COVID-19–Associated Hospitalizations and Maternal Vaccination Among Infants Aged 6 Months — COVID-NET, 12 States, October 2022–April 2024

Fiona P. Havers, MD1; Michael Whitaker, MPH1; Bhoomija Chatwani, MPH1,2; Monica E. Patton, MD1; Christopher A. Taylor, PhD1; Shua J. Chai, MD3,4; Breanna Kawasaki, MPH5; Kimberly Yousey-Hindes, MPH6; Kyle P. Openo, DrPH7,8,9; Patricia A. Ryan, MS10; Lauren Leegwater, MPH11; Ruth Lynfield, MD12; Daniel M. Sosin, MD13; Bridget J. Anderson, PhD14; Brenda Tesini, MD15; Melissa Sutton, MD16; H. Keipp Talbot, MD17; Andrea George, MPH18; Jennifer Milucky, MSPH1; COVID-NET Surveillance Team (

Summary

What is already known about this topic?

Infants aged What is added by this report?

COVID-19–associated hospitalization rates among infants aged What are the implications for public health practice?

COVID-19 can cause severe disease in infants aged Figures

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Abstract

Infants aged

Introduction

COVID-19 can cause severe disease in children, and infants aged 1,2). These infants are not yet age-eligible to receive COVID-19 vaccination, and maternal vaccination during pregnancy protects young infants from COVID-19–associated hospitalization (3–5). Data from the COVID-19–Associated Hospitalization Surveillance Network (COVID-NET) during October 2022–April 2024 were analyzed to describe hospitalization rates, maternal vaccination status, clinical outcomes, and codetections of other viruses among infants aged

Data Sources

COVID-NET conducts population-based surveillance for laboratory-confirmed COVID-19–associated hospitalization, defined as documentation of a positive SARS-CoV-2 test result during hospitalization or ≤14 days preceding hospital admission, among residents of a predefined catchment area. Demographic data were collected for all COVID-19–associated hospitalizations in 90 counties across 12 states* and were used to calculate age-stratified hospitalization rates.

This analysis describes weekly and seasonal cumulative hospitalization rates among infants aged † Unadjusted weekly COVID-19–associated hospitalization rates (hospitalizations per 100,000 population)§ with rate ratios (RRs) were calculated by dividing the total number of hospitalized patients by age group–specific population estimates for the counties included in the surveillance catchment area. When comparing cumulative rates among infants across seasons, the period was limited to October–April for both periods for comparability. When comparing rates between age groups, cumulative and weekly data comparing pediatric age groups are presented for 2022–2024; cumulative data comparing all age groups are presented for 2023–24 only.

Using previously described methods (6), clinical data (signs and symptoms at admission,¶ underlying medical conditions,** viral codetections, and clinical outcomes) were abstracted for a random sample of hospitalized infants.†† Maternal vaccination, defined as receipt of any COVID-19 vaccination at any time during pregnancy, was obtained through state immunization information systems; infant characteristics were compared by maternal vaccination status. The analysis of clinical data excluded newborns who received a positive SARS-CoV-2 test result during their birth hospitalization§§ because the clinical significance of a positive test result in this setting is difficult to determine.

Statistical Methods

Wilcoxon rank-sum tests and Fisher’s exact chi-square tests were used to compare medians and proportions, respectively; p-values ¶¶

COVID-19–Associated Hospitalization Rates

During October 2022–April 2024, a total of 1,470 COVID-19–associated hospitalizations among infants aged

Full chart reviews were conducted for a random sample of 1,266 (86%) of 1,470 hospitalized infants; among these, 118 (9.4%) were newborns who received a positive SARS-CoV-2 test result during their birth hospitalization and were excluded from the analysis of clinical data. Among these 118 infants who received a positive test result during the birth hospitalization, 23 (18.3%) had COVID-19–related signs and symptoms recorded, compared with 1,071 (92.6%) of 1,148 infants hospitalized with COVID-19 during a nonbirth hospitalization (Supplementary Table 1, https://stacks.cdc.gov/view/cdc/162444).

Maternal COVID-19 Vaccination Status

Among 1,148 infants for whom the clinical course was assessed (

Characteristics of Infant COVID-19–Associated Hospitalizations

The median age at hospital admission for the 1,148 infants for whom clinical information was reviewed was 64 days (IQR = 28–121 days) (Table). A total of 260 (22.1%) infants were admitted to an intensive care unit (ICU), and nine (0.8%) died in hospital; 245 (21.4%) received high-flow nasal cannula or bilevel positive airway pressure/continuous positive airway pressure (BiPAP/CPAP) oxygen support, and 56 (4.8%) received mechanical ventilation. Approximately one quarter (290; 24.0%) of infants had one or more underlying medical condition; the most common conditions identified were prematurity*** (196; 17.1%), cardiovascular disease (74; 6.6%), chronic lung disease††† (58; 4.7%), and neurologic disorders (35; 3.3%). Among 999 (87.1%) hospitalized infants who were tested for additional viruses, at least one other virus was detected among 286 (29.7%), including 19.3% (175 of 979) who received a positive respiratory syncytial virus test result, 12.2% (64 of 521) who received a positive rhinovirus/enterovirus test result, and 1.9% (21 of 992) who received a positive influenza test result. Among 233 (89.8%) of 260 young infants admitted to an ICU who were tested for additional pathogens, an additional virus was detected among 97 (41.2%), including 56 (25.1%) with respiratory syncytial virus detected.

Discussion

Infants aged Infants aged 5,7). Maternal vaccination during pregnancy has been shown to be safe and effective in protecting young infants from COVID-19 hospitalization (3–5); COVID-19 vaccination is recommended by CDC for all persons aged ≥6 months, including those who are pregnant (8,9). Findings from this analysis are consistent with other evidence demonstrating low COVID-19 vaccine coverage among pregnant persons (5), including a 2023 survey of pregnant persons that found that nearly one quarter (24.7%) received a COVID-19 vaccination during pregnancy (10). High rates of COVID-19–associated hospitalization among young infants reflect the ongoing vulnerability of this population to severe COVID-19–associated outcomes and indicate an urgent need to improve COVID-19 vaccination coverage among pregnant persons to protect vulnerable infants.

Limitations

The findings in this report are subject to at least four limitations. First, maternal vaccination information in immunization information systems might not be complete, and misclassification might have occurred. Second, population estimates for infants aged Infants aged

Acknowledgments

Respiratory Virus Hospitalization Surveillance Network surveillance officers and participating partners; Kendra Delk, Eagle Health Analytics.

COVID-NET Surveillance Team

Darpun Sachdev, California Department of Public Health; Nisha Alden, Colorado Department of Public Health & Environment; Emily Zmek, Connecticut Emerging Infections Program, Yale School of Public Health; Lucy Witt, Division of Infectious Diseases, Emory University of Medicine, Georgia Emerging Infections Program; Maya L. Monroe, Maryland Department of Health; Elizabeth McCormick, Michigan Department of Health and Human Services; Paige D’Heilly, Minnesota Department of Health; Susan L. Ropp, New Mexico Department of Health; Kerianne Engesser, New York State Department of Health; Erin Licherdell, University of Rochester School of Medicine and Dentistry; Sam Hawkins, Public Health Division, Oregon Health Authority; William Schaffner, Vanderbilt University Medical Center; Holly Staten, Salt Lake County Health Department.

Corresponding author: Fiona P. Havers, fhavers@cdc.gov.

1Coronavirus and Other Respiratory Viruses Division, National Center for Immunization and Respiratory Diseases, CDC; 2Eagle Health Analytics, Atlanta, Georgia; 3California Emerging Infections Program, Oakland, California; 4Career Epidemiology Field Officer Program, CDC; 5Colorado Department of Public Health & Environment; 6Connecticut Emerging Infections Program, Yale School of Public Health, New Haven, Connecticut; 7Emory University School of Medicine, Atlanta, Georgia; 8Georgia Emerging Infections Program, Georgia Department of Public Health; 9Atlanta Veterans Affairs Medical Center, Decatur, Georgia; 10Maryland Department of Health; 11Michigan Department of Health and Human Services; 12Minnesota Department of Health; 13New Mexico Department of Health; 14New York State Department of Health; 15University of Rochester School of Medicine and Dentistry, Rochester, New York; 16Public Health Division, Oregon Health Authority; 17Vanderbilt University Medical Center, Nashville, Tennessee; 18Salt Lake County Health Department, Salt Lake City, Utah.

All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Andrea George reports grants from the Council of State and Territorial Epidemiologists during the study. Lauren Leegwater reports grants from the Michigan Department of Health and Human Services during the study. No other potential conflicts of interest were disclosed.

• COVID-NET sites contributing data to this analysis include selected counties in California, Colorado, Connecticut, Georgia, Maryland, Michigan, Minnesota, New Mexico, New York, Oregon, Tennessee, and Utah, representing approximately 10% of the U.S. population.

† Clinical data are complete through April 2024. October–April has been historically defined as the respiratory virus season, although COVID-19 circulates year-round. For October 2021–September 2022 and October 2022–September 2023, 34.9% and 23.6% of pediatric cases, respectively, were reported during the May–September period.

§ Rates are calculated using the National Center for Health Statistics’ unbridged-race postcensal population estimates for the counties or county equivalents included in surveillance. Because population estimates are available in 1-year age increments, population denominators for hospitalization rates among infants aged ¶ COVID-19–related signs and symptoms included respiratory conditions (congestion/runny nose, cough, nausea/vomiting, rash, seizures, shortness of breath/respiratory distress, upper respiratory infection, and wheezing) and nonrespiratory conditions (apnea, conjunctivitis, diarrhea, cyanosis, decreased vocalization/stridor, dehydration, fever, hypothermia, inability to eat/poor feeding, and lethargy). Signs and symptoms data were abstracted from medical charts and might be incomplete.

** Defined as one or more of the following conditions: blood disorder, cardiovascular disease including congenital heart disease, chronic lung disease of prematurity/bronchopulmonary dysplasia, asthma/reactive airway disease or airway abnormality, chronic metabolic disease, gastrointestinal disease, genetic disorder, immunosuppressive condition, neurologic disorders, prematurity, renal disease, or other underlying condition.

†† During October 2022–April 2024, some sites chose to complete all charts for pediatric patients; the remainder did a random sample. Random numbers (1–100) were generated and assigned to each patient to produce random samples for medical record abstraction stratified by site, age group, and month. Unweighted case counts and weighted percentages that better represent the hospitalized population of the catchment area are presented for sampled data. Percentages were weighted to account for probability of selection for sampled patients.

§§ A birth hospitalization was defined as the hospitalization during which the infant was born.

¶¶ 45 C.F.R. part 46.102(l)(2), 21 C.F.R. part 56; 42 U.S.C. Sect. 241(d); 5 U.S.C. Sect. 552a; 44 U.S.C. Sect. 3501 et seq.

*** Prematurity was defined as gestational age at birth of ††† For infants aged

References

• Hamid S, Woodworth K, Pham H, et al.; COVID-NET Surveillance Team. COVID-19–associated hospitalizations among U.S. infants aged ](http://doi.org/10.15585/mmwr.mm7145a3) PMID:36355608
• Marks KJ, Whitaker M, Anglin O, et al.; COVID-NET Surveillance Team. Hospitalizations of children and adolescents with laboratory-confirmed COVID-19—COVID-NET, 14 states, July 2021–January 2022. MMWR Morb Mortal Wkly Rep 2022;71:271–8. https://doi.org/10.15585/mmwr.mm7107e4 PMID:35176003
• Simeone RM, Zambrano LD, Halasa NB, et al.; Overcoming COVID-19 Investigators. Effectiveness of maternal mRNA COVID-19 vaccination during pregnancy against COVID-19–associated hospitalizations in infants aged ](http://doi.org/10.15585/mmwr.mm7239a3) PMID:37874864
• Halasa NB, Olson SM, Staat MA, et al.; Overcoming COVID-19 Investigators; Overcoming COVID-19 Network. Effectiveness of maternal vaccination with mRNA COVID-19 vaccine during pregnancy against COVID-19–associated hospitalization in infants aged ](http://doi.org/10.15585/mmwr.mm7107e3) PMID:35176002
• Rawal S, Tackett RL, Stone RH, Young HN. COVID-19 vaccination among pregnant people in the United States: a systematic review. Am J Obstet Gynecol MFM 2022;4:100616. https://doi.org/10.1016/j.ajogmf.2022.100616 PMID:35283351
• O’Halloran A, Whitaker M, Patel K, et al. Developing a sampling methodology for timely reporting of population-based COVID-19-associated hospitalization surveillance in the United States, COVID-NET 2020–2021. Influenza Other Respir Viruses 2023;17:e13089. https://doi.org/10.1111/irv.13089 PMID:36625234
• CDC. COVID-19: how to protect yourself and others. Atlanta, GA: US Department of Health and Human Services, CDC; 2024. https://www.cdc.gov/covid/prevention/
• CDC. COVID-19: COVID-19 vaccination for people who are pregnant or breastfeeding. Atlanta, GA: US Department of Health and Human Services, CDC; 2024. https://www.cdc.gov/covid/vaccines/pregnant-or-breastfeeding.html
• The American College of Obstetricians and Gynecologists. COVID-19 vaccination considerations for obstetric-gynecologic care. Washington, DC: The American College of Obstetricians and Gynecologists; 2023. https://www.acog.org/clinical/clinical-guidance/practice-advisory/articles/2020/12/covid-19-vaccination-considerations-for-obstetric-gynecologic-care
• Black CL, Kriss JL, Razzaghi H, et al. Influenza, updated COVID-19, and respiratory syncytial virus vaccination coverage among adults—United States, fall 2023. MMWR Morb Mortal Wkly Rep 2023;72:1377–82. https://doi.org/10.15585/mmwr.mm7251a4 PMID:38127675

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• Number of patients with a laboratory-confirmed COVID-19–associated hospitalization per 100,000 population.

† Selected counties in California, Colorado, Connecticut, Georgia, Maryland, Michigan, Minnesota, New Mexico, New York, Oregon, Tennessee, and Utah.

• Excluding birth hospitalizations. A birth hospitalization was defined as the hospitalization during which the infant was born.
  † Selected counties in California, Colorado, Connecticut, Georgia, Maryland, Michigan, Minnesota, New Mexico, New York, Oregon, Tennessee, and Utah.
  § Data are from a weighted sample of hospitalized children with completed medical record abstractions. Sample sizes presented are unweighted with weighted percentages.
  ¶ Persons of Hispanic or Latino (Hispanic) origin might be of any race but are categorized as Hispanic; all racial groups are non-Hispanic. Persons of all other races include non-Hispanic American Indian or Alaska Native and multiracial persons. If ethnicity was unknown, non-Hispanic ethnicity was assumed.
  ** Defined as one or more of the following conditions: blood disorder, cardiovascular disease including congenital heart disease, chronic lung disease of prematurity/bronchopulmonary dysplasia, asthma/reactive airway disease or airway abnormality, chronic metabolic disease, gastrointestinal disease, genetic disorder, immunosuppressive condition, neurologic disorders, prematurity, renal disease, or other underlying condition.
  †† For infants aged §§ COVID-19–related signs and symptoms included respiratory conditions (congestion/runny nose, cough, nausea/vomiting, rash, seizures, shortness of breath/respiratory distress, upper respiratory infection, and wheezing) and non-respiratory conditions (apnea, conjunctivitis, cyanosis, decreased vocalization/stridor, dehydration, diarrhea, fever, hypothermia, inability to eat/poor feeding, and lethargy). Signs and symptoms data were abstracted from medical charts and might be incomplete.
  ¶¶ Results reported among infants who received testing (as opposed to all hospitalized infants). Because of differing testing practices, denominators differed among the viral respiratory pathogens: 999 infants for any additional virus; 979 infants for RSV, 992 for influenza (influenza A, influenza B, and influenza not subtyped), 521 for rhinovirus/enterovirus, and 523 for other viruses (adenovirus, human metapneumovirus, parainfluenza 1, parainfluenza 2, parainfluenza 3, parainfluenza 4, and other non–SARS-CoV-2 coronaviruses).
  *** Maternal vaccination is defined as receipt of COVID-19 vaccine during the pregnancy of the infant hospitalized. A total of 83 (7.4%) infants had unknown maternal vaccination status and were excluded from maternal vaccination status. Proportions presented are calculated with those with known vaccination status (1,065) as the denominator.

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• Excluding birth hospitalizations. A birth hospitalization was defined as the hospitalization during which the infant was born.

† With 95% CIs indicated by error bars.

§ The 2022–23 season is defined as occurring during October 1, 2022–September 30, 2023, and the 2023–24 season is defined as occurring during October 1, 2023–April 30, 2024.

¶ Selected counties in California, Colorado, Connecticut, Georgia, Maryland, Michigan, Minnesota, New Mexico, New York, Oregon, Tennessee, and Utah.

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