Will achieving herd immunity be a road to success to end the COVID-19 pandemic?
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ABSTRACT:
SUBMITTER: Kwok KO
PROVIDER: S-EPMC8189733 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The COVID-19 pandemic has been a global threat. Through rapid and effective surveillance and control, the newly confirmed patients have been fluctuated at a very low level and imported case explained most of them through March, 2020 to the present, indicating China's response has achieved a stage victory. By contrast, the epidemic of COVID-19 in other countries out of China is bursting. Different countries are adopting varied response strategy in terms of their public health system to prevent the spread. Herd immunity has been a hot topic since the outbreak of COVID-19 pandemic. Can it be a possible strategy to combat COVID-19? To fully interpret the knowledge regarding the term upon the background of COVID-19-related health crisis, we aim to systematically review the definition, describe the effective measures of acquiring herd immunity, and discuss its feasibility in COVID-19 prevention. Findings from this review would promote and strengthen the international cooperation and joint efforts when confronting with COVID-19.
| S-EPMC7543944 | biostudies-literature
Project description:There is an urgent need for effective countermeasures against the current emergence and accelerating expansion of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Induction of herd immunity by mass vaccination has been a very successful strategy for preventing the spread of many infectious diseases, hence protecting the most vulnerable population groups unable to develop immunity, for example individuals with immunodeficiencies or a weakened immune system due to underlying medical or debilitating conditions. Therefore, vaccination represents one of the most promising counter-pandemic measures to COVID-19. However, to date, no licensed vaccine exists, neither for SARS-CoV-2 nor for the closely related SARS-CoV or Middle East respiratory syndrome-CoV. In addition, a few vaccine candidates have only recently entered human clinical trials, which hampers the progress in tackling COVID-19 infection. Here, we discuss potential prophylactic interventions for SARS-CoV-2 with a focus on the challenges existing for vaccine development, and we review pre-clinical progress and ongoing human clinical trials of COVID-19 vaccine candidates. Although COVID-19 vaccine development is currently accelerated via so-called fast-track programs, vaccines may not be timely available to have an impact on the first wave of the ongoing COVID-19 pandemic. Nevertheless, COVID-19 vaccines will be essential in the future for reducing morbidity and mortality and inducing herd immunity, if SARS-CoV-2 becomes established in the population like for example influenza virus.
| S-EPMC7385234 | biostudies-literature
Project description:The COVID-19 pandemic has affected the entire world causing substantial numbers of cases and deaths in most countries. Many have implemented nationwide stringent control to avoid overburdening the health care system. This has paralyzed economic and social activities and may continue to do so until the large-scale availability of a vaccine. We propose an alternative exit strategy to develop herd immunity in a predictable and controllable way: a phased lift of control. This means that successive parts of the country (e.g. provinces) stop stringent control, and COVID-19-related IC admissions are distributed over the country as a whole. Importantly, vulnerable individuals need to be shielded until herd immunity has developed in their area. We explore the characteristics and duration of this strategy using a novel individual-based model for geographically stratified transmission of COVID-19 in a country. The model predicts that individuals will have to experience stringent control for about 14 months on average, but this duration may be almost halved by further developments (more IC beds, better treatments). Clearly, implementation of this strategy would have a profound impact on individuals and society, and should therefore be considered carefully by various other disciplines (e.g. health systems, ethics, economics) before actual implementation.
| S-EPMC7904921 | biostudies-literature
Project description: Not available
| S-EPMC7698825 | biostudies-literature
Project description:In Korea, where the successful control of the coronavirus disease 2019 (COVID-19) epidemic have been implemented by the follow-up survey management (containment) of COVID-19-infected persons, the number of infected persons has increased rapidly, and a re-epidemic trend is emerging. The Korean government is strengthening epidemic prevention activities, such as increasing the social distance in the metropolitan area to four levels and increasing the vaccination rate. The public has been complaining of dissatisfaction with the atrophy of socioeconomic activities and of distrust of epidemic prevention policies. Australia started with an incidence similar to that of Korea, but its social activities are more flexible than those of Korea, where the incidence is maintained at approximately 0.1 per 100,000 people. In comparing the differences between both countries in terms of the Oxford COVID-19 Government Response Tracker Stringency Index, it was found that Australia effectively regulates the number of infected cases by high-intensity intermittent mitigation and the subsequent allowance of social activities. Korea has also recommended a high-intensity intermittent mitigation policy as in Australia until community herd immunity via vaccination is formed.
| S-EPMC8666682 | biostudies-literature
Project description: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.
| S-EPMC7568326 | biostudies-literature
Project description:In this note we discuss the issues involved in attempting to model pandemic dynamics. More specifically, we show how it may be possible to make projections for the ongoing H1N1 pandemic as extrapolated from knowledge of seasonal influenza. We derive first-approximation parameter estimates for the SIR model to describe seasonal influenza, and then explore the implications of the existing classical epidemiological theory for the case of a pandemic virus. In particular, we note the dramatic nonlinear increase in attack rate as a function of the percentage of susceptibles initially present in the population. This has severe consequences for the pandemic, given the general lack of immunity in the global population.
| S-EPMC2837721 | biostudies-literature
Project description:Vaccination remains a critical element in the eventual solution to the COVID-19 public health crisis. Many vaccines are already being mass produced and supplied in many countries. However, the COVID-19 vaccination programme will be the biggest in history. Reaching herd immunity will require an unprecedented mass immunisation campaign that will take several months and millions of dollars. Using different network models, COVID-19 pandemic dynamics of different countries can be recapitulated such as in Italy. Stochastic computational simulations highlight that peak epidemic sizes in a population strongly depend on the network structure. Assuming a vaccine efficacy of at least 80% in a mass vaccination program, at least 70% of a given population should be vaccinated to obtain herd immunity, independently of the network structure. If the vaccine efficacy reports lower levels of efficacy in practice, then the coverage of vaccination would be needed to be even higher. Simulations suggest that the "Ring of Vaccination" strategy, vaccinating susceptible contact and contact of contacts, would prevent new waves of COVID -19 meanwhile a high percent of the population is vaccinated.
| S-EPMC8426151 | biostudies-literature
Project description:The proportion of population vaccinated cannot be directly translated into the herd immunity. We have to account for the age-stratified contact patterns to calculate the population immunity level, since not every individual gathers evenly. Here, we calculated the contact-adjusted population immunity against severe acute respiratory syndrome coronavirus 2 in South Korea using age-specific incidence and vaccine uptake rate. We further explored options to achieve the theoretical herd immunity with age-varying immunity scenarios. As of June 21, 2021, when a quarter of the population received at least one dose of a coronavirus disease 2019 (COVID-19) vaccine, the contact-adjusted immunity level was 12.5% under the social distancing level 1. When 80% of individuals aged 10 years and over gained immunity, we could achieve a 58.2% contact-adjusted immunity level. The pros and cons of vaccinating children should be weighed since the risks of COVID-19 for the young are less than the elderly, and the long-term safety of vaccines is still obscure.
| S-EPMC8490791 | biostudies-literature
Project description:Introduction: Racial minority groups have been disproportionately affected by the 2019 novel coronavirus disease (COVID-19). Vaccine hesitancy may be a major barrier to achieving equitable herd immunity and must be addressed to reduce the excess morbidity and mortality of COVID-19 in disproportionately affected communities. This study aimed to determine if COVID-19 vaccine hesitancy, and its factors vaccine complacency and confidence, are more prominent among disproportionately affected racial minority groups. Methods:We collected data from participants aged 18 years or older from the four most populous U.S. states, including New York, California, Florida, and Texas, and Canada. Data were collected using a web-based survey platform. Data are available at http://www.covid19-database.com. Results:Data from 4,434 participants were included [mean (SD) age = 48.7 (17.2) and 50.4% women]. Vaccine hesitancy was higher in Black, Indigenous (Native American and Indigenous People of Canada, including First Nations, Inuit and Métis), and Latinx compared to White participants, while no difference was found between East Asian and White participants. The group differences in vaccine hesitancy for Indigenous and Black compared to White participants remained after controlling for sociodemographic factors. Determinants of vaccine complacency were equivalent between disproportionately affected racial groups and white participants. Vaccine confidence (i.e., trust in vaccine benefit) was generally lower in all racial groups compared to White participants. Differences in vaccine mistrust comparing Black and East Asian to White participants remained after controlling for sociodemographic factors. Discussion:Disproportionately affected racial minorities may have higher vaccine hesitancy and lower confidence in COVID-19 vaccines. Public health and other relevant government services should address vaccine hesitancy among racial minorities using a culturally sensitive, community-centered approach to attain equitable herd immunity.
| S-EPMC8652048 | biostudies-literature