The role of antiviral treatment in curbing the COVID-19 pandemic: a modeling study.

Despite the development of safe and effective vaccines, effective treatments for COVID-19 disease are still desperately needed. Recently, two antiviral drugs have shown to be effective in reducing hospitalizations in clinical trials. In the present work, we use an agent-based mathematical model to assess the potential population impact of the use of antiviral treatments in four countries, corresponding to four current levels of vaccination coverage: Kenya, Mexico, United States (US) and Belgium, with 1.5, 38, 57 and 74% of their populations vaccinated. For each location, we varied antiviral coverage and antiviral effect in reducing viral load (25, 50, 75 or 100% reduction). Irrespective of location, widespread antiviral treatment of symptomatic infections (≥50% coverage) is expected to prevent the majority of COVID-19 deaths. Furthermore, even treating 20% of adult symptomatic infections, is expected to reduce mortality by a third in all countries, irrespective of the assumed treatment efficacy in reducing viral load. Our results suggest that early antiviral treatment is needed to mitigate transmission, with early treatment (within two days of symptoms) preventing 50% more infections compared to late treatment (started on days 3 to 5 after developing symptoms). Our results highlight the synergistic effect of vaccination and antiviral treatment: as vaccination rate increased, antiviral treatment had a bigger impact on overall transmission. These results suggest that antiviral treatments can become a strategic tool that, in combination with vaccination, can significantly control SASRS-CoV-2 transmission and reduce COVID-19 hospitalizations and deaths.

Proximity of IQOS and JUUL points of sale to schools in Israel: a geospatial analysis

SignificanceExploring proximity and density of heated tobacco product (HTP) and electronic nicotine delivery system (ENDS) points of sale (POS) to schools is critical for understanding youth marketing exposure and informing policy and enforcement to protect youth. This study examined IQOS and JUUL POS (prominent HTPs and ENDS), specifically their proximity to and density around schools in Israel.MethodsUsing geospatial analysis and IQOS/JUUL website data, distance matrices were used to calculate distance from each school in Israel (grades 1–12) to the nearest POS and number of POS within 1 km, accounting for schools’ neighbourhood socioeconomic status (SES) ranking.ResultsAn average of 8.7 IQOS POS and 5.2 JUUL POS were within walking distance (1 km) from schools. Average distances from schools to nearest IQOS and JUUL POS were 954 m (median=365 m) and 1535 m (median=579 m), respectively. The percentages of schools with at least one IQOS or JUUL POS within 1 km were 86% and 74%, respectively. The average numbers of POS within 1 km of schools in low-SES, middle-SES, and high-SES neighbourhoods were 7.5, 9.9, and 7.6 for IQOS and 4.1, 5.9, and 5.5 for JUUL, respectively. Median distances from schools in low-SES, middle-SES, and high-SES neighbourhoods to nearest POS were 428 m, 325 m, and 403 m for IQOS and 1044 m, 483 m, and 525 m for JUUL.ConclusionsYouth experience high environmental exposure to IQOS and JUUL POS, particularly IQOS. POS were more densely located near schools in middle-SES neighbourhoods. Thus, regulating HTP and ENDS POS near schools and in certain neighbourhoods is key to reducing youth population impact in Israel and elsewhere.

Population impact of SARS-CoV-2 variants with enhanced transmissibility and/or partial immune escape

SummarySARS-CoV-2 variants of concern exhibit varying degrees of transmissibility and, in some cases, escape from infection- and vaccine-induced immunity. Much effort has been devoted to measuring these phenotypes, but predicting their impact on the course of the pandemic – especially that of immune escape – remains a challenge. Here, we use a mathematical model to simulate the dynamics of wildtype and variant strains of SARS-CoV-2 in the context of vaccine rollout and nonpharmaceutical interventions. We show that variants with enhanced transmissibility easily rise to high frequency, whereas partial immune escape, on its own, often fails to do so. However, when these phenotypes are combined, enhanced transmissibility can carry the variant to high frequency, at which point partial immune escape may limit the ability of vaccination to control the epidemic. Our findings suggest that moderate immune escape poses a low risk unless combined with a substantial increase in transmissibility.

COVID-19 vaccines that reduce symptoms but do not block infection need higher coverage and faster rollout to achieve population impact

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.