Modeling COVID-19 vaccine efficacy and coverage towards herd-immunity in the Basque Country, Spain

Vaccines have measurable efficacies, obtained first from vaccine trials. However, vaccine efficacy is not a static measure upon licensing, and the long term population studies are very important to evaluate vaccine performance and impact. COVID-19 vaccines were developed in record time and although the extent of sterilizing immunity is still under evaluation, the currently licensed vaccines are extremely effective against severe disease, with vaccine efficacy significantly higher after the full immunization schedule. We investigate the impact of vaccines which have different efficacies after first dose and after the second dose administration schedule, eventually considering different efficacies against severe disease as opposed to overall infection. As a proof of concept, we model the vaccine performance of hospitalization reduction at the momentary scenario of the Basque Country, Spain, with population in a mixed vaccination setting, giving insights into the population coverage needed to achieve herd immunity in the current vaccination context.

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Impact of Meningococcal Serogroup C Conjugate Vaccines on Carriage and Herd Immunity

The Journal of Infectious Diseases ◽

10.1086/527401 ◽

2008 ◽

Vol 197 (5) ◽

pp. 737-743 ◽

Cited By ~ 312

Author(s):

Martin C J Maiden ◽

Ana Belén Ibarz-Pavón ◽

Rachel Urwin ◽

Stephen J Gray ◽

Nicholas J Andrews ◽

...

Keyword(s):

Vaccine Efficacy ◽

Rate Ratio ◽

Herd Immunity ◽

Age Groups ◽

Carriage Rate ◽

Vaccine Introduction ◽

The United Kingdom ◽

Asymptomatic Carriage ◽

The Impact

AbstractBackground. In 1999, meningococcal serogroup C conjugate (MCC) vaccines were introduced in the United Kingdom for those under 19 years of age. The impact of this intervention on asymptomatic carriage of meningococci was investigated to establish whether serogroup replacement or protection by herd immunity occurred.Methods. Multicenter surveys of carriage were conducted during vaccine introduction and on 2 successive years, resulting in a total of 48,309 samples, from which 8599 meningococci were isolated and characterized by genotyping and phenotyping.Results. A reduction in serogroup C carriage (rate ratio, 0.19) was observed that lasted at least 2 years with no evidence of serogroup replacement. Vaccine efficacy against carriage was 75%, and vaccination had a disproportionate impact on the carriage of sequence type (ST)-11 complex serogroup C meningococci that (rate ratio, 0.06); these meningococci also exhibited high rates of capsule expression.Conclusions. The impact of vaccination with MCC vaccine on the prevalence of carriage of group C meningococci was consistent with herd immunity. The high impact on the carriage of ST-11 complex serogroup C could be attributed to high levels of capsule expression. High vaccine efficacy against disease in young children, who were not protected long-term by the schedule initially used, is attributed to the high vaccine efficacy against carriage in older age groups.

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The Impact of Serotype Cross-Protection on Vaccine Trials: DENVax as a Case Study

Vaccines ◽

10.3390/vaccines8040674 ◽

2020 ◽

Vol 8 (4) ◽

pp. 674

Author(s):

Maíra Aguiar ◽

Nico Stollenwerk

Keyword(s):

Vaccine Efficacy ◽

Careful Consideration ◽

Dengue Vaccine ◽

Serious Adverse Events ◽

Post Vaccination ◽

Vaccine Trials ◽

Long Time ◽

Health Need ◽

The Impact ◽

Over Time

There is a growing public health need for effective preventive interventions against dengue, and a safe, effective and affordable dengue vaccine against the four serotypes would be a significant achievement for disease prevention and control. Two tetravalent dengue vaccines, Dengvaxia (CYD-TDV—Sanofi Pasteur) and DENVax (TAK 003—Takeda Pharmaceutical Company), have now completed phase 3 clinical trials. Although Dengvaxia resulted in serious adverse events and had to be restricted to individuals with prior dengue infections, DENVax has shown, at first glance, some encouraging results. Using the available data for the TAK 003 trial, we estimate, via the Bayesian approach, vaccine efficacy (VE) of the post-vaccination surveillance periods of 12 and 18 months. Although better measurement over a long time was expected for the second part of the post-vaccination surveillance, variation in serotype-specific efficacy needs careful consideration. Besides observing that individual serostatus prior to vaccination is determinant of DENVax vaccine efficacy, such as for Dengvaxia, we also noted, after comparing the VE estimations for 12- and 18-month periods, that vaccine efficacy is decreasing over time. The comparison of efficacies over time is informative and very important, and brings up the discussion of the role of temporary cross-immunity in dengue vaccine trials and the impact of serostatus prior to vaccination in the context of dengue fever epidemiology.

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Impact of Prior Infection on Severe Acute Respiratory Syndrome Coronavirus 2 Transmission in Syrian Hamsters

Frontiers in Microbiology ◽

10.3389/fmicb.2021.722178 ◽

2021 ◽

Vol 12 ◽

Author(s):

Cheng Zhang ◽

Zhendong Guo ◽

Nan Li ◽

Huan Cui ◽

Keyin Meng ◽

...

Keyword(s):

Severe Acute Respiratory Syndrome ◽

Direct Contact ◽

Herd Immunity ◽

Healthy Population ◽

Syrian Hamsters ◽

Vaccination Coverage Rate ◽

Contact Transmission ◽

The Impact ◽

Prior Infection ◽

Sterilizing Immunity

Prior infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) provides protective immunity against reinfection. However, whether prior infection blocks SARS-CoV-2 transmission is not yet clear. Here, we evaluated the impact of prior infection on SARS-CoV-2 transmission in Syrian hamsters. Our results showed that prior infection significantly reduced SARS-CoV-2 replication in Syrian hamsters, but sterilizing immunity was not achieved. Prior infection blocked the airborne transmission of SARS-CoV-2 from previously infected Syrian hamsters to naïve Syrian hamsters and previously infected Syrian hamsters. Moreover, prior infection substantially reduced the efficiency of direct contact transmission between previously infected Syrian hamsters. However, prior infection had limited impact on SARS-CoV-2 transmission from previously infected Syrian hamsters to naïve Syrian hamsters via direct contact in the early course of infection. Human reinfection and SARS-CoV-2 transmission between a previously infected population and a healthy population would be likely, and a higher vaccination coverage rate was needed to reach herd immunity. Our work will aid the implementation of appropriate public health and social measures to control coronavirus infectious disease 2019 (COVID-19) pandemic.

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SARS-CoV-2 (COVID-19) and the Endocrine System

Journal of the Endocrine Society ◽

10.1210/jendso/bvaa144 ◽

2020 ◽

Vol 4 (11) ◽

Author(s):

Michelle D Lundholm ◽

Caroline Poku ◽

Nicholas Emanuele ◽

Mary Ann Emanuele ◽

Norma Lopez

Keyword(s):

Severe Disease ◽

Clinical Manifestations ◽

Endocrine System ◽

The Body ◽

Active Area ◽

Gonadal Function ◽

Long Term Effects ◽

The World ◽

The Impact

Abstract As SARS-CoV-2 (COVID-19) overtakes the world, causing moderate to severe disease in about 15% of infected patients, COVID-19 is also found to have widespread effects throughout the body with a myriad of clinical manifestations including the endocrine system. This manuscript reviews what is known about the impact of COVID-19 on the pathophysiology and management of diabetes (both outpatient and inpatient) as well as pituitary, adrenal, thyroid, bone, and gonadal function. Findings in this area are evolving, and long-term effects of infection remain an active area of further research.

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Vaccination is Australia's most important COVID-19 public health action, even though herd immunity is unlikely

10.1101/2021.07.16.21260642 ◽

2021 ◽

Author(s):

Emma S McBryde ◽

Michael T Meehan ◽

Jamie Sziklay ◽

Adeshina Adekunle ◽

Abdul Kuddus ◽

...

Keyword(s):

Reproduction Number ◽

Control Strategies ◽

Severe Disease ◽

Herd Immunity ◽

Public Health Action ◽

Herd Protection ◽

Health Action ◽

The Impact ◽

Indirect Protection ◽

Better Than

The Australian National Cabinet four-step plan to transition to post-pandemic re-opening begins with vaccination to achieve herd protection and protection of the health system against a surge in COVID-19 cases. Assuming a pre-vaccination reproduction number for the Delta variant of 5, we show that for the current Mixed program of vaccinating over 60s with AstraZeneca and 16-60s with Pfizer we would not achieve herd immunity. We would need to cover 85% of the population (including many 5-16 year-olds to achieve herd immunity). At lower reproduction number of 3 and our current Mixed strategy, we can achieve herd immunity without vaccinating 5-15 year olds. This will be achieved at a 60% coverage pursuing a strategy targetting high transmitters or 70% coverage using a strategy targetting the vulnerable first. A reproduction number of 7 precludes achieving herd immunity, however vaccination is able to prevent 75% of deaths compared with no vaccination. We also examine the impact of vaccination on death in the event that herd immunity is not achieved. Direct effects of vaccination on reducing death are very good for both Pfizer and AstraZeneca vaccines. However we estimate that the Mixed or Pfizer program performs better than the AstraZeneca program. Furthermore, vaccination levels below the herd immunity threshold can lead to substantial (albeit incomplete) indirect protection for both vaccinated and unvaccinated populations. Given the potential for not reaching herd immunity, we need to consider what level of severe disease and death is acceptable, balanced against the consequences of ongoing aggressive control strategies.

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Impact of booster COVID-19 vaccine for Moroccan adults: A discrete age-structured model approach

10.1101/2021.03.14.21253555 ◽

2021 ◽

Author(s):

Aayah Hammoumi ◽

Hanane Hmarrass ◽

Redouane Qesmi

Keyword(s):

Vaccine Efficacy ◽

Adult Population ◽

Herd Immunity ◽

Vaccine Uptake ◽

Vaccination Program ◽

Model Parameters ◽

Structured Model ◽

Age Structured ◽

Age Structured Model ◽

The Impact

AbstractPublic health control strategies, such as lockdown, seem to be effective in reducing the spread of the pandemic, but are ineffective as a whole since lockdown is responsible of global economic crisis and badly lived by the majority of children and adults who have developed mental health disorders and familial problems as well. Thus, the development of a vaccine against COVID-19 is needed to control this disease. We have developed a discrete age-structured model and followed the Moroccan vaccination program to assess the impact of booster vaccination targeting Moroccan adults against COVID-19. Using the derived model, we estimated some relevant model parameters related to COVID-19 using collected cumulative mortality and reported Moroccan data. A control reproduction number Rc, which determines the necessary level of vaccine uptake that lead to COVID-19 eradication is determined. Furthermore, a herd immunity threshold above which the population can be protected from COVID-19 infection is derived. Analyzing the model, sufficient and necessary conditions for the eradication of the disease are obtained as well. Next, we perform numerical simulations to study the impact of several uptake levels of the potential vaccine on the persistence and the extinction of COVID-19 pandemic. Our results show that the COVID-19 is expected to last past 2021 in the absence of a vaccination program. Moreover, a vaccination of the adult population at rate 0.6% per day needs at least 67% of vaccine efficacy and 90% of immunogenicity rate to eradicate the disease. Using Sinopharm vaccine, the herd immunity can be achieved when about half of Moroccan adult population is immunized against the COVID-19. However, using Oxford-Astrazeneca vaccine, less than 60% of adult population must be immunized against the disease to achieve the herd immunity. Finally, if vaccine efficacy is about 80% and the immunogenicity is about 50% then vaccinating adults at rate of 0.6% per day could protect roughly 22% of children from COVID-19 infection.

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The Impact of Serotype Cross-Protection on Vaccine Trials: DENVax as a Case Study

10.20944/preprints202009.0671.v1 ◽

2020 ◽

Author(s):

Maíra Aguiar ◽

Nico Stollenwerk

Keyword(s):

Vaccine Efficacy ◽

Careful Consideration ◽

Dengue Vaccine ◽

Serious Adverse Events ◽

Post Vaccination ◽

Vaccine Trials ◽

Long Time ◽

Health Need ◽

The Impact ◽

Over Time

There is a growing public health need for effective preventive interventions against dengue, and a safe, effective and affordable dengue vaccine against the four serotypes would be a significant achievement for disease prevention and control. Two tetravalent dengue vaccines, Dengvaxia (Sanofi Pasteur) and DENVax (Takeda Pharmaceutical Company), have now completed phase 3 clinical trials. While Dengvaxia resulted in serious adverse events and is restricted to individuals with prior dengue infections, DENVax has shown, at first glance, some encouraging results. Using the available data for the TAK 003 trial, we estimate, via the Bayesian approach, vaccine efficacy (VE) of the post-vaccination surveillance periods. Although better measurement over long time was expected for the second part of the post-vaccination surveillance, variation in serotype-specific efficacy needs careful consideration. Besides observing that individual serostatus prior to vaccination is determinant of DENVax vaccine efficacy, we also compare the VE estimations for 12 and 18 months and we observe that the efficacy is decreasing over time. The comparison of efficacies over time is informative and very important, bring up the discussion of the role of temporary cross-immunity in dengue vaccine trials and the impact of serostatus prior to vaccination in the context of dengue fever epidemiology.

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How a school holiday led to persistent COVID-19 outbreaks in Europe

Scientific Reports ◽

10.1038/s41598-021-03927-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Björn Thor Arnarson

Keyword(s):

Herd Immunity ◽

European Regions ◽

Large Outbreak ◽

Winter School ◽

Using Data ◽

The Impact ◽

Over Time

AbstractThis paper investigates the role of large outbreaks on the persistence of Covid-19 over time. Using data from 650 European regions in 14 countries, I first show that winter school holidays in late February/early March 2020 (weeks 8, 9 and 10) led to large regional outbreaks of Covid-19 in the spring with the spread being 60% and up-to over 90% higher compared to regions with earlier school holidays. While the impact of these initial large outbreaks fades away over the summer months, it systematically reappears from the fall as regions with school holidays in weeks 8, 9 and 10 had 30–70% higher spread. This suggests that following a large outbreak, there is a strong element of underlying (latent) regional persistence of Covid-19. The strong degree of persistence highlights the long-term benefits of effective (initial) containment policies, as once a large outbreak has occurred, Covid-19 persists. This result emphasizes the need for vaccinations against Covid-19 in regions that have recently experienced large outbreaks but are well below herd-immunity, to avoid a new surge of cases.

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Optimising social mixing strategies achieving COVID-19 herd immunity while minimising mortality in six European countries

10.1101/2020.08.25.20182162 ◽

2020 ◽

Cited By ~ 1

Author(s):

Romain Ragonnet ◽

Guillaume Briffoteaux ◽

Bridget M. Williams ◽

Julian Savulescu ◽

Matthew Segal ◽

...

Keyword(s):

Time Horizon ◽

Herd Immunity ◽

Mitigation Strategies ◽

Social Contacts ◽

The Past ◽

Social Mixing ◽

The Uk ◽

The Impact ◽

Related Mortality

AbstractStrategies are needed to minimise the impact of COVID-19 in the medium-to-long term, until safe and effective vaccines can be used. Using a mathematical model in a formal optimisation framework, we identified contact mitigation strategies that minimised COVID-19-related mortality over a time-horizon of 15 months while achieving herd immunity in six or 12 months, in Belgium, France, Italy, Spain, Sweden, and the UK. We show that manipulation of social contacts by age can reduce the impact of COVID-19 considerably in the presence of intense transmission. If immunity was persistent, the optimised scenarios would result in herd immunity while causing a number of deaths considerably lower than that observed during the March-April European wave in Belgium, France, Spain and Sweden, whereas the numbers of deaths required to achieve herd immunity would be comparable to somewhat larger that the past epidemics in Italy and the UK. Our results also suggest that countries’ herd immunity thresholds may be considerably lower than first estimated for SARS-CoV-2. If post-infection immunity was short-lived, ongoing contact mitigation would be required to prevent major epidemic resurgence.

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Modelling the impact of Plasma Therapy and Immunotherapy for Recovery of COVID-19 Infected Individuals

10.1101/2020.05.23.20110973 ◽

2020 ◽

Author(s):

Nita H. Shah ◽

Ankush H. Suthar ◽

Ekta N. Jayswal ◽

Nehal Shukla ◽

Jagdish Shukla

Keyword(s):

Viral Infections ◽

Control Strategies ◽

Herd Immunity ◽

Limited Data ◽

Plasma Therapy ◽

Linear Ordinary Differential Equations ◽

Viral Loads ◽

First Case ◽

The Impact

AbstractSince the first case of COVID-19 was detected in Wuhan, China in December 2019, COVID-19 has become a pandemic causing a global economic and public health emergency. There is no known treatment or vaccine available for COVID-19 to date. Immunotherapy and plasma therapy has been used with satisfactory efficacy over the past two decades in many viral infections like SARS (Systemic Acute Respiratory Syndrome), MERS (Middle East Respiratory Syndrome), and H1N1. Limited data from China show clinical benefit, radiological resolution, reduction in viral loads, and improved survival. Our aim is to create a mathematical model for COVID-19 transmission and then apply various control parameters to see their effects on recovery from COVID-19 disease. We have formulated a system of non-linear ordinary differential equations, calculated basic reproduction R0, and applied five different controls (self-isolation, quarantine, herd immunity, immunotherapy, plasma therapy) to test the effectiveness of control strategy. Control optimality was checked by Lagrangian functions. Numerical simulations and bifurcation analyses were carried out. The study concludes that the COVID-19 outbreak can be controlled up to a significant level three weeks after applying all the control strategies together. These strategies lead to a reduction in hospitalization and a rise in recovery from infection. Immunotherapy is highly effective initially in hospitalized infected individuals however better results were seen in the long term with plasma therapy.

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