The vaccination threshold for SARS-CoV-2 depends on the indoor setting and room ventilation

Abstract Background Effective vaccines are now available for SARS-CoV-2 in the 2nd year of the COVID-19 pandemic, but there remains significant uncertainty surrounding the necessary vaccination rate to safely lift occupancy controls in public buildings and return to pre-pandemic norms. The aim of this paper is to estimate setting-specific vaccination thresholds for SARS-CoV-2 to prevent sustained community transmission using classical principles of airborne contagion modeling. We calculated the airborne infection risk in three settings, a classroom, prison cell block, and restaurant, at typical ventilation rates, and then the expected number of infections resulting from this risk at varying percentages of occupant immunity. Results We estimate the setting-specific immunity threshold for control of wild-type SARS-CoV-2 to range from a low of 40% for a mechanically ventilation classroom to a high of 85% for a naturally ventilated restaurant. Conclusions If vaccination rates are limited to a theoretical minimum of approximately two-thirds of the population, enhanced ventilation above minimum standards for acceptable air quality is needed to reduce the frequency and severity of SARS-CoV-2 superspreading events in high-risk indoor environments.

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The Vaccination Threshold for SARS-CoV-2 Depends on the Indoor Setting and Room Ventilation

10.1101/2021.07.28.21261300 ◽

2021 ◽

Author(s):

Alex Mikszewski ◽

Luca Stabile ◽

Giorgio Buonanno ◽

Lidia Morawska

Keyword(s):

Vaccination Rate ◽

Indoor Environments ◽

Expected Number ◽

Vaccination Rates ◽

Susceptibility To Infection ◽

Airborne Infection ◽

Community Transmission ◽

Second Year ◽

Ventilation Rates ◽

Theoretical Minimum

Background: Effective vaccines are now available for SARS-CoV-2 in the second year of the COVID-19 pandemic, but there remains significant uncertainty surrounding the necessary vaccination rate to safely lift occupancy controls in public buildings and return to pre-pandemic norms. The aim of this paper is to estimate setting-specific vaccination thresholds for SARS-CoV-2 to prevent sustained community transmission using classical principles of airborne contagion modeling. We calculated the airborne infection risk in three settings, a classroom, prison cell block, and restaurant, at typical ventilation rates, and then the expected number of infections resulting from this risk at varying levels of occupant susceptibility to infection. Results: We estimate the vaccination threshold for control of SARS-CoV-2 to range from a low of 40% for a mechanically ventilation classroom to a high of 85% for a naturally ventilated restaurant. Conclusions: If vaccination rates are limited to a theoretical minimum of approximately two-thirds of the population, enhanced ventilation above minimum standards for acceptable air quality is needed to reduce the frequency and severity of SARS-CoV-2 superspreading events in high-risk indoor environments.

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Predictive and retrospective modelling of airborne infection risk using monitored carbon dioxide

Indoor and Built Environment ◽

10.1177/1420326x211043564 ◽

2021 ◽

pp. 1420326X2110435

Author(s):

Henry C. Burridge ◽

Shiwei Fan ◽

Roderic L. Jones ◽

Catherine J. Noakes ◽

P. F. Linden

Keyword(s):

Carbon Dioxide ◽

Absolute Risk ◽

Infection Risk ◽

Expected Number ◽

Indoor Space ◽

Airborne Infection ◽

Secondary Infections ◽

School Classroom ◽

Open Plan ◽

Ventilation Rates

The risk of long range, herein ‘airborne', infection needs to be better understood and is especially urgent during the COVID-19 pandemic. We present a method to determine the relative risk of airborne transmission that can be readily deployed with either modelled or monitored CO2 data and occupancy levels within an indoor space. For spaces regularly, or consistently, occupied by the same group of people, e.g. an open-plan office or a school classroom, we establish protocols to assess the absolute risk of airborne infection of this regular attendance at work or school. We present a methodology to easily calculate the expected number of secondary infections arising from a regular attendee becoming infectious and remaining pre/asymptomatic within these spaces. We demonstrate our model by calculating risks for both a modelled open-plan office and by using monitored data recorded within a small naturally ventilated office. In addition, by inferring ventilation rates from monitored CO2, we show that estimates of airborne infection can be accurately reconstructed, thereby offering scope for more informed retrospective modelling should outbreaks occur in spaces where CO2 is monitored. Well-ventilated spaces appear unlikely to contribute significantly to airborne infection. However, even moderate changes to the conditions within the office, or new variants of the disease, typically result in more troubling predictions.

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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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SARS-CoV-2 lineage dynamics in England from January to March 2021 inferred from representative community samples

10.1101/2021.05.08.21256867 ◽

2021 ◽

Author(s):

Oliver Eales ◽

Andrew Page ◽

Sonja N. Tang ◽

Caroline E. Walters ◽

Haowei Wang ◽

...

Keyword(s):

Reproduction Number ◽

Sequence Data ◽

Community Sample ◽

Age Groups ◽

Health Interventions ◽

Wild Type ◽

Rt Pcr ◽

Community Surveys ◽

Community Transmission ◽

Middle Aged Adults

Genomic surveillance for SARS-CoV-2 lineages informs our understanding of possible future changes in transmissibility and vaccine efficacy. However, small changes in the frequency of one lineage over another are often difficult to interpret because surveillance samples are obtained from a variety of sources. Here, we describe lineage dynamics and phylogenetic relationships using sequences obtained from a random community sample who provided a throat and nose swab for rt-PCR during the first three months of 2021 as part of the REal-time Assessment of Community Transmission-1 (REACT-1) study. Overall, diversity decreased during the first quarter of 2021, with the B.1.1.7 lineage (first identified in Kent) predominant, driven by a 0.3 unit higher reproduction number over the prior wild type. During January, positive samples were more likely B.1.1.7 in younger and middle-aged adults (aged 18 to 54) than in other age groups. Although individuals infected with the B.1.1.7 lineage were no more likely to report one or more classic COVID-19 symptoms compared to those infected with wild type, they were more likely to be antibody positive 6 weeks after infection. Viral load was higher in B.1.1.7 infection as measured by cycle threshold (Ct) values, but did not account for the increased rate of testing positive for antibodies. The presence of infections with non-imported B.1.351 lineage (first identified in South Africa) during January, but not during February or March, suggests initial establishment in the community followed by fade-out. However, this occurred during a period of stringent social distancing and targeted public health interventions and does not immediately imply similar lineages could not become established in the future. Sequence data from representative community surveys such as REACT-1 can augment routine genomic surveillance.

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

10.1101/2021.11.22.21266721 ◽

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.

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

10.1101/2021.02.23.21252299 ◽

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.

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COVID-19 Vaccination Rates by Global Universal Health Care Coverage Status

International Journal of Translational Medical Research and Public Health ◽

10.21106/ijtmrph.328 ◽

2021 ◽

Vol 5 (1) ◽

pp. 33-36

Author(s):

Deepa Dongarwar ◽

Hamisu M. Salihu

Keyword(s):

Health Care ◽

Herd Immunity ◽

Vaccination Rate ◽

Universal Health Care ◽

Vaccination Rates ◽

Creative Commons ◽

Universal Health Care Coverage ◽

Universal Health ◽

Open Access Article ◽

Better Than

Healthcare coverage and the type of insurance have always played huge roles in public health outcomes. With coronavirus disease-2019 (COVID-19) vaccination now available across the world, we sought to determine vaccination rates across countries with Universal Health Care (UHC) coverage versus those without. We utilized the vaccination information from the Coronavirus (COVID-19) Vaccinations website, and calculated early vaccination rate for each country as of January, 13, 2021 by dividing the total number of vaccinations given to the total population of the country. We observed that the average early vaccination rate for countries with UHC was 1.55%, whereas that for countries without UHC was 0.51%. Countries with UHC are performing much better than those without UHC in this initial race for providing herd immunity across the globe. Copyright © 2021 Dongarwar and Salihu. Published by Global Health and Education Projects, Inc. This is an open-access article distributed under the terms of the Creative Commons Attribution License CC BY 4.0.

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Modeling-Based Estimate of the Vaccination Rate, Lockdown Rules and COVID-19

Healthcare ◽

10.3390/healthcare9101245 ◽

2021 ◽

Vol 9 (10) ◽

pp. 1245

Author(s):

Chinlin Guo ◽

Wei-Chiao Chang

Keyword(s):

Critical Factor ◽

Economic Loss ◽

Vaccination Rate ◽

Slight Reduction ◽

High Morbidity ◽

Vaccination Rates ◽

Significant Difference ◽

Simulation Scenario ◽

Set Up ◽

Spread Of Infection

COVID-19 has become a severe infectious disease and has caused high morbidity and mortality worldwide. Restriction rules such as quarantine and city lockdown have been implemented to mitigate the spread of infection, leading to significant economic impacts. Fortunately, development and inoculation of COVID-19 vaccines are being conducted on an unprecedented scale. The effectiveness of vaccines raises a hope that city lockdown might not be necessary in the presence of ongoing vaccination, thereby minimizing economic loss. The question, however, is how fast and what type of vaccines should be inoculated to control the disease without limiting economic activity. Here, we set up a simulation scenario of COVID-19 outbreak in a modest city with a population of 2.5 million. The basic reproduction number (R0) was ranging from 1.0 to 5.5. Vaccination rates at 1000/day, 10,000/day and 100,000/day with two types of vaccine (effectiveness v = 51% and 89%) were given. The results indicated that R0 was a critical factor. Neither high vaccination rate (10,000 persons/day) nor high-end vaccine (v = 89%) could control the disease when the scenario was at R0 = 5.5. Unless an extremely high vaccination rate was given (>4% of the entire population/per day), no significant difference was found between two types of vaccine. With the population scaled to 25 million, the required vaccination rate was >1,000,000/day, a quite unrealistic number. Nevertheless, with a slight reduction of R0 from 5 to 3.5, a significant impact of vaccine inoculation on disease control was observed. Thus, our study raised the importance of estimating transmission dynamics of COVID-19 in a city before determining the subsequent policy.

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Use Of A Mobile Cart Influenza Program For Vaccination Of Hospital Employees

Infection Control and Hospital Epidemiology ◽

10.1086/502320 ◽

2004 ◽

Vol 25 (11) ◽

pp. 918-922 ◽

Cited By ~ 99

Author(s):

Catherine Sartor ◽

Herve Tissot-Dupont ◽

Christine Zandotti ◽

Francoise Martin ◽

Pierre Roques ◽

...

Keyword(s):

Influenza Vaccination ◽

Vaccination Rate ◽

Associate Professor ◽

University Hospital ◽

Vaccination Program ◽

Vaccination Rates ◽

Vaccination Acceptance ◽

The Impact ◽

Haenszel Test

AbstractObjective:Rates of annual influenza vaccination of healthcare workers (HCWs) remained low in our university hospital. This study was conducted to evaluate the impact of a mobile cart influenza vaccination program on HCW vaccination.Methods:From 2000 to 2002, the employee health service continued its annual influenza vaccination program and the mobile cart program was implemented throughout the institution. This program offered influenza vaccination to all employees directly on the units. Each employee completed a questionnaire. Vaccination rates were analyzed using the Mantel–Haenszel test.Results:The program proposed vaccination to 50% to 56% of the employees. Among the nonvaccinated employees, 52% to 53% agreed to be vaccinated. The compliance with vaccination varied from 61% to 77% among physicians and medical students and from 38% to 55% among nurses and other employees. Vaccination of the chief or associate professor of the unit was associated with a higher vaccination rate of the medical staff (P < .01). Altogether, the vaccination program led to an increase in influenza vaccination among employees from 6% in 1998 and 7% in 1999 before the mobile cart program to 32% in 2000, 35% in 2001, and 32% in 2002 (P < .001).Conclusions:The mobile cart program was associated with a significantly increased vaccination acceptance. Our study was able to identify HCW groups for which the mobile cart was effective and highlight the role of the unit head in its success.

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