scholarly journals Can a COVID-19 vaccination program guarantee the return to a pre-pandemic lifestyle?

2021 ◽  
Author(s):  
Juan Yang ◽  
Valentina Marziano ◽  
Xiaowei Deng ◽  
Giorgio Guzzetta ◽  
Juanjuan Zhang ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Data Driven ◽  
Vaccination Program ◽  
Transmission Model ◽  
Natural Immunity ◽  
Epidemic Threshold ◽  
Large Populations ◽  
One Year ◽  
Pharmaceutical Interventions ◽  
Key Questions

AbstractCOVID-19 vaccination has been initiated in several countries to control SARS-CoV-2 transmission. Whether and when non-pharmaceutical interventions (NPIs) can be lifted as vaccination builds up remains key questions. To address them, we built a data-driven SARS-CoV-2 transmission model for China. We estimated that, to prevent local outbreaks to escalate to major widespread epidemics, stringent NPIs need to remain in place at least one year after the start of vaccination. Should NPIs be capable to keep the reproduction number (Rt) around 1.3, vaccination could reduce up to 99% of COVID-19 burden and bring Rt below the epidemic threshold in 9 months. Maintaining strict NPIs throughout 2021 is of paramount importance to reduce COVID-19 burden while vaccines are distributed, especially in large populations with little natural immunity.

scholarly journals Can a COVID-19 vaccination program guarantee the return to a pre-pandemic lifestyle?

2021 ◽  
Author(s):  
Hongjie Yu ◽  
Juan Yang ◽  
Valentina Marziano ◽  
Xiaowei Deng ◽  
Giorgio Guzzetta ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Data Driven ◽  
Vaccination Program ◽  
Natural Immunity ◽  
Epidemic Threshold ◽  
Policy Makers ◽  
Vaccination Programs ◽  
Large Populations ◽  
One Year ◽  
Key Questions

Abstract COVID-19 vaccination programs have been initiated in several countries to control SARS-CoV-2 transmission and return to a pre-pandemic lifestyle. However, understanding when non-pharmaceutical interventions (NPIs) can be lifted as vaccination builds up and how to update priority groups for vaccination in real-time remain key questions for policy makers. To address these questions, we built a data-driven model of SARS-CoV-2 transmission for China. We estimated that, to prevent local outbreaks to escalate to major widespread epidemics, stringent NPIs need to remain in place at least one year after the start of vaccination. Should NPIs be capable to keep the reproduction number (Rt) around 1.3, a vaccination program could reduce up to 99% of COVID-19 burden and bring Rt below the epidemic threshold in about 9 months. Maintaining strict NPIs throughout 2021 is of paramount importance to reduce COVID-19 burden while vaccines are distributed to the population, especially in large populations with little natural immunity.

scholarly journals Despite vaccination, China needs non-pharmaceutical interventions to prevent widespread outbreaks of COVID-19 in 2021

2021 ◽  
Author(s):  
Juan Yang ◽  
Valentina Marziano ◽  
Xiaowei Deng ◽  
Giorgio Guzzetta ◽  
Juanjuan Zhang ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Synergetic Effect ◽  
Data Driven ◽  
Natural Immunity ◽  
Epidemic Threshold ◽  
Policy Makers ◽  
Large Populations ◽  
One Year ◽  
Pharmaceutical Interventions

AbstractCOVID-19 vaccination is being conducted in over 200 countries and regions to control SARS-CoV-2 transmission and return to a pre-pandemic lifestyle. However, understanding when non-pharmaceutical interventions (NPIs) can be lifted as immunity builds up remains a key question for policy makers. To address this, we built a data-driven model of SARS-CoV-2 transmission for China. We estimated that, to prevent the escalation of local outbreaks to widespread epidemics, stringent NPIs need to remain in place at least one year after the start of vaccination. Should NPIs alone be capable of keeping the reproduction number (Rt) around 1.3, the synergetic effect of NPIs and vaccination could reduce the COVID-19 burden by up to 99% and bring Rt below the epidemic threshold in about 9 months. Maintaining strict NPIs throughout 2021 is of paramount importance to reduce COVID-19 burden while vaccines are distributed to the population, especially in large populations with little natural immunity.

scholarly journals The effects of non-pharmaceutical interventions on SARS-CoV-2 transmission in different socioeconomic populations in Kuwait: a modeling study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Fatima Khadadah ◽  
Abdullah A. Al-Shammari ◽  
Ahmad Alhashemi ◽  
Dari Alhuwail ◽  
Bader Al-Saif ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Reproduction Number ◽  
Transmission Model ◽  
Socioeconomic Groups ◽  
Before And After ◽  
Cross Transmission ◽  
Community Transmission ◽  
The Impact ◽  
Pharmaceutical Interventions ◽  
The Basic Reproduction Number

Abstract Background Aggressive non-pharmaceutical interventions (NPIs) may reduce transmission of SARS-CoV-2. The extent to which these interventions are successful in stopping the spread have not been characterized in countries with distinct socioeconomic groups. We compared the effects of a partial lockdown on disease transmission among Kuwaitis (P1) and non-Kuwaitis (P2) living in Kuwait. Methods We fit a modified metapopulation SEIR transmission model to reported cases stratified by two groups to estimate the impact of a partial lockdown on the effective reproduction number ($$ {\mathcal{R}}_e $$ R e ). We estimated the basic reproduction number ($$ {\mathcal{R}}_0 $$ R 0 ) for the transmission in each group and simulated the potential trajectories of an outbreak from the first recorded case of community transmission until 12 days after the partial lockdown. We estimated $$ {\mathcal{R}}_e $$ R e values of both groups before and after the partial curfew, simulated the effect of these values on the epidemic curves and explored a range of cross-transmission scenarios. Results We estimate $$ {\mathcal{R}}_e $$ R e at 1·08 (95% CI: 1·00–1·26) for P1 and 2·36 (2·03–2·71) for P2. On March 22nd, $$ {\mathcal{R}}_e $$ R e for P1 and P2 are estimated at 1·19 (1·04–1·34) and 1·75 (1·26–2·11) respectively. After the partial curfew had taken effect, $$ {\mathcal{R}}_e $$ R e for P1 dropped modestly to 1·05 (0·82–1·26) but almost doubled for P2 to 2·89 (2·30–3·70). Our simulated epidemic trajectories show that the partial curfew measure greatly reduced and delayed the height of the peak in P1, yet significantly elevated and hastened the peak in P2. Modest cross-transmission between P1 and P2 greatly elevated the height of the peak in P1 and brought it forward in time closer to the peak of P2. Conclusion Our results indicate and quantify how the same lockdown intervention can accentuate disease transmission in some subpopulations while potentially controlling it in others. Any such control may further become compromised in the presence of cross-transmission between subpopulations. Future interventions and policies need to be sensitive to socioeconomic and health disparities.

scholarly journals SARS-Cov-2 trajectory predictions and scenario simulations from a global perspective: a modelling study

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tianan Yang ◽  
Yexin Liu ◽  
Wenhao Deng ◽  
Weigang Zhao ◽  
Jianwei Deng
Keyword(s):  
Reproduction Number ◽  
Human Mobility ◽  
International Travel ◽  
Global Perspective ◽  
Transmission Model ◽  
Social Distancing ◽  
Global Epidemic ◽  
Intervention Level ◽  
Imported Cases ◽  
Pharmaceutical Interventions

Abstract The coronavirus SARS-CoV-2 emerging from Wuhan, China has developed into a global epidemic. Here, we combine both human mobility and non-pharmaceutical interventions (social-distancing and suspected-cases isolation) into SEIR transmission model to understand how coronavirus transmits in a global environment. Dynamic trends of region-specific time-variant reproduction number, social-distancing rate, work-resumption rate, and suspected-cases isolation rate have been estimated and plotted for each region by fitting stochastic transmission processes to the real total confirmed cases reported of each region. We find after shutdown in Wuhan, the reproduction number in Wuhan greatly declined from 6·982 (95% CI 2·558–14·668) on January 23rd, 2020 to 1.130 (95% CI 0.289–3.279) on February 7th, 2020, and there was a higher intervention level in terms of social-distancing and suspected-cases isolation in Wuhan than the Chinese average and Western average, for the period from the shutdown in Wuhan to mid-March. Future epidemic trajectories of Western countries up to October 10th, 2020, have been predicted with 95% confidence intervals. Through the scenario simulation, we discover the benefits of earlier international travel ban and rigorous intervention strategies, and the significance of non-pharmaceutical interventions. From a global perspective, it is vital for each country to control the risks of imported cases, and execute rigorous non-pharmaceutical interventions before successful vaccination development.

scholarly journals Time-varying optimization of COVID-19 vaccine prioritization in the context of limited vaccination capacity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shasha Han ◽  
Jun Cai ◽  
Juan Yang ◽  
Juanjuan Zhang ◽  
Qianhui Wu ◽  
...  
Keyword(s):  
Early Phase ◽  
Reproduction Number ◽  
Mechanistic Model ◽  
Vaccination Campaign ◽  
Data Driven ◽  
Vaccination Program ◽  
Time Varying ◽  
New Wave ◽  
Target Groups ◽  
Epidemiological Situation

AbstractDynamically adapting the allocation of COVID-19 vaccines to the evolving epidemiological situation could be key to reduce COVID-19 burden. Here we developed a data-driven mechanistic model of SARS-CoV-2 transmission to explore optimal vaccine prioritization strategies in China. We found that a time-varying vaccination program (i.e., allocating vaccines to different target groups as the epidemic evolves) can be highly beneficial as it is capable of simultaneously achieving different objectives (e.g., minimizing the number of deaths and of infections). Our findings suggest that boosting the vaccination capacity up to 2.5 million first doses per day (0.17% rollout speed) or higher could greatly reduce COVID-19 burden, should a new wave start to unfold in China with reproduction number ≤1.5. The highest priority categories are consistent under a broad range of assumptions. Finally, a high vaccination capacity in the early phase of the vaccination campaign is key to achieve large gains of strategic prioritizations.

scholarly journals Retrospective study of the first wave of COVID-19 in Spain: analysis of counterfactual scenarios

2021 ◽  
Author(s):  
Benjamin Steinegger ◽  
Clara Granell ◽  
Giacomo Rapisardi ◽  
Sergio Gómez ◽  
Joan T. Matamalas ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Retrospective Analysis ◽  
Reproduction Number ◽  
Natural Immunity ◽  
Containment Measures ◽  
Backward Analysis ◽  
The Impact ◽  
Near Future ◽  
Pharmaceutical Interventions

One of the most important questions on the COVID-19 pandemic is ascertaining the correct timing to introduce non-pharmaceutical interventions (NPIs), based mainly on mobility restrictions, to control the rising of the daily incidence in a specific territory. Here, we make a retrospective analysis of the first wave of the epidemic in Spain and provide a set of useful insights to optimize actions in the near future. We have reconstructed the exposure times, from infection to detectability, to correctly estimate the reproduction number Rt. This enables us to analyze counterfactual scenarios to understand the impact of earlier or later responses, decoupling containment measures from natural immunity. Our results quantify the differences in the number of fatalities for earlier and later responses to the epidemic in Spain.Teaser“We propose a backward analysis of pandemic incidence in a region to determine the correct timing of authorities’ non-pharmaceutical interventions to fight COVID-19”

scholarly journals SARS-Cov-2 trajectory predictions and scenario simulations from a global perspective: a modelling study

2020 ◽  
Author(s):  
Tianan Yang ◽  
Yexin Liu ◽  
Wenhao Deng ◽  
Weigang Zhao ◽  
Jianwei Deng
Keyword(s):  
Reproduction Number ◽  
Human Mobility ◽  
International Travel ◽  
Global Perspective ◽  
Transmission Model ◽  
Suspected Case ◽  
Social Distancing ◽  
Global Epidemic ◽  
Intervention Level ◽  
Pharmaceutical Interventions

Abstract The coronavirus SARS-CoV-2 emerging from Wuhan, China has developed into a global epidemic. Here, we combine both human mobility and non-pharmaceutical interventions (social-distancing and suspected-cases isolation) into SEIR transmission model to understand how coronavirus transmits in a global environment. Dynamic trends of region-specific time-variant reproduction number, social-distancing rate, work-resumption rate, and suspected-cases isolation rate have been estimated and plotted for each region by fitting random walk transmission processes to the real total confirmed cases of each region. We find after shutdown in Wuhan, the reproduction number in Wuhan greatly declined from 6·982 (95% CI, 2·558-14·668) on January 23, 2020 to 1·130 (95% CI, 0·289-3·279) on February 7, 2020, and there was a higher intervention level in terms of social distancing and suspected-case isolation in Wuhan than the Chinese average and Western average, for the period from the shutdown in Wuhan to mid-March. Future epidemic trajectories of Western countries up to October 10, 2020, have been predicted with 95% confidence intervals. Through the scenario simulation, we discover the benefits of earlier international travel ban and rigorous intervention strategies, and the significance of non-pharmaceutical interventions. From a global perspective, it is vital for each country to control the risks of imported cases, and execute rigorous non-pharmaceutical interventions before successful vaccination development.

scholarly journals Accounting for underreporting in mathematical modelling of transmission and control of COVID-19 in Iran

2020 ◽  
Author(s):  
Meead Saberi ◽  
Homayoun Hamedmoghadam ◽  
Kaveh Madani ◽  
Helen M. Dolk ◽  
Andrei S. Morgan ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Estimation Method ◽  
Case Fatality ◽  
Transmission Model ◽  
School Closures ◽  
The Public ◽  
Case Fatality Ratio ◽  
And Control ◽  
The Impact ◽  
Pharmaceutical Interventions

SUMMARYBackgroundIran has been the hardest hit country by the outbreak of SARS-CoV-2 in the Middle East with 74,877 confirmed cases and 4,683 deaths as of 15 April 2020. With a relatively high case fatality ratio and limited testing capacity, the number of confirmed cases reported is suspected to suffer from significant under-reporting. Therefore, understanding the transmission dynamics of COVID-19 and assessing the effectiveness of the interventions that have taken place in Iran while accounting for the uncertain level of underreporting is of critical importance. We use a mathematical epidemic model utilizing official confirmed data and estimates of underreporting to understand how transmission in Iran has been changing between February and April 2020.MethodsWe developed a compartmental transmission model to estimate the effective reproduction number and its fluctuations since the beginning of the outbreak in Iran. We associate the variations in the effective reproduction number with a timeline of interventions and national events. The estimation method also accounts for the underreporting due to low case ascertainment by estimating the percentage of symptomatic cases using delay-adjusted case fatality ratio based on the distribution of the delay from hospitalization-to-death.FindingsOur estimates of the effective reproduction number ranged from 0.66 to 1.73 between February and April 2020, with a median of 1.16. We estimate a reduction in the effective reproduction number during this period, from 1.73 (95% CI 1.60 – 1.87) on 1 March 2020 to 0.69 (95% CI 0.68-0.70) on 15 April 2020, due to various non-pharmaceutical interventions including school closures, a ban on public gatherings including sports and religious events, and full or partial closure of non-essential businesses. Based on these estimates and given that a near complete containment is no longer feasible, it is likely that the outbreak may continue until the end of the 2020 if the current level of physical distancing and interventions continue and no effective vaccination or therapeutic are developed and made widely available.InterpretationThe series of non-pharmaceutical interventions and the public compliance that took place in Iran are found to be effective in slowing down the speed of the spread of COVID-19 within the studied time period. However, we argue that if the impact of underreporting is overlooked, the estimated transmission and control dynamics could mislead the public health decisions, policy makers, and general public especially in the earlier stages of the outbreak.FundingNil.

scholarly journals Assessing the impact of non-pharmaceutical interventions on SARS-CoV-2 transmission in Switzerland

2020 ◽  
Author(s):  
Joseph. C. Lemaitre ◽  
Javier Perez-Saez ◽  
Andrew S. Azman ◽  
Andrea Rinaldo ◽  
Jacques Fellay
Keyword(s):  
Disease Transmission ◽  
Large Scale ◽  
Transmission Model ◽  
Natural Immunity ◽  
Close Monitoring ◽  
Mobility Patterns ◽  
Individual Level ◽  
Transmission Reduction ◽  
The Impact ◽  
Pharmaceutical Interventions

AbstractFollowing the rapid dissemination of COVID-19 cases in Switzerland, large-scale non-pharmaceutical interventions (NPIs) were implemented by the cantons and the federal government between February 28 and March 20. Estimates of the impact of these interventions on SARS-CoV-2 transmission are critical for decision making in this and future outbreaks. We here aim to assess the impact of these NPIs on disease transmission by estimating changes in the basic reproduction number (R0) at national and cantonal levels in relation to the timing of these NPIs. We estimate the time-varying R0 nationally and in twelve cantons by fitting a stochastic transmission model explicitly simulating within hospital dynamics. We use individual-level data of >1,000 hospitalized patients in Switzerland and public daily reports of hospitalizations and deaths. We estimate the national R0 was 3.15 (95% CI: 2.13-3.76) at the start of the epidemic. Starting from around March 6, we find a strong reduction in R0 with a 85% median decrease (95% quantile range, QR: 83%-90%) to a value of 0.44 (95% QR: 0.27-0.65) in the period of March 29-April 5. At the cantonal-level R0 decreased over the course of the epidemic between 71% and 94%. We found that reductions in R0 were synchronous with changes in mobility patterns as estimated through smartphone activity, which started before the official implementation of NPIs. We found that most of the reduction of transmission is due to behavioural changes as opposed to natural immunity, the latter accounting for only about 3% of the total reduction in effective transmission. As Switzerland considers relaxing some of the restrictions of social mixing, current estimates of R0 well below one are promising. However most of inferred transmission reduction was due to behaviour change (<3% due to natural immunity buildup), with an estimated 97% (95% QR: 96.6%-97.2%) of the Swiss population still susceptible to SARS-CoV-2 as of April 24. These results warrant a cautious relaxation of social distance practices and close monitoring of changes in both the basic and effective reproduction numbers.

scholarly journals Model-based evaluation of school- and non-school-related measures to control the COVID-19 pandemic

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ganna Rozhnova ◽  
Christiaan H. van Dorp ◽  
Patricia Bruijning-Verhagen ◽  
Martin C. J. Bootsma ◽  
Janneke H. H. M. van de Wijgert ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Additional Benefit ◽  
Transmission Model ◽  
Time Points ◽  
School Based ◽  
Admission Data ◽  
Age Structured ◽  
The Impact ◽  
Pandemic Wave

AbstractThe role of school-based contacts in the epidemiology of SARS-CoV-2 is incompletely understood. We use an age-structured transmission model fitted to age-specific seroprevalence and hospital admission data to assess the effects of school-based measures at different time points during the COVID-19 pandemic in the Netherlands. Our analyses suggest that the impact of measures reducing school-based contacts depends on the remaining opportunities to reduce non-school-based contacts. If opportunities to reduce the effective reproduction number (Re) with non-school-based measures are exhausted or undesired and Re is still close to 1, the additional benefit of school-based measures may be considerable, particularly among older school children. As two examples, we demonstrate that keeping schools closed after the summer holidays in 2020, in the absence of other measures, would not have prevented the second pandemic wave in autumn 2020 but closing schools in November 2020 could have reduced Re below 1, with unchanged non-school-based contacts.

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