Incidence Rates of Medically Attended COVID-19 in Infants Less Than 6 Months of Age.

BACKGROUND: Studies suggest infants may be at increased risk of severe coronavirus disease 2019 (COVID-19) relative to older children, but few data exist regarding the incidence of COVID-19 episodes and associated risk factors. We estimate incidence rates and describe characteristics associated with medically attended COVID-19 episodes among infants younger than 6 months of age. METHODS: We analyzed electronic medical record data from a cohort of infants born March 1, 2020-February 28, 2021. Data from 3 health care delivery systems included demographic characteristics, maternal and infant outpatient visit and hospitalization diagnoses and severe acute respiratory syndrome coronavirus syndrome 2 (SARS-CoV-2) test results. Medically attended COVID-19 episodes were defined by positive SARS-CoV-2 clinical tests and/or COVID-19 diagnosis codes during medical care visits. Unadjusted and site-adjusted incidence rates by infant month of age, low and high SARS-CoV-2 circulation periods and maternal COVID-19 diagnosis were calculated. RESULTS: Among 18,192 infants <6 months of age whose mothers received prenatal care within the 3 systems, 173 (1.0%) had medically attended COVID-19 episodes. Incidence rates were highest among infants under 1 month of age (2.0 per 1000 person-weeks) and 1 month (2.0 per 1000 person-weeks) compared with older infants. Incidence rates were also higher for infants born to women with postpartum COVID-19 compared with women without known COVID-19 and women diagnosed with COVID-19 during pregnancy. CONCLUSIONS: Infants of women with postpartum COVID-19 had a higher risk of medically attended COVID-19 than infants born to mothers who were diagnosed during pregnancy or never diagnosed underscoring the importance of COVID-19 prevention measures for their household members and caregivers to prevent infections in infants.

Factors Associated with Hospitalization with Symptomatic COVID-19 Illness Among Pregnant Individuals: A Multi-Center Retrospective Cohort Study

Background Pregnant individuals are at increased risk of COVID-19 hospitalization and death, and primary and booster COVID-19 vaccination is recommended for this population. Methods Among a cohort of pregnant individuals who received prenatal care at three healthcare systems in the United States, we estimated the cumulative incidence of hospitalization with symptomatic COVID-19 illness. We also identified factors associated with COVID-19 hospitalization using a multivariable Cox proportional-hazards model with pregnancy weeks as the timescale and a time-varying adjustor that accounted for SARS-CoV-2 circulation;model covariates included site, age, race, ethnicity, insurance status, pre-pregnancy weight status, and selected underlying medical conditions. Data were collected primarily through medical record extraction. Results Among 19,456 pregnant individuals with an estimated due date March 1, 2020-February 28, 2021, 75 (0.4%) were hospitalized with symptomatic COVID-19. Factors associated with hospitalization for symptomatic COVID-19 were Hispanic ethnicity (aHR: 2.7;95% CI: 1.3,5.5), native Hawaiian or Pacific Islander race (aHR: 12;95% CI: 3.2,45.5), age <25 years (aHR: 3.1;95% CI: 1.3,7.6), pre-pregnancy obesity (aHR: 2.1;95% CI: 1.1,3.9), diagnosis of a metabolic disorder (aHR: 2.2;95% CI: 1.2,3.8), lung disease excluding asthma (aHR: 49;95% CI: 28,84) and cardiovascular disease (aHR: 2.6;95% CI: 1.5,4.7). Conclusion Although hospitalization with symptomatic COVID-19 was uncommon, pregnant individuals should be aware of risk factors associated with severe illness when considering COVID-19 vaccination.