Early mathematical models of COVID-19 vaccination in high-income countries: a systematic review.

OBJECTIVES: Since COVID-19 first emerged in 2019, mathematical models have been developed to predict transmission and provide insight into disease control strategies. A key research need now is for models to inform long-term vaccination policy. We aimed to review the early modelling methods utilised during the pandemic period (2019-2023) in order to identify gaps in the literature and highlight areas for future model development. STUDY DESIGN: This study was a systematic review. METHODS: We searched PubMed, Embase and Scopus from 1 January 2019 to 6 February 2023 for peer-reviewed, English-language articles describing age-structured, dynamic, mathematical models of COVID-19 transmission and vaccination in high-income countries that include waning immunity or reinfection. We extracted details of the structure, features and approach of each model and combined them in a narrative synthesis. RESULTS: Of the 1109 articles screened, 47 were included. Most studies used deterministic, compartmental models set in Europe or North America that simulated a time horizon of 3.5 years or less. Common outcomes included cases, hospital utilisation and deaths. Only nine models included long COVID, costs, life years or quality of life-related measures. Two studies explored the potential impact of new variants beyond Omicron. CONCLUSIONS: This review demonstrates a need for long-term models that focus on outcome measures such as quality-adjusted life years, the population-level effects of long COVID and the cost effectiveness of future policies - all of which are essential considerations in the planning of long-term vaccination strategies.

Has the HCV cascade of care changed among people who inject drugs in England since the introduction of direct-acting antivirals?

BACKGROUND: In England, over 80 % of those with hepatitis C virus (HCV) infection have injected drugs. We quantified the HCV cascade of care (CoC) among people who inject drugs (PWID) in England and determined whether this improved after direct-acting antivirals (DAAs) were introduced. METHODS: We analysed data from nine rounds of national annual cross-sectional surveys of PWID recruited from drug services (2011-2019; N = 12,320). Study rounds were grouped as: 'Pre-DAAs' (2011-2014), 'Prioritised DAAs' (2015-2016) and 'Unrestricted DAAs' (2017-2019). Participants were anonymously tested for HCV antibodies and RNA and completed a short survey. We assessed the proportion of PWID recently (current/previous year) tested for HCV. For participants ever HCV treatment eligible (past chronic infection with history of treatment or current chronic infection), we assessed the CoC as: HCV testing (ever), received a positive test result, seen a specialist nurse/doctor, and ever treated. We used logistic regression to determine if individuals progressed through the CoC differently depending on time-period, whether time-period was associated with recent testing (all participants) and lifetime HCV treatment (ever eligible participants), and predictors of HCV testing and treatment in the Unrestricted DAAs period. RESULTS: The proportion of ever HCV treatment eligible PWID reporting lifetime HCV treatment increased from 12.5 % in the Pre-DAAs period to 25.6 % in the Unrestricted DAAs period (aOR:2.40, 95 %CI:1.95-2.96). There were also increases in seeing a specialist nurse/doctor. The largest loss in the CoC was at treatment for all time periods. During the Unrestricted DAAs period, recent (past year) homelessness (vs never, aOR:0.66, 95 %CI:0.45-0.97), duration of injecting (≤3 years vs >3 years; aOR:0.26, 95 %CI:0.12-0.60), never (vs current, aOR:0.31, 95 %CI:0.13-0.75) or previously being prescribed OAT (vs current, aOR:0.67, 95 %CI:0.47-0.95), and never using a NSP (vs past year, aOR:0.27, 95 %CI:0.08-0.89) were negatively associated with lifetime HCV treatment. The proportion of PWID reporting recent HCV testing was higher during Unrestricted DAAs (56 %) compared to Pre-DAAs (48 %; aOR:1.28, 95 %CI:1.06-1.54). CONCLUSION: COC stages from seeing a specialist onwards improved after DAAs became widely available. Further improvements in HCV testing are needed to eliminate HCV in England.

State-level estimates of childhood obesity prevalence in the United States corrected for report bias.

BACKGROUND/OBJECTIVES: State-specific obesity prevalence data are critical to public health efforts to address the childhood obesity epidemic. However, few states administer objectively measured body mass index (BMI) surveillance programs. This study reports state-specific childhood obesity prevalence by age and sex correcting for parent-reported child height and weight bias. SUBJECTS/METHODS: As part of the Childhood Obesity Intervention Cost Effectiveness Study (CHOICES), we developed childhood obesity prevalence estimates for states for the period 2005-2010 using data from the 2010 US Census and American Community Survey (ACS), 2003-2004 and 2007-2008 National Survey of Children's Health (NSCH) (n=133 213), and 2005-2010 National Health and Nutrition Examination Surveys (NHANES) (n=9377; ages 2-17). Measured height and weight data from NHANES were used to correct parent-report bias in NSCH using a non-parametric statistical matching algorithm. Model estimates were validated against surveillance data from five states (AR, FL, MA, PA and TN) that conduct censuses of children across a range of grades. RESULTS: Parent-reported height and weight resulted in the largest overestimation of childhood obesity in males ages 2-5 years (NSCH: 42.36% vs NHANES: 11.44%). The CHOICES model estimates for this group (12.81%) and for all age and sex categories were not statistically different from NHANES. Our modeled obesity prevalence aligned closely with measured data from five validation states, with a 0.64 percentage point mean difference (range: 0.23-1.39) and a high correlation coefficient (r=0.96, P=0.009). Estimated state-specific childhood obesity prevalence ranged from 11.0 to 20.4%. CONCLUSION: Uncorrected estimates of childhood obesity prevalence from NSCH vary widely from measured national data, from a 278% overestimate among males aged 2-5 years to a 44% underestimate among females aged 14-17 years. This study demonstrates the validity of the CHOICES matching methods to correct the bias of parent-reported BMI data and highlights the need for public release of more recent data from the 2011 to 2012 NSCH.