scholarly journals A Mathematical Model of U.S. COVID-19 Deaths, Incidence and Quarantine Adjusted Herd Immunity by Age

2021 ◽  
Author(s):  
Vikki Lovvoll
Keyword(s):  
Case Reports ◽  
Critical Mass ◽  
Herd Immunity ◽  
Age Groups ◽  
P Value ◽  
Younger Adults ◽  
Social Distancing ◽  
Social Mixing ◽  
Steep Decline ◽  
Disease Testing

Abstract In January 2021, a steep decline in U.S. COVID-19 deaths and case reports were noted, well before herd immunity or vaccinations would have been expected make an impact. This model predicts COVID-19 deaths and infections based on three insights. First, mortality rates differ significantly by age. Second, heterogeneous social mixing by age during quarantine may result in older adults (higher risk) to have more effectively quarantined conferring lower incidence relative to younger adults (lower risk and disproportionate essential frontline work). Third, deaths and Infection Fatality Rates may more reliably predict incidence relative to reported cases by removing uncertainty introduced from asymptomatic disease, testing availability, and false results. Age stratified IFR and deaths through December 5 were used to projected deaths (99% significance, P-value .002). Sensitivities for IFR, immune durability, and vaccinations were also modeled. By end 2020, 42% of the U.S. population had immunity differing significantly by age with 25-44-year-olds near 80%. A “critical mass” of immunity in these ages segments conferred herd immunity to other age groups. Herd immunity exists in the context of historic social distancing (quarantine). A significant percent of high-risk individuals remains susceptible and may facilitate another wave if social distancing restrictions are lifted prior to vaccination. Vaccine administrations through mid-February contributed a nominal amount to declining deaths.

scholarly journals SARS-CoV-2 antibody seroprevalence in Lebanon: findings from the first nationwide serosurvey

2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Abbas Hoballah ◽  
Rana El Haidari ◽  
Ghina Siblany ◽  
Fadi Abdel Sater ◽  
Samir Mansour ◽  
...  
Keyword(s):  
Test Performance ◽  
Point Of Care ◽  
Vaccination Campaign ◽  
Herd Immunity ◽  
Age Groups ◽  
Rapid Test ◽  
Population Based ◽  
P Value ◽  
Cumulative Number ◽  
Population Weight

Abstract Background Lebanon, a small country in the Middle East, remains severely affected by the COVID-19 pandemic. Seroprevalence surveys of anti-SARS-CoV-2 antibodies provide accurate estimates of SARS-CoV-2 infection and hence evaluate the extent of the pandemic. The present study aimed to evaluate the prevalence of SARS-CoV-2 antibodies in Lebanon and to compare the estimated cumulative number of COVID-19 cases with the officially registered number of laboratory-confirmed cases up to January 15, 2021. Methods A nationwide population-based serosurvey study was conducted in Lebanon between December 7, 2020, and January 15, 2021, before the initiation of the national vaccination program. The nCOVID-19 IgG & IgM point-of-care (POCT) rapid test was used to detect the presence of anti-SARS-COV-2 immunoglobulin G (IgG) in the blood. Seroprevalence was estimated after weighting for sex, age, and area of residence and adjusting for the test performance. Results Of the 2058 participants, 329 were positive for IgG SARS-COV-2, resulting in a crude seroprevalence of 16.0% (95% CI 14.4–17.6). The weighed seroprevalence was 15.9% (95% CI of 14.4 and 17.4). After adjusting for test performance, the population weight-adjusted seroprevalence was 18.5% (95% CI 16.8–20.2). This estimate implies that 895,770 individuals of the general population were previously infected by COVID-19 up to January 15, 2021 in Lebanon. The overall estimated number of subjects with previous SARS-CoV-2 infection was three times higher than the officially reported cumulative number of confirmed cases. Seroprevalence was similar across age groups and sexes (p-value > 0.05). However, significant differences were revealed across governorates. Conclusions Our results suggest that the Lebanese population is still susceptible to SARS-CoV-2 infection and far from achieving herd immunity. These findings represent an important contribution to the surveillance of the COVID-19 pandemic in Lebanon and to the understanding of how this virus spreads. Continued surveillance for COVID-19 cases and maintaining effective preventive measures are recommended to control the epidemic spread in conjunction with a national vaccination campaign to achieve the desired level of herd immunity against COVID-19.

scholarly journals COVID-19 Epidemic in Algeria: Assessment of the implemented preventive strategy

2020 ◽  
Author(s):  
Mohamed Hamidouche
Keyword(s):  
Herd Immunity ◽  
Mitigation Measures ◽  
Bivariate Analysis ◽  
P Value ◽  
Efficacy Rate ◽  
Preventive Strategy ◽  
Way Of Life ◽  
Social Distancing ◽  
Demand For Health ◽  
Second Wave

AbstractSince the spread of the COVID-19 epidemic in China, several preventive strategies have been implemented worldwide to fight against the spread of SARS-CoV-2, in Algeria the control actions have been mainly social distancing, movement’s restriction, quarantine and lockdown.In order to assess the preventive strategy adopted in Algeria, we studied three zones (whole country, the main outbreak at Blida, and whole country except Blida), we used as a indicator the basic reproduction number R0, we compared the mean R0-before and R0-after the implementation of the mitigation measures using bivariate analysis, then we used the results we found to estimate the number of COVID-19 cases avoided by these measures, then after, we predicted the peak of the epidemic’s first wave.We note that the decrease in R0 after the preventive measures implementation was statistically significant (p value<10−4) in the three areas, thus, the preventive strategy in Algeria has been effective in its entirety. Our projection revealed that 15613 cases of COVID-19 were avoided in 14 days (from April 6, to April 19, 2020) in the whole country, and 1747 cases were prevented in Blida during the same period. We estimate that the peak of the first wave of the epidemic in Algeria will be reached with herd immunity of 15.93% as of November 2020, however, at least 56% of people with protective immunity would be needed to be sufficient to avoid a second wave. The used method to carry out the evaluation has given us a good overview, but, R0 is not the only factor to consider when estimating the burden of the epidemic, to do that, the number of daily admissions to intensive care units and hospitalizations remain good indicators.In order to better the epidemic control in Algeria, it is possible to act on contact efficacy rate by adding an instruction to wear medical mask by ordinary population outside, this measure has been reported to be effective in some countries.To conclude, it is good to keep in mind that a new way of life based on good hygiene habits and social distancing must therefore be in place and adopted by the population for at least several months, otherwise the demand for health care will exceed the availability.

scholarly journals Transmission dynamics reveal the impracticality of COVID-19 herd immunity strategies

2020 ◽  
Vol 117 (41) ◽  
pp. 25897-25903 ◽  
Author(s):  
Tobias S. Brett ◽  
Pejman Rohani
Keyword(s):  
Transmission Rate ◽  
Herd Immunity ◽  
Age Groups ◽  
Extended Period ◽  
Target Population ◽  
Transmission Model ◽  
Social Distancing ◽  
The United Kingdom ◽  
Age Structured ◽  
Nonpharmaceutical Interventions

The rapid growth rate of COVID-19 continues to threaten to overwhelm healthcare systems in multiple countries. In response, severely affected countries have had to impose a range of public health strategies achieved via nonpharmaceutical interventions. Broadly, these strategies have fallen into two categories: 1) “mitigation,” which aims to achieve herd immunity by allowing the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus to spread through the population while mitigating disease burden, and 2) “suppression,” aiming to drastically reduce SARS-CoV-2 transmission rates and halt endogenous transmission in the target population. Using an age-structured transmission model, parameterized to simulate SARS-CoV-2 transmission in the United Kingdom, we assessed the long-term prospects of success using both of these approaches. We simulated a range of different nonpharmaceutical intervention scenarios incorporating social distancing applied to differing age groups. Our modeling confirmed that suppression of SARS-CoV-2 transmission is possible with plausible levels of social distancing over a period of months, consistent with observed trends. Notably, our modeling did not support achieving herd immunity as a practical objective, requiring an unlikely balancing of multiple poorly defined forces. Specifically, we found that 1) social distancing must initially reduce the transmission rate to within a narrow range, 2) to compensate for susceptible depletion, the extent of social distancing must be adaptive over time in a precise yet unfeasible way, and 3) social distancing must be maintained for an extended period to ensure the healthcare system is not overwhelmed.

scholarly journals COVID-19 herd immunity strategies: walking an elusive and dangerous tightrope

2020 ◽  
Author(s):  
Tobias S Brett ◽  
Pejman Rohani
Keyword(s):  
Transmission Rate ◽  
Herd Immunity ◽  
Age Groups ◽  
Target Population ◽  
Transmission Model ◽  
Social Distancing ◽  
Long Duration ◽  
Age Structured ◽  
The Uk ◽  
Public Health Strategies

AbstractThe rapid growth in cases of COVID-19 has threatened to overwhelm healthcare systems in multiple countries. In response, severely affected countries have had to consider a range of public health strategies achieved by implementing non-pharmaceutical interventions. Broadly, these strategies have fallen into two categories: i) “mitigation”, which aims to achieve herd immunity by allowing the SARS-CoV-2 virus to spread through the population while mitigating disease burden, and ii) “suppression”, aiming to drastically reduce SARS-CoV-2 transmission rates and halt endogenous transmission in the target population. Using an age-structured transmission model, parameterised to simulate SARS-CoV-2 transmission in the UK, we assessed the prospects of success using both of these approaches. We simulated a range of different non-pharmaceutical intervention scenarios incorporating social distancing applied to differing age groups. We found that it is possible to suppress SARS-CoV-2 transmission if social distancing measures are sustained at a sufficient level for a period of months. Our modelling did not support achieving herd immunity as a practical objective, requiring an unlikely balancing of multiple poorly-defined forces. Specifically, we found that: i) social distancing must initially reduce the transmission rate to within a narrow range, ii) to compensate for susceptible depletion, the extent of social distancing must be vary over time in a precise but unfeasible way, and iii) social distancing must be maintained for a long duration (over 6 months).

Cognitive Load Affects Speech Motor Performance Differently in Older and Younger Adults

2019 ◽  
Vol 62 (5) ◽  
pp. 1258-1277 ◽  
Author(s):  
Megan K. MacPherson
Keyword(s):  
Older Adults ◽  
Cognitive Load ◽  
Motor Performance ◽  
Age Groups ◽  
Incongruent Condition ◽  
Sentence Production ◽  
Movement Duration ◽  
Production Task ◽  
Younger Adults ◽  
Speech Motor

PurposeThe aim of this study was to determine the impact of cognitive load imposed by a speech production task on the speech motor performance of healthy older and younger adults. Response inhibition, selective attention, and working memory were the primary cognitive processes of interest.MethodTwelve healthy older and 12 healthy younger adults produced multiple repetitions of 4 sentences containing an embedded Stroop task in 2 cognitive load conditions: congruent and incongruent. The incongruent condition, which required participants to suppress orthographic information to say the font colors in which color words were written, represented an increase in cognitive load relative to the congruent condition in which word text and font color matched. Kinematic measures of articulatory coordination variability and movement duration as well as a behavioral measure of sentence production accuracy were compared between groups and conditions and across 3 sentence segments (pre-, during-, and post-Stroop).ResultsIncreased cognitive load in the incongruent condition was associated with increased articulatory coordination variability and movement duration, compared to the congruent Stroop condition, for both age groups. Overall, the effect of increased cognitive load was greater for older adults than younger adults and was greatest in the portion of the sentence in which cognitive load was manipulated (during-Stroop), followed by the pre-Stroop segment. Sentence production accuracy was reduced for older adults in the incongruent condition.ConclusionsIncreased cognitive load involving response inhibition, selective attention, and working memory processes within a speech production task disrupted both the stability and timing with which speech was produced by both age groups. Older adults' speech motor performance may have been more affected due to age-related changes in cognitive and motoric functions that result in altered motor cognition.

Video Games and Emotion Regulation

GeroPsych ◽  
2018 ◽  
Vol 31 (4) ◽  
pp. 205-213 ◽  
Author(s):  
Kathryn L. Ossenfort ◽  
Derek M. Isaacowitz
Keyword(s):  
Older Adults ◽  
Emotion Regulation ◽  
Video Games ◽  
Age Differences ◽  
Interactive Media ◽  
Age Groups ◽  
Younger Adults ◽  
Media Usage ◽  
The Everyday ◽  
Media Preferences

Abstract. Research on age differences in media usage has shown that older adults are more likely than younger adults to select positive emotional content. Research on emotional aging has examined whether older adults also seek out positivity in the everyday situations they choose, resulting so far in mixed results. We investigated the emotional choices of different age groups using video games as a more interactive type of affect-laden stimuli. Participants made multiple selections from a group of positive and negative games. Results showed that older adults selected the more positive games, but also reported feeling worse after playing them. Results supplement the literature on positivity in situation selection as well as on older adults’ interactive media preferences.

Sources of cognitive conflict and their relevance to Theory of Mind proficiency in healthy ageing. A preregistered study.

2018 ◽  
Author(s):  
Foyzul Rahman ◽  
Sabrina Javed ◽  
Ian Apperly ◽  
Peter Hansen ◽  
Carol Holland ◽  
...  
Keyword(s):  
Theory Of Mind ◽  
Executive Control ◽  
Spatial Working Memory ◽  
Age Groups ◽  
Response Speed ◽  
Cognitive Conflict ◽  
Mental States ◽  
Younger Adults ◽  
Age Related ◽  
Outcome Knowledge

Age-related decline in Theory of Mind (ToM) may be due to waning executive control, which is necessary for resolving conflict when reasoning about others’ mental states. We assessed how older (OA; n=50) versus younger adults (YA; n=50) were affected by three theoretically relevant sources of conflict within ToM: competing Self-Other perspectives; competing cued locations and outcome knowledge. We examined which best accounted for age-related difficulty with ToM. Our data show unexpected similarity between age groups when representing a belief incongruent with one’s own. Individual differences in attention and motor response speed best explained the degree of conflict experienced through conflicting Self-Other perspectives. However, OAs were disproportionately affected by managing conflict between cued locations. Age and spatial working memory were most relevant for predicting the magnitude of conflict elicited by conflicting cued locations. We suggest that previous studies may have underestimated OA’s ToM proficiency by including unnecessary conflict in ToM tasks.

Corona Virus (COVID-19) Awareness Assessment - A Survey Study Amongst the Indian Population

2020 ◽  
Author(s):  
Gabriela Fernandes
Keyword(s):  
Health Care ◽  
Social Media ◽  
Health Care Workers ◽  
Indian Population ◽  
Age Groups ◽  
Survey Study ◽  
Social Distancing ◽  
Corona Virus ◽  
Care Workers ◽  
Amount Of Knowledge

Aim: The aim of this survey study was to assess the level of awareness amongst Indian population regarding the COVID-19. Method: A survey was conducted amongst 745 individuals to assess their level of awareness regarding COVID-19 and steps to be taken for its prevention. Result: The results revealed that a considerable percentage of individuals learned about the pandemic through social media and news and were aware of the mode of spread of the virus and also steps to be taken to prevent it from spreading. But considerable percentage of people was also not fully aware regarding the age groups this virus will be affecting. Conclusion: Upon understanding the percentage of people not aware about the age groups this virus will be affecting, keeping in mind good amount of knowledge amongst individuals about maintaining hygiene and social distancing, this survey would help the health care workers to create awareness regarding the effect of this virus on different age groups to help prevent carelessness amongst youth in following the regime.

The Prevalence of Insecticide Treated Net/malaria :cross section study (Preprint)

2019 ◽  
Author(s):  
Chanda Chalela
Keyword(s):  
Study Design ◽  
Age Groups ◽  
Cross Sectional Study ◽  
Malaria Prevalence ◽  
Malaria Patient ◽  
P Value ◽  
Sectional Study ◽  
Cross Sectional ◽  
Itn Use ◽  
Structured Questionnaire

BACKGROUND ABSTRACT Introduction a study on prevalence of ITN use was carried out in Buchi community Kitwe Zambia from August to October 2019 OBJECTIVE Prevalence of ITN in BUchi METHODS Methodology: This was a cross sectional study design. A structured questionnaire was used to ascertain ownership and utilization and oral interviews, 200 households were targeted 844 individual covered across the 200 households. Data was analyzed with SPSS version 23. RESULTS ABSTRACT Introduction a study on prevalence of ITN use was carried out in Buchi community Kitwe Zambia from August to October 2019 Methodology: This was a cross sectional study design. A structured questionnaire was used to ascertain ownership and utilization and oral interviews, 200 households were targeted 844 individual covered across the 200 households. Data was analyzed with SPSS version 23. Findings: household ownership of at least an ITN was 52% and individual utilization at 37.6%, with 0.825 ITN/households and 0.195ITN /individual. Malaria prevalence of 52.4% /household and a 12.4% of the population. With 47.6% malaria patient coming from households with ITN and 60% of households with ITN have insufficient coverage.61% of malaria patient were female and 31 % male. however there was no significant relation between Gender and malaria prevalence in study area (p value was >0.05). Malaria cases distribution with age groups, 0-15yrs old represented 49.5%, 16-30 yrs., was at 27.6% and the over 30 yrs. case were at 22.9% .use of other preventive measures 23% used mosquito repellent ,others methods 1% with those not using any other methods 76%. CONCLUSIONS Conclusion The study showed clearly that malaria still poses a problem .the prevalence rate of malaria was still high 12.4% of the population and 52.4% of households. With high prevalence of malaria of 49.5% for 0-15yrs.the difference between ownership 52% and Utilization 37.6% showed that even household with ITN, the ITN were not sufficient.60% of households with ITN, the ITN were not sufficient for all occupants

Seroprevalence of anti-SARS-CoV-2 IgG antibodies in hospitalized patients at a tertiary referral center in North India (Preprint)

2020 ◽  
Author(s):  
Dr. Animesh Ray ◽  
Dr. Komal Singh ◽  
Souvick Chattopadhyay ◽  
Farha Mehdi ◽  
Dr. Gaurav Batra ◽  
...  
Keyword(s):  
Tertiary Care ◽  
Age Groups ◽  
Hospitalized Patients ◽  
North India ◽  
P Value ◽  
Care Hospital ◽  
Igg Antibodies ◽  
Igg Antibody ◽  
Increased Risk ◽  
Significant Difference

BACKGROUND Seroprevalence of IgG antibodies against SARS-CoV-2 is an important tool to estimate the true extent of infection in a population. However, seroprevalence studies have been scarce in South East Asia including India, which, as of now, carries the third largest burden of confirmed cases in the world. The present study aimed to estimate the seroprevalence of anti-SARS-CoV-2 IgG antibody among hospitalized patients at one of the largest government hospital in India OBJECTIVE The primary objective of this study is to estimate the seroprevalence of SARS-CoV-2 antibody among patients admitted to the Medicine ward and ICU METHODS This cross-sectional study, conducted at a tertiary care hospital in North India, recruited consecutive patients who were negative for SARS-CoV-2 by RT-PCR or CB-NAAT. Anti-SARS-CoV-2 IgG antibody levels targeting recombinant spike receptor-binding domain (RBD) protein of SARS CoV-2 were estimated in serum sample by the ELISA method RESULTS A total of 212 hospitalized patients were recruited in the study with mean age (±SD) of 41.2 (±15.4) years and 55% male population. Positive serology against SARS CoV-2 was detected in 19.8%patients(95% CI 14.7-25.8). Residency in Delhi conferred a higher frequency of seropositivity 26.5% (95% CI 19.3-34.7) as compared to that of other states 8% (95% CI 3.0-16.4) with p-value 0.001. No particular age groups or socio-economic strata showed a higher proportion of seropositivity CONCLUSIONS Around, one-fifth of hospitalized patients, who were not diagnosed with COVID-19 before, demonstrated seropositivity against SARS-CoV-2. While there was no significant difference in the different age groups and socio-economic classes; residence in Delhi was associated with increased risk (relative risk of 3.62, 95% CI 1.59-8.21)

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