Is COVID-19 seasonal? A time series modeling approach

BackgroundDetermining whether SARS-CoV-2 is or will be seasonal like other respiratory viruses is critical for public health planning, including informing vaccine policy regarding the optimal timing for deploying booster doses. To help answer this urgent public health question, we evaluated whether COVID-19 case rates in the United States and Europe followed a seasonal pattern using time series models. MethodsWe analyzed COVID-19 data from Our World in Data from Mar 2020 through Apr 2022 for the United States (and Census Region) and five European countries (Italy, France, Germany, Spain, and the United Kingdom). For each, anomalies were identified using Twitters decomposition method and Generalized Extreme Studentized Deviate tests. We performed sensitivity analyses to determine the impact of data source (i.e., using US Centers for Disease Control and Prevention [CDC] data instead of OWID) and whether findings were similar after adjusting for multiple covariates. Finally, we determined whether our time series models accurately predicted seasonal influenza trends using US CDC FluView data. ResultsAnomaly plots detected COVID-19 rates that were higher than expected between November and March each year in the United States and Europe. In the US Southern Census Region, in addition to seasonal peaks in the fall/winter, a second peak in Aug/Sep 2021 was identified as anomalous. Results were robust to sensitivity analyses. ConclusionsOur results support employing annual protective measures against SARS-CoV-2 such as administration of seasonal booster vaccines or other non-pharmaceutical interventions in a similar timeframe as those already in place for influenza prevention. Summary of the Main PointAlthough SARS-CoV-2 continues to cause morbidity and mortality year-round due to its high transmissibility and rapid viral evolution, our results suggest that COVID-19 activity in the United States and Europe peaks during the traditional winter viral respiratory season.

COVID-19-Associated Hospitalizations Among Children Less Than 12 Years of Age in the United States

ObjectivesTo describe the characteristics, healthcare resource use and costs associated with initial hospitalization and readmissions among pediatric patients with COVID-19 in the US. MethodsHospitalized pediatric patients, 0-11 years of age, with a primary or secondary discharge diagnosis code for COVID-19 (ICD-10 code U07.1) were selected from 1 April 2020 through 30 September 2021 in the US Premier Healthcare Database Special Release (PHD SR). Patient characteristics, hospital length of stay (LOS), in-hospital mortality, hospital costs, hospital charges, and COVID-19-associated readmission outcomes were evaluated and stratified by age groups (0-4, 5-11), four COVID-19 disease progression states based on intensive care unit (ICU) and invasive mechanical ventilation (IMV) usage, and three sequential calendar periods. Sensitivity analyses were performed using the US HealthVerity claims database and restricting the analyses to primary discharge code. ResultsAmong 4,573 hospitalized pediatric patients aged 0-11 years, 68.0% were 0-4 years and 32.0% were 5-11 years, with a mean (median) age of 3.2 (1) years; 56.0% were male, and 67.2% were covered by Medicaid. Among the overall study population, 25.7% had immunocompromised condition(s), 23.1% were admitted to the ICU and 7.3% received IMV. The mean (median) hospital LOS was 4.3 (2) days, hospital costs and charges were $14,760 ($6,164) and $58,418 ($21,622), respectively; in-hospital mortality was 0.5%. LOS, costs, charges, and in-hospital mortality increased with ICU admission and/or IMV usage. In total, 2.1% had a COVID-19-associated readmission. Study outcomes appeared relatively more frequent and/or higher among those 5-11 than those 0-4. Results using the HealthVerity data source were generally consistent with main analyses. LimitationsThis retrospective administrative database analysis relied on coding accuracy and inpatient admissions with validated hospital costs. ConclusionsThese findings underscore that children aged 0-11 years can experience severe COVID-19 illness requiring hospitalization and substantial hospital resource use, further supporting recommendations for COVID-19 vaccination.

COVID-19 vaccine effectiveness among immunocompromised populations: a targeted literature review of real-world studies

IntroductionFrom July through October of 2021, several countries issued recommendations for increased COVID-19 vaccine protection for individuals with one or more immunocompromised (IC) conditions. It is critically important to understand the vaccine effectiveness (VE) of COVID-19 vaccines among IC populations as recommendations are updated over time in response to the evolving COVID-19 pandemic. Areas coveredA targeted literature review was conducted to identify real-world studies that assessed COVID-19 VE in IC populations between December 2020 and September 2021. A total of 10 studies from four countries were identified and summarized in this review. Expert opinion/commentaryVE of the widely available COVID-19 vaccines, including BNT162b2 (Pfizer/BioNTech), mRNA-1273 (Moderna), Ad26.COV2.S (Janssen), and ChAdOx1 nCoV-19 (Oxford/AstraZeneca), ranged from 64%-90% against SARS-CoV-2 infection, 73%-84% against symptomatic illness, 70%-100% against severe illness, and 63%-100% against COVID-19-related hospitalization among the fully vaccinated IC populations included in the studies. COVID-19 VE for most outcomes in the IC populations included in these studies was lower than in the general populations. These findings provide preliminary evidence that the IC population requires greater protective measures to prevent COVID-19 infection and associated illness, hence should be prioritized while implementing recommendations of additional COVID-19 vaccine doses.

Evaluation of COVID-19 vaccine breakthrough infections among immunocompromised patients fully vaccinated with BNT162b2

ObjectiveTo evaluate COVID-19 vaccine breakthrough infections among immunocompromised (IC) individuals. MethodsIndividuals vaccinated with BNT162b2 were selected from the US HealthVerity database (12/10/2020-7/8/2021). COVID-19 vaccine breakthrough infections were examined in fully vaccinated ([≥]14 days after 2nd dose) IC individuals (IC cohort), 12 mutually exclusive IC condition groups, and a non-IC cohort. IC conditions were identified using an algorithm based on diagnosis codes and immunosuppressive (IS) medication usage. ResultsOf 1,277,747 individuals [≥]16 years of age who received 2 BNT162b2 doses, 225,796 (17.7%) were identified as IC (median age: 58 years; 56.3% female). The most prevalent IC conditions were solid malignancy (32.0%), kidney disease (19.5%), and rheumatologic/inflammatory conditions (16.7%). Among the fully vaccinated IC and non-IC cohorts, a total of 978 breakthrough infections were observed during the study period; 124 (12.7%) resulted in hospitalization and 2 (0.2%) were inpatient deaths. IC individuals accounted for 38.2% (N=374) of all breakthrough infections, 59.7% (N=74) of all hospitalizations, and 100% (N=2) of inpatient deaths. The proportion with breakthrough infections was 3 times higher in the IC cohort compared to the non-IC cohort (N=374 [0.18%] vs. N=604 [0.06%]; unadjusted incidence rates were 0.89 and 0.34 per 100 person-years, respectively. Organ transplant recipients had the highest incidence rate; those with >1 IC condition, antimetabolite usage, primary immunodeficiencies, and hematologic malignancies also had higher incidence rates compared to the overall IC cohort. Incidence rates in older ([≥]65 years old) IC individuals were generally higher versus younger IC individuals (<65). LimitationsThis retrospective analysis relied on coding accuracy and had limited capture of COVID-19 vaccine receipt. ConclusionsCOVID-19 vaccine breakthrough infections are rare but are more common and severe in IC individuals. The findings from this large study support FDA authorization and CDC recommendations to offer a 3rd vaccine dose to increase protection among IC individuals.

Estimates of presumed population immunity to SARS-CoV-2 by state in the United States, August 2021

BackgroundInformation is needed to monitor progress toward a level of population immunity to SARS-CoV-2 sufficient to disrupt viral transmission. We estimated the percentage of the United States (US) population with presumed immunity to SARS-CoV-2 due to vaccination, natural infection, or both as of August 26, 2021. MethodsPublicly available data as of August 26, 2021, from the Centers for Disease Control and Prevention (CDC) were used to calculate presumed population immunity by state. Seroprevalence data were used to estimate the percentage of the population previously infected with SARS-CoV-2, with adjustments for underreporting. Vaccination coverage data for both fully and partially vaccinated persons were used to calculate presumed immunity from vaccination. Finally, we estimated the percentage of the total population in each state with presumed immunity to SARS-CoV-2, with a sensitivity analysis to account for waning immunity, and compared these estimates to a range of population immunity thresholds. ResultsPresumed population immunity varied among states (43.1% to 70.6%), with 19 states with 60% or less of their population having been infected or vaccinated. Four states have presumed immunity greater than thresholds estimated to be sufficient to disrupt transmission of less infectious variants (67%), and none were greater than the threshold estimated for more infectious variants (78% or higher). ConclusionsThe US remains a distance below the threshold sufficient to disrupt viral transmission, with some states remarkably low. As more infectious variants emerge, it is critical that vaccination efforts intensify across all states and ages for which the vaccines are approved. SummaryAs of August 26, 2021, no state has reached a population level of immunity thought to be sufficient to disrupt transmission. (78% or higher), with some states having remarkably low presumed immunity.