scholarly journals What serosurveillance studies tell us about the 2009 influenza pandemic

2011 ◽  
Vol 32 (1) ◽  
pp. 18
Author(s):  
Gary K Dowse ◽  
Ian Barr
Keyword(s):  
Influenza Pandemic ◽  
Herd Immunity ◽  
Case Fatality ◽  
Antigenic Drift ◽  
Surveillance Systems ◽  
Pandemic H1n1 ◽  
Infection Rates ◽  
Vaccination Programs ◽  
Pandemic Virus ◽  
The Impact

Surveillance of the impact of pandemic (H1N1) 2009 influenza during its initial seasons in both hemispheres relied on routinely available indicators, including numbers and rates of laboratory-detected cases, hospitalisations, ICU admissions and deaths, along with monitoring of influenza-like illness (ILI) from primary care sentinel surveillance systems. Estimates of the clinical attack rate and the case fatality ratio were imperfect. Understanding of the pathogenicity of the pandemic virus and prediction of the impact in subsequent seasons was hindered by a lack of information on actual infection rates in the population. Results of a number of serosurveys conducted in Australia and overseas countries have now become available, revealing that the arrival of the pandemic virus in modern urbanised and non-immune populations resulted in relatively similar infection rates in both the southern and northern hemispheres. Around 30?50% of children and teenagers were infected during the first pandemic season, with lower rates, around 10?20%, in young and middle-aged adults, and very few infections in older adults. There were significant numbers of mild or asymptomatic infections, and case fatality and hospitalisation ratios were much lower than those contemplated in pandemic plans. Many populations, including Australia, achieved a significant level of herd immunity during the first wave, and community susceptibility was further reduced by vaccination programs, although coverage was lower than expected. In the absence of significant antigenic drift or changes in virulence, the impact of the pandemic H1N1 virus should continue to decline in future influenza seasons.

scholarly journals Pandemic influenza in a southern hemisphere setting: the experience in Peru from May to September, 2009

2009 ◽  
Vol 14 (42) ◽  
Author(s):  
J Gómez ◽  
C V Munayco ◽  
J C Arrasco ◽  
L Suarez ◽  
V A Laguna-Torres ◽  
...  
Keyword(s):  
Respiratory Infections ◽  
Case Fatality ◽  
Respiratory Illness ◽  
H1n1 Influenza ◽  
Sentinel Surveillance ◽  
Surveillance Systems ◽  
Acute Respiratory Infections ◽  
Pandemic H1n1 ◽  
Pandemic H1n1 Influenza ◽  
The Impact

This paper presents a description of Peru’s experience with pandemic H1N1 influenza 2009. It is based on data from four main surveillance systems: a) ongoing sentinel surveillance of influenza-like illness cases with virological surveillance of influenza and other respiratory viruses; b) sentinel surveillance of severe acute respiratory infections and associated deaths; c) surveillance of acute respiratory infections in children under the age of five years and pneumonia in all age groups; and d) case and cluster surveillance. On 9 May 2009, the first confirmed case of pandemic H1N1 influenza in Peru was diagnosed in a Peruvian citizen returning from New York with a respiratory illness. By July, community transmission of influenza had been identified and until 27 September 2009, a total of 8,381 cases were confirmed. The incidence rate per 10,000 persons was 4.4 (in the 0–9 year-olds) and 4.1 (in the 10–19 year-olds). During epidemiological weeks (EW) 26 to 37, a total of 143 fatal cases were notified (a case fatality of 1.71%, based on confirmed cases). The maximum peak in the number of cases was reached in EW 30 with 37 deaths. Currently, the impact of the pandemic in the Peruvian population has not been too severe, and fortunately, healthcare centres have not been overwhelmed. However, the future of this pandemic is uncertain and despite the fact that our country has not been seriously affected, we should be prepared for upcoming pandemic waves.

scholarly journals Estimating asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan: a mathematical modeling study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xi Huo ◽  
Jing Chen ◽  
Shigui Ruan
Keyword(s):  
Disease Transmission ◽  
Large Scale ◽  
Transmission Rate ◽  
Control Strategies ◽  
Herd Immunity ◽  
Antibody Prevalence ◽  
Screening Process ◽  
Vaccination Programs ◽  
Prevalence Level ◽  
The Impact

Abstract Background The COVID-19 outbreak in Wuhan started in December 2019 and was under control by the end of March 2020 with a total of 50,006 confirmed cases by the implementation of a series of nonpharmaceutical interventions (NPIs) including unprecedented lockdown of the city. This study analyzes the complete outbreak data from Wuhan, assesses the impact of these public health interventions, and estimates the asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan. Methods By taking different stages of the outbreak into account, we developed a time-dependent compartmental model to describe the dynamics of disease transmission and case detection and reporting. Model coefficients were parameterized by using the reported cases and following key events and escalated control strategies. Then the model was used to calibrate the complete outbreak data by using the Monte Carlo Markov Chain (MCMC) method. Finally we used the model to estimate asymptomatic and undetected cases and approximate the overall antibody prevalence level. Results We found that the transmission rate between Jan 24 and Feb 1, 2020, was twice as large as that before the lockdown on Jan 23 and 67.6% (95% CI [0.584,0.759]) of detectable infections occurred during this period. Based on the reported estimates that around 20% of infections were asymptomatic and their transmission ability was about 70% of symptomatic ones, we estimated that there were about 14,448 asymptomatic and undetected cases (95% CI [12,364,23,254]), which yields an estimate of a total of 64,454 infected cases (95% CI [62,370,73,260]), and the overall antibody prevalence level in the population of Wuhan was 0.745% (95% CI [0.693%,0.814%]) by March 31, 2020. Conclusions We conclude that the control of the COVID-19 outbreak in Wuhan was achieved via the enforcement of a combination of multiple NPIs: the lockdown on Jan 23, the stay-at-home order on Feb 2, the massive isolation of all symptomatic individuals via newly constructed special shelter hospitals on Feb 6, and the large scale screening process on Feb 18. Our results indicate that the population in Wuhan is far away from establishing herd immunity and provide insights for other affected countries and regions in designing control strategies and planing vaccination programs.

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.

RISK FACTORS AND PROTECTION FACTORS FOR THE COVID-19 EPIDEMIC AND VACCINATION AS A POSSIBLE MEANS OF CONTROLLING THE EPIDEMIC

2017 ◽  
Author(s):  
Oksana Romaniv ◽  
◽  
Bohdan Klyapchuk ◽  
Keyword(s):  
Risk Factors ◽  
Economic Integration ◽  
Herd Immunity ◽  
Vaccination Program ◽  
Special Method ◽  
Vaccination Programs ◽  
Regional Dynamics ◽  
Spatio Temporal ◽  
The Impact

A study of the impact of especially contextual on COVID-19 factors of the epidemic (geopolitical, climatic, socio-economic integration, social, including religious, demographic and others) was conducted. The regional dynamics of the epidemic in the Scandinavian countries was analyzed. The spatio-temporal changes of the epidemic indicators in the conditions of loyalty to risk factors (Sweden) and in the conditions of controlled risks (in other countries of the Scandinavian region) were revealed. The current research of scientists on the formation of herd immunity in the population with and without vaccination programs was generalized. The article evaluated the quality of the vaccination program in Ukraine. The threshold indicator "herd immunity" and the number of months to achieve herd immunity in Ukraine without vaccination were calculated according to a special method.

scholarly journals COVID-19 Healthcare Planning: Predicting Mortality and the Role of the Herd Immunity Barrier in the General Population

2020 ◽  
Vol 12 (13) ◽  
pp. 5228
Author(s):  
Julio Emilio Marco-Franco ◽  
Natividad Guadalajara-Olmeda ◽  
Silvia González-de Julián ◽  
David Vivas-Consuelo
Keyword(s):  
General Population ◽  
Case Fatality Rate ◽  
Meta Analysis ◽  
Herd Immunity ◽  
Case Fatality ◽  
Fatality Rate ◽  
Daily Monitoring ◽  
Age Related ◽  
The Impact ◽  
Carlos Iii

Using a mathematical model for COVID-19 incorporating data on excess of mortality compared to the corresponding period of the previous year obtained from the daily monitoring of mortality in Spain (MoMo), the prediction of total number of casualties in Spain for the first outbreak has been computed. From this figure, and following a stepwise meta-analysis of available reports, the case fatality rate (CFR) and the infectious case fatality rate (IFR) for the outbreak have been estimated. As the impact of age on these rates is notable, it is proposed to include an age-related adjusted fatality ratio in future comparative analyses between studies, calculated by adjusting the results by risk ratio to a reference age band (e.g., 60–69). From the casualty figures, and the corresponding CFR and IFR ratios, the forecast of serologically positive cases in the general Spanish population has been estimated at approximately 1% (0.87–1.3%) of the samples. If the data are confirmed by the ongoing study of the Carlos III Institute, until a vaccine is found, the immunity acquired in the general population after the infectious outbreak is far from the 65–70% herd immunity required as a barrier for COVID-19.

scholarly journals 2716. Persistence of 13-Valent Pneumococcal Conjugate Vaccine (PCV13) Serotypes in Invasive Pneumococcal Disease in Adults in Southern Ontario Canada Despite Routine Pediatric Vaccination

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S955-S956
Author(s):  
Allison McGeer ◽  
Agron Plevneshi ◽  
Karen Green ◽  
Brenda Coleman ◽  
Sarah Nayani ◽  
...  
Keyword(s):  
Invasive Pneumococcal Disease ◽  
Pneumococcal Disease ◽  
Medical Information ◽  
Herd Immunity ◽  
Case Fatality ◽  
Population Data ◽  
Vaccination Programs ◽  
Significant Difference ◽  
Statistics Canada ◽  
Pediatric Vaccination

Abstract Background In Ontario, Canada, PCV13 is covered for immunocompromised (IC) adults over 50y. PCV13 programs are thought not to be cost-effective in other adults because it is assumed that herd immunity from pediatric vaccination programs (PCV7 since 2005; PCV13 since 2010) will reduce PCV13 disease burden dramatically in adults. We analyzed data from the Toronto Invasive Bacterial Diseases Network (TIBDN) to ask whether PCV13-type invasive pneumococcal disease (IPD) in adults persists in our population. Methods TIBDN performs population-based surveillance for IPD in Toronto+Peel Region, Ontario (pop4.1M). All microbiology laboratories receiving specimens from residents report cases of IPD and submit isolates to a central study lab for serotyping; annual audits are conducted. Demographic, medical and vaccination information are obtained from patients, families and physicians. Population data are from Statistics Canada. Results Since 1995, 10,365 episodes of IPD have been identified; detailed medical information was available for 9,801 (95%) and serotyping for 9411 (91%). Among 8658 adult cases, 4,273 (49%) were in those aged 15–64 years, and 4,285 (51%) in those aged >645 years. The most common diagnoses were pneumonia (5,978/8,025, 74%) and bacteremia without focus (1,030, 13%); 470 (4.6%) cases had meningitis; the case fatality rate (CFR) was 21%. The incidence of disease due to STs in PCV13 in adults declined from 7.0/100,000/year 2001 to 2.9/100,000/year in 2015–2018 and was stable from 2015–2018 (Figure 1). The incidence was > 5/100,000/year in non-IC patients over 65 years, and younger patients with cancer and kidney disease (Figure 2). In IPD from 2015 to 2018, adult patients with PCV13 ST disease were younger (median age 64 years vs. 67 years, P = .03) than other patients; there was no significant difference in the proportion with at least one underlying chronic condition (253, 69% PCV13ST, vs. 541,74% other ST, P = 0.08), or in CFR (59, 16% PCV13 vs. 145, 20% other, P = 0.13). The ST distribution of cases due to PCV13 STs is shown in Figure 3. Conclusion A significant burden of IPD due to PCV13 serotypes persists in adults in our population despite 8 years of routine pediatric PCV13 vaccination. This burden needs to be considered in assessing the value and cost-effectiveness of PCV programs for adults. Disclosures All authors: No reported disclosures.

scholarly journals Laboratory diagnosis of influenza and the impact of the pandemic (H1N1) 2009 virus

2011 ◽  
Vol 32 (1) ◽  
pp. 7
Author(s):  
Jen Kok ◽  
David W Smith ◽  
Dominic E Dwyer
Keyword(s):  
Diagnostic Testing ◽  
Nucleic Acid Amplification ◽  
Pandemic H1n1 ◽  
Public Health Perspective ◽  
Retrospective Diagnosis ◽  
Vaccination Programs ◽  
Preparedness Planning ◽  
Pandemic H1n1 2009 ◽  
Tract Infections ◽  
The Impact

Aetiological confirmation of respiratory tract infections in patients facilitates appropriate antimicrobial use and infection control procedures. From a public health perspective, the laboratory confirmation of influenza allows assessment of circulating viruses, community attack rates and the efficacy of vaccination programs, while assisting modelling as part of pandemic preparedness planning. Rapid antigen and immunofluorescent antigen tests are relatively insensitive in detecting pandemic (H1N1) 2009 influenza compared to seasonal subtypes, and influenza subtype-specific nucleic acid amplification tests should be used as the ?gold-standard? for diagnosis. Pathogen-specific serological testing aids the retrospective diagnosis of infection, and is used in seroprevalence studies. Influenza virus isolation is needed for vaccine assessment and formulation. Although some challenges surrounding diagnostic testing during pandemic (H1N1) 2009 have been resolved, others remain; this may test laboratories again in future pandemics.

scholarly journals Impact and effectiveness of meningococcal vaccines: a review

2017 ◽  
Vol 41 ◽  
pp. 1
Author(s):  
Lucia Helena De Oliveira ◽  
Barbara Jauregui ◽  
Ana Flavia Carvalho ◽  
Norberto Giglio
Keyword(s):  
Conjugate Vaccine ◽  
Meningococcal Disease ◽  
Age Groups ◽  
Epidemiological Surveillance ◽  
Surveillance Systems ◽  
Protein Subunit ◽  
Conjugate Vaccines ◽  
Vaccination Programs ◽  
Meta Analyses ◽  
The Impact

Objectives.To summarize and critically evaluate the evidence on the impact and effectiveness of meningococcal vaccination programs around the world in order to inform decisionmaking in Latin America and the Caribbean.Methods.A review of the literature was conducted following several components of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed Central® was searched for papers published in any language from January 1999 – March 2017.Results.In all, 32 studies were included, most of which evaluated the meningococcal C conjugate vaccine. Fourteen studies measured effectiveness and 30 measured impact. The effectiveness of polysaccharide vaccines was 65% – 83.7% (different age groups), while the effectiveness of the conjugate vaccines was 66% – 100%. Incidence decline of laboratory-confirmed meningococcal disease for the conjugate vaccine ranged from 77% – 100% among different ages groups. The only study that evaluated the protein subunit vaccine reported a vaccine effectiveness of 82.9%.Conclusions.The studies reviewed show impact and effectiveness of both polysaccharide vaccines and conjugate vaccines on vaccine-serogroup meningococcal disease. The conjugate vaccines, however, show higher impact and effectiveness with longer-lasting protection over the polysaccharide vaccines. Given the variance in potential use of a meningococcal vaccine, epidemiological surveillance systems should be strengthened to inform national decisions.

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