A spatial vaccination strategy to reduce the risk of vaccine-resistant variants

Abstract The process of vaccinating the world population against COVID-19 is expected to take well over a year to complete. As vaccination progresses and population immunity increases, a counteracting relaxation of social distancing measures is observed. The result will be a prolonged period of high disease prevalence combined with a fitness advantage for vaccine-resistant variants, implying a considerably increased probability that a resistant variant will spread in the population. In this paper we propose a spatial vaccination strategy that has the potential to dramatically reduce this risk. Instead of spreading the vaccination effort equally throughout a country, distinct geographic regions of the country are sequentially vaccinated, quickly bringing each to effective herd immunity. Regions with high vaccination rates will then have low infection rates and vice versa. Since people primarily interact with others in their own region, spatial vaccination will reduce the number of encounters between infected people (the source of mutations) and vaccinated people (who facilitate the spread of vaccine-resistant strains). Thus with proper logistic preparations, a spatial vaccination campaign could be highly effective in reducing the global risk of vaccine-resistant variants.

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Case study of COVID 19 from August to end of December 2020 in Babylon, Iraq

Iraq Medical Journal ◽

10.22317/imj.v5i3.1078 ◽

2021 ◽

Vol 5 (3) ◽

Keyword(s):

Herd Immunity ◽

Health Department ◽

Public Health Department ◽

Infected People ◽

The Public ◽

Population Immunity ◽

Previous Infection ◽

Study Case ◽

Indirect Protection

Objectives: The aim of study is to study Case study of COVID 19 in Babylon Province in Iraq. Method: In January 2021 we started searching for the official source for the numbers of people infected with COVID19 within the borders of Babylon Governorate, where the Babylon Health Department was reviewed, and after that we were directed with official authorization to the Public Health Department in Babylon Governorate / Department of Communicable Diseases / Respiratory Diseases Unit (weekly periodic visit). Where the official numbers were obtained for the number of infected people and the number of deaths that occur due to complication with this infection, as well as the number of recovery cases from the date of 01/08/2020 to 01/01/2021. Results: related to the number of infected cases we see decrease the no. of infected with corona virus in Babylon Governorate from beginning the study to become lest at the end of 2020 with the significant decrease (P < 0.05) (The highest infected cases were notices in first month (1/8 – 31/8) while the lowest cases were seen in last month (1/12 – 31/12)) that may be due to: The main cause may be the most people may have gained herd immunity or population immunity, is the indirect protection from an infectious disease that happens when a population is have immunity developed through previous infection, that may refer to the end of first wave of this pandemic which start from the June. Conclusion: Knowing the pathogenesis of the virus and risk factors, increasing the experience of doctors and working cadres, increasing clinical capacity, providing specialized treatments, increasing the number of ICU beds, in addition to increasing the number of respiratory ventilators and increasing the number of tests.

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Adapting French COVID-19 vaccination campaign duration to variant dissemination

10.1101/2021.03.17.21253739 ◽

2021 ◽

Author(s):

Simon Pageaud ◽

Nicolas Ponthus ◽

Romain Gauchon ◽

Catherine Pothier ◽

Christophe Rigotti ◽

...

Keyword(s):

Disease Transmission ◽

Vaccination Campaign ◽

Virus Transmission ◽

International Health ◽

Vaccination Strategy ◽

Health Crisis ◽

Population Immunity ◽

Best Response ◽

Rapid Dissemination ◽

Vaccination Campaigns

Background The outbreak of SARS-CoV-2 virus has caused a major international health crisis with serious consequences in terms of public health and economy. In France, two lockdown periods were decided in 2020 to avoid the saturation of intensive care units (ICU) and an increase in mortality. The rapid dissemination of variant SARS-CoV-2 VOC 202012/01 has strongly influenced the course of the epidemic. Vaccines have been rapidly developed. Their efficacy against the severe forms of the disease has been established, and their efficacy against disease transmission is under evaluation. The aim of this paper is to compare the efficacy of several vaccination strategies in the presence of variants in controlling the COVID-19 epidemic through population immunity. Methods An agent-based model was designed to simulate with different scenarios the evolution of COVID-19 pandemic in France over 2021 and 2022. The simulations were carried out ignoring the occurrence of variants then taking into account their diffusion over time. The expected effects of three Non-Pharmaceutical Interventions (Relaxed-NPI, Intensive-NPI, and Extended-NPI) to limit the epidemic extension were compared. The expected efficacy of vaccines were the values recently estimated in preventing severe forms of the disease (75% and 94%) for the current used vaccines in France (Pfizer-BioNTech and Moderna since January 11, 2021, and AstraZeneca since February 2, 2021). All vaccination campaigns reproduced an advanced age-based priority advised by the Haute Autoritć de Santć. Putative reductions of virus transmission were fixed at 0, 50, 75 and 90%. The effects of four vaccination campaign durations (6-month, 12-month, 18-month and 24-month) were compared. Results In the absence of vaccination, the presence of variants led to reject the Relaxed-NPI because of a high expected number of deaths (170 to 210 thousands) and the significant overload of ICUs from which 35 thousand patients would be deprived. In comparison with the situation without vaccination, the number of deaths was divided by 7 without ICU saturation with a 6-month vaccination campaign. A 12-month campaign would divide the number of deaths by 3 with Intensive-NPI and by 6 with Extended-NPI (the latter being necessary to avoid ICU saturation). With 18-month and 24-month vaccination campaigns without Extended-NPI, the number of deaths and ICU admissions would explode. Conclusion Among the four compared strategies the 6-month vaccination campaign seems to be the best response to changes in the dynamics of the epidemic due to the variants. The race against the COVID-19 epidemic is a race of vaccination strategy. Any further vaccination delay would increase the need of strengthened measures such as Extended-NPI to limit the number of deaths and avoid ICU saturation.

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ANALYSIS OF POPULATION IMMUNITY AGAINST INFLUENZA PRIOR TO 2014 AND 2015 EPIDEMIC SEASONS

Journal of microbiology epidemiology immunobiology ◽

10.36233/0372-9311-2017-2-53-60 ◽

2017 ◽

pp. 53-60 ◽

Cited By ~ 2

Author(s):

A. V. Shipovalov ◽

A. G. Durymanov ◽

O. V. Petrova ◽

E. V. Ivanova ◽

A. V. Epanchintseva ◽

...

Keyword(s):

Human Blood ◽

Influenza A ◽

Seasonal Influenza ◽

Vaccination Campaign ◽

Herd Immunity ◽

Influenza Viruses ◽

The Urals ◽

Population Immunity ◽

Clade 2.3.2.1C ◽

Sera Samples

Aim. Control for the population herd immunity against seasonal influenza viruses as well as for emergence of antibodies against influenza with pandemic potential in human blood sera. Materials and methods. HAI reaction against vaccine and epidemic influenza viruses as well as HPAI viruses A/rook/Chany/32/2015 (H5N1) (clade 2.3.2.1c.) andA/Anhui/01/2013 (H7N9). Results. Among all the sera samples collected in the autumn of 2014 and 2015, none had reacted in HAI against A(H5N1) and A(H7N9) antigens even at 1:10 dilution. Among samples collected in autumn 2014, 41% were positive to A/Califorrna/07/09(HlNlpdm09) virus, 36% - A/Texas/50/2012 (H3N2), 40% - B/Brisbane/60/2008 (Vict.lin.) and 47% reacted in HAI against the B/Massachusetts/2/2012 (Yam.lin.) strain. 22% of all the samples had a titer of at least 40 against all the antigens and only 10% in HAI had a titer of 40 or more against all the vaccine strains. Among the samples collected in autumn 2015, the number of seropositive against A/Califorrna/07/09(HlNlpdm09) varied from 31% in the Urals FD to 46% in the Southern FD. The amount of seropositive against A/Switzerland/9715293/13 (H3N2) strain was at the level of 4 - 13% in all the FDs except Urals, where this parameter was slightly above 30%. The amount of seropositive against vaccine influenza В viruses varied from 23 to 76%. Only 2% of sera had titers in HAI of 40 or above against all the vaccine strains, 29% of all the samples were seronegative. Conclusion. Population immunity in Russia against influenza A(H3N2) is at a very low level, thus socially significant consequences of influenza epidemics in many aspects will depend on the vaccination campaign of autumn 2016.

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To Vaccinate or Not to Vaccinate—This Is the Question among Swiss University Students

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18179210 ◽

2021 ◽

Vol 18 (17) ◽

pp. 9210

Author(s):

Julia Dratva ◽

Aylin Wagner ◽

Annina Zysset ◽

Thomas Volken

Keyword(s):

Vaccine Development ◽

Herd Immunity ◽

Vaccination Strategy ◽

Collective Responsibility ◽

Subjective Health ◽

Demographic Characteristics ◽

Vaccine Hesitancy ◽

Subjective Health Status ◽

Vaccination Rates ◽

Vaccination History

The speed and innovation of the COVID-19 vaccine development has been accompanied by insecurity and skepticism. Young adults’ attitude to vaccination remains under investigation, although herd immunity cannot be reached without them. The HEalth in Students during the Corona pandemic study (HES-C) provided the opportunity to investigate vaccination intention in 1478 students in the sixth survey wave (January 2021), including vaccination intention, psychological antecedents of vaccine hesitancy, trust in government’s vaccination strategy, and vaccination history. Associations with vaccination intention were analyzed with multivariate ordinal regression and predicted margins were calculated adjusting for gender, age, anxiety, health profession, and subjective health status. A third was decided (yes 25.1%, no 7.6%), and 68% were unsure about getting the COVID-19 vaccine when available. Next to demographic characteristics, vaccination history (influenza vaccination OR = 1.39; 95% CI: 1.06–1.83, travel vaccination OR = 1.29; 95% CI: 1.04–1.60), trust in vaccination strategy (OR = 2.40; 95% CI: 1.89–3.05), and 5C dimensions were associated with vaccination intention: confidence (OR = 2.52; 95% CI: 2.09–3.03), complacency (OR = 0.79; 95% CI: 0.66–0.96), calculation (OR = 0.79; 95% CI: 0.70–0.89), constraints (OR = 1.18; 95% CI: 0.99–1.41), and collective responsibility (OR = 4.47; 95% CI: 3.69–5.40). Addressing psychological antecedents and strengthening trust in official strategies through targeted campaigns and interventions may increase decisiveness and result in higher vaccination rates.

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Modelling an optimum vaccination strategy against ZIKA virus for outbreak use

Epidemiology and Infection ◽

10.1017/s0950268819000712 ◽

2019 ◽

Vol 147 ◽

Cited By ~ 2

Author(s):

Eduardo Massad ◽

Francisco Antonio Bezerra Coutinho ◽

Annelies Wilder-Smith

Keyword(s):

Zika Virus ◽

Vaccination Campaign ◽

Herd Immunity ◽

Vaccination Strategy ◽

Target Population ◽

Time Frame ◽

Critical Threshold ◽

Mass Vaccination Campaign ◽

The Moment ◽

Short Time

AbstractWe present a model to optimise a vaccination campaign aiming to prevent or to curb a Zika virus outbreak. We show that the optimum vaccination strategy to reduce the number of cases by a mass vaccination campaign should start when the Aedes mosquitoes' density reaches the threshold of 1.5 mosquitoes per humans, the moment the reproduction number crosses one. The maximum time it is advisable to wait for the introduction of a vaccination campaign is when the first ZIKV case is identified, although this would not be as effective to minimise the number of infections as when the mosquitoes' density crosses the critical threshold. This suboptimum strategy, however, would still curb the outbreak. In both cases, the catch up strategy should aim to vaccinate at least 25% of the target population during a concentrated effort of 1 month immediately after identifying the threshold. This is the time taken to accumulate the herd immunity threshold of 56.5%. These calculations were done based on theoretical assumptions that vaccine implementation would be feasible within a very short time frame.

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Influence of heterogeneous age-group contact patterns on critical vaccination rates for herd immunity to SARS-CoV-2

10.1101/2021.11.03.21265897 ◽

2021 ◽

Author(s):

Joan Saldana ◽

Caterina M Scoglio

Keyword(s):

Vaccination Coverage ◽

Herd Immunity ◽

Age Groups ◽

Social Contact ◽

Vaccination Strategy ◽

Primary Concern ◽

Vaccination Rates ◽

Contact Patterns ◽

Group Contact ◽

Age Structured

Currently, several western countries have more than half of their population fully vaccinated against COVID-19. At the same time, some of them are experiencing a fourth or even a fifth wave of cases, most of them concentrated in sectors of the populations whose vaccination coverage is lower than the average. So, the initial scenario of vaccine prioritization has given way to a new one where achieving herd immunity is the primary concern. Using an age-structured vaccination model with waning immunity, we show that, under a limited supply of vaccines, a vaccination strategy based on minimizing the basic reproduction number allows for the deployment of a number of vaccine doses lower than the one required for maximizing the vaccination coverage. Such minimization is achieved by giving greater protection to those age groups that, for a given social contact pattern, have smaller fractions of susceptible individuals at the endemic equilibrium without vaccination, that is, to those groups that are more vulnerable to infection.

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Predicting the impact of measles vaccination in England and Wales: model validation and analysis of policy options

Epidemiology and Infection ◽

10.1017/s0950268800057976 ◽

1995 ◽

Vol 114 (2) ◽

pp. 319-344 ◽

Cited By ~ 68

Author(s):

H. R. Babad ◽

D. J. Nokes ◽

N. J. Gay ◽

E. Miller ◽

P. Morgan-Capner ◽

...

Keyword(s):

Vaccine Coverage ◽

Case Reports ◽

Vaccination Campaign ◽

Herd Immunity ◽

Vaccination Strategy ◽

School Age Children ◽

Policy Options ◽

England And Wales ◽

Measles Vaccination ◽

The Impact

SummaryMeasles incidence in England and Wales has fallen to an all-time low. Attention is now focused on preventing local outbreaks, and, in the long run, on the elimination of indigenous measles. A realistic age-structured (RAS) mathematical model of measles transmission is used to reconstruct the impact of measles vaccination in England and Wales from 1968 to the present and to evaluate the merits of future policy options. In general, the predictions of the model show good agreement with long-term age stratified case reports and seroprevalence surveys. The model underestimates the proportion of cases that are notified in 0–2-year-old children. However, recent work suggests a high degree of misdiagnosis in this age group. Projections on the basis of the existing vaccination strategy in the UK suggest that the present level of measles vaccine coverage will be insufficient to eliminate small seasonal outbreaks of measles. This result is, however, sensitive to the assumed level of vaccine efficacy. Explorations of a variety of changes to current vaccination strategy favour a 2-dose schedule with the second dose administered at age 4 years irrespective of vaccination history. A vaccination campaign in school-age children, to reduce deficits in herd immunity, would accelerate progress towards measles elimination.

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COVID-19 Vaccine Intention among Healthcare Workers in Saudi Arabia: A Cross-Sectional Survey

Vaccines ◽

10.3390/vaccines9080835 ◽

2021 ◽

Vol 9 (8) ◽

pp. 835

Author(s):

Mohammed Noushad ◽

Mohammad Zakaria Nassani ◽

Anas B. Alsalhani ◽

Pradeep Koppolu ◽

Fayez Hussain Niazi ◽

...

Keyword(s):

Saudi Arabia ◽

Healthcare System ◽

Healthcare Workers ◽

Vaccine Coverage ◽

Vaccination Campaign ◽

Herd Immunity ◽

Positive Sign ◽

Cross Sectional Survey ◽

Cross Sectional ◽

Public Health Strategies

The COVID-19 pandemic has caused largescale morbidity and mortality and a tremendous burden on the healthcare system. Healthcare workers (HCWs) require adequate protection to avoid onward transmission and minimize burden on the healthcare system. Moreover, HCWs can also influence the general public into accepting the COVID-19 vaccine. Therefore, determining COVID-19 vaccine intention among HCWs is of paramount importance to plan tailor-made public health strategies to maximize vaccine coverage. A structured questionnaire was administered in February and March 2021 among HCWs in Saudi Arabia using convenience sampling, proceeding the launch of the vaccination campaign. HCWs from all administrative regions of Saudi Arabia were included in the study. In total, 674 out of 1124 HCWs responded and completed the survey (response rate 59.9%). About 65 percent of the HCWs intended to get vaccinated. The intention to vaccinate was significantly higher among HCWs 50 years of age or older, Saudi nationals and those who followed the updates about COVID-19 vaccines (p < 0.05). The high percentage (26 percent) of those who were undecided in getting vaccinated is a positive sign. As the vaccination campaign gathers pace, the attitude is expected to change over time. Emphasis should be on planning healthcare strategies to convince the undecided HCWs into accepting the vaccine in order to achieve the coverage required to achieve herd immunity.

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Correlates of Improved Influenza Vaccination of Healthcare Personnel: A Survey of Hospitals in Louisiana

Infection Control and Hospital Epidemiology ◽

10.1086/670992 ◽

2013 ◽

Vol 34 (7) ◽

pp. 723-729 ◽

Cited By ~ 6

Author(s):

Kayla L. Fricke ◽

Mariella M. Gastañaduy ◽

Renee Klos ◽

Rodolfo E. Bégué

Keyword(s):

Intensive Care Unit ◽

Intensive Care ◽

Influenza Vaccination ◽

Vaccination Campaign ◽

Vaccination Rate ◽

Healthcare Personnel ◽

Patient Contact ◽

Hospital Type ◽

Vaccination Rates ◽

Item Questionnaire

Objective.To describe practices for influenza vaccination of healthcare personnel (HCP) with emphasis on correlates of increased vaccination rates.Design.Survey.Participants.Volunteer sample of hospitals in Louisiana.Methods.All hospitals in Louisiana were invited to participate. A 17-item questionnaire inquired about the hospital type, patients served, characteristics of the vaccination campaign, and the resulting vaccination rate.Results.Of 254 hospitals, 153 (60%) participated and were included in the 124 responses that were received. Most programs (64%) required that HCP either receive the vaccine or sign a declination form, and the rest were exclusively voluntary (36%); no program made vaccination a condition of employment. The median vaccination rate was 67%, and the vaccination rate was higher among hospitals that were accredited by the Joint Commission; provided acute care; served children, pregnant women, oncology patients, or intensive care unit patients; required a signed declination form; or imposed consequences for unvaccinated HCP (the most common of which was to require that a mask be worn on patient contact). Hospitals that provided free vaccine, made vaccine widely available, advertised the program extensively, required a declination form, and imposed consequences had the highest vaccination rates (median, 86%; range, 81%–91%).Conclusions.The rate of influenza vaccination of HCP remains low among the hospitals surveyed. Recommended practices may not be enough to reach 90% vaccination rates unless a signed declination requirement and consequences are implemented. Wearing a mask is a strong consequence. Demanding influenza vaccination as a condition of employment was not reported as a practice by the participating hospitals.

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The Effect of Vaccination Rates on the Infection of COVID-19 under the Vaccination Rate below the Herd Immunity Threshold

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18147491 ◽

2021 ◽

Vol 18 (14) ◽

pp. 7491

Author(s):

Yi-Tui Chen

Keyword(s):

Infection Rate ◽

Herd Immunity ◽

The United States ◽

Vaccination Rate ◽

Infection Rates ◽

Vaccination Rates ◽

The United Kingdom ◽

The World ◽

Almost All ◽

The Impact

Although vaccination is carried out worldwide, the vaccination rate varies greatly. As of 24 May 2021, in some countries, the proportion of the population fully vaccinated against COVID-19 has exceeded 50%, but in many countries, this proportion is still very low, less than 1%. This article aims to explore the impact of vaccination on the spread of the COVID-19 pandemic. As the herd immunity of almost all countries in the world has not been reached, several countries were selected as sample cases by employing the following criteria: more than 60 vaccine doses per 100 people and a population of more than one million people. In the end, a total of eight countries/regions were selected, including Israel, the UAE, Chile, the United Kingdom, the United States, Hungary, and Qatar. The results find that vaccination has a major impact on reducing infection rates in all countries. However, the infection rate after vaccination showed two trends. One is an inverted U-shaped trend, and the other is an L-shaped trend. For those countries with an inverted U-shaped trend, the infection rate begins to decline when the vaccination rate reaches 1.46–50.91 doses per 100 people.

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