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2.
Math Biosci Eng ; 19(6): 5699-5716, 2022 04 01.
Article in English | MEDLINE | ID: covidwho-1792335

ABSTRACT

The rapid spread of highly transmissible SARS-CoV-2 variants combined with slowing pace of vaccination in Fall 2021 created uncertainty around the future trajectory of the epidemic in King County, Washington, USA. We analyzed the benefits of offering vaccination to children ages 5-11 and expanding the overall vaccination coverage using mathematical modeling. We adapted a mathematical model of SARS-CoV-2 transmission, calibrated to data from King County, Washington, to simulate scenarios of vaccinating children aged 5-11 with different starting dates and different proportions of physical interactions (PPI) in schools being restored. Dynamic social distancing was implemented in response to changes in weekly hospitalizations. Reduction of hospitalizations and estimated time under additional social distancing measures are reported over the 2021-2022 school year. In the scenario with 85% vaccination coverage of 12+ year-olds, offering early vaccination to children aged 5-11 with 75% PPI was predicted to prevent 756 (median, IQR 301-1434) hospitalizations cutting youth hospitalizations in half compared to no vaccination and largely reducing the need for additional social distancing measures over the school year. If, in addition, 90% overall vaccination coverage was reached, 60% of remaining hospitalizations would be averted and the need for increased social distancing would almost certainly be avoided. Our work suggests that uninterrupted in-person schooling in King County was partly possible because reasonable precaution measures were taken at schools to reduce infectious contacts. Rapid vaccination of all school-aged children provides meaningful reduction of the COVID-19 health burden over this school year but only if implemented early. It remains critical to vaccinate as many people as possible to limit the morbidity and mortality associated with future epidemic waves.


Subject(s)
COVID-19 , Vaccines , Adolescent , COVID-19/epidemiology , COVID-19/prevention & control , Child , Humans , SARS-CoV-2 , Vaccination , Vaccination Coverage , Washington/epidemiology
3.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-294315

ABSTRACT

Background The mass rollout of COVID vaccination in early 2021 allowed local and state authorities to relax mobility and social interaction regulations in spring 2021 including lifting all restrictions for vaccinated people and restoring in-person schooling. However, the emergence and rapid spread of highly transmissible variants combined with slowing down the pace of vaccination created uncertainty around the future trajectory of the epidemic. In this study we analyze the expected benefits of offering vaccination to children age 5-11 under differing conditions for in-person schooling. Methods We adapted a mathematical model of SARS-CoV-2 transmission, calibrated to data from King County, Washington, to handle multiple variants with increased transmissibility and virulence as well as differential vaccine efficacies against each variant. Reactive social distancing is implemented driven by fluctuations in the number of hospitalizations in the county. We simulate scenarios offering vaccination to children aged 5-11 with different starting dates and different proportions of physical interactions (PPI) in schools being restored. The impact of improving overall vaccination coverage among the eligible population is also explored. Cumulative hospitalizations, percentage reduction of hospitalizations and proportion of time at maximum social distancing over the 2021-2022 school year are reported. Findings In the base-case scenario with 85% vaccination coverage of 12+ year-olds, our model projects 4945 (median, IQR 4622-5341) total COVID-19 hospitalizations and 325 (median, IQR 264-400) pediatric hospitalizations if physical contacts at schools are fully restored (100% PPI) for the entire school year compared to 3675 (median, IQR 2311-4725) and 163 (median, IQR 95-226) if schools remained closed. Reducing contacts in schools to 75% PPI or 50% PPI through masking, ventilation and distancing is expected to decrease the overall cumulative hospitalizations by 2% and 4% respectively and youth hospitalizations by 8% and 23% respectively. Offering early vaccination to children aged 5-11 with 75% PPI is expected to prevent 756 (median, IQR 301-1434) hospitalizations and cut hospitalizations in the youngest age group in half compared to no vaccination. It will largely reduce the need of additional social distancing over the school year. If, in addition, 90% overall vaccination coverage is reached, 60% of remaining hospitalizations will be averted and the need of extra mitigation measures almost certainly avoided. Conclusions Our work highlights that in-person schooling is possible if reasonable precaution measures are taken at schools to reduced infectious contacts. Rapid vaccination of all school-aged children will provide meaningful reduction of the COVID health burden over this school year but only if implemented early. Finally, it remains critical to vaccinate as many people as possible to limit the morbidity and mortality associated with the current surge in Delta variant cases.

5.
Sci Rep ; 11(1): 15531, 2021 07 30.
Article in English | MEDLINE | ID: covidwho-1333987

ABSTRACT

Trial results for two COVID-19 vaccines suggest at least 90% efficacy against symptomatic disease (VEDIS). It remains unknown whether this efficacy is mediated by lowering SARS-CoV-2 infection susceptibility (VESUSC) or development of symptoms after infection (VESYMP). We aim to assess and compare the population impact of vaccines with different efficacy profiles (VESYMP and VESUSC) satisfying licensure criteria. We developed a mathematical model of SARS-CoV-2 transmission, calibrated to data from King County, Washington. Rollout scenarios starting December 2020 were simulated with combinations of VESUSC and VESYMP resulting in up to 100% VEDIS. We assumed no reduction of infectivity upon infection conditional on presence of symptoms. Proportions of cumulative infections, hospitalizations and deaths prevented over 1 year from vaccination start are reported. Rollouts of 1 M vaccinations (5000 daily) using vaccines with 50% VEDIS are projected to prevent 23-46% of infections and 31-46% of deaths over 1 year. In comparison, vaccines with 90% VEDIS are projected to prevent 37-64% of infections and 46-64% of deaths over 1 year. In both cases, there is a greater reduction if VEDIS is mediated mostly by VESUSC. The use of a "symptom reducing" vaccine will require twice as many people vaccinated than a "susceptibility reducing" vaccine with the same 90% VEDIS to prevent 50% of the infections and death over 1 year. Delaying the start of the vaccination by 3 months decreases the expected population impact by more than 50%. Vaccines which prevent COVID-19 disease but not SARS-CoV-2 infection, and thereby shift symptomatic infections to asymptomatic infections, will prevent fewer infections and require larger and faster vaccination rollouts to have population impact, compared to vaccines that reduce susceptibility to infection. If uncontrolled transmission across the U.S. continues, then expected vaccination in Spring 2021 will provide only limited benefit.


Subject(s)
COVID-19 Vaccines/therapeutic use , COVID-19/prevention & control , Adolescent , Adult , Aged , Aged, 80 and over , COVID-19/diagnosis , COVID-19/epidemiology , COVID-19/transmission , Child , Child, Preschool , Hospitalization , Humans , Infant , Middle Aged , SARS-CoV-2/isolation & purification , Vaccination , Young Adult
6.
Infect Dis Model ; 6: 24-35, 2021.
Article in English | MEDLINE | ID: covidwho-954780

ABSTRACT

BACKGROUND: In late March 2020, a "Stay Home, Stay Healthy" order was issued in Washington State in response to the COVID-19 pandemic. On May 1, a 4-phase reopening plan began. We investigated whether adjunctive prevention strategies would allow less restrictive physical distancing to avoid second epidemic waves and secure safe school reopening. METHODS: We developed a mathematical model, stratifying the population by age, infection status and treatment status to project SARS-CoV-2 transmission during and after the reopening period. The model was parameterized with demographic and contact data from King County, WA and calibrated to confirmed cases, deaths and epidemic peak timing. Adjunctive prevention interventions were simulated assuming different levels of pre-COVID physical interactions (pC_PI) restored. RESULTS: The best model fit estimated ~35% pC_PI under the lockdown which prevented ~17,000 deaths by May 15. Gradually restoring 75% pC_PI for all age groups between May 15-July 15 would have resulted in ~350 daily deaths by early September 2020. Maintaining <45% pC_PI was required with current testing practices to ensure low levels of daily infections and deaths. Increased testing, isolation of symptomatic infections, and contact tracing permitted 60% pC_PI without significant increases in daily deaths before November and allowed opening of schools with <15 daily deaths. Inpatient antiviral treatment was predicted to reduce deaths significantly without lowering cases or hospitalizations. CONCLUSIONS: We predict that widespread testing, contact tracing and case isolation would allow relaxation of physical distancing, as well as opening of schools, without a surge in local cases and deaths.

7.
Age Ageing ; 49(5): 701-705, 2020 08 24.
Article in English | MEDLINE | ID: covidwho-247828

ABSTRACT

The COVID-19 pandemic has disproportionately affected care home residents internationally, with 19-72% of COVID-19 deaths occurring in care homes. COVID-19 presents atypically in care home residents and up to 56% of residents may test positive whilst pre-symptomatic. In this article, we provide a commentary on challenges and dilemmas identified in the response to COVID-19 for care homes and their residents. We highlight the low sensitivity of polymerase chain reaction testing and the difficulties this poses for blanket screening and isolation of residents. We discuss quarantine of residents and the potential harms associated with this. Personal protective equipment supply for care homes during the pandemic has been suboptimal and we suggest that better integration of procurement and supply is required. Advance care planning has been challenged by the pandemic and there is a need to for healthcare staff to provide support to care homes with this. Finally, we discuss measures to implement augmented care in care homes, including treatment with oxygen and subcutaneous fluids, and the frameworks which will be required if these are to be sustainable. All of these challenges must be met by healthcare, social care and government agencies if care home residents and staff are to be physically and psychologically supported during this time of crisis for care homes.


Subject(s)
Coronavirus Infections , Delivery of Health Care , Homes for the Aged , Long-Term Care , Nursing Homes , Pandemics , Pneumonia, Viral , Quarantine , Aged , Betacoronavirus/isolation & purification , COVID-19 , COVID-19 Testing , Clinical Laboratory Techniques/methods , Clinical Laboratory Techniques/standards , Coronavirus Infections/diagnosis , Coronavirus Infections/epidemiology , Coronavirus Infections/prevention & control , Coronavirus Infections/therapy , Delivery of Health Care/organization & administration , Delivery of Health Care/standards , Health Services Needs and Demand , Homes for the Aged/organization & administration , Homes for the Aged/standards , Humans , Long-Term Care/methods , Long-Term Care/standards , Nursing Homes/organization & administration , Nursing Homes/standards , Pandemics/prevention & control , Pneumonia, Viral/epidemiology , Pneumonia, Viral/prevention & control , Pneumonia, Viral/therapy , Quarantine/organization & administration , Quarantine/psychology , SARS-CoV-2
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