Publications by authors named "Kristin Dascomb"
Influenza vaccination is particularly important for pregnant women. Using a test-negative, case-control design, we estimated the effectiveness of 2023-2024 seasonal influenza vaccination against influenza-associated emergency department and urgent care (ED/UC) encounters among pregnant and non-pregnant women of reproductive age using data from seven healthcare systems. Eligible encounters were among individuals aged 18-49 years with documented female sex.
View Article and Find Full Text PDFEstimated 2023-2024 COVID-19 Vaccine Effectiveness in Adults.
JAMA Netw Open
June 2025
Importance: SARS-CoV-2 continues to evolve, population immunity changes, and COVID-19 vaccine formulas have been updated, necessitating ongoing COVID-19 vaccine effectiveness (VE) monitoring.
Objectives: To evaluate the VE of 2023-2024 COVID-19 vaccines against COVID-19-associated emergency department (ED) and urgent care (UC) encounters, hospitalizations, and critical illness, including during XBB- and JN.1-predominant periods.
Patterns in prescribing and dispensing of influenza antivirals among adults with influenza presenting to urgent care and emergency department settings, VISION Network, 2023-2024.
Clin Infect Dis
April 2025
Background: We describe prescribing and dispensing patterns of influenza antivirals among patients with laboratory-confirmed influenza within U.S. urgent care and emergency department settings.
View Article and Find Full Text PDFAnnual influenza vaccination is recommended for all persons aged ≥6 months in the United States. Interim influenza vaccine effectiveness (VE) was calculated among patients with acute respiratory illness-associated outpatient visits and hospitalizations from four VE networks during the 2024-25 influenza season (October 2024-February 2025). Among children and adolescents aged <18 years, VE against any influenza was 32%, 59%, and 60% in the outpatient setting in three networks, and against influenza-associated hospitalization was 63% and 78% in two networks.
View Article and Find Full Text PDFCOVID-19 vaccination averted approximately 68,000 hospitalizations during the 2023-24 respiratory season. In June 2024, CDC and the Advisory Committee on Immunization Practices (ACIP) recommended that all persons aged ≥6 months receive a 2024-2025 COVID-19 vaccine, which targets Omicron JN.1 and JN.
View Article and Find Full Text PDFInfluenza vaccine effectiveness against hospitalizations and emergency department or urgent care encounters for children, adolescents, and adults during the 2023-2024 season, United States.
Clin Infect Dis
December 2024
Background: The 2023-2024 influenza season had predominant influenza A(H1N1)pdm09 virus activity, but A(H3N2) and B viruses co-circulated. Seasonal influenza vaccine strains were well-matched to these viruses.
Methods: Using health care encounters data from health systems in 8 states, we evaluated influenza vaccine effectiveness (VE) against influenza-associated medical encounters from October 2023-April 2024.
Background: Respiratory syncytial virus vaccines first recommended for use during 2023 were efficacious against lower respiratory tract disease in clinical trials. Limited real-world data regarding respiratory syncytial virus vaccine effectiveness are available. To inform vaccine policy and address gaps in evidence from the clinical trials, we aimed to assess the effectiveness against respiratory syncytial virus-associated hospitalisations and emergency department encounters among adults aged at least 60 years.
View Article and Find Full Text PDFArticle Synopsis
- Pregnant individuals are at a higher risk for severe COVID-19, leading to current guidelines recommending updated vaccinations for everyone aged 6 months and older, regardless of pregnancy status.
- A study evaluated COVID-19 vaccine effectiveness among pregnant people aged 18 to 45 from June 2022 to August 2023, finding that vaccine effectiveness during pregnancy was 52%, compared to 28% when vaccination was received less than 6 months before pregnancy and only 6% when received more than 6 months prior.
- The findings suggest that pregnant individuals should remain up-to-date with recommended COVID-19 vaccinations for better protection against the virus.
Article Synopsis
- The 2022-2023 influenza season in the U.S. experienced high hospitalization rates and early influenza activity, primarily driven by A(H3N2) viruses, with some A(H1N1)pdm09 cases.
- A study using the test-negative design assessed the effectiveness of the influenza vaccine by comparing cases of influenza-positive patients to those who tested negative among adults with respiratory illness from October 2022 to March 2023.
- The results showed moderate vaccine effectiveness of 44% for emergency department visits and 35% for hospitalizations, indicating that vaccination helps reduce the impact of influenza during a challenging season with other circulating respiratory viruses.
Article Synopsis
- The CDC recommended the updated 2023-2024 COVID-19 vaccination (monovalent XBB.1.5) for everyone aged 6 months and older to help prevent severe disease caused by COVID-19.
- For individuals with immunocompromising conditions, additional vaccine doses may be needed due to their increased risk of severe illness and potentially weaker vaccine responses.
- Vaccine effectiveness for the updated dose was about 38% for hospitalized adults with immunocompromising conditions 7-59 days post-vaccination and 34% between 60-119 days, but only 18% of this high-risk group had received the updated vaccine.
Risk of COVID-19 Hospitalization and Protection Associated With mRNA Vaccination Among US Adults With Psychiatric Disorders.
Influenza Other Respir Viruses
March 2024
Background: Although psychiatric disorders have been associated with reduced immune responses to other vaccines, it remains unknown whether they influence COVID-19 vaccine effectiveness (VE). This study evaluated risk of COVID-19 hospitalization and estimated mRNA VE stratified by psychiatric disorder status.
Methods: In a retrospective cohort analysis of the VISION Network in four US states, the rate of laboratory-confirmed COVID-19-associated hospitalization between December 2021 and August 2022 was compared across psychiatric diagnoses and by monovalent mRNA COVID-19 vaccination status using Cox proportional hazards regression.
Interim Effectiveness of Updated 2023-2024 (Monovalent XBB.1.5) COVID-19 Vaccines Against COVID-19-Associated Emergency Department and Urgent Care Encounters and Hospitalization Among Immunocompetent Adults Aged ≥18 Years - VISION and IVY Networks, September 2023-January 2024.
MMWR Morb Mortal Wkly Rep
February 2024
Article Synopsis
- In September 2023, the CDC recommended the updated 2023-2024 monovalent XBB.1.5 COVID-19 vaccine for everyone aged 6 months and older to help prevent COVID-19, including severe cases.
- An analysis of vaccine effectiveness (VE) found that during the first 59 days after vaccination, the VE against COVID-19-related emergency department visits was 51%, which dropped to 39% after 60-119 days.
- The updated COVID-19 vaccine showed increased protection, with VE against hospitalizations being 52% and 43% between two networks, supporting CDC's guidelines for vaccination.
Interim Estimates of 2023-24 Seasonal Influenza Vaccine Effectiveness - United States.
MMWR Morb Mortal Wkly Rep
February 2024
In the United States, annual influenza vaccination is recommended for all persons aged ≥6 months. Using data from four vaccine effectiveness (VE) networks during the 2023-24 influenza season, interim influenza VE was estimated among patients aged ≥6 months with acute respiratory illness-associated medical encounters using a test-negative case-control study design. Among children and adolescents aged 6 months-17 years, VE against influenza-associated outpatient visits ranged from 59% to 67% and against influenza-associated hospitalization ranged from 52% to 61%.
View Article and Find Full Text PDFArticle Synopsis
- The 2022-2023 influenza season in the U.S. saw the highest rate of pediatric hospitalization since 2010-2011, primarily caused by Influenza A/H3N2 infections.
- A study analyzed nearly 45,000 emergency department visits and hospitalizations for children aged 6 months to 17 years, focusing on the effectiveness of the influenza vaccine using a comparison between vaccinated and unvaccinated patients.
- Results showed that vaccination significantly reduced the risk of influenza-related emergency visits and hospitalizations by approximately 40-48%, emphasizing the importance of flu shots in preventing severe illness in kids and teens.
Clinical Epidemiology and Risk Factors for Critical Outcomes Among Vaccinated and Unvaccinated Adults Hospitalized With COVID-19-VISION Network, 10 States, June 2021-March 2023.
Clin Infect Dis
February 2024
Background: The epidemiology of coronavirus disease 2019 (COVID-19) continues to develop with emerging variants, expanding population-level immunity, and advances in clinical care. We describe changes in the clinical epidemiology of COVID-19 hospitalizations and risk factors for critical outcomes over time.
Methods: We included adults aged ≥18 years from 10 states hospitalized with COVID-19 June 2021-March 2023.
Effectiveness of Monovalent and Bivalent mRNA Vaccines in Preventing COVID-19-Associated Emergency Department and Urgent Care Encounters Among Children Aged 6 Months-5 Years - VISION Network, United States, July 2022-June 2023.
MMWR Morb Mortal Wkly Rep
August 2023
Article Synopsis
- - On June 19, 2022, the FDA approved mRNA COVID-19 vaccines for young children based on safety and efficacy data from trials, with Pfizer-BioNTech for ages 6 months-4 years and Moderna for ages 6 months-5 years.
- - The CDC updated vaccine recommendations on December 9, 2022, including the use of bivalent vaccines for children aged 6 months and older, after assessing their effectiveness against hospital visits for COVID-19-like illness.
- - Effectiveness of two Moderna doses was found to be 29%, while three Pfizer doses showed 43% effectiveness; however, children who received at least one bivalent dose had an 80% effectiveness in preventing
Article Synopsis
- Immunocompromised (IC) individuals face a higher risk of severe COVID-19 and have reduced vaccine effectiveness compared to non-immunocompromised (non-IC) individuals.
- A study analyzed emergency department visits and hospitalizations among IC and non-IC adults, finding that vaccine effectiveness was significantly lower in IC patients, particularly for those who received 3 doses of mRNA vaccines or 1-2 doses of viral-vector vaccines.
- Despite some protection from vaccines, the results indicate a pressing need for additional safeguards for IC adults, especially transplant recipients who showed the lowest vaccine effectiveness.
Estimates of Bivalent mRNA Vaccine Durability in Preventing COVID-19-Associated Hospitalization and Critical Illness Among Adults with and Without Immunocompromising Conditions - VISION Network, September 2022-April 2023.
Am J Transplant
July 2023
Number needed to vaccinate with a COVID-19 booster to prevent a COVID-19-associated hospitalization during SARS-CoV-2 Omicron BA.1 variant predominance, December 2021-February 2022, VISION Network: a retrospective cohort study.
Lancet Reg Health Am
July 2023
Article Synopsis
- The study aims to evaluate the effectiveness of COVID-19 booster doses in preventing hospitalizations and emergency department visits, providing insight for public health policies.
- Data was collected from over 1.2 million adults at five health systems during the Omicron variant's rise, showing that approximately 37% received a booster dose.
- The median number needed to vaccinate (NNV) to prevent one hospitalization was 205, with lower NNV for adults aged 65 and older and those with health conditions, indicating booster effectiveness varies by age and health status.
Estimates of Bivalent mRNA Vaccine Durability in Preventing COVID-19-Associated Hospitalization and Critical Illness Among Adults with and Without Immunocompromising Conditions - VISION Network, September 2022-April 2023.
MMWR Morb Mortal Wkly Rep
May 2023
On September 1, 2022, CDC's Advisory Committee on Immunization Practices (ACIP) recommended a single bivalent mRNA COVID-19 booster dose for persons aged ≥12 years who had completed at least a monovalent primary series. Early vaccine effectiveness (VE) estimates among adults aged ≥18 years showed receipt of a bivalent booster dose provided additional protection against COVID-19-associated emergency department and urgent care visits and hospitalizations compared with that in persons who had received only monovalent vaccine doses (1); however, insufficient time had elapsed since bivalent vaccine authorization to assess the durability of this protection. The VISION Network* assessed VE against COVID-19-associated hospitalizations by time since bivalent vaccine receipt during September 13, 2022-April 21, 2023, among adults aged ≥18 years with and without immunocompromising conditions.
View Article and Find Full Text PDFArticle Synopsis
- A study evaluated the effectiveness of the BNT162b2 COVID-19 vaccine on children and adolescents during the Omicron BA.4/BA.5 period, focusing on its ability to protect against mild to moderate and severe cases of COVID-19.
- The research compared data from nearly 10,000 emergency department cases and over 70,000 controls, finding that vaccine effectiveness decreased over time, especially during the Omicron variant's spread.
- It concluded that while the vaccine offered significant protection initially, especially against hospitalizations, booster doses enhanced effectiveness, highlighting the importance of completing the vaccination schedule for children and adolescents.
Early Estimates of Bivalent mRNA Vaccine Effectiveness in Preventing COVID-19-Associated Emergency Department or Urgent Care Encounters and Hospitalizations Among Immunocompetent Adults - VISION Network, Nine States, September-November 2022.
MMWR Morb Mortal Wkly Rep
March 2023
Article Synopsis
- - During mid-2022, the Omicron BA.5 variant was the dominant strain of SARS-CoV-2 in the U.S., and bivalent mRNA vaccines were introduced containing both the original virus strain and components targeting Omicron BA.4/BA.5.
- - A single bivalent booster was recommended for adults who had completed their primary vaccination and had not received a dose in the past two months, with effectiveness being evaluated from September to November 2022.
- - Results showed that the bivalent booster significantly reduced the risk of COVID-19-related emergency visits (56% effectiveness) and hospitalizations (59% effectiveness) compared to those unvaccinated or with only monovalent vaccines, highlighting the importance
Article Synopsis
- The Omicron sublineages BA.4 and BA.5 show increased immune evasion, reducing the effectiveness of COVID-19 mRNA vaccines in preventing illness among immunocompetent adults.
- A study across 10 states focused on vaccinated adults, assessing the effectiveness of 2 to 4 vaccine doses during periods of BA.4 and BA.5 circulation, and examining the severity of COVID-19 in hospitalized patients across different Omicron sublineages.
- Results indicated that in a large sample of emergency department and hospitalized patients, a significant portion tested positive for SARS-CoV-2, highlighting ongoing challenges in vaccine effectiveness and patient outcomes during these variant periods.
Article Synopsis
- A study was conducted in the U.S. to evaluate the effectiveness of COVID-19 mRNA vaccines and previous SARS-CoV-2 infections during Delta and Omicron variant periods.
- The research found that both 2- or 3-dose vaccinated individuals and those with a prior infection had high protection against hospitalizations and emergency care during the Delta period (91%-97%), but this protection decreased during the Omicron period (77%-90%).
- The results highlight that staying up-to-date with COVID-19 vaccinations continues to offer significant protection against severe illness, regardless of prior exposure to the virus.
Article Synopsis
- The 2021-2022 influenza season in the U.S. experienced a resurgence following very low activity the previous year, primarily due to the A(H3N2) virus strain.
- A study analyzed vaccine effectiveness (VE) among adults over 18 through hospital and urgent care visits, revealing that vaccination reduced the odds of influenza by 25% for both ED/UC encounters and hospitalizations.
- The vaccine was notably less effective for older adults (≥65 years) and those with weakened immune systems, indicating a need for better vaccine formulations against A(H3N2) strains.