Publications by authors named "Kristin Andrejko"

Background: (pneumococcus) causes invasive pneumococcal disease (IPD) and non-invasive acute respiratory infections (ARIs). Three pneumococcal conjugate vaccines (PCVs) are recommended in the United States with additional products in clinical trials. We aimed to estimate 1) proportions of IPD cases and pneumococcal ARIs caused by serotypes targeted by existing and pipeline PCVs and 2) annual U.

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Article Synopsis
  • The study investigated the bacterial causes of acute otitis media (AOM) in children and the impact of new higher-valency pneumococcal vaccines on these infections.
  • It involved analyzing samples from well-child visits and AOM onset in children aged 6-36 months from 2021 to 2023, focusing on common bacteria: Streptococcus pneumoniae (Spn), Haemophilus influenzae (Hflu), and Moraxella catarrhalis (Mcat).
  • Findings revealed that non-PCV15 and non-PCV20 serotypes of Spn were prevalent, with Hflu being the most common cause of AOM; also, antibiotic resistance was noted, suggesting the need for stronger treatment
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Objective: To describe the implementation of a test-negative design case-control study in California during the Coronavirus Disease 2019 (COVID-19) pandemic.

Study Design: Test-negative case-control study.

Methods: Between February 24, 2021 - February 24, 2022, a team of 34 interviewers called 38,470 Californians, enrolling 1,885 that tested positive for SARS-CoV-2 (cases) and 1,871 testing negative for SARS-CoV-2 (controls) for 20-minute telephone survey.

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Background: A U.S. case-control study (2010-2014) demonstrated vaccine effectiveness (VE) for ≥ 1 dose of the thirteen-valent pneumococcal conjugate vaccine (PCV13) against vaccine-type (VT) invasive pneumococcal disease (IPD) at 86 %; however, it lacked statistical power to examine VE by number of doses and against individual serotypes.

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Background: In 2022-2023, 15- and 20-valent pneumococcal conjugate vaccines (PCV15/PCV20) were recommended for infants. We aimed to estimate the incidence of outpatient visits and antibiotic prescriptions in US children (≤17 years) from 2016-2019 for acute otitis media, pneumonia, and sinusitis associated with PCV15- and PCV20-additional (non-PCV13) serotypes to quantify PCV15/20 potential impacts.

Methods: We estimated the incidence of PCV15/20-additional serotype-attributable visits and antibiotic prescriptions as the product of all-cause incidence rates, derived from national health care surveys and MarketScan databases, and PCV15/20-additional serotype-attributable fractions.

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Importance: is a known etiology of acute respiratory infections (ARIs), which account for large proportions of outpatient visits and antibiotic use in children. In 2023, 15- and 20-valent pneumococcal conjugate vaccines (PCV15, PCV20) were recommended for routine use in infants. However, the burden of outpatient healthcare utilization among U.

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Introduction: Uptake of COVID-19 vaccination remains suboptimal in the United States and other settings. Though early reports indicated that a strong majority of people were interested in receiving the COVID-19 vaccine, the association between vaccine intention and uptake is not yet fully understood. Ourobjective was todescribe predictors of vaccine uptake, and estimate the sensitivity, specificity, and predictive values of self-reported COVID-19 vaccine status compared to a comprehensive statewide COVID-19 vaccine registry.

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Concerns about the duration of protection conferred by coronavirus disease 2019 (COVID-19) vaccines have arisen in postlicensure evaluations. "Depletion of susceptibles," a bias driven by differential accrual of infection among vaccinated and unvaccinated individuals, may obscure vaccine effectiveness (VE) estimates, hindering interpretation. We enrolled California residents who received molecular SARS-CoV-2 tests in a matched, test-negative design, case-control study to estimate VE of mRNA-based COVID-19 vaccines between February 23 and December 5, 2021.

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Background: Despite lower circulation of influenza virus throughout 2020-2022 during the COVID-19 pandemic, seasonal influenza vaccination has remained a primary tool to reduce influenza-associated illness and death. The relationship between the decision to receive a COVID-19 vaccine and/or an influenza vaccine is not well understood.

Methods: We assessed predictors of receipt of 2021-2022 influenza vaccine in a secondary analysis of data from a case-control study enrolling individuals who received SARS-CoV-2 testing.

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Mathematical modeling studies are frequently conducted to guide policy in global health. However, the contribution of mathematical modeling studies to World Health Organization (WHO) guideline recommendations, and the quality of evidence contributed by these studies remains unknown. We conducted a systematic review of the WHO Guidelines Review Committee database to identify guideline recommendations that included evidence from mathematical modeling studies since inception of the Guidelines Review Committee on 1 December, 2007.

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Background: The San Francisco Bay Area was the first region in the United States to enact school closures to mitigate SARS-CoV-2 transmission. The effects of closures on contact patterns for schoolchildren and their household members remain poorly understood.

Methods: We conducted serial cross-sectional surveys (May 2020, September 2020, February 2021) of Bay Area households with children to estimate age-structured daily contact rates for children and their adult household members.

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The use of face masks or respirators (N95/KN95) is recommended to reduce transmission of SARS-CoV-2, the virus that causes COVID-19 (1). Well-fitting face masks and respirators effectively filter virus-sized particles in laboratory conditions (2,3), though few studies have assessed their real-world effectiveness in preventing acquisition of SARS-CoV-2 infection (4). A test-negative design case-control study enrolled randomly selected California residents who had received a test result for SARS-CoV-2 during February 18-December 1, 2021.

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Background: Hundreds of thousands of biodigesters have been constructed in Nepal. These household-level systems use human and animal waste to produce clean-burning biogas used for cooking, which can reduce household air pollution from woodburning cookstoves and prevent respiratory illnesses. The biodigesters, typically operated by female caregivers, require the handling of animal waste, which may increase domestic fecal contamination, exposure to diarrheal pathogens, and the risk of enteric infections, especially among young children.

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Background: Non-pharmaceutical interventions (NPIs) are recommended for COVID-19 prevention. However, the effectiveness of NPIs in preventing SARS-CoV-2 transmission remains poorly quantified.

Methods: We conducted a test-negative design case-control study enrolling cases (testing positive for SARS-CoV-2) and controls (testing negative) with molecular SARS-CoV-2 diagnostic test results reported to California Department of Public Health between 24 February-12 November, 2021.

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Background: We examined school reopening policies amidst ongoing transmission of the highly transmissible Delta variant, accounting for vaccination among individuals ≥12 years.

Methods: We collected data on social contacts among school-aged children in the California Bay Area and developed an individual-based transmission model to simulate transmission of the Delta variant of SARS-CoV-2 in schools. We evaluated the additional infections in students and teachers/staff resulting over a 128-day semester from in-school instruction compared to remote instruction when various NPIs (mask use, cohorts, and weekly testing of students/teachers) were implemented, across various community-wide vaccination coverages (50%, 60%, 70%), and student (≥12 years) and teacher/staff vaccination coverages (50% - 95%).

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Background: Pneumococcal serotypes differ in antimicrobial susceptibility. However, patterns and causes of this variation are not comprehensively understood.

Methods: We undertook a systematic review of epidemiologic studies of pneumococci isolated from carriage or invasive disease among children globally from 2000-2019.

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Background: Pneumococcal diseases are a leading cause of morbidity and mortality among children globally, and the burden of these diseases might be worsened by antimicrobial resistance. To understand the effect of pneumococcal conjugate vaccine (PCV) deployment on antimicrobial resistance in pneumococci, we assessed the susceptibility of paediatric pneumococcal isolates to various antimicrobial drugs before and after PCV implementation.

Methods: We did a systematic review of studies reporting antimicrobial susceptibility profiles of paediatric pneumococcal isolates between 2000 and 2020 using PubMed and the Antimicrobial Testing Leadership and Surveillance database (ATLAS; Pfizer).

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Background: We examined school reopening policies amidst rising transmission of the highly transmissible Delta variant, accounting for vaccination among individuals aged 12 years and older, with the goal of characterizing risk to students and teachers under various within-school non-pharmaceutical interventions (NPIs) combined with specific vaccination coverage levels.

Methods: We developed an individual-based transmission model to simulate transmission of the Delta variant of SARS-CoV-2 among a synthetic population, representative of Bay Area cities. We parameterized the model using community contact rates from vaccinated households ascertained from a household survey of Bay Area families with children conducted between February - April, 2021.

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Background: Estimates of coronavirus disease 2019 (COVID-19) vaccine effectiveness under real-world conditions, and understanding of barriers to uptake, are necessary to inform vaccine rollout.

Methods: We enrolled cases (testing positive) and controls (testing negative) from among the population whose SARS-CoV-2 molecular diagnostic test results from 24 February to 29 April 2021 were reported to the California Department of Public Health. Participants were matched on age, sex, and geographic region.

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Background: Vaccines are needed to reduce the burden of group A Streptococcus (GAS). We assessed the potential health-economic value of GAS vaccines achievable through prevention of invasive disease and acute upper respiratory infections in the United States.

Methods: We estimated annual incidence of invasive GAS disease and associated costs incurred from hospitalization and management of long-term sequelae, as well as productivity losses resulting from acute illness, long-term disability, and mortality.

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School closures may reduce the size of social networks among children, potentially limiting infectious disease transmission. To estimate the impact of K-12 closures and reopening policies on children's social interactions and COVID-19 incidence in California's Bay Area, we collected data on children's social contacts and assessed implications for transmission using an individual-based model. Elementary and Hispanic children had more contacts during closures than high school and non-Hispanic children, respectively.

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During the ongoing coronavirus disease (COVID-19) pandemic, farmworkers in the United States are considered essential personnel and continue in-person work. We conducted prospective surveillance for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and antibody prevalence among farmworkers in Salinas Valley, California, during June 15-November 30, 2020. We observed 22.

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Background Large-scale school closures have been implemented worldwide to curb the spread of COVID-19. However, the impact of school closures and re-opening on epidemic dynamics remains unclear. Methods We simulated COVID-19 transmission dynamics using an individual-based stochastic model, incorporating social-contact data of school-aged children during shelter-in-place orders derived from Bay Area (California) household surveys.

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Malaria in pregnancy (MiP) contributes to devastating maternal and neonatal outcomes. Coverage of intermittent preventive treatment during pregnancy (IPTp) remains alarmingly low. Data was compiled from MiP programme reviews and performed a literature search on access to and determinants of IPTp.

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Background: Malaria infection poses a significant risk in pregnancy, yet chemoprophylaxis for pregnant women is limited. A systematic review was conducted to evaluate the incidence of adverse outcomes after atovaquone-proguanil (AP) exposure during pregnancy.

Methods: Following PRISMA guidelines, the authors searched PubMed, MEDLINE, and the Malaria in Pregnancy Consortium Library to identify relevant literature including infant outcomes after exposure to atovaquone, proguanil, or AP in pregnancy.

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