Untangling the changing impact of non-pharmaceutical interventions and vaccination on European Covid-19 trajectories

Abstract Non-pharmaceutical interventions (NPIs) and vaccination are two fundamental approaches to mitigate the coronavirus disease 2019 (Covid-19) pandemic. Vaccination strategies are generally less costly and socially/economically disruptive than NPI strategies, such as business closures, social distancing, and face mask mandates, as evidenced by highly vaccinated countries generally rolling back NPIs. However, the respective real-world impact of an NPI strategy versus vaccination strategy, or the combination of both, on mitigating Covid-19 transmission remains uncertain. To address this, we built a Bayesian inference model to explore the changing effectiveness of NPIs and vaccination based on the assembled large-scale dataset, including epidemiological parameters, variants, vaccines, and control variable. Here we show that NPIs were still considerably complementary or even synergistic to vaccination in the effort to curb the Covid-19 infection before reaching herd immunity. We found that (1) the synergistic effect of NPIs and vaccination was 46.9% (reduction in reproduction number) in September 2021, whereas the effects of NPIs and vaccination alone were 20.7% and 28.8%, respectively; (2) effectiveness of NPIs is less sensitive to emerging COVID-19 variants but decreases with vaccination progress, as NPIs may unnecessarily restrict the vaccinated population. The effectiveness of NPIs alone declined approximately 23% since the introduction of vaccination strategies, where the relaxation of NPIs promoted the decline from May 2021. Our results demonstrate that the decision to relax NPIs should consider the real-world vaccination rate of the relevant population, which is determined by the observed vaccine efficacy in relation to extant and emerging variants.

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Stages of COVID-19 pandemic and paths to herd immunity by vaccination: dynamical model comparing Austria, Luxembourg and Sweden

10.1101/2020.12.31.20249088 ◽

2021 ◽

Author(s):

Françoise Kemp ◽

Daniele Proverbio ◽

Atte Aalto ◽

Laurent Mombaerts ◽

Aymeric Fouquier d’Hérouël ◽

...

Keyword(s):

Social Interaction ◽

Social Interactions ◽

Herd Immunity ◽

Healthcare Systems ◽

Vaccination Rate ◽

Epidemic Dynamics ◽

Vaccination Strategies ◽

Open Question ◽

Shed Light ◽

Pharmaceutical Interventions

AbstractBackgroundWorldwide more than 72 million people have been infected and 1.6 million died with SARS-CoV-2 by 15th December 2020. Non-pharmaceutical interventions which decrease social interaction have been implemented to reduce the spread of SARS-CoV-2 and to mitigate stress on healthcare systems and prevent deaths. The pandemic has been tackled with disparate strategies by distinct countries resulting in different epidemic dynamics. However, with vaccines now becoming available, the current urgent open question is how the interplay between vaccination strategies and social interaction will shape the pandemic in the next months.MethodsTo address this question, we developed an extended Susceptible-Exposed-Infectious-Removed (SEIR) model including social interaction, undetected cases and the progression of patients trough hospitals, intensive care units (ICUs) and death. We calibrated our model to data of Luxem-bourg, Austria and Sweden, until 15th December 2020. We incorporated the effect of vaccination to investigate under which conditions herd immunity would be achievable in 2021.ResultsThe model reveals that Sweden has the highest fraction of undetected cases, Luxembourg displays the highest fraction of infected population, and all three countries are far from herd immunity as of December 2020. The model quantifies the level of social interactions, and allows to assess the level which would keep Reff (t) below 1. In December 2020, this level is around 1/3 of what it was before the pandemic for all the three countries. The model allows to estimate the vaccination rate needed for herd immunity and shows that 2700 vaccinations/day are needed in Luxembourg to reach it by mid of April and 45,000 for Austria and Sweden. The model estimates that vaccinating the whole country’s population within 1 year could lead to herd immunity by July in Luxembourg and by August in Austria and Sweden.ConclusionThe model allows to shed light on the dynamics of the epidemics in different waves and countries. Our results emphasize that vaccination will help considerably but not immediately and therefore social measures will remain important for several months before they can be fully alleviated.

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Will the Large-scale Vaccination Succeed in Containing the COVID-19 Epidemic and How Soon?

10.1101/2021.04.16.21255543 ◽

2021 ◽

Author(s):

Shilei Zhao ◽

Tong Sha ◽

Yongbiao Xue ◽

Chung-I Wu ◽

Hua Chen

Keyword(s):

United States Of America ◽

Vaccine Efficacy ◽

Large Scale ◽

Herd Immunity ◽

Vaccination Rate ◽

Epidemic Dynamics ◽

Intervention Measures ◽

Vaccination Scheme ◽

Mutant Strains ◽

Promising Solution

The availability of vaccines provides a promising solution to containing the COVID-19 pandemic. Here, we develop an epidemiological model to quantitatively analyze and predict the epidemic dynamics of COVID-19 under vaccination. The model is applied to the daily released numbers of confirmed cases of Israel and United States of America to explore and predict the trend under vaccination based on their current epidemic status and intervention measures. For Israel, of which 53.83% of the population was fully vaccinated, under the current intensity of NPIs and vaccination scheme, the pandemic is predicted to end between May 14, 2021 to May 16, 2021 depending on an immunity duration between 180 days and 365 days; Assuming no NPIs after March 24, 2021, the pandemic will ends later, between July 4, 2021 to August 26, 2021. For USA, if we assume the current vaccination rate (0.268% per day) and intensity of NPIs, the pandemic will end between February 3, 2022 and August 17, 2029 depending on an immunity duration between 180 days and 365 days. However, assuming an immunity duration of 180 days and with no NPIs, the pandemic will not end, and instead reach an equilibrium state with a proportion of the population remaining actively infected. Overall the daily vaccination rate should be chosen according to the vaccine efficacy and the immunity duration to achieve herd immunity. In some situations, vaccination alone cannot stop the pandemic, and NPIs are necessary both to supplement vaccination and accelerate the end of the pandemic. Considering that vaccine efficacy and duration of immunity may be reduced for new mutant strains, it is necessary to remain cautiously optimistic about the prospect of the pandemic under vaccination.

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Toward Achieving a Vaccine-Derived Herd Immunity Threshold for COVID-19 in the U.S.

Frontiers in Public Health ◽

10.3389/fpubh.2021.709369 ◽

2021 ◽

Vol 9 ◽

Author(s):

Abba B. Gumel ◽

Enahoro A. Iboi ◽

Calistus N. Ngonghala ◽

Gideon A. Ngwa

Keyword(s):

Public Health ◽

United States ◽

Herd Immunity ◽

Face Mask ◽

The United States ◽

Mortality Data ◽

Deterministic System ◽

Therapeutic Benefits ◽

The U.S ◽

Pharmaceutical Interventions

A novel coronavirus emerged in December of 2019 (COVID-19), causing a pandemic that inflicted unprecedented public health and economic burden in all nooks and corners of the world. Although the control of COVID-19 largely focused on the use of basic public health measures (primarily based on using non-pharmaceutical interventions, such as quarantine, isolation, social-distancing, face mask usage, and community lockdowns) initially, three safe and highly-effective vaccines (by AstraZeneca Inc., Moderna Inc., and Pfizer Inc.), were approved for use in humans in December 2020. We present a new mathematical model for assessing the population-level impact of these vaccines on curtailing the burden of COVID-19. The model stratifies the total population into two subgroups, based on whether or not they habitually wear face mask in public. The resulting multigroup model, which takes the form of a deterministic system of nonlinear differential equations, is fitted and parameterized using COVID-19 cumulative mortality data for the third wave of the COVID-19 pandemic in the United States. Conditions for the asymptotic stability of the associated disease-free equilibrium, as well as an expression for the vaccine-derived herd immunity threshold, are rigorously derived. Numerical simulations of the model show that the size of the initial proportion of individuals in the mask-wearing group, together with positive change in behavior from the non-mask wearing group (as well as those in the mask-wearing group, who do not abandon their mask-wearing habit) play a crucial role in effectively curtailing the COVID-19 pandemic in the United States. This study further shows that the prospect of achieving vaccine-derived herd immunity (required for COVID-19 elimination) in the U.S., using the Pfizer or Moderna vaccine, is quite promising. In particular, our study shows that herd immunity can be achieved in the U.S. if at least 60% of the population are fully vaccinated. Furthermore, the prospect of eliminating the pandemic in the U.S. in the year 2021 is significantly enhanced if the vaccination program is complemented with non-pharmaceutical interventions at moderate increased levels of compliance (in relation to their baseline compliance). The study further suggests that, while the waning of natural and vaccine-derived immunity against COVID-19 induces only a marginal increase in the burden and projected time-to-elimination of the pandemic, adding the impacts of therapeutic benefits of the vaccines into the model resulted in a dramatic reduction in the burden and time-to-elimination of the pandemic.

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Effects of worldwide interventions and vaccination on COVID-19 between waves and countries

10.21203/rs.3.rs-396989/v1 ◽

2021 ◽

Author(s):

Yong Ge ◽

Wenbin Zhang ◽

Haiyan Liu ◽

Corrine W Ruktanonchai ◽

Maogui Hu ◽

...

Keyword(s):

Infectious Diseases ◽

Large Scale ◽

International Travel ◽

Spatiotemporal Variations ◽

School Closures ◽

Vaccination Strategies ◽

Travel Restrictions ◽

The Impact ◽

Second Wave ◽

Pharmaceutical Interventions

Abstract Worldwide governments have rapidly deployed non-pharmaceutical interventions (NPIs) to mitigate the COVID-19 pandemic, together with the large-scale rollout of vaccines since late 2020. However, the effect of these individual NPI and vaccination measures across space and time has not been sufficiently explored. By the decay ratio in the suppression of COVID-19 infections, we investigated the performance of different NPIs across waves in 133 countries, and their integration with vaccine rollouts in 63 countries as of 25 March 2021. The most effective NPIs were gathering restrictions (contributing 27.83% in the infection rate reductions), facial coverings (16.79%) and school closures (10.08%) in the first wave, and changed to facial coverings (30.04%), gathering restrictions (17.51%) and international travel restrictions (9.22%) in the second wave. The impact of NPIs had obvious spatiotemporal variations across countries by waves before vaccine rollouts, with facial coverings being one of the most effective measures consistently. Vaccinations had gradually contributed to the suppression of COVID-19 transmission, from 0.71% and 0.86% within 15 days and 30 days since Day 12 after vaccination, to 1.23% as of 25 March 2021, while NPIs still dominated the pandemic mitigation. Our findings have important implications for continued tailoring of integrated NPI or NPI-vaccination strategies against future COVID-19 waves or similar infectious diseases.

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Returning to a normal life via COVID-19 vaccines in the USA: a large-scale agent-based simulation study (Preprint)

10.2196/preprints.27419 ◽

2021 ◽

Cited By ~ 1

Author(s):

Junjiang Li ◽

Philippe Giabbanelli

Keyword(s):

Large Scale ◽

Vaccination Campaign ◽

Vaccination Strategy ◽

Current Evidence ◽

Logistic Growth ◽

Agent Based ◽

Pharmaceutical Intervention ◽

Current Availability ◽

The Usa ◽

Pharmaceutical Interventions

BACKGROUND In 2020, COVID-19 has claimed more than 300,000 deaths in the US alone. While non-pharmaceutical interventions were implemented by federal and state governments in the USA, these efforts have failed to contain the virus. Following the FDA approval of two COVID-19 vaccines, however, the hope for the return to normalcy is renewed. This hope rests on an unprecedented nation-wide vaccine campaign, which faces many logistical challenges and is also contingent on several factors whose values are currently unknown. OBJECTIVE We study the effectiveness of a nation-wide vaccine campaign in response to different vaccine efficacies, the willingness of the population to be vaccinated, and the daily vaccine capacity under two different federal plans. To characterize the possible outcomes most accurately, we also account for the interactions between non-pharmaceutical interventions and vaccines, through six scenarios that capture a range of possible impact from non-pharmaceutical interventions. METHODS We use large-scale cloud-based agent-based simulations by implementing the vaccination campaign using Covasim, an open-source ABM for COVID-19 that has been used in several peer-reviewed studies and accounts for individual heterogeneity as well as a multiplicity of contact networks. Several modifications to the parameters and simulation logic were made to better align the model with current evidence. We chose six non-pharmaceutical intervention scenarios and applied the vaccination intervention following both the plan proposed by Operation Warp Speed (former Trump administration) and the plan of one million vaccines per day, proposed by the Biden administration. We accounted for unknowns in vaccine efficacies and levels of population compliance by varying both parameters. For each experiment, the cumulative infection growth is fitted to a logistic growth model, and the carrying capacities and the growth rates are recorded. RESULTS For both vaccination plans and all non-pharmaceutical intervention scenarios, the presence of the vaccine intervention considerably lowers the total number of infections when life returns to normal, even when the population compliance to vaccines is as low at 20%. We noted an unintended consequence: given the vaccine availability estimates under both federal plans and the focus on vaccinating individuals by age categories, a significant reduction in non-pharmaceutical interventions results in a counterintuitive situation in which higher vaccine compliance then leads to more total infections. CONCLUSIONS Although potent, vaccines alone cannot effectively end the pandemic given the current availability estimates and the adopted vaccination strategy. Non-pharmaceutical interventions need to continue and be enforced to ensure high compliance, so that the rate of immunity established by vaccination outpaces that induced by infections.

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OPTIMAL VACCINATION STRATEGIES FOR AN INFLUENZA EPIDEMIC MODEL

Journal of Biological System ◽

10.1142/s0218339013400068 ◽

2013 ◽

Vol 21 (04) ◽

pp. 1340006 ◽

Cited By ~ 2

Author(s):

QINGWEN HU ◽

XINGFU ZOU

Keyword(s):

Optimal Control ◽

Shooting Method ◽

Vaccination Strategy ◽

Vaccination Rate ◽

Control Model ◽

Influenza Epidemic ◽

Vaccination Strategies ◽

Open Population ◽

Per Capita ◽

Bang Bang Control

We present an optimal control model for influenza vaccination strategies in an open population. The model is based on an extended Kermack–McKendrick model with the vaccination rate being a measurable function. The objective of this optimal control model is to describe the vaccination strategies so that the total cost arising from vaccination and infections is minimized. We show that the optimal control is a non-singular bang-bang control which has a finite number of switchings. A scheme for the solution of the optimal control problem is formulated using the shooting method. We also carry out numerical simulations to illustrate the general results and to examine the effects of parameters on the optimal vaccination strategy. The simulations show that the ratio of the per capita treatment cost and per capita vaccination cost has a significant effect on the optimal strategy, while the vaccination rate of the newly recruited class turns out to have less effect.

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COVID-19 Vaccination Strategies Considering Hesitancy Using Particle-Based Epidemic Simulation

10.1101/2021.09.26.21264153 ◽

2021 ◽

Author(s):

Aknur Karabay ◽

Askat Kuzdeuov ◽

Huseyin Atakan Varol

Keyword(s):

Herd Immunity ◽

Vaccination Rate ◽

Vaccine Hesitancy ◽

Public Health Issue ◽

Critical Factors ◽

Epidemic Modeling ◽

Vaccination Strategies ◽

Epidemic Simulation ◽

Source Particle ◽

Vaccination Campaigns

Vaccine hesitancy is one of the critical factors in achieving herd immunity and suppressing the COVID-19 epidemic. Many countries face this as an acute public health issue that diminishes the efficacy of their vaccination campaigns. Epidemic modeling and simulation can be used to predict the effects of different vaccination strategies. In this work, we present an open-source particle-based COVID-19 simulator with a vaccination module capable of taking into account the vaccine hesitancy of the population. To demonstrate the efficacy of the simulator, we conducted extensive simulations for the province of Lecco, Italy. The results indicate that the combination of both high vaccination rate and low hesitancy leads to faster epidemic suppression.

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WHO vaccination protocol can be improved to save more lives

10.21203/rs.3.rs-148826/v1 ◽

2021 ◽

Author(s):

Marcelo Moret ◽

Tarcisio Rocha Filho ◽

José Mendes ◽

Thiago Murari ◽

Aloísio Nascimento Filho ◽

...

Keyword(s):

Large Scale ◽

Herd Immunity ◽

Vaccination Strategy ◽

The United States ◽

The European Union ◽

Vaccine Candidates ◽

Vaccination Protocol ◽

Total Death ◽

Social Difficulties ◽

Maximal Reduction

Abstract Coronavirus disease 2019 (COVID-19) pandemic, a virus infection caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, has impacted all countries of the world, and the main 2021’s challenge is clearly vaccinating the greater number of persons, in the shortest time span, for a maximal reduction in the number of deaths and in the significant economic impacts. Large-scale vaccination aimed to achieve herd immunity poses many logistic and social difficulties [1], with different vaccine candidates and designs [2,3], and vaccination priorities will determine the evolution of the current COVID-19 pandemic. In this paper we explicitly propose an alternative vaccination protocol that can be more effective than those already being deployed, as the ones in the European Union [4] and in the United States [5]. We report strong evidence based on an epidemiological model for the importance of contact hubs (or superspreaders), having a much larger average number of contacts than in the rest of the population [6-11], on the effectiveness of the vaccination strategy. We show that carefully choosing who will be in the first group to be vaccinated can significantly impact on both health services demand and total death toll, by increasing the overall numbers of lives saved and of hospitalizations. We argue that the approach here considered, which does not coincide with current proposals, and given the current conditions with a lack of basic resources for proper vaccination in several countries, and with a significant reduction in mobility and social isolation restrictions, should be considered by all authorities participating in the design of COVID-19 vaccination with the intent of maximising the number of human lives saved.

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Vaccination as a control strategy against the coccidial parasitesEimeria,ToxoplasmaandNeospora

Parasitology ◽

10.1017/s0031182006001855 ◽

2006 ◽

Vol 133 (S2) ◽

pp. S145-S168 ◽

Cited By ~ 100

Author(s):

E. A. INNES ◽

A. N. VERMEULEN

Keyword(s):

Immune System ◽

Immune Responses ◽

Large Scale ◽

Neospora Caninum ◽

Vaccination Strategy ◽

Host Immune System ◽

Scale Production ◽

Vaccination Strategies ◽

Development Of Resistance ◽

Causes Of Disease

The protozoan parasitesEimeriaspp.Toxoplasma gondiiandNeospora caninumare significant causes of disease in livestock worldwide andT. gondiiis also an important human pathogen. Drugs have been used with varying success to help control aspects of these diseases and commercial vaccines are available for all three groups of parasites. However, there are issues with increasing development of resistance to many of the anti-coccidial drugs used to help control avian eimeriosis and public concerns about the use of drugs in food animals. In addition there are no drugs available that can act against the tissue cyst stage of eitherT. gondiiorN. caninumand thus cure animals or people of infection. All three groups of parasites multiply within the cells of their host species and therefore cell mediated immune mechanisms are thought to be an important component of host protective immunity. Successful vaccination strategies for bothEimeriaandToxoplasmahave relied on using a live vaccination approach using attenuated parasites which allows correct processing and presentation of antigen to the host immune system to stimulate appropriate cell mediated immune responses. However, live vaccines can have problems with safety, short shelf-life and large-scale production; therefore there is continued interest in devising new vaccines using defined recombinant antigens. The major challenges in devising novel vaccines are to select relevant antigens and then present them to the immune system in an appropriate manner to enable the induction of protective immune responses. With all three groups of parasites, vaccine preparations comprising antigens from the different life cycle stages may also be advantageous. In the case ofEimeriaparasites there are also problems with strain-specific immunity therefore a cocktail of antigens from different parasite strains may be required. Improving our knowledge of the different parasite transmission routes, host-parasite relationships, disease pathogenesis and determining the various roles of the host immune response being at times host-protective, parasite protective and in causing immunopathology will help to tailor a vaccination strategy against a particular disease target. This paper discusses current vaccination strategies to help combat infections withEimeria,ToxoplasmaandNeosporaand recent research looking towards developing new vaccine targets and approaches.

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Returning to a normal life via COVID-19 vaccines in the USA: a large-scale agent-based simulation study

10.1101/2021.01.31.21250872 ◽

2021 ◽

Author(s):

Junjiang Li ◽

Philippe J. Giabbanelli

Keyword(s):

Large Scale ◽

Vaccination Campaign ◽

Vaccination Strategy ◽

Current Evidence ◽

Logistic Growth ◽

Agent Based ◽

Pharmaceutical Intervention ◽

Current Availability ◽

The Usa ◽

Pharmaceutical Interventions

AbstractBackgroundIn 2020, COVID-19 has claimed more than 300,000 deaths in the US alone. While non-pharmaceutical interventions were implemented by federal and state governments in the USA, these efforts have failed to contain the virus. Following the FDA approval of two COVID-19 vaccines, however, the hope for the return to normalcy is renewed. This hope rests on an unprecedented nation-wide vaccine campaign, which faces many logistical challenges and is also contingent on several factors whose values are currently unknown.ObjectiveWe study the effectiveness of a nation-wide vaccine campaign in response to different vaccine efficacies, the willingness of the population to be vaccinated, and the daily vaccine capacity under two different federal plans. To characterize the possible outcomes most accurately, we also account for the interactions between non-pharmaceutical interventions and vaccines, through six scenarios that capture a range of possible impact from non-pharmaceutical interventions.MethodsWe use large-scale cloud-based agent-based simulations by implementing the vaccination campaign using Covasim, an open-source ABM for COVID-19 that has been used in several peer-reviewed studies and accounts for individual heterogeneity as well as a multiplicity of contact networks. Several modifications to the parameters and simulation logic were made to better align the model with current evidence. We chose six non-pharmaceutical intervention scenarios and applied the vaccination intervention following both the plan proposed by Operation Warp Speed (former Trump administration) and the plan of one million vaccines per day, proposed by the Biden administration. We accounted for unknowns in vaccine efficacies and levels of population compliance by varying both parameters. For each experiment, the cumulative infection growth is fitted to a logistic growth model, and the carrying capacities and the growth rates are recorded.ResultsFor both vaccination plans and all non-pharmaceutical intervention scenarios, the presence of the vaccine intervention considerably lowers the total number of infections when life returns to normal, even when the population compliance to vaccines is as low at 20%. We noted an unintended consequence: given the vaccine availability estimates under both federal plans and the focus on vaccinating individuals by age categories, a significant reduction in non-pharmaceutical interventions results in a counterintuitive situation in which higher vaccine compliance then leads to more total infections.ConclusionsAlthough potent, vaccines alone cannot effectively end the pandemic given the current availability estimates and the adopted vaccination strategy. Non-pharmaceutical interventions need to continue and be enforced to ensure high compliance, so that the rate of immunity established by vaccination outpaces that induced by infections.

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