Household Secondary Attack Rates of SARS-CoV-2 by Variant and Vaccination Status

JAMA Network Open, Journal Year: 2022, Volume and Issue: 5(4), P. e229317 - e229317

Published: April 28, 2022

Importance

An overall household secondary attack rate (SAR) of 18.9% (95% CI, 16.2%-22.0%) through June 17, 2021 was previously reported for SARS-CoV-2. Emerging variants concern and increased vaccination have affected transmission rates.

Objective

To evaluate how SARs changed over time whether varied by viral variant index case contact status.

Data Sources

PubMed medRxiv from 18, 2021, March 8, 2022, reference lists eligible articles. Preprints were included.

Study Selection

Articles with original data reporting the number infected total contacts. Search terms includedSARS-CoV-2,COVID-19,variant,vaccination,secondary rate,secondary infection rate,household,index case, family contacts,close contacts,andfamily transmission. Extraction Synthesis The Preferred Reporting Items Systematic Reviews Meta-Analyses guideline followed. Meta-analyses used generalized linear mixed models to obtain SAR estimates 95% CIs.

Main Outcomes Measures

stratified covariates according variant, status, identification period. estimate vaccine effectiveness on basis probability susceptibility (VES,p), infectiousness given (VEI,p), (VET,p).

Results

Household higher 33 studies midpoints in 2022 (37.3%; 32.7% 42.1%) compared 63 April 2020 (15.5%; 13.2% 18.2%). 42.7% 35.4% 50.4%) Omicron (7 studies), 36.4% 33.4% 39.5%) Alpha (11 29.7% 23.0% 37.3%) Delta (16 22.5% 18.6% 26.8%) Beta (3 studies). For full vaccination,VES,pwas 78.6% 76.0% 80.9%) Alpha, 56.4% 54.6% 58.1%) Delta, 18.1% −18.3% 43.3%) Omicron;VEI,pwas 75.3% 69.9% 79.8%) 21.9% 11.0% 31.5%) 18.2% 0.6% 32.6%) Omicron; andVET,pwas 94.7% 93.3% 95.8%) 64.4% 58.0% 69.8%) 35.8% 13.0% 52.6%) Omicron.

Conclusions Relevance

These results suggest that emerging SARS-CoV-2 transmissibility. Full associated reductions infectiousness, but more so than changes estimated underscore challenges developing effective vaccines concomitant evolution.

Language: Английский

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Challenges for modelling interventions for future pandemics

Epidemics, Journal Year: 2022, Volume and Issue: 38, P. 100546 - 100546

Published: Feb. 11, 2022

Mathematical modelling and statistical inference provide a framework to evaluate different non-pharmaceutical pharmaceutical interventions for the control of epidemics that has been widely used during COVID-19 pandemic. In this paper, lessons learned from previous are highlight challenges future pandemic control. We consider availability use data, as well need correct parameterisation calibration model frameworks. discuss arise in describing distinguishing between interventions, within structures, allowing both host dynamics. also health economic political aspects interventions. Given diversity these challenges, broad variety interdisciplinary expertise is needed address them, combining mathematical knowledge with biological social insights, including economics communication skills. Addressing requires strong cross-disciplinary collaboration together close scientists policy makers.

Language: Английский

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Rapid review and meta-analysis of serial intervals for SARS-CoV-2 Delta and Omicron variants

BMC Infectious Diseases, Journal Year: 2023, Volume and Issue: 23(1)

Published: June 26, 2023

The serial interval is the period of time between symptom onset in primary case and secondary case. Understanding important for determining transmission dynamics infectious diseases like COVID-19, including reproduction number attack rates, which could influence control measures. Early meta-analyses COVID-19 reported intervals 5.2 days (95% CI: 4.9-5.5) original wild-type variant 4.87-5.47) Alpha variant. has been shown to decrease over course an epidemic other respiratory diseases, may be due accumulating viral mutations implementation more effective nonpharmaceutical interventions. We therefore aggregated literature estimate Delta Omicron variants.

Language: Английский

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Nowcasting and forecasting the 2022 U.S. mpox outbreak: Support for public health decision making and lessons learned

Epidemics, Journal Year: 2024, Volume and Issue: 47, P. 100755 - 100755

Published: March 2, 2024

In June of 2022, the U.S. Centers for Disease Control and Prevention (CDC) Mpox Response wanted timely answers to important epidemiological questions which can now be answered more effectively through infectious disease modeling. Infectious models have shown valuable tools decision making during outbreaks; however, model complexity often makes communicating results limitations makers difficult. We performed nowcasting forecasting 2022 mpox outbreak in United States using R package EpiNow2. generated nowcasts/forecasts at national level, by Census region, jurisdictions reporting greatest number cases. Modeling were shared situational awareness within CDC publicly on website. retrospectively evaluated forecast predictions four key phases (early, exponential growth, peak, decline) three metrics, weighted interval score, mean absolute error, prediction coverage. compared performance EpiNow2 with a naïve Bayesian generalized linear (GLM). The had less probabilistic error than GLM every phase except early phase. share our experiences an existing tool nowcasting/forecasting highlight areas improvement development future tools. also reflect lessons learned regarding data quality issues adapting modeling different audiences.

Language: Английский

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From bench to clinic: the development of VLA1553/IXCHIQ, a live-attenuated chikungunya vaccine

Journal of Travel Medicine, Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 9, 2024

Abstract Background Over the past 20 years, over 5 million cases of chikungunya, a mosquito-transmitted viral disease, have been reported in 110 countries. Until recently, preventative strategies for chikungunya were largely ineffective, relying on vector control and individual avoidance mosquito bites. Methods This review outlines preclinical clinical efficacy safety data that led to approval VLA1553 (IXCHIQ®), live-attenuated vaccine against disease. It also describes innovative development pathway VLA1553, based an immunological surrogate protection, discusses ongoing future post-licensure studies. Results In mice non-human primate models, elicited high titres neutralizing antibodies, conferred protection wild-type virus challenge raised no concerns. A Phase 1 trial demonstrated 100% seroconversion among 120 healthy participants, with sustained antibody after 12 months. These results determination marker advancement directly into 3 development, as agreed US Food Drug Administration (FDA) European Medicines Agency. The pivotal met its primary immunogenicity endpoint, achieving seroprotective levels immuno-bridging baseline seronegative participants 28 days post-vaccination. findings enabled submission Biologics Licence Application FDA accelerated adults aged ≥18 years. Ongoing planned studies will confirm efficacy/effectiveness younger individuals, generate endemic countries highest unmet need. Conclusion is first approved prevention disease adults, following serological protection. adds reduce spread burden populations travellers.

Language: Английский

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Mathematical modelling for vaccine efficacy trials during the future epidemics of emerging respiratory infections

Human Vaccines & Immunotherapeutics, Journal Year: 2025, Volume and Issue: 21(1)

Published: Feb. 19, 2025

Assessing vaccine efficacy (VE) during emerging epidemics is challenging due to unpredictable disease transmission dynamics. We aimed investigate the impact of randomized controlled trials (RCTs) timing on estimates VE and sample sizes future respiratory diseases. developed an age-structured susceptible-exposed-infected-asymptomatically infected-removed (SEIAR) compartment models using 2022 Korean population, COVID-19 2009 A/H1N1 pandemic influenza parameters. Various RCT scenarios were tested calculate estimates, size power by varying timings (using epidemic peak as base, ±10%, ±20%, ±30% relative time peak) with follow-up durations (4 weeks 8 12 weeks), recruitment 2, 8, non-pharmaceutical intervention (NPI) levels in reducing R0 10% 20%. Additionally, assumptions regarding baseline cumulative incidences evaluated for calculations. The results showed that remained relatively stable across trial timings; however, required varied significantly timing. Sample requirements initially decreased after a then increased steeply progressed. Initiating RCTs 30% earlier than peak, along extended duration, could reduce without compromising VE. NPIs effectively feasible timeframe RCTs. based simulated case numbers placebo group slightly underestimated, consistently above 85%. In contrast, calculations incidence over 4 pretrial or entire study duration lead overpowered underpowered studies.

Language: Английский

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An influential study of a time-delayed epidemic model incorporating vaccination and treatment interventions

Advances in Continuous and Discrete Models, Journal Year: 2025, Volume and Issue: 2025(1)

Published: Feb. 26, 2025

Abstract A mathematical model delineating the dynamics of infectious diseases under appropriate vaccination and treatment efforts is analyzed. The study thoroughly investigates implications time delays inherent in vaccine preparation administration, transition from to recovery, timeline exposure infection. strengthened by establishing essential properties such as nonnegativity, boundedness, existence solutions, equilibria. An estimate basic reproduction number provided facilitate a preliminary understanding disease behavior. Furthermore, local stability disease-free endemic equilibria examined relation number, highlighting model’s capacity predict dynamics. Moreover, global for ultimate impact disease, initial incidence may or not continue its influence presence counteracting effects throughout system. Finally, results are tested with parameters chosen recently collected data on COVID-19, numerical examples presented support theoretical concepts proposed. Simulations visualize these examples.

Language: Английский

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Household secondary attack rates of SARS-CoV-2 by variant and vaccination status: an updated systematic review and meta-analysis

medRxiv (Cold Spring Harbor Laboratory), Journal Year: 2022, Volume and Issue: unknown

Published: Jan. 11, 2022

We previously reported a household secondary attack rate (SAR) for SARS-CoV-2 of 18.9% through June 17, 2021. To examine how emerging variants and increased vaccination have affected transmission rates, we searched PubMed from 18, 2021, January 7, 2022. Meta-analyses used generalized linear mixed models to obtain SAR estimates 95%CI, disaggregated by several covariates. SARs were estimate vaccine effectiveness based on the probability susceptibility (

Language: Английский

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The ring vaccination trial design for the estimation of vaccine efficacy and effectiveness during infectious disease outbreaks

Clinical Trials, Journal Year: 2022, Volume and Issue: 19(4), P. 402 - 406

Published: Jan. 21, 2022

The ring vaccination trial is a recently developed approach for evaluating the efficacy and effectiveness of vaccines, modeled after surveillance containment strategy vaccination. Contacts contacts newly identified disease case form ring, these rings are randomized as part cluster-randomized or with individual randomization within rings. Key advantages design include its flexibility to follow epidemic it progresses targeting high-risk participants increase power. We describe application estimate an Ebola vaccine during 2014–2016 West African epidemic. has several notable statistical features. Because occurs around time exposure, particularly sensitive choice per protocol analysis period. If incidence wanes before period begins (due slow-acting fast-moving pathogen), power can be substantially reduced. Mathematical modeling valuable exploring suitability in different settings. Another feature zero inflation, which occur if chain transmission does not take off ring. In Ebola, majority had subsequent cases. extended ways, including definition (e.g. contact-based, spatial, occupational). will settings where spatio-temporal spread pathogen highly focused unpredictable.

Language: Английский

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Modelling: Understanding pandemics and how to control them

Epidemics, Journal Year: 2022, Volume and Issue: 39, P. 100588 - 100588

Published: May 31, 2022

New disease challenges, societal demands and better or novel types of data, drive innovations in the structure, formulation analysis epidemic models. Innovations modelling can lead to new insights into processes use available yielding improved control stimulating collection data types. Here we identify key challenges for formulation, mathematical models pathogen transmission relevant current future pandemics.

Language: Английский

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