Dear Editor,
Cytomegalovirus (CMV) seroprevalence among U.S. children 1-5 years of age was 28.2% during 2017–2018 in the National Health and Nutrition Examination Survey (NHANES) [1]. In this report, we provide updated estimates of CMV IgG seroprevalence using the larger NHANES 2017–March 2020 pre-pandemic dataset.
Data collected from 2019 to March 2020, when survey field operations were suspended due to the COVID-19 pandemic, were combined with the 2017–2018 cycle to create a nationally representative NHANES 2017–March 2020 pre-pandemic dataset [2]. We calculated national estimates using the examination sample weights to account for the differential probabilities of selection, nonresponse, and noncoverage, as previously described [2]. We calculated standard errors using Taylor Series Linearization in SUDAAN to account for the complex sample design and 95% confidence intervals (CI) using the exact method developed by Korn and Graubard [3]. We assessed CMV IgG seroprevalence overall and the weighted proportion of combined low and intermediate IgG avidity indicating recent (≤4 months) CMV infection among IgG-positive children. We examined factors associated with overall CMV IgG seroprevalence (i.e., age, sex, race and Hispanic origin, poverty index, education of the head of the household, mother’s age when the child was born, breastfeeding history, and number of children ≤5 years in the household) using univariate analysis and multivariable models.
Among the 1,574 children 1-5 years of age examined, 957 (60.8%) were tested for CMV IgG antibody. Overall weighted CMV IgG seroprevalence was 29.0% (95% CI: 24.4%-33.9%). Among IgG-positive children, 14.4% (95% CI: 9.0%-21.3%) were determined to have recent CMV infection. In univariate and multivariable analyses, CMV IgG seroprevalence was significantly higher in children 4-5 years of age (vs. 1 year), whose head of household had not completed high school (vs. those who completed high school, high school equivalency or some college), and in children who were breastfed either <6 months or ≥6 months (vs. never) (Table 1).
Table 1.
Cytomegalovirus (CMV) IgG Seroprevalence in U.S. Children 1-5 Years of Age by Selected Factors, NHANES, 2017 – March 2020 Pre-pandemic dataset
| Variable | 2017-2020 Pre-pandemic |
P- valuea |
Odds Ratiob | Odds Ratioc | |||
|---|---|---|---|---|---|---|---|
| Children Examined |
Children Tested for CMV |
CMV IgG weighted Seroprevalence |
|||||
| n | n (%) | % (95% CI) | (95% CI) | (95% CI) | |||
| Total | 1574 | 957 (60.8) | 29.0 (24.4-33.9) | ||||
| Age group (years) | |||||||
| 1 (ref) | 357 | 197 (55.2) | 23.2 (16.8-30.7) | 1.0 | 1.0 | ||
| 2-3 | 658 | 391 (59.4) | 24.1 (17.5-31.8) | 0.837 | 0.9 (0.6-1.5) | 0.9 (0.6-1.5) | |
| 4-5 | 559 | 369 (66.0) | 35.9 (29.0-43.3) | 0.013 | 1.6 (0.9-2.8) | 1.7 (1.0-2.8) | |
| Sex | |||||||
| Male (ref) | 812 | 498 (61.3) | 26.3 (21.2-31.9) | 1.0 | |||
| Female | 762 | 459 (60.2) | 31.9 (24.9-39.4) | 0.171 | 1.2 (0.8-2.0) | ||
| Race and Hispanic origin | |||||||
| Non-Hispanic White (ref) | 537 | 347 (64.6) | 25.7 (19.6-32.6) | 1.0 | |||
| Non-Hispanic Black | 428 | 247 (57.7) | 21.8 (15.2-29.8) | 0.411 | 1.0 (0.6-1.8) | ||
| All Hispanic | 348 | 214 (61.5) | 33.6 (24.8-43.5) | 0.104 | 1.1 (0.7-1.8) | ||
| Poverty level | |||||||
| Below poverty line | 494 | 314 (63.6) | 29.1 (21.8-37.2) | 1.0 | |||
| At or above poverty line (ref) | 894 | 535 (59.8) | 28.5 (23.7-33.8) | 0.879 | 1.0 (0.7-1.5) | ||
| Education of the head of household | |||||||
| Less than high school diploma (ref) | 231 | 151 (65.4) | 38.2 (28.5-48.8) | 1.0 | 1.0 | ||
| High school/GED or some college | 870 | 536 (61.6) | 23.7 (18.0-30.1) | 0.010 | 0.5 (0.3-1.0) | 0.5 (0.3-0.9) | |
| Completed college or more | 379 | 212 (55.9) | 34.7 (27.4-42.6) | 0.544 | 0.6 (0.3-1.4) | 0.8 (0.5-1.3) | |
| Mother’s age when born | |||||||
| 14-19 years (ref) | 116 | 76 (65.5) | 25.7 (13.0-42.3) | 1.0 | |||
| 20-29 years | 832 | 496 (59.6) | 29.6 (24.2-35.5) | 0.547 | 1.4 (0.7-2.8) | ||
| 30-49 years | 617 | 380 (61.6) | 29.0 (21.6-37.4) | 0.660 | 1.3 (0.5-3.0) | ||
| Breastfeeding history | |||||||
| Never (ref) | 329 | 209 (63.5) | 15.6 (10.5-22.0) | 1.0 | |||
| <6 months | 676 | 402 (59.5) | 27.4 (21.2-34.3) | 0.002 | 2.1 (1.4-3.3) | 2.0 (1.3-3.2) | |
| ≥6 months | 560 | 339 (60.5) | 35.6 (30.2-41.2) | <0.001 | 3.1 (1.9-5.2) | 2.7 (1.7-4.3) | |
| Number of other children ≤5 years of age living in the household | |||||||
| None (ref) | 751 | 460 (61.3) | 26.1 (20.8-31.9) | 1.0 | |||
| ≥1 | 823 | 497 (60.4) | 31.9 (25.8-38.4) | 0.103 | 1.2 (0.9-1.6) | ||
P-value <0.05 from t-statistic comparing subgroup to reference group for each covariable
Odds ratio adjusted for age group, sex, race and Hispanic origin, poverty level, education of the head of household, mother’s age when born, breastfeeding history, and number of other children ≤5 years of age living in the household using logistic regression model (full model)
Odds ratio adjusted for age group, education of the head of household, and breastfeeding history (reduced model with significant variables)
ref=reference group
All estimates met data presentation standards for proportions [9], except the estimate for the non-Hispanic Asian subgroup, therefore estimates for that group are not reported separately.
In summary, roughly one in three U.S. children 1-5 years of age were CMV-seropositive during the pre-pandemic period 2017–2020. CMV seroprevalence appeared to increase from 20.7% in 2011–2012 [4] to 29.0% in 2017–March 2020. Compared with 2011–2012, CMV seroprevalence no longer differed by race and Hispanic origin, poverty index, and having another child ≤5 years of age in the household [4, 5]. Additionally, this larger sample provided more reliable CMV seroprevalence estimates for non-Hispanic Black children than the 2017–2018 NHANES [1]. Breastfeeding remained the factor most strongly associated with CMV seroprevalence.
It is unknown whether the pandemic will further influence CMV transmission. Mitigation measures in childcare facilities (e.g. smaller class sizes and increased hand hygiene and disinfection) may decrease exposures to CMV [6]. Although the lockdown may have negatively affected counseling and social support for breastfeeding initiation [7], women may have spent more time at home with their infants during the pandemic, possibly breastfeeding longer [8]. Continued monitoring of CMV seroprevalence among young children may help better understand the potential impact of the pandemic on CMV seroprevalence.
Funding:
No external funding was used for this study.
Footnotes
Disclaimer: The findings and conclusions in this article are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.
Conflict of Interest: All authors have no conflicts of interest.
References
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