prevention.

INTRODUCTION

Cytomegalovirus (CMV) belongs to a large family of herpesviruses that commonly infects humans of all ages [1, 2]. Although the primary infection is normally asymptomatic in healthy individuals, CMV establishes a lifelong latent infection [1, 2]. CMV poses critical clinical consequences in certain populations, particularly in newborns with congenital infections [1] and immunocompromised hosts following allogeneic hematopoietic cell or solid-organ transplantation [3, 4]. The CMV reactivation rate can approach up to 70% when recipients are CMV-seropositive [5], and previous studies suggest that CMV viremia is associated with higher all-cause mortality and transplant-related mortality in allogeneic hematopoietic stem cell transplantation recipients [6, 7].

Serological testing for CMV-specific IgG is a widely used method for screening and assessing evidence of prior CMV infection and identifying individuals at high risk for CMV infection or reactivation [8]. CMV-seropositivity data help estimate the disease burden in different populations and provide baseline information for developing management strategies for transplant recipients and guiding vaccine development, highlighting the importance of regularly updated seropositivity monitoring. Previous studies conducted in other countries revealed seroepidemiological CMV differences based on geographic, ethnic, cultural, and socioeconomic factors [9, 10].

A global meta-analysis revealed that the CMV IgG seropositivity was approximately 83% in the general population and 86% in women of childbearing age, with substantial regional variations: from 66% in the European region to over 90% in Southeast Asia and the Eastern Mediterranean regions [11]. Developed countries showed lower CMV seropositivity than did developing countries [11].

Despite being a developed country, Republic of Korea has a very high CMV IgG seropositivity of over 95% in women [12], over 98% in pregnant women [13], and over 94% in the general population during a 20-yr study [14]. Nevertheless, published data on this topic remain limited, and recent studies are especially scarce, making the current trends in CMV seropositivity in the Korean population unclear. Most previous studies were based on retrospectively collected data over extended periods and may not accurately reflect the current CMV IgG seropositivity in the general Korean population. Many of these studies focused on specific groups, such as transplant recipients or pregnant women [13, 15, 16], which limits their generalizability to the overall population.

To estimate the most recent CMV seropositivity in the general Korean adult population, we measured CMV IgG levels in individuals who underwent regular health checkups across various age groups in 2024. We also reviewed and compared previously published studies to assess recent CMV-seropositivity trends in the Korean population and contextualize our findings.

MATERIALS AND METHODS

Study design and population

This study was conducted at Konkuk University Medical Center (KUMC) in Seoul and Seoul Clinical Laboratories (SCL) in Yongin, Republic of Korea. KUMC is a tertiary referral academic medical center, whereas SCL is one of the largest referral clinical laboratories in Korea. Both institutions provide clinical specimen-analysis services for CMV IgG. Between April and June 2024, residual samples from individuals who visited healthcare centers for regular checkups were collected and analyzed CMV IgG measurements. All participants completed a self-reported health questionnaire as part of the screening process. At KUMC, samples were obtained and tested within the same institution, whereas SCL analyzed samples that were referred from various healthcare centers across the country. Because we investigated the current CMV IgG seropositivity in the general Korean adult population, the following exclusion criteria were applied: (1) conditions that could lead to immunosuppression; (2) suspected infectious disease at the time of sampling; (3) non-Korean nationality; (4) age below 20 yrs; and (5) age 60 yrs or above, given the potential of underlying medical conditions. Based on each individual’s age, participants were classified into one of the four age groups (20–29, 30–39, 40–49, and 50–59 yrs). After applying the exclusion criteria, 1,978 individuals (937 men and 1,041 women) with measured CMV IgG concentrations were included in this study.

Ethical considerations

No study-specific interventions or additional blood collections were conducted, and the study protocol was designed in accordance with the principles of the Declaration of Helsinki. This retrospective observational study was reviewed and approved by the Institutional Review Boards (IRBs) of KUMC (approval No: 2024-05-018) and SCL (approval No: IRB-24-022). Informed consent was waived by both IRBs because of the retrospective nature of this study and the analysis of anonymized clinical data.

Serum CMV IgG measurements

CMV IgG was measured using a commercial chemiluminescent microparticle immunoassay (CMIA) (Alinity i CMV IgG Reagent Kit; Abbott, Abbott Park, IL, USA) using an Alinity i system (Abbott). All procedures were performed according to the manufacturer’s instructions. Sample results were interpreted as “reactive” when the CMV IgG concentration was ≥6.0 arbitrary units (AU)/mL or as “nonreactive” when CMV IgG was <6.0 AU/mL. CMV IgG seropositivity was defined as the proportion of reactive results over the proportion of reactive plus nonreactive individuals.

Literature review

We conducted a systematic literature search for CMV IgG in the Korean population using PubMed, KoreaMed, and Google Scholar databases. Reports were filtered using search terms such as “CMV IgG,” “Korean,” “immunoassay,” “healthy population,” and “general population.” Duplicates were removed, and articles written in either English or Korean were initially selected. The inclusion criteria were: (1) a study population consisting of Koreans, (2) publication dates between 2005 and 2024, (3) use of an immunoassay method for CMV detection, and (4) clear reporting of the CMV IgG seropositivity (%). The exclusion criteria were: (1) studies not meeting the inclusion criteria, (2) studies focusing on elderly Koreans, (3) studies with fewer than 100 participants, and (4) review articles. Two reviewers independently screened the titles and abstracts, and discrepancies were resolved by consensus.

Statistical analysis

Data were expressed as medians and interquartile ranges for continuous variables and as frequencies and percentages for categorical variables. Normality of the distribution was tested using the Shapiro–Wilk test, and nonparametric analyses were used when normality was rejected. The chi-square test or Fisher’s exact test was used to compare proportions, and Yates’ correction for continuity was applied when appropriate. The Cochran–Armitage test was performed to evaluate trends in CMV IgG seropositivity across the four age groups. Among individuals with positive CMV IgG results, CMV IgG concentrations between age groups were compared using Mann–Whitney or Kruskal–Wallis tests. Post-hoc analyses were performed using Dunn’s test with Bonferroni correction. The threshold for statistical significance was set at P<0.05. Statistical analyses were performed using R software, version 4.5.0 (R Foundation for Statistical Computing, Vienna, Austria).

RESULTS

Patient characteristics

Among the 1,978 individuals enrolled in this study, a similar number of samples were collected from both institutions (KUMC, N=964; SCL, N=1,014). The age groups were relatively evenly distributed, with 23.0% (N=455), 29.6% (N=586), 24.7% (N=488), and 22.7% (N=449) of samples from individuals aged 20–29, 30–39, 40–49, and 50–59 yrs, respectively (Table 1).

Table 1. Baseline patient characteristics (total and by institution).

Variable	Total (N=1,978)*	KUMC (N=964)	SCL (N=1,014)	P †
Age group (yrs)				<0.001
20–29	455 (23.0%)	210 (21.8%)	245 (24.2%)
30–39	586 (29.6%)	330 (34.2%)	256 (25.2%)
40–49	488 (24.7%)	233 (24.2%)	255 (25.1%)
50–59	449 (22.7%)	191 (19.8%)	258 (25.4%)
Sex				0.480
Male	937 (47.4%)	465 (48.2%)	472 (46.5%)
Female	1,041 (52.6%)	499 (51.8%)	542 (53.5%)
CMV IgG seropositivity				0.997
Reactive	1,778 (89.9%)	866 (89.8%)	912 (89.9%)
Nonreactive	200 (10.1%)	98 (10.2%)	102 (10.1%)

*Data are presented as numbers (percentages).

^†P was derived via chi-squared testing, and P<0.05 was considered to reflect a statistically significant difference.

Abbreviations: KUMC, Konkuk University Medical Center; SCL, Seoul Clinical Laboratories; CMV, cytomegalovirus.

The baseline patient characteristics are summarized in Table 1. The sex distribution and CMV IgG seropositivity did not differ between the two institutions. However, the age group distributions differed significantly between the two institutions (chi-square test, P<0.001). Standardized residuals from the chi-square test showed that KUMC included a higher proportion of participants aged 30–39 yrs (P<0.001), whereas SCL included a higher proportion of participants aged 50–59 yrs (P=0.003). However, CMV IgG seropositivities did not differ significantly between the 30–39 yr and 50–59 yr age groups (P=0.287 by chi-square test and P=0.425 by Fisher’s exact test, respectively; data not shown).

Serum CMV IgG seropositivity analysis

Seropositivity results are shown in Table 2. The overall CMV IgG seropositivity across all age groups was 89.9% (1,778/1,978). The overall seropositivity was significantly higher in men (91.7%, 859/937) than in women (88.3%, 919/1,041) (difference: 3.4%; 95% confidence interval: 0.8%–6.0%; P=0.012, chi-square test). No significant differences were found in seropositivity between sexes within each age group. Seropositivity increased across age groups, from 76.3% (347/455) in the youngest age group (aged 20–29 yrs) to 99.8% (448/449) in the oldest age group (aged 50–59 yrs) (P for trend <0.001). A similar trend was observed in subgroup analysis stratified by sex (P for trend <0.001).

Table 2. Cytomegalovirus IgG seropositivity in each age group.

Group*	Total					Men					Women				P
	N (%)	Reactive	Nonreactive	Seropositivity (%)		N (%)	Reactive	Nonreactive	Seropositivity (%)		N (%)	Reactive	Nonreactive	Seropositivity (%)
20–29	455 (23.0)	347	108	76.3		147 (15.7)	113	34	76.9		308 (29.6)	234	74	76.0	0.833
30–39	586 (29.6)	510	76	87.0		256 (27.3)	220	36	85.9		330 (31.7)	290	40	87.9	0.488
40–49	488 (24.7)	473	15	96.9		266 (28.4)	259	7	97.4		222 (21.3)	214	8	96.4	0.536
50–59	449 (22.7)	448	1	99.8		268 (28.6)	267	1	99.6		181 (17.4)	181	0	100.0	0.411
Total	1,978 (100.0)	1,778	200	89.9		937 (100.0)	859	78	91.7		1,041 (100.0)	919	122	88.3	0.012
				P for trend <0.001					P for trend <0.001					P for trend <0.001

*The age groups represent the age in years.

CMV IgG concentration analysis

We analyzed serum CMV IgG concentrations in 1,778 seropositive samples. The distribution of CMV IgG concentrations differed between each age group (Fig. 1, Kruskal–Wallis test, P<0.001). Post-hoc analysis using Dunn’s test with Bonferroni correction (P<0.0083) showed that CMV IgG concentrations increased with age. Among the four age groups, relatively young adults aged 20–29 yrs showed the lowest CMV IgG concentrations (median: 133 AU/mL), whereas older adults aged 50–59 yrs had the highest CMV IgG concentrations (median: 202.4 AU/mL). Identical trends were also observed with most subgroup analyses performed for each sex (P<0.0083; Fig. 1A and 1B), although the results for women aged 40–49 yrs did not differ significantly (P≥0.0083) from those for the 30–39 yr and 50–59 yr age groups (Fig. 1C).

Fig. 1. CMV IgG concentrations of each age group among seropositive individuals. Panels (A–C) represent (A) total, (B) male, and (C) female individuals. In all cases, P for the Kruskal–Wallis test was <0.001. Post-hoc analyses were performed using Dunn’s test with Bonferroni correction, and P<0.0083 was considered to represent a significant difference. “N” refers to the number of seropositive individuals in each age group.

Abbreviations: CMV, cytomegalovirus; AU, arbitrary units.

Additional analysis was performed to compare the CMV IgG concentrations between seropositive men and women in each age group. In all age groups except for those aged 50–59 yrs, men exhibited significantly lower CMV IgG concentrations than did women (Mann–Whitney test). In individuals aged 20–29 yrs, the median CMV IgG concentrations in men and women were 106.1 AU/mL and 142.7 AU/mL, respectively (P<0.001). In individuals aged 30–39 yrs, the median CMV IgG concentrations in men and women were 140.0 AU/mL and 172.6 AU/mL, respectively (P<0.001). In individuals aged 40–49 yrs, the median CMV IgG concentrations in men and women were 165.1 AU/mL and 196.0 AU/mL, respectively (P<0.001).

Literature review of CMV IgG seropositivity in the Korean population

Among previous reports, six were selected and analyzed in this study [12–17]. Two studies were excluded based on their study populations and sample sizes. The previous and current results are summarized in Table 3. Heterogeneity was observed between the studies. For example, the study periods varied; only one previous study was cross-sectional, similar to our study [13], whereas seropositivities were investigated over longer periods (range: 4–21 yrs) in other previous studies [12, 14–17]. The number of enrolled individuals also varied across studies, ranging from several hundreds to tens of thousands (range: 217–18,818). The study population and age also varied across studies. In contrast to our study, which included a relatively unbiased group of individuals, previous studies have primarily focused on specific groups, such as pregnant women or women of childbearing age. Among the CMV IgG immunoassays used in the included studies, the Alinity i CMV IgG Reagent Kit (Abbott) was used exclusively in this study. Most previous reports showed higher average IgG seropositivities (>94.0%; range 83.9%–98.1%) than those observed in this study (89.9%).

Table 3. Summary of results from previous CMV IgG seropositivity studies for the general Korean population.

Authors	Study period	Publication year	Size (N)	Study group	Median age (IQR)	Immunoassay method (reagent kit, manufacturer)	Average IgG seropositivity (%)
Seo et al. [17]	2001–2004	2006	217	Children	23.0 mo (11.0–38.0 mo)*	Enzyme-linked immunosorbent assay (CMV IgG Enzygnost, Dade Behring)	83.9
Seo et al. [13]	2008	2009	744	Pregnant women	NA	Chemiluminescent microparticle immunoassay (ARCHITECT CMV IgG Reagent Kit, Abbott)	98.1
Shin et al. [15]	2006–2011	2017	18,818	Pregnant women	31.0 yrs (28.0–33.0)	Chemiluminescent microparticle immunoassay (ARCHITECT CMV IgG Reagent Kit, Abbott)	98.1
Choi et al. [14]	1995–2015	2018	11,584	All patients underwent anti-CMV IgG tests	46.3 yrs (27.6–55.6)*	Enzyme-linked fluorescent immunoassay (VIDAS CMV IgG, BioMérieux)	94.1
La et al. [16]	2006–2017	2019	3,015	Healthy solid-organ transplantation donors†	50.5 yrs (33.0–50.5)*‡	Enzyme-linked fluorescent immunoassay (VIDAS CMV IgG, BioMérieux)	88.6
Choi et al. [12]	2009–2019	2021	6,837	Women of childbearing age	32.3 yrs (28.4–37.5)	Chemiluminescent microparticle immunoassay (ARCHITECT CMV IgG Reagent Kit, Abbott)	95.8
Current study	2024	2025	1,978	Adult health-checkup attendees	39.0 yrs (30.0–49.0)	Chemiluminescent microparticle immunoassay(Alinity i CMV IgG Reagent Kit, Abbott)	89.9

*The midpoints were approximated based on the age group intervals.

^†Subgroup analysis was conducted through a literature review.

^‡In this study, individuals aged 41–60 yrs (midpoint: 50.5 yrs) were categorized into a single age group. The median and the 3rd quartile were both 50.5 yrs.

Abbreviations: CMV, cytomegalovirus; N, number in study population; IQR, interquartile range; mo, months; NA, not applicable.

This downward trend over time was observed in the overall population across all age groups and within each age group. We thoroughly reviewed previous literature and compared CMV IgG seropositivity among individuals aged 20–59 yrs, analyzing age group-specific data along with our findings (Table 4). Although the study periods and populations differed among the reviewed studies, a temporal shift was observed, where CMV IgG seropositivity was lower in younger individuals and in more recent sampling periods. Among the reviewed studies, those utilizing the same general method as used in this study (CMIA) were selected for further comparison [12, 15], and age group-specific CMV IgG seropositivity is presented in Supplemental Data Fig. S1.

Table 4. Comparison of CMV IgG seropositivity results by age groups in Korean adult populations across studies.

Author (study period)	Shin et al.*† [15] (2006–2011)	Choi et al.*‡ [14] (1995–2015)	La et al.*‡§ [16] (2006–2017)	Choi et al.*† [12] (2009–2019)	Current study (2024)
Age of 20–29 yrs, total (N)	6,978	1,170	588	1,659	455
Reactive (N)	6,799	1,099	424	1,558	347
Nonreactive (N)	179	71	164	101	108
Seropositivity (%)	97.4	93.9	72.1	93.9	76.3
Age of 30–39 yrs, total (N)	11,574	1,810	610	2,568	586
Reactive (N)	11,400	1,765	536	2,523	510
Nonreactive (N)	174	45	74	45	76
Seropositivity (%)	98.5	97.5	87.9	98.2	87.0
Age of 40–49 yrs, total (N)	198	2,122	1,154	778	488
Reactive (N)	196	2,107	1,088	769	473
Nonreactive (N)	2	15	66	9	15
Seropositivity (%)	99.0	99.3	94.3	98.8	96.9
Age of 50–59 yrs, total (N)	NA	2,327	NA	NA	449
Reactive (N)	–	2,308	–	–	448
Nonreactive (N)	–	19	–	–	1
Seropositivity (%)	–	99.2	–	–	99.8

*To ensure comparability, data for individuals aged 20–59 yrs are presented in this table (exceptions noted below).

^†Only women were studied in the indicated studies.

^‡Although these studies used different age groupings (e.g., 21–30 yrs, 31–40 yrs, etc.), the age group labels in this table were standardized to 20–29, 30–39, etc., for consistency. The original proportions reported in each study were not recalculated.

^§In this study, individuals aged 41–60 yrs were categorized into a single age group, which does not align with the 10 yr intervals used in this table. This group was assigned to 40–49 yr group in this table.

Abbreviations: CMV, cytomegalovirus; NA, not applicable.

DISCUSSION

We measured CMV IgG in adults aged 20–59 yrs from two independent institutions and found that the overall seropositivity in the general Korean adult population in 2024 was 89.9%. The current seropositivity of CMV in the Korean population remained relatively high, where a worldwide meta-analysis of CMV seropositivity data reported in 2019 showed that the eastern Mediterranean region had the highest CMV seropositivity (90%) [11], comparable with that in this study. Country-specific estimates showed that developed countries (including Germany and Canada) have seropositivities below 60%, whereas some developing countries showed seropositivities over 90%. However, many Asian countries (irrespective of their developmental status) have shown high seropositivities. For example, Singapore and Japan showed seropositivities of approximately 80%, whereas China and Korea showed seropositivities comparable with that of our study [11].

Although the study population’s characteristics slightly differed between institutions, both institutions employed the same immunoassay platform and used identical CMV IgG reagent kits, ensuring a consistent testing method. Even though the age distribution of the study populations slightly varied between the two institutions, age group-specific seropositivities were not significantly different (data not shown). These findings support the consistency and reliability of our results across both institutions.

According to the latest Korean External Quality Assessment Scheme proficiency testing report on viral serology [18], the Alinity i system (Abbott) is currently the most widely used platform for testing CMV IgG in Korean clinical laboratories. This system was developed to optimize the sample throughput and testing efficiency through a compact and scalable design [19]. Its analytical performance was comparable with that of the ARCHITECT i2000_SR platform [20], which was commonly utilized in previous studies (Table 3). To our knowledge, this is the first study on CMV seropositivity in the Korean population using the Alinity i immunoassay platform (Abbott). We assessed the current trend of CMV IgG seropositivity in the Korean adult population utilizing the most up-to-date and widely used platform in Korean medical institutions.

Our findings showed that CMV IgG seropositivity increased with age, likely reflecting cumulative lifelong exposure to the virus. Notably, individuals aged 20–29 yrs exhibited the lowest seropositivity (76.3%), whereas nearly all individuals aged 50–59 yrs were seropositive (99.8%). This trend aligns with previous CMV IgG seropositivity data from studies performed in Korea [12, 14–16]. Compared to previous reports, our data showed a relatively lower CMV IgG seropositivity, suggesting a declining trend over time. For example, previous reports covering the periods 1995–2015 and 2009–2019 demonstrated that CMV seropositivity exceeded 93% in all age groups over 20 yrs [12, 14]. In contrast, our results showed that in 2024, individuals aged 20–29 yrs and 30–39 yrs had relatively lower seropositivities of 76.3% and 87.0%, respectively.

This dynamic can be conceptualized with a two-dimensional framework. Along the age axis (X-axis), CMV IgG seropositivity increased, reflecting the cumulative nature of the infection over a lifetime. Along the time axis (Y-axis), CMV IgG seropositivity within the same age groups decreased, reflecting generational changes in the exposure risk. These findings suggest that Korea may be undergoing a gradual shift in the epidemiology of CMV, similar to that in Western countries. Younger generations today are less likely to be seropositive than previous generations at the same age, potentially because of reduced CMV exposure. Contributing factors, including improved hygiene, reduced household crowding, and lower fertility rates in Korea, can reduce early-life CMV transmission [9–11, 21, 22].

This dual trend raises public health concerns. Declining seropositivity in younger age groups (especially for women of reproductive age) increases the risk of primary CMV infection during pregnancy and its impact on congenital CMV transmission. Additionally, seronegative transplant recipients may be at a higher risk for severe CMV disease if they receive organs or stem cells from seropositive donors. Unfortunately, developing an effective vaccine against CMV remains an ongoing challenge [23]. Thus, our findings underscore the need for continued monitoring, targeted education, transplantation matching, and age-stratified analysis of CMV seropositivity.

In addition to analyzing seropositivity, we observed an age-related upward trend in CMV IgG concentrations among seropositive individuals, an aspect not addressed in previous Korean studies, which focused solely on seropositivity [12–17]. In another study with healthy individuals, the anti-CMV antibody titer increased with age, suggesting its role as a potential biomarker [24]. The age-associated increase in CMV IgG titers observed in this study can be explained by cumulative exposure or repeated immune stimulation from latent infection and subclinical viral reactivation [25, 26]. This phenomenon differs from vaccine-induced antibody levels, which typically wane over time and have been correlated with decreased vaccine effectiveness [27]. Another interesting observation in this study was that women had significantly higher CMV IgG concentrations than men (Fig. 1). Although CMV IgG seropositivities have been analyzed previously in both sexes [14, 28, 29], the sex-related differences observed were inconsistent, and CMV IgG concentrations were not analyzed. The sex-related differences observed in this study might be attributable to higher exposure through caregiving roles or pregnancy-related immune modulation [30]. Considering that higher levels of preexisting maternal CMV IgG can serve as a protective factor against congenital CMV infection in newborns [31], our findings provide important insights for further public health studies. Such studies could focus on a specific population, including women of childbearing age. Future analyses should include intensive investigations of CMV IgG concentrations and sex-related differences.

The strengths of this study include the use of recent data from a relatively unbiased population, unlike most previous Korean studies that focused primarily on pregnant women. We included a relatively balanced cohort of young male and female adults, offering a current perspective on age-specific and sex-specific CMV immunity, as well as a generalizable estimate of CMV seropositivity in the Korean population. We also used the most widely adopted modern platform for CMV serology.

This study has some limitations. First, the absence of data on participants’ residential regions precluded any assessment of regional variations in CMV seropositivities, even though an identical assay was employed in both centers. Previous cross-sectional findings on rubella seropositivity in Korean women highlighted regional differences [32], suggesting that a similar trend might exist for CMV seropositivities. Future multicenter studies should ensure comparable demographic characteristics across centers, including geographical regions, sample size, age distribution, and socioeconomic status. Second, because we used leftover serum samples from health-checkup attendees, our results might not be entirely representative of the general adult population, as some possibility of sampling bias cannot be fully excluded. Previous reports on rubella and congenital CMV also highlighted the challenges posed by missing data, retrieving follow-up data, and bias issues [32, 33]. Third, the cross-sectional nature of this study limits our ability to assess temporal changes at the individual level. Previous reports on CMV seroconversion mainly focused on specific populations, such as pregnant women and healthcare workers [34–36]. In contrast, our study represents a broader adult population; however, follow-up CMV serology testing was not feasible. To our knowledge, no previous study has longitudinally followed individuals from the general population to assess CMV seroconversion over time. Lastly, our study population may have included individuals with chronic medical conditions, such as diabetes, hypertension, or dyslipidemia. Gathering more detailed clinical information is recommended in future studies.

In conclusion, we provided the most up-to-date estimate of CMV IgG seropositivity in the general Korean adult population and compared our findings with those of previous Korean studies to assess temporal trends. Notably, our results demonstrate an age-related increase in CMV seropositivity and a gradual decline in seropositivity based on comparison with earlier reports, suggesting an epidemiological shift. These findings have implications for transplant-recipient risk assessment, congenital CMV prevention, and future vaccine planning. Periodic surveillance of CMV seropositivity will be essential for informing public health strategies.

SUPPLEMENTARY MATERIALS

Supplementary materials can be found via https://doi.org/10.3343/alm.2025.0326.