scholarly journals Likelihood of infecting or getting infected with COVID-19 as a function of vaccination status, as investigated with a stochastic model for New Zealand (Aotearoa)

2021 ◽  
Author(s):  
Leighton M Watson
Keyword(s):  
New Zealand ◽  
Process Model ◽  
Branching Process ◽  
Total Population ◽  
Population Level ◽  
Vaccination Rate ◽  
Vaccination Status ◽  
Government Action ◽  
Vaccination Rates ◽  
Eligible Population

Aim: The New Zealand government is transitioning from the Alert Level framework, which relies on government action and population level controls, to the COVID-19 Protection Framework, which relies on vaccination rates and allows for greater freedoms (for the vaccinated). As restrictions are eased, there is significant interest in understanding the relative risk of spreading COVID-19 posed by unvaccinated and vaccinated individuals. Methods: A stochastic branching process model is used to simulate the spread of COVID-19 for outbreaks seeded by unvaccinated or vaccinated individuals. The likelihood of infecting or getting infected with COVID-19 is calculated based on vaccination status. Results: A vaccinated traveler infected with COVID-19 is 9x less likely to seed an outbreak than an unvaccinated traveler infected with COVID-19. For a vaccination rate of 50%, unvaccinated individuals are responsible for 87% of all infections whereas 3% of infections are from vaccinated to vaccinated. When normalized by population, a vaccinated individual is 6.8x more likely to be infected by an unvaccinated individual than by a vaccinated individual. For a total population vaccination rate of 78.7%, which is equivalent to the 90% vaccination target for the eligible population (over 12 years old), this means that vaccinated individuals are 1.9x more likely to be infected by an unvaccinated individual than by a vaccinated, even though there are 3.7x more vaccinated individuals in the population. Conclusions: This work demonstrates that most new infections are caused by unvaccinated individuals. These simulations illustrate the importance of vaccination in stopping individuals from becoming infected with COVID-19 and in preventing onward transmission.

scholarly journals Simulating the impact of vaccination rates on the initial stages of a COVID-19 outbreak in New Zealand (Aotearoa) with a stochastic model

2021 ◽  
Author(s):  
Leighton M Watson
Keyword(s):  
New Zealand ◽  
Stochastic Model ◽  
Process Model ◽  
Branching Process ◽  
Total Population ◽  
Median Number ◽  
Vaccination Rate ◽  
Vaccination Rates ◽  
The Impact ◽  
Different Levels

Aim: The August 2021 COVID-19 outbreak in Auckland has caused the New Zealand government to transition from an elimination strategy to suppression, which relies heavily on high vaccination rates in the population. As restrictions are eased and as COVID-19 leaks through the Auckland boundary, there is a need to understand how different levels of vaccination will impact the initial stages of COVID-19 outbreaks that are seeded around the country. Method: A stochastic branching process model is used to simulate the initial spread of a COVID-19 outbreak for different vaccination rates. Results: High vaccination rates are effective at minimizing the number of infections and hospitalizations. Increasing vaccination rates from 20% (approximate value at the start of the August 2021 outbreak) to 80% (approximate proposed target) of the total population can reduce the median number of infections that occur within the first four weeks of an outbreak from 1011 to 14 (25th and 75th quantiles of 545-1602 and 2-32 for V=20% and V=80%, respectively). As the vaccination rate increases, the number of breakthrough infections (infections in fully vaccinated individuals) and hospitalizations of vaccinated individuals increases. Unvaccinated individuals, however, are 3.3x more likely to be infected with COVID-19 and 25x more likely to be hospitalized. Conclusion: This work demonstrates the importance of vaccination in protecting individuals from COVID-19, preventing high caseloads, and minimizing the number of hospitalizations and hence limiting the pressure on the healthcare system.

scholarly journals The Public Health Impact of Delaying a Second Dose of the BNT162b2 or mRNA-1273 COVID-19 Vaccine

2021 ◽  
Author(s):  
Santiago Romero-Brufau ◽  
Ayush Chopra ◽  
Alex J Ryu ◽  
Esma Gel ◽  
Ramesh Raskar ◽  
...  
Keyword(s):  
Vaccination Strategy ◽  
Population Level ◽  
Health Impact ◽  
Vaccination Rate ◽  
Agent Based Modeling ◽  
Sensitivity Analyses ◽  
Agent Based ◽  
Cumulative Mortality ◽  
Vaccination Rates ◽  
The Public

AbstractObjectivesTo estimate population health outcomes under delayedsecond dose versus standard schedule SARS-CoV-2 mRNA vaccination.DesignAgent-based modeling on a simulated population of 100,000 based on a real-world US county. The simulation runs were replicated 10 times. To test the robustness of these findings, simulations were performed under different estimates for single-dose efficacy and vaccine administration rates, and under the possibility that a vaccine prevents only symptoms but not asymptomatic spread.Settingpopulation level simulation.Participants100,000 agents are included in the simulation, with a representative distribution of demographics and occupations. Networks of contacts are established to simulate potentially infectious interactions though occupation, household, and random interactionsInterventionswe simulate standard Covid-19 vaccination, versus delayed-second-dose vaccination prioritizing first dose. Sensitivity analyses include first-dose vaccine efficacy of 70%, 80% and 90% after day 12 post-vaccination; vaccination rate of 0.1%, 0.3%, and 1% of population per day; assuming the vaccine prevents only symptoms but not asymptomatic spread; and an alternative vaccination strategy that implements delayed-second-dose only for those under 65 years of age.Main outcome measurescumulative Covid-19 mortality over 180 days, cumulative infections and hospitalizations.ResultsOver all simulation replications, the median cumulative mortality per 100,000 for standard versus delayed second dose was 226 vs 179; 233 vs 207; and 235 vs 236; for 90%, 80% and 70% first-dose efficacy, respectively. The delayed-second-dose strategy was optimal for vaccine efficacies at or above 80%, and vaccination rates at or below 0.3% population per day, both under sterilizing and non-sterilizing vaccine assumptions, resulting in absolute cumulative mortality reductions between 26 and 47 per 100,000. The delayed-second-dose for those under 65 performed consistently well under all vaccination rates tested.ConclusionsA delayed-second-dose vaccination strategy, at least for those under 65, could result in reduced cumulative mortality under certain conditions.

Vaccination Against Seasonal or Pandemic Influenza in Emergency Medical Services

2016 ◽  
Vol 31 (2) ◽  
pp. 155-162 ◽  
Author(s):  
Alexandre Moser ◽  
Cédric Mabire ◽  
Olivier Hugli ◽  
Victor Dorribo ◽  
Giorgio Zanetti ◽  
...  
Keyword(s):  
Emergency Medical Services ◽  
Pandemic Influenza ◽  
Work Experience ◽  
Good Health ◽  
Vaccination Rate ◽  
Vaccination Status ◽  
Medical Services ◽  
Publication Type ◽  
Vaccination Rates ◽  
Emergency Medical

AbstractIntroductionInfluenza is a major concern for Emergency Medical Services (EMS); EMS workers’ (EMS-Ws) vaccination rates remain low despite promotion. Determinants of vaccination for seasonal influenza (SI) or pandemic influenza (PI) are unknown in this setting.HypothesisThe influence of the H1N1 pandemic on EMS-W vaccination rates, differences between SI and PI vaccination rates, and the vaccination determinants were investigated.MethodsA survey was conducted in 2011 involving 65 Swiss EMS-Ws. Socio-professional data, self-declared SI/PI vaccination status, and motives for vaccine refusal or acceptation were collected.ResultsResponse rate was 95%. The EMS-Ws were predominantly male (n=45; 73%), in good health (87%), with a mean age of 36 (SD=7.7) years. Seventy-four percent had more than six years of work experience. Self-declared vaccination rates were 40% for both SI and PI (PI+/SI+), 19% for PI only (PI+/SI-), 1.6% for SI only (PI-/SI+), and 39% were not vaccinated against either (PI-/SI-). Women’s vaccination rates specifically were lower in all categories but the difference was not statistically significant. During the previous three years, 92% of PI+/SI+ EMS-Ws received at least one SI vaccination; it was 8.3% in the case of PI-/SI- (P=.001) and 25% for PI+/SI- (P=.001). During the pandemic, SI vaccination rate increased from 26% during the preceding year to 42% (P=.001). Thirty percent of the PI+/SI+ EMS-Ws declared that they would not get vaccination next year, while this proportion was null for the PI-/SI- and PI+/SI- groups. Altruism and discomfort induced by the surgical mask required were the main motivations to get vaccinated against PI. Factors limiting PI or SI vaccination included the option to wear a mask, avoidance of medication, fear of adverse effects, and concerns about safety and effectiveness.ConclusionAverage vaccination rate in this study’s EMS-Ws was below recommended values, particularly for women. Previous vaccination status was a significant determinant of PI and future vaccinations. The new mask policy seemed to play a dual role, and its net impact is probably limited. This population could be divided in three groups: favorable to all vaccinations; against all, even in a pandemic context; and ambivalent with a “pandemic effect.” These results suggest a consistent vaccination pattern, only altered by exceptional circumstances.MoserA, MabireC, HugliO, DorriboV, ZanettiG, Lazor-BlanchetC, CarronPN. Vaccination against seasonal or pandemic influenza in Emergency Medical Services. Prehosp Disaster Med. 2016;31(2):155–162.

scholarly journals Rapid Impact Analysis of B 1.1.7 Variant on the Spread of SARS-CoV-2 in North Carolina

2021 ◽  
Author(s):  
Michael DeWitt
Keyword(s):  
North Carolina ◽  
Impact Analysis ◽  
Reproduction Number ◽  
Population Level ◽  
Vaccination Rate ◽  
Vaccination Rates ◽  
Current Vaccine ◽  
Spread Of Infection ◽  
The Impact ◽  
Pharmaceutical Interventions

AbstractBackgroundSeveral cases of the B1.1.7 variant of the SARS-CoV-2 virus were identified in North Carolina first on January 23, 2021 in Mecklenburg County and later in Guilford County on January 28, 2021.[1,2] This variant has been associated with higher levels of transmissibility.[3–6] This study examines the potential impact of increased transmissibility as the B1.1.7 variant becomes more predominant given current vaccine distribution plans and existing non-pharmaceutical interventions (NPIs).MethodWe explored the anticipated impact on the effective reproduction number for North Carolina and Guilford County given the date of import of B1.1.7. The approximate growth rate in proportion of B1.1.7 observed in the United Kingdom was fit and used to establish the estimate share of B1.1.7 circulating in North Carolina. Using the nowcasted reproduction numbers, a stochastic discrete compartmental model was fit with the current vaccination rates and B1.1.7 transmissibility to estimate the impact on the effective reproduction number.ResultsWe found that the effective reproduction number for North Carolina and Guilford County may exceed one, indicating a return to accelerating spread of infection in April as the proportion of B1.1.7 increases. The effective reproduction number will likely decrease into March, then increase as the proportion of B1.1.7 increases in circulation in the population.ConclusionsExisting non-pharmaceutical interventions will need to remain in effect through the spring. Given the current vaccination rate and these interventions, it is likely that there will be an increase in SARS-CoV-2 infections. The impact of the variant will likely be heterogeneous across North Carolina given the reproduction number and volume of susceptible persons in each county at the time of introduction of the variant. Age-based vaccinations will likely reduce the overall impact on hospitalizations. This analysis underlines the need for population level genetic surveillance to confirm the proportion of variants circulating.

scholarly journals Tracking the uptake and trajectory of COVID-19 vaccination coverage in 15 West African countries: an interim analysis

2021 ◽  
Vol 6 (12) ◽  
pp. e007518
Author(s):  
Muhammed Olanrewaju Afolabi ◽  
Oghenebrume Wariri ◽  
Yauba Saidu ◽  
Akaninyene Otu ◽  
Semeeh Akinwale Omoleke ◽  
...  
Keyword(s):  
Vaccination Coverage ◽  
Total Population ◽  
Vaccine Development ◽  
Population Level ◽  
West African ◽  
African Countries ◽  
Vaccination Rates ◽  
Vaccination Coverage Rate ◽  
Country Level ◽  
Heads Of State

The African Union Bureau of Heads of State and Government endorsed the COVID-19 Vaccine Development and Access Strategy to vaccinate at least 60% of each country’s population with a safe and efficacious vaccine by 2022, to achieve the population-level immunity needed to bring the pandemic under control. Using publicly available, country-level population estimates and COVID-19 vaccination data, we provide unique insights into the uptake trends of COVID-19 vaccinations in the 15 countries that comprise the Economic Community of West Africa States (ECOWAS). Based on the vaccination rates in the ECOWAS region after three months of commencing COVID-19 vaccinations, we provide a projection of the trajectory and speed of vaccination needed to achieve a COVID-19 vaccination coverage rate of at least 60% of the total ECOWAS population. After three months of the deployment of COVID-19 vaccines across the ECOWAS countries, only 0.27% of the region’s total population had been fully vaccinated. If ECOWAS countries follow this trajectory, the sub-region will have less than 1.6% of the total population fully vaccinated after 18 months of vaccine deployment. Our projection shows that to achieve a COVID-19 vaccination coverage of at least 60% of the total population in the ECOWAS sub-region after 9, 12 and 18 months of vaccine deployment; the speed of vaccination must be increased to 10, 7 and 4 times the current trajectory, respectively. West African governments must deploy contextually relevant and culturally acceptable strategies for COVID-19 vaccine procurements, distributions and implementations in order to achieve reasonable coverage and save lives, sooner rather than later.

scholarly journals Early intervention is the key to success in COVID-19 control

2021 ◽  
Vol 8 (11) ◽  
Author(s):  
Rachelle N. Binny ◽  
Michael G. Baker ◽  
Shaun C. Hendy ◽  
Alex James ◽  
Audrey Lustig ◽  
...  
Keyword(s):  
New Zealand ◽  
Early Intervention ◽  
Process Model ◽  
Branching Process ◽  
Time Frame ◽  
Early Introduction ◽  
Community Transmission ◽  
And Control ◽  
At Home

New Zealand responded to the COVID-19 pandemic with a combination of border restrictions and an Alert Level (AL) system that included strict stay-at-home orders. These interventions were successful in containing an outbreak and ultimately eliminating community transmission of COVID-19 in June 2020. The timing of interventions is crucial to their success. Delaying interventions may reduce their effectiveness and mean that they need to be maintained for a longer period. We use a stochastic branching process model of COVID-19 transmission and control to simulate the epidemic trajectory in New Zealand's March–April 2020 outbreak and the effect of its interventions. We calculate key measures, including the number of reported cases and deaths, and the probability of elimination within a specified time frame. By comparing these measures under alternative timings of interventions, we show that changing the timing of AL4 (the strictest level of restrictions) has a far greater impact than the timing of border measures. Delaying AL4 restrictions results in considerably worse outcomes. Implementing border measures alone, without AL4 restrictions, is insufficient to control the outbreak. We conclude that the early introduction of stay-at-home orders was crucial in reducing the number of cases and deaths, enabling elimination.

scholarly journals Overview: The international group for indigenous health measurement and COVID-19

2021 ◽  
pp. 1-6
Author(s):  
Michele Connolly ◽  
Kalinda Griffiths ◽  
John Waldon ◽  
Malcolm King ◽  
Alexandra King ◽  
...  
Keyword(s):  
New Zealand ◽  
Total Population ◽  
Indigenous Health ◽  
Health Data ◽  
Indigenous Populations ◽  
Health Measurement ◽  
Country Group ◽  
International Group ◽  
The Us ◽  
The Impact

The International Group for Indigenous Health Measurement (IGIHM) is a 4-country group established to promote improvements in the collection, analysis, interpretation and dissemination of Indigenous health data, including the impact of COVID-19. This overview provides data on cases and deaths for the total population as well as the Indigenous populations of each country. Brief summaries of the impact are provided for Canada and New Zealand. The Overview is followed by. separate articles with more detailed discussion of the COVID-19 experience in Australia and the US.

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

2013 ◽  
Vol 34 (7) ◽  
pp. 723-729 ◽  
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.

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

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.

Exploring a Hidden Epidemic: Drowning Among Adults Aged 65 Years and Older

2021 ◽  
pp. 089826432110147
Author(s):  
Tessa Clemens ◽  
Amy E. Peden ◽  
Richard C. Franklin
Keyword(s):  
Older Adults ◽  
New Zealand ◽  
Retrospective Analysis ◽  
Older Adult ◽  
Total Population ◽  
Downward Trend ◽  
Population Projections ◽  
Prevention Strategies ◽  
Drowning Prevention

Objectives: To explore trends in unintentional fatal drowning among older adults (65 years and older). Methods: Total population retrospective analysis of unintentional fatal drowning among people aged 65 years and older in Australia, Canada and New Zealand (2005–2014) was conducted. Results: 1459 older adults died. Rates ranged from 1.69 (Canada) to 2.20 (New Zealand) per 100,000. Trends in crude drowning rates were variable from year to year. A downward trend was observed in New Zealand (y = −.507ln(x) + 2.9918), with upward trends in Australia (y = .1056ln(x) + 1.5948) and Canada (y = .1489ln(x) + 1.4571). Population projections suggest high annual drowning deaths by 2050 in Australia (range: 120–190; 1.69–2.76/100,000) and Canada (range: 209–430; 1.78–3.66/100,000). Significant locations and activities associated with older adult drowning differed by country and age band. Conclusions: Drowning among older adults is a hidden epidemic claiming increasing lives as the population ages. Targeted drowning prevention strategies are urgently needed in Australia, Canada, New Zealand and other similar countries.

Sign in / Sign up

Export Citation Format

Share Document