Top 5 Takeaways

  1. Increased Hospitalization Rates: During the Omicron variant-predominant periods, hospitalization rates among infants aged <6 months increased compared to the Delta variant period, but severe disease indicators among hospitalized infants did not increase.
  2. Comparison with Other Age Groups: The average weekly COVID-19-associated hospitalization rate for infants <6 months was similar to adults aged 65–74 years and higher than other pediatric age groups and younger adults.
  3. Role of Maternal Vaccination: Maternal COVID-19 vaccination during pregnancy might offer protection to infants through transplacental transfer of antibodies. Effectiveness varies with variants and time since vaccination.
  4. Study Limitations: Limitations include assumptions in population estimates, changes in public health policies, unassessed maternal immunity, variant predominance periods, and limited generalizability due to the catchment area.
  5. Public Health Implications: Emphasizes the importance of vaccinating pregnant women and implementing nonpharmaceutical interventions to protect infants ineligible for vaccination.

Original Article Author and Citation

Corresponding Author

Sarah Hamid,

Suggested Citation

Hamid S, Woodworth K, Pham H, et al. COVID-19–Associated Hospitalizations Among U.S. Infants Aged <6 Months — COVID-NET, 13 States, June 2021–August 2022. MMWR Morb Mortal Wkly Rep 2022;71:1442–1448. DOI:


This article presents an analysis of COVID-19-associated hospitalizations among U.S. infants aged <6 months during various SARS-CoV-2 variant-predominant periods, focusing on the impact of the Omicron variant. The study utilized data from the Coronavirus Disease 2019–Associated Hospitalization Surveillance Network (COVID-NET) and compared the rate and severity of hospitalizations during the Delta and Omicron variant periods.


The study involved collecting demographic and clinical data from COVID-19-associated hospitalizations in 13 states, specifically focusing on infants aged <6 months. The analysis included comparing weekly hospitalization rates, clinical characteristics, and severity indicators across different SARS-CoV-2 variant periods. Statistical methods like rate ratios, Wilcoxon rank-sum tests, and chi-square tests were used for comparisons.


The findings indicated a significant increase in hospitalization rates among infants aged <6 months during the Omicron period compared to the Delta period. However, the severity of the disease among hospitalized infants did not increase. The study also highlighted the potential protective effect of maternal vaccination against COVID-19.


The study underscores the continued vulnerability of infants aged <6 months, who are ineligible for vaccination, to COVID-19-associated hospitalizations, particularly during the Omicron variant-predominant period. It stresses the importance of maternal vaccination and nonpharmaceutical interventions to protect this high-risk group.


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