Three Harm-Based Arguments for a Moral Obligation to Vaccinate

A particularly strong reason to vaccinate against transmittable diseases, based on considerations of harm, is to contribute to the realization of population-level herd immunity. We argue, however, that herd immunity alone is insufficient for deriving a strong harm-based moral obligation to vaccinate in all circumstances, since the obligation significantly weakens well above and well below the herd immunity threshold. The paper offers two additional harm-based arguments that, together with the herd immunity argument, consolidates our moral obligation. First, we argue that individuals should themselves aim not to expose others to risk of harm, and that this consideration becomes stronger the more non-vaccinated people there are, i.e., the further we are below herd immunity. Second, we elaborate on two pragmatic reasons to vaccinate beyond the realization of herd immunity, pertaining to instability of vaccination rates and population heterogeneity, and argue that vaccinating above the threshold should serve as a precautionary measure for buttressing herd immunity. We also show that considerations of harm have normative primacy in establishing this obligation over considerations of fairness. Although perfectly sound, considerations of fairness are, at worst secondary, or at best complementary to considerations of harm.

Seroprevalence of SARS-CoV-2 antibodies in the general population of Oman: results from four successive nationwide sero-epidemiological surveys

OBJECTIVE

To assess the seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in Oman and longitudinal changes in antibody levels over time within the first 11 months of the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

This nationwide cross-sectional study was conducted as a four-cycle serosurvey using a multi-stage stratified sampling method from July to November 2020. A questionnaire was used and included demographics, history of acute respiratory infection and list of symptoms, COVID-19 contact, previous diagnosis or admission, travel history and risk factors.

RESULTS

In total, 17,457 participants were surveyed. Thirty percent were female and 66.3% were Omani. There was a significant increase in seroprevalence throughout the study cycles, from 5.5% (4.8-6.2%) in Cycle 1 to 22% (19.6-24.6%) in Cycle 4. There was no difference in seroprevalence between genders, but significant differences were found between age groups. There was a transition of seroprevalence from being higher in non-Omanis than Omanis in Cycle 1 [9.1% (7.6-10.9%) vs 3.2% (2.6-3.9%)] to being higher in Omanis than non-Omanis in Cycle 4 [24.3% (21.0-27.9%) vs 16.8% (14.9-18.9%)]. There was remarkable variation in the seroprevalence of SARS-CoV-2 according to governorate. Close contacts of people with COVID-19 had a 96% higher risk of having the disease [adjusted odds ratio (AOR) 1.96, 95% confidence intervals (CI) 1.64-2.34]. Labourers had 58% higher risk of infection compared with office workers (AOR 1.58, 95% CI 1.04-2.35).

CONCLUSION

This study showed a wide variation in the spread of SARS-CoV-2 across governorates in Oman, with higher estimated seroprevalence in migrants in the first two cycles. Prevalence estimates remain low and are insufficient to provide herd immunity.

COVID-19 rhapsody: Rage towards advanced diagnostics and therapeutic strategy

The deadly global outbreak of coronavirus disease-2019 (COVID-19) has forged an unrivaled threat to human civilization. Contemplating its profuse impact, initial risk management and therapies are needed, as well as rapid detection strategies alongside treatments with existing drugs or traditional treatments to provide better clinical support for critical patients. Conventional detection techniques have been considered but do not sufficiently meet the current challenges of effective COVID-19 diagnosis. Therefore, several modern techniques including point-of-care diagnosis with a biosensor, clustered regularly interspaced short palindromic repeats (CRISPR)-associated proteins that function as nuclease (Cas) technology, next-generation sequencing, serological, digital, and imaging approaches have delivered improved and noteworthy success compared to that using traditional strategies. Conventional drug treatment, plasma therapy, and vaccine development are also ongoing. However, alternative medicines including Ayurveda, herbal drugs, homeopathy, and Unani have also been enlisted as prominent treatment strategies for developing herd immunity and physical defenses against COVID-19. All considered, this review can help develop rapid and simplified diagnostic strategies, as well as advanced evidence-based modern therapeutic approaches that will aid in combating the global pandemic.

The economic burden of COVID-19 in the United States: Estimates and projections under an infection-based herd immunity approach

OBJECTIVES

To assess the economic burden of COVID-19 that would arise absent behavioral or policy responses under the herd immunity approach in the United States and compare it to the total burden that also accounts for estimates of the value of lives lost.

METHODS

We use the trajectories of age-specific human and physical capital in the production process to calculate output changes based on a human capital-augmented production function. We also calculate the total burden that results when including the value of lives lost as calculated from mortality rates of COVID-19 and estimates for the value of a statistical life in the United States based on studies assessing individual's willingness to pay to avoid risks.

RESULTS

Our results indicate that the GDP loss associated with unmitigated COVID-19 would amount to a cumulative US$1.4 trillion by 2030 assuming that 60 percent of the population is infected over three years. This is equivalent to around 7.7 percent of GDP in 2019 (in constant 2010 US$) or an average tax on yearly output of 0.6 percent. After applying the value of a statistical life to account for the value of lives lost, our analyses show that the total burden can mount to between US$17 and 94 trillion over the next decade, which is equivalent to an annual tax burden between 8 and 43 percent.

CONCLUSION

Our results show that the United States would incur a sizeable burden if it adopted a non-interventionist herd immunity approach.

FUNDING

Research reported in this paper was supported by the Alexander von Humboldt Foundation, the Bill & Melinda Gates Foundation (Project INV-006261), and the Sino-German Center for Research Promotion (Project C-0048), which is funded by the German Research Foundation (DFG) and the National Natural Science Foundation of China (NSFC). Preparation of this article was also supported by the Value of Vaccination Research Network (VoVRN) through a grant from the Bill & Melinda Gates Foundation (Grant OPP1158136). The content is solely the responsibility of the authors.

Severe acute respiratory syndrome-coronavirus-2 seroprevalence study in Pimpri-Chinchwad, Maharashtra, India coinciding with falling trend - Do the results suggest imminent herd immunity?

Background

COVID-19 is a public health concern currently demanding continuous efforts to understand its epidemiology. Pimpri-Chinchwad township with a population of over 25 lakhs is located in Maharashtra, one of the worst affected states in India. After the incidence peaked in the township in mid-September 2020, cases started declining even as lockdown restrictions were eased.

Objectives

A seroprevalence study was conducted to understand the transmission dynamics of the pandemic in this region.

Methods

We carried out a population-based seroprevalence study for IgG antibodies for severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) among 5000 residents 12 years and above selected by the cluster random sampling. We selected 50 clusters in slums, 80 clusters in tenements, and 70 clusters from housing societies. The field work for collection of samples was carried out from October 07 to October 17, 2020. We used kit from Abbott (SARS-CoV-2 IgG), which employs chemiluminescent microparticle immunoassay technology. The prevalence of IgG antibodies was expressed as point estimates with 95% confidence intervals (CIs). These were weighted for areas and cluster effect and further adjusted for test performance.

Results

The overall seropositivity for IgG was 34.04% (95% CIl 31.3%-36.8%). Slum dwellers had 40.9% positivity rate (95% CI 37.0%-44.7%), those in tenements 41.2% (95% CI 37.7%-44.8%) and people living in housing societies had 29.8% positivity (95% CI 25.8%-33.8%).

Conclusion

A considerable proportion of population had encountered the novel coronavirus approaching partial, if not complete, herd immunity, which may partly explain the declining trend in spite of easing of lockdown restrictions.

Will vaccine-derived protective immunity curtail COVID-19 variants in the US?

Multiple effective vaccines are currently being deployed to combat the COVID-19 pandemic, and are viewed as the major factor in marked reductions of disease burden in regions with moderate to high vaccination coverage. The effectiveness of COVID-19 vaccination programs is, however, significantly threatened by the emergence of new SARS-COV-2 variants that, in addition to being more transmissible than the wild-type (original) strain, may at least partially evade existing vaccines. A two-strain (one wild-type, one variant) and two-group (vaccinated or otherwise) mechanistic mathematical model is designed and used to assess the impact of the vaccine-induced cross-protective efficacy on the spread the COVID-19 pandemic in the United States. Rigorous analysis of the model shows that, in the absence of any co-circulating SARS-CoV-2 variant, the vaccine-derived herd immunity threshold needed to eliminate the wild-type strain can be achieved if 59% of the US population is fully-vaccinated with either the Pfizer or Moderna vaccine. This threshold increases to 76% if the wild-type strain is co-circulating with the Alpha variant (a SARS-CoV-2 variant that is 56% more transmissible than the wild-type strain). If the wild-type strain is co-circulating with the Delta variant (which is estimated to be 100% more transmissible than the wild-type strain), up to 82% of the US population needs to be vaccinated with either of the aforementioned vaccines to achieve the vaccine-derived herd immunity. Global sensitivity analysis of the model reveal the following four parameters as the most influential in driving the value of the reproduction number of the variant strain (hence, COVID-19 dynamics) in the US: (a) the infectiousness of the co-circulating SARS-CoV-2 variant, (b) the proportion of individuals fully vaccinated (using Pfizer or Moderna vaccine) against the wild-type strain, (c) the cross-protective efficacy the vaccines offer against the variant strain and (d) the modification parameter accounting for the reduced infectiousness of fully-vaccinated individuals experiencing breakthrough infection. Specifically, numerical simulations of the model show that future waves or surges of the COVID-19 pandemic can be prevented in the US if the two vaccines offer moderate level of cross-protection against the variant (at least 67%). This study further suggests that a new SARS-CoV-2 variant can cause a significant disease surge in the US if (i) the vaccine coverage against the wild-type strain is low (roughly <66%) (ii) the variant is much more transmissible (e.g., 100% more transmissible), than the wild-type strain, or (iii) the level of cross-protection offered by the vaccine is relatively low (e.g., less than 50%). A new SARS-CoV-2 variant will not cause such surge in the US if it is only moderately more transmissible (e.g., the Alpha variant, which is 56% more transmissible) than the wild-type strain, at least 66% of the population of the US is fully vaccinated, and the three vaccines being deployed in the US (Pfizer, Moderna, and Johnson & Johnson) offer a moderate level of cross-protection against the variant.

COVID-19 Vaccines: Speedy Development and their Use to be Saviour of Humanity

COVID-19 disease is caused by a novel coronavirus (SARS-CoV-2), and it was declared as a pandemic by WHO within two and half months of detection of first case. The pandemic situation induced unprecedented cooperation amongst countries, academia, public sector institutions and industry in sharing knowledge, resources and strategies. In this article, development of vaccines and their delivery system is discussed. The regulatory toxicology and clinical trials are the most important factors to ensure safety and formation of neutralizing antibodies for efficacy. The article creates awareness about the global cooperation and efforts in developing the vaccines speedily for the society. Finally, results show that all the COVID-19 vaccines trigger an immune response to enable your body to fight and kill virus and none of them cause COVID-19 disease.

Methods for estimating the direct and indirect effect of 10 valent pneumococcal vaccine on nasopharyngeal carriage in children under 2 years in Matiari, Pakistan

Pneumonia is the leading cause of morbidity and mortality in children worldwide. The ten valent pneumococcal vaccine (PCV10) was introduced in Pakistan's Expanded Program on Immunization (EPI) in 2012 as a 3 + 0 schedule without catchup immunization. Nasopharyngeal carriage is taken as a surrogate marker to measure the impact of pneumococcal vaccine on populations. Carriage surveys are necessary to monitor the persistence of Vaccine Type (VT) serotypes, the emergence of Non-Vaccine Type (NVT) serotypes, and their role in both transmission and disease. This article describes various troubleshooting measures which we undertook to adopt the protocol to our setting. We also used an innovative approach to describe various epidemiological parameters of vaccine effectiveness against carriage. It is important to publish these methods to allow for valid regional and temporal comparisons of results in different settings. Thus, in this article, we describe the following methods for isolating upper airway pneumococcal carriage:•Methods for the collection, transport, and storage of nasopharyngeal samples.•Methods for identification and serotyping of pneumococci.•Methods for estimation of the direct and indirect effects of pneumococcal vaccines on nasopharyngeal carriage.

Herd immunity: challenges and the way forward in Korea

Vaccination is considered to be the most effective measure for preventing the spread of coronavirus disease 2019 (COVID-19). Many countries, including of Korea, are focusing on achieving herd immunity with the goal of reaching a vaccination rate of 70-80%. However, achieving herd immunity does not mean eradicating COVID-19, and the following challenges can occur in the process of achieving herd immunity. First, as the vaccination rate is likely to slow down over time, it is necessary to promote the benefits of vaccination through risk communication strategies and provide incentives for those who have been vaccinated. Second, a booster dose may be required depending on future studies on vaccine-induced immunity. Third, since variants capable of evading immunity and with higher transmissibility can emerge, rapid contract tracing and regular community genomic surveillance could help mitigate the impact of new variants. When the impact of COVID-19 is controlled to the level of seasonal influenza, the current public health measures that have been strictly imposed on society since the beginning of the pandemic will no longer be needed. The overall response strategy to COVID-19 will need to change accordingly, based on evaluations of the level of population immunity. These changes will include more efficient and targeted contact tracing and eased quarantine measures for vaccinated close contacts and travelers. Mask wearing and a minimum of social distancing will still be required in the journey towards the end of the pandemic. The COVID-19 pandemic will end, but the virus will not disappear.

Immunity and security using holism, ambient intelligence, triangulation, and stigmergy: Sensitivity analysis confronts fake news and COVID-19 using open set transduction

This paper introduces a multi-faceted security methodology based on Holism, Ambient Intelligence, Triangulation, and Stigmergy (HATS) to combat the spread of current pandemics such as fake news and COVID-19. HATS leverages the apparent complementarity and similarity of physical and mental pandemics using adversarial learning and transduction to promote immunity on both using conformal prediction and principled symbiosis. As such, HATS confronts both mental and physical adversity found in misinformation and disinformation. It confers herd immunity using holism and triangulation that call to advantage on sensitivity analysis using open set transduction and meta-reasoning. Ambient intelligence and stigmergy further mediate meta-reasoning and re-identification in building and sharing immunity. As change is constant and everything is fluid, as truth is not always reality and reality is not always truth, and as truth is imponderable and lie can become truth, two things have to happen. First, reconditioning and reconfiguration engage random deficiency to discern familiarity from strangeness and a-typicality. Second, transfer learning using trans-adaptation and transposition, serve adaptation and interoperability. Together, this empowers open set transduction in facing adaptive persistent threats such as deception and denial when it engages moving target defense using modification and de-identification. Immunology and security further come together using to advantage the coupling of active and adversarial learning.

Long-term persistence of crAss-like phage crAss001 is associated with phase variation in Bacteroides intestinalis

BACKGROUND

The crAss-like phages are ubiquitous and highly abundant members of the human gut virome that infect commensal bacteria of the order Bacteroidales. Although incapable of lysogeny, these viruses demonstrate long-term persistence in the human gut microbiome, dominating the virome in some individuals.

RESULTS

Here we show that rapid phase variation of alternate capsular polysaccharides in Bacteroides intestinalis cultures plays an important role in a dynamic equilibrium between phage sensitivity and resistance, allowing phage and bacteria to multiply in parallel. The data also suggests the role of a concomitant phage persistence mechanism associated with delayed lysis of infected cells, similar to carrier state infection. From an ecological and evolutionary standpoint, this type of phage-host interaction is consistent with the Piggyback-the-Winner model, which suggests a preference towards lysogenic or other "benign" forms of phage infection when the host is stably present at high abundance.

CONCLUSION

Long-term persistence of bacteriophage and host could result from mutually beneficial mechanisms driving bacterial strain-level diversity and phage survival in complex environments.

Prosocial vaccination

Most vaccines not only directly protect vaccinated individuals but also provide a social benefit through community protection. Therefore, vaccination can be considered a prosocial act to protect others. We review the recent empirical evidence on (i) how prosocial concerns relate to vaccination intentions and (ii) promoting prosocial vaccination through explaining community protection or inducing concern for vulnerable others. The available evidence suggests that promoting the prosocial aspect of vaccinations could be a vaccination communication strategy to improve vaccine uptake. We point to several areas in which future research can test the boundary conditions of this approach and increase its effectiveness.

Invasive Haemophilus influenzae type b infection in a patient with transient hypogammaglobulinemia of infancy

We describe a patient with invasive Haemophilus influenzae type b (Hib) infection despite being completely immunized by a conjugate Hib vaccine. Although Hib vaccination has contributed to significant reduction in invasive Hib infection, there are some case reports of invasive Hib infections despite immunization. Immunoglobulin (Ig) deficiency is the main cause of primary vaccine failure, and IgG2 subclass deficiency is known to be the leading cause. A previously healthy 13-month-old boy visited the outpatient clinic with a 5-day history of fever (40.0 °C), cough, and vomiting, and was diagnosed with bacterial meningitis, purulent pericarditis, and arthritis. Hib was recovered from blood, cerebrospinal fluid, and pericardial fluid. Immunological examination revealed subnormal IgG and IgA titers at 13 and 17 months of age. Serum IgG2 titer was recovered at 17 months of age despite being low at 13 months. Comprehensive gene analysis for primary immunodeficiency syndromes (primary antibody deficiency, common variable immunodeficiency, and toll-like receptor abnormalities) were negative. The antibody titer against Hib [anti-polyribosylribitol phosphate (PRP) antibody] was lower than the long-term protective titer (1.0 μg/ml) at 13 months of age, but was reactively increased to 2.38 μg/mL two months after booster immunization. Transient hypogammaglobulinemia of infancy (THI) is described as an accentuation and prolongation of the physiologic Ig nadir that is normally observed during infancy and defined as low IgG and IgA levels in the first three years of life. We speculate that he developed an invasive Hib infection as a result of primary Hib vaccine failure caused by THI.

Forecasting fully vaccinated people against COVID-19 and examining future vaccination rate for herd immunity in the US, Asia, Europe, Africa, South America, and the World

Coronavirus disease 2019 (COVID-2019) has spread rapidly all over the world and it is known that the most effective way to eliminate the disease is vaccination. Although the traditional vaccine development process is quite long, more than ten COVID-19 vaccines have been approved for use in about a year. The COVID-19 vaccines that have been administered are highly effective enough, but achieving herd immunity is required to end the pandemic. The motivation of this study is to contribute to review the countries’ vaccine policies and adjusting the manufacturing plans of the vaccine companies. In this study, the total number of people fully vaccinated against COVID-19 was forecasted in the US, Asia, Europe, Africa, South America, and the World with the Autoregressive Integrated Moving Average (ARIMA) model, which is a new approach in vaccination studies. Additionally, for herd immunity, the percentage of fully vaccinated people in these regions at the beginning of 2021 summer was determined. ARIMA results show that in the US, Asia, Europe, Africa, South America, and the World will reach 139 million, 109 million, 127 million, 8 million, 38 million, and 441 million people will be fully vaccinated on 1 June 2021, respectively. According to these results, 41.8% of the US, 2.3% of Asia, 17% of Europe, 0.6% of Africa, 8.8% of South America, and 5.6% of the World population will be fully vaccinated people against the COVID-19. Results show that countries are far from the herd immunity threshold level desired to reach for safely slow or stop the COVID-19 epidemic.

[Pneumococcal vaccination]

Pneumokokken sind der häufigste bakterielle Erreger der ambulant erworbenen Pneumonie und gehören weltweit zu den häufigsten impfpräventablen Todesursachen. Es gibt einen Polysaccharidimpfstoff, der die Kapselpolysaccharide von 23 der über 90 bekannten Serotypen enthält, einen guten Schutz vor invasiven Pneumokokkeninfektionen vermittelt, aber T‑Zellen nicht stimuliert und damit kein immunologisches Gedächtnis hinterlässt. Bei Immunsupprimierten hat er eine eingeschränkte Wirksamkeit. Zunächst für Kleinkinder und später auch für Erwachsene wurde ein 13-valenter Konjugatimpfstoff zugelassen, der weniger Serotypen erfasst, aber ein immunologisches Gedächtnis hinterlässt und eine mukosale Immunität, d. h. die Eradikation gesunder Pneumokokkenträger und damit Herdenprotektionseffekte, vermittelt. Die STIKO empfiehlt derzeit bei verschiedenen Komorbiditäten sowie als Standardimpfung ab 60 Jahre die Indikationsimpfung mit PPV23, ggf. mit Wiederholungsimpfung nach frühestens 6 Jahren. Patienten mit Immunsuppression, chronischem Nierenversagen oder chronischer Leberinsuffizienz sollten wegen der eingeschränkten Wirksamkeit von PPV23 sowie einem hohen Risiko für Infektionen eine sequenzielle Impfung (zuerst PCV13, gefolgt von PPV23 nach 6 bis 12 Monaten) erhalten.

High seroprevalence for SARS-CoV-2 infection in South America, but still not enough for herd immunity!

Herd immunity is considered to be a relevant aspect of COVID-19 epidemiology. In this regard, seroprevalence studies are essential for understanding how far countries and regions are from that potential point. This study analyzed seroprevalence data in nine studies from South America, which is a region that has been badly affected by COVID-19. Seroprevalence values ​​were high, with percentages up to 70.0% (95% CI 67.0-73.4%) in Iquitos, Peru. A meta-analysis of such data enabled a pooled seroprevalence to be obtained, estimated at 33.6% (95% CI 28.6-38.5%). Despite this, the COVID-19 pandemic in South America continues to significantly affect countries such as Brazil, Colombia, and Peru.

Politicizing COVID-19 Vaccines in the Press: A Critical Discourse Analysis

Undoubtedly and unfortunately, COVID-19 pandemic has been politicized in media see Abbas (Int J Semiot Law, 2020), Rui Zhang (Media Asia 48:89-107, 2021). Although vaccines play a crucial role in eliminating the pandemic, they have been politicized by media. This article aims to show how COVID-19 vaccines are politicized in the press. The article collects some selected reports on vaccines taken from American and Chinese media. The reports are analyzed according to an analytical framework suggested by the researcher. The framework and data collection and description are clearly presented in the method section. Based on data analysis, the article shows that COVID-19 vaccines have been politicized. The study recommends that diseases and vaccines should not be politicized. In other words, we should respect and trust science and our scientists for no other purpose than to reach herd immunity and overcome a dangerous pandemic that has taken and is still taking thousands of innocent lives.

A novel compartmental model to capture the nonlinear trend of COVID-19

The COVID-19 pandemic took the world by surprise and surpassed the expectations of epidemiologists, governments, medical experts, and the scientific community as a whole. The majority of epidemiological models failed to capture the non-linear trend of the susceptible compartment and were unable to model this pandemic accurately. This study presents a variant of the well-known SEIRD model to account for social awareness measures, variable death rate, and the presence of asymptomatic infected individuals. The proposed SEAIRDQ model accounts for the transition of individuals between the susceptible and social awareness compartments. We tested our model against the reported cumulative infection and death data for different states in the US and observed over 98.8% accuracy. Results of this study give new insights into the prevailing reproduction number and herd immunity across the US.

SARS-CoV-2 outbreak in a synagogue community: longevity and strength of anti-SARS-CoV-2 IgG responses

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) pandemic is still ongoing along with the global vaccination efforts against it. Here, we aimed to understand the longevity and strength of anti-SARS-CoV-2 IgG responses in a small community (n = 283) six months following local SARS-COV-2 outbreak in March 2020. Three serological assays were compared and neutralisation capability was also determined. Overall 16.6% (47/283) of the participants were seropositive and 89.4% (42/47) of the IgG positives had neutralising antibodies. Most of the symptomatic individuals confirmed as polymerase chain reaction (PCR) positive during the outbreak were seropositive (30/32, 93.8%) and 33.3% of the individuals who quarantined with a PCR confirmed patient had antibodies. Serological assays comparison revealed that Architect (Abbott) targeting the N protein LIASON^® (DiaSorin) targeting the S protein and enzyme-linked immunosorbent assay (ELISA) targeting receptor binding domain detected 9.5% (27/283), 17.3% (49/283) and 17% (48/283), respectively, as IgG positives. The latter two assays highly agreed (kappa = 0.89) between each other. In addition, 95%, (19/20, by ELISA) and 90.9% (20/22, with LIASON) and only 71.4% (15/21, by Architect) of individuals that were seropositive in May 2020 were found positive also in September. The unexpected low rate of overall immunity indicates the absence of un-noticed, asymptomatic infections. Lack of overall high correlation between the assays is attributed mainly to target-mediated antibody responses and suggests that using a single serological assay may be misleading.

COVID-19: individual and herd immunity

Immunity to the SARS-CoV-2 virus ensures protection against reinfection by this virus thanks to the combined action of neutralizing antibodies and T lymphocytes specific to viral proteins, in particular the Spike protein. It must be distinguished from the immune response that ensures healing of the infection following contamination that involves innate immunity, particularly type 1 interferons, and which is followed by adaptive cellular and humoral immunity. The importance of the effect of interferons is highlighted by the occurrence of severe forms of the disease in genetically deficient subjects or in patients with antibodies neutralizing type 1 interferon. Herd immunity is not an individual biological property. It is a mathematical property that qualifies the fact that when the proportion of subjects with individual immunity is high enough, there is little chance that an epidemic can occur. The level of that proportion-the herd immunity of the population can be computed under theoretical, often unrealistic, hypotheses, and is difficult to assess in natural conditions.

Will achieving herd immunity be a road to success to end the COVID-19 pandemic?

As the COVID-19 pandemic continues, the availability of several different new vaccines, their varying supply levels, effectiveness, and immunity duration across different ethnic populations, together with natural infection rates, will have an impact on when each country can reach herd immunity (ranging from 15.3% to 77.1%). Here we estimate the population proportions still required to gain immunity (ranging from 0.01% to 48.8%) to reach an overall herd immunity level to stop the exponential virus spread in 32 selected countries.

Effect of population heterogeneity on herd immunity and on vaccination decision making process

We study the influence of population heterogeneity on herd immunity level and on individual's vaccination decision making process. We first formulate the mathematical model in a population with two subgroups, based on different activity levels or different susceptibilities. The herd immunity threshold is derived and discussed. It is calculated that the required vaccine coverage level for herd immunity in a heterogeneous mixing population can be varied significantly. The required vaccine coverage level is lower than the classical herd immunity level, if the vaccine coverage level in the more active group or more susceptible group is higher than the other subgroup. It is suggested that the classical herd immunity levels can be misleading in the process of planning mass vaccination programs. The analysis is further extended to study the population with more subgroups. We then study the formal vaccination games to simulate the process of vaccination decision making, in either homogeneous or heterogeneous mixing populations. It is proved that the Nash equilibrium in the vaccination game is not unique if population heterogeneity is considered. Moreover, herd immunity is not achieved if individuals are solely driven by self-interests.

A theoretical exploration of the origin and early evolution of a pandemic

A virus that can cause a global pandemic must be highly adaptive to human conditions. Such adaptation is not likely to have emerged suddenly but, instead, may have evolved step by step with each step favored by natural selection. It is thus necessary to develop a theory about the origin in order to guide the search. Here, we propose such a model whereby evolution occurs in both the virus and the hosts (where the evolution is somatic; i.e., in the immune system). The hosts comprise three groups - the wild animal hosts, the nearby human population, and farther-away human populations. The theory suggests that the conditions under which the pandemic has initially evolved are: (i) an abundance of wild animals in the place of origin (PL0); (ii) a nearby human population of low density; (iii) frequent and long-term animal-human contacts to permit step-by-step evolution; and (iv) a level of herd immunity in the animal and human hosts. In this model, the evolving virus may have regularly spread out of PL0 although such invasions often fail, leaving sporadic cases of early infections. The place of the first epidemic (PL1), where humans are immunologically naïve to the virus, is likely a distance away from PL0. Finally, this current model is only a first attempt and more theoretical models can be expected to guide the search for the origin of SARS-CoV-2.

Seroprevalence of COVID-19 and associated factors in a medical institution in Pakistan

Objective

This study investigates the association of preventive measures with coronavirus disease (COVID-19) seropositivity.

Methods

This cross-sectional study was conducted at the Combined Military Hospital Kharian Medical College, Pakistan, in September 2020. A total of 442 participants from three different strata (faculty, students, and administration/technical staff) were enrolled using a convenient sampling technique. A rapid antibody testing method was used to detect antibodies. The Ichroma™ COVID-19 Ab test is an in vitro diagnostic device that helps in the rapid identification of COVID-19 by measuring the levels of IgG and IgM antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the blood. An automated fluorescent immunoassay system (AFIAS-6), with a clinical sensitivity of 95.8% and specificity of 96.7%, was used for qualitative analysis. A self-administered questionnaire was used to collect data, and data analysis was performed using SPSS version 25.

Results

In total, 442 participants were included in the study: 40 (9%) faculty members, 299 (67%) students, and 103 (23.3%) administrative/technical staff. As many as 14.9% of the participants were symptomatic; 32.4% always used masks, and 14% never wore masks. Furthermore, 69.7% of participants frequently washed their hands for 20 s, and 75.6% were aware of social distancing. A total of 16.96% of participants tested positive for IgG antibodies. Moreover, most of the administration/technical staff who tested positive for IgG were asymptomatic (68.42%). A significant association (p < 0.001) was found between following the safety guidelines (wearing masks, handwashing, and social distancing) and the occurrence of COVID-19.

Conclusion

This study showed a higher seroprevalence rate than other studies as it was conducted toward the end of the first wave of the COVID-19 pandemic. However, we are still far from achieving herd immunity. Furthermore, strict compliance with preventive measures is the only way to ensure safety until an effective vaccine is developed.

Regional disparity of covid-19 infections: an investigation using state-level Indian data

Using the state-level panel data for India, we establish that Covid infections are clustered in more urbanized, and prosperous states. Poverty lowers cases showing evidence of herd immunity of poor which stands in sharp contrast with the developed part of the world. Our dynamic panel regression results indicate that Covid infections are persistent across states and unlocking has aggravated the infections. We also find that richer and more urbanised states with better health infrastructure and governance perform more tests. The policy lesson from this exercise is that the authorities should monitor immunization and Covid protocols in densely populated urban areas.

Modelling the COVID-19 Pandemic: Asymptomatic Patients, Lockdown and Herd Immunity

The SARS-Cov-2 is a type of coronavirus that has caused the COVID-19 pandemic. In traditional epidemiological models such as SEIR (Susceptible, Exposed, Infected, Removed), the exposed group E does not infect the susceptible group S. A distinguishing feature of COVID-19 is that, unlike with previous viruses, there is a distinct "asymptomatic" group A, who do not show any symptoms, but can nevertheless infect others, at the same rate as infected patients. This situation is captured in a model known as SAIR (Susceptible, Asymptomatic, Infected, Removed), introduced in Robinson and Stilianakis (2013). The dynamical behavior of the SAIR model is quite different from that of the SEIR model. In this paper, we use Lyapunov theory to establish the global asymptotic stabiilty of the SAIR model. Next, we present methods for estimating the parameters in the SAIR model. We apply these estimation methods to data from several countries including India, and show that the predicted trajectories of the disease closely match actual data.

Modeling the impact of racial and ethnic disparities on COVID-19 epidemic dynamics

Background

The impact of variable infection risk by race and ethnicity on the dynamics of SARS-CoV-2 spread is largely unknown.

Methods

Here, we fit structured compartmental models to seroprevalence data from New York State and analyze how herd immunity thresholds (HITs), final sizes, and epidemic risk change across groups.

Results

A simple model where interactions occur proportionally to contact rates reduced the HIT, but more realistic models of preferential mixing within groups increased the threshold toward the value observed in homogeneous populations. Across all models, the burden of infection fell disproportionately on minority populations: in a model fit to Long Island serosurvey and census data, 81% of Hispanics or Latinos were infected when the HIT was reached compared to 34% of non-Hispanic whites.

Conclusions

Our findings, which are meant to be illustrative and not best estimates, demonstrate how racial and ethnic disparities can impact epidemic trajectories and result in unequal distributions of SARS-CoV-2 infection.

Funding

K.C.M. was supported by National Science Foundation GRFP grant DGE1745303. Y.H.G. and M.L. were funded by the Morris-Singer Foundation. M.L. was supported by SeroNet cooperative agreement U01 CA261277.

The assembly effect: the connectedness between populations is a double-edged sword for public health interventions

Background

Many public health interventions lead to disruption or decrease of transmission, providing a beneficial effect for people in the population regardless of whether or not they individually participate in the intervention. This protective benefit has been referred to as a herd or community effect and is dependent on sufficient population participation. In practice, public health interventions are implemented at different spatial scales (i.e., at the village, district, or provincial level). Populations, however defined (i.e., neighbourhoods, villages, districts) are frequently connected to other populations through human movement or travel, and this connectedness can influence potential herd effects.

Methods

The impact of a public health intervention (mass drug administration for malaria) was modelled, for different levels of connectedness between populations that have similar disease epidemiology (e.g., two nearby villages which have similar baseline malaria incidences and similar malaria intervention measures), or between populations of varying disease epidemiology (e.g., two nearby villages which have different baseline malaria incidences and/or malaria intervention measures).

Results

The overall impact of the interventions deployed could be influenced either positively (adding value to the intervention) or negatively (reducing the impact of the intervention) by how much the intervention units are connected with each other (e.g., how frequent people go to the other village or town) and how different the disease intensity between them are. This phenomenon is termed the “assembly effect”, and it is a meta-population version of the more commonly understood “herd effect”.

Conclusions

The connectedness of intervention units or populations is an important factor to be considered to achieve success in public health interventions that could provide herd effects. Appreciating the assembly effect can improve the cost-effective strategies for global disease elimination projects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03726-x.

The impact of childhood pneumococcal conjugate vaccine immunisation on all-cause pneumonia admissions in Hong Kong: A 14-year population-based interrupted time series analysis

BACKGROUND

Nine years after the introduction of pneumococcal conjugate vaccine (PCV) in the United States, Hong Kong (HK) introduced the vaccine to its universal childhood immunisation programme in 2009. We aimed to assess the impact of childhood PCV immunisation on all-cause pneumonia (ACP) admissions among the overall population of HK.

METHODS

In this population-based interrupted time series analysis, we used territory-wide population-representative electronic health records in HK to evaluate the vaccine impact. We identified hospitalised patients with a diagnosis of pneumonia from any cause between 2004 and 2017. We applied segmented Poisson regression to assess the gradual change in the monthly incidence of ACP admissions between pre- and post-vaccination periods. Negative outcome control, subgroup and sensitivity analyses were used to test the robustness of the main analysis.

FINDINGS

Over the 14-year study period, a total of 587,607 ACP episodes were identified among 357,950 patients. The monthly age-standardised incidence of ACP fluctuated between 33.42 and 87.44 per 100,000-persons. There was a marginal decreasing trend in pneumonia admissions after PCV introduction among overall population (incidence rate ratio [IRR]: 0·9965, 95% confidence interval [CI]: 0·9932-0·9998), and older adults (≥65 years, IRR: 0·9928, 95% CI: 0·9904-0·9953) but not in younger age groups.

INTERPRETATION

There was a marginally declining trend of overall ACP admissions in HK up to eight years after childhood PCV introduction. The significance disappeared when fitting sensitivity analyses. The results indicate the complexities of using non-specific endpoints for measuring vaccine effect and the necessity of enhancing serotype surveillance systems for replacement monitoring.

FUNDING

Health and Medical Research Fund, Food and Health Bureau of the Government of Hong Kong (Reference number: 18171272).

The New Totalitarians: The Swedish COVID-19 strategy and the implications of consensus culture and media policy for public health

Aims

The aim is to discuss implications of consensus culture in combination with media policy in Sweden with regard to the Swedish COVID-19 strategy in the spring of 2020.

Methods

Investigation of prerequisites for scrutiny by the Swedish mass media of the Swedish strategy in the spring of 2020 based on discussion regarding consensus culture, media structure and postmodernism in science, politics and administration.

Results

The Swedish strategy entailed strong initial confidence in herd immunity (although not officially stated), individual responsibility, evidence based medicine and substantial neglect to cooperate internationally. The strategy may be regarded partly as a result of the postmodern view of science and society predominant in Sweden. A tradition of top down consensus culture combined with mass media's financial and partly structural dependence of the state may help explain the comparative lack of critical questions regarding the strategy at the press conferences in the spring of 2020.

Conclusions

Mass media in Sweden should become more financially and structurally independent of the state. The reporting by Swedish media in the spring of 2020 should be subject to peer-reviewed research.

From "Coffin Dodger" to "Boomer Remover": Outbreaks of Ageism in Three Countries With Divergent Approaches to Coronavirus Control

OBJECTIVES

This article compares responses to coronavirus control in Australia, the United Kingdom, and the United States, 3 countries in which public ageism erupted over the social and economic costs of protecting older adults from Covid-19.

METHODS

Thirty-five (35) newspapers, media websites, and current affairs magazines were sourced for the study: 8 for Australia, 12 for the United Kingdom, and 15 for the United States. Searches were conducted daily from April to June 2020, using key words to identify age-related themes on pandemic control.

RESULTS

Despite divergent policies in the 3 countries, ageism took similar forms. Public responses to lockdowns and other measures cast older adults as a problem to be ignored or solved through segregation. Name-calling, blame, and "so-be-it" reactions toward age vulnerability were commonplace. Policies banning visits to aged care homes angered many relatives and older adults. Indefinite isolation for older adults was widely accepted, especially as a vehicle to end public lockdowns and economic crises.

DISCUSSION

Older adults have and will continue to bear the brunt of Covid-19 in terms of social burdens and body counts as the pandemic continues to affect people around the globe. The rhetoric of disposability underscores age discrimination on a broader scale, with blame toward an age cohort considered to have lived past its usefulness for society and to have enriched itself at the expense of future generations.

COVID-19: Is herd immunity the only option for fragile Yemen?

The first case of COVID-19 in Yemen was confirmed on 10 April 2020. Having faced with a six-year long conflict that has destroyed half of its healthcare facilities and displaced millions, predictions of infections and mortality in Yemen suggested a looming healthcare catastrophe. Difficulty in implementing coordinated lockdowns and preventive measures due to the daily labor working nature of the majority of the population, provided the perfect breeding ground for the SARS-CoV-2 virus. However, official figures of infections and mortality are very low and there have not been confirmed reports of excess mortality. This could indicate that Yemen is silently marching towards forced herd immunity. Seroprevalence studies will provide useful insight into the COVID-19 transmission trajectory in Yemen, which can serve as a guide in planning vaccine distribution strategies and allocating the limited funds wisely.

The burden of influenza in older adults: meeting the challenge

Influenza is an acute respiratory infection for which vaccination is our best prevention strategy. Small seasonal changes in circulating influenza viruses (antigenic drift) result in the need for annual influenza vaccination, in which the vaccine formulation is updated to better match the predominant circulating influenza viruses that have undergone important antigenic changes. Although the burden of influenza infection and its complications is the highest in older adults, vaccine effectiveness is the lowest in this vulnerable population. This is largely due to waning of the immune response with age known as "immune senescence", and presents an important, unmet challenge. Possible strategies to tackle this include adjuvant and high-dose vaccines, and herd immunity induced by greater vaccine uptake.

How best can finite-time social distancing reduce epidemic final size?

Given maximal social distancing duration and intensity, how can one minimize the epidemic final size, or equivalently the total number of individuals infected during the outbreak? A complete answer to this question is provided and demonstrated here for the SIR epidemic model. In this simplified setting, the optimal solution consists in enforcing the highest confinement level during the longest allowed period, beginning at a time instant that is the unique solution to certain 1D optimization problem. Based on this result, we present numerical essays showing the best possible performance for a large set of basic reproduction numbers and lockdown durations and intensities.

COVID-19 herd immunity in the absence of a vaccine: an irresponsible approach

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread rapidly throughout the human population, the concept of “herd immunity” has attracted the attention of both decision-makers and the general public. In the absence of a vaccine, this entails that a large proportion of the population will be infected to develop immunity that would limit the severity and/or extent of subsequent outbreaks. We argue that adopting such an approach should be avoided for several reasons. There are significant uncertainties about whether achieving herd immunity is possible. If possible, achieving herd immunity would impose a large burden on society. There are gaps in protection, making it difficult to shield the vulnerable. It would defeat the purpose of avoiding harm caused by the virus. Lastly, dozens of countries are showing that containment is possible.

Role of ACE2 receptor and the landscape of treatment options from convalescent plasma therapy to the drug repurposing in COVID-19

Since the first case reports in Wuhan, China, the SARS-CoV-2 has caused a pandemic and took lives of > 8,35,000 people globally. This single-stranded RNA virus uses Angiotensin-converting enzyme 2 (ACE2) as a receptor for entry into the host cell. Overexpression of ACE2 is mainly observed in hypertensive, diabetic and heart patients that make them prone to SARS-CoV-2 infection. Mitigations strategies were opted globally by the governments to minimize transmission of SARS-CoV-2 via the implementation of social distancing norms, wearing the facemasks, and spreading awareness using digital platforms. The lack of an approved drug treatment regimen, and non-availability of a vaccine, collectively posed a challenge for mankind to fight against the SARS-CoV-2 pandemic. In this scenario, repurposing of existing drugs and old treatment options like convalescent plasma therapy can be one of the potential alternatives to treat the disease. The drug repurposing provides a selection of drugs based on the scientific rationale and with a shorter cycle of clinical trials, while plasma isolated from COVID-19 recovered patients can be a good source of neutralizing antibody to provide passive immunity. In this review, we provide in-depth analysis on these two approaches currently opted all around the world to treat COVID-19 patients. For this, we used "Boolean Operators" such as AND, OR & NOT to search relevant research articles/reviews from the PUBMED for the repurposed drugs and the convalescent plasma in the COVID-19 treatment. The repurposed drugs like Chloroquine and Hydroxychloroquine, Tenofovir, Remdesivir, Ribavirin, Darunavir, Oseltamivir, Arbidol (Umifenovir), Favipiravir, Anakinra, and Baricitinib are already being used in clinical trials to treat the COVID-19 patients. These drugs have been approved for a different indication and belong to a diverse category such as anti-malarial/anti-parasitic, anti-retroviral/anti-viral, anti-cancer, or against rheumatoid arthritis. Although, the vaccine would be an ideal option for providing active immunity against the SARS-CoV-2, but considering the current situation, drug repurposing and convalescent plasma therapy and repurposed drugs are the most viable option against SARS-CoV-2.

COVID-19 pandemic management and the rheumatology patient

We discuss the evidence behind mask use, including evidence for homemade masks, social distancing, and the local coronavirus disease-2019 (COVID-19) epidemics in countries that initially employed more limited public health interventions. Given the absence of data for specific interventions in the rheumatic disease population, we reviewed the evidence available for the general population. The risk of poor outcomes with COVID-19 in patients with rheumatic diseases is a potential concern given the immunosuppression associated with these conditions and disease-modifying anti-rheumatic drug therapy, as well as advancing age and many of the comorbidities present in such patients. Infection prevention is key, for both individual patients and their community. Given the data collected from the general population, we recommend ongoing proper mask use, social distancing, and hand hygiene for patients with rheumatic diseases and encourage providers to counsel these patients in prevention strategies and attempt to dispel abundant misinformation.

Direct and indirect effect of 10 valent pneumococcal vaccine on nasopharyngeal carriage in children under 2 years of age in Matiari, Pakistan

Background

Pakistan introduced Ten-valent pneumococcal-conjugate-vaccine PCV10 in 2012 as a 3 + 0 schedule without catch-up.

Methods

Children <2 years old in Matiari, Sindh provided nasopharyngeal swabs between 2014 and 2018, which were cultured for pneumococcus and serotyped through multiplex PCR at the Aga Khan University Hospital. Carriage rates over time for Vaccine-Type (VT) and Non-VT (NVT) serotypes were used to estimate direct, indirect, total and overall effects of vaccination. Regression analysis was used to determine factors associated with VT carriage.

Results

Pneumococcus was detected in 2370/3140 (75%). VT carriage decreased overall, 16.1–9.6% (p-trend <0.001); vaccinated (all 3 doses of PCV10 received) 11.3–8.1% (p-trend 0.031) and unvaccinated (no PCV10 dose received) 17.4–10.3% (p-trend 0.003) with a decline in serotypes 6B, 9V/9A and 19F. Immunization increased from 41.0% to 68.4% (p-trend 0.001). Direct effect of vaccine was 32.8% (95% CI 14.7–47.0%) and indirect effect 44.6%(95% CI 40.6–48.6%). Factors associated with decreased VT colonization were education 1–5 years (aOR 0.7, 95%CI 0.6–1.0), history of difficulty breathing (aOR 0.7, 95%CI 0.5–1.0), exposure to smoke (aOR 0.8, 95% CI 0.6–1.0), child fully immunized (aOR 0.7, 95%CI 0.5–1.0) and enrolled in 3rd (aOR 0.6, 95%CI 0.4–0.8) and 4th (aOR 0.6, 95%CI 0.5–0.9) year of the study whereas history of runny nose (aOR 1.5, 95% CI 1.2–1.9) was positively associated.

Conclusions

Decrease in VT pneumococcal carriage in vaccinated and unvaccinated children indicates herd immunity. Sustained increase in vaccine coverage and close long-term surveillance is warranted.

The impact of human vaccines on bacterial antimicrobial resistance. A review

At present, the dramatic rise in antimicrobial resistance (AMR) among important human bacterial pathogens is reaching a state of global crisis threatening a return to the pre-antibiotic era. AMR, already a significant burden on public health and economies, is anticipated to grow even more severe in the coming decades. Several licensed vaccines, targeting both bacterial (Haemophilus influenzae type b, Streptococcus pneumoniae, Salmonella enterica serovar Typhi) and viral (influenza virus, rotavirus) human pathogens, have already proven their anti-AMR benefits by reducing unwarranted antibiotic consumption and antibiotic-resistant bacterial strains and by promoting herd immunity. A number of new investigational vaccines, with a potential to reduce the spread of multidrug-resistant bacterial pathogens, are also in various stages of clinical development. Nevertheless, vaccines as a tool to combat AMR remain underappreciated and unfortunately underutilized. Global mobilization of public health and industry resources is key to maximizing the use of licensed vaccines, and the development of new prophylactic vaccines could have a profound impact on reducing AMR.

The fastest national COVID vaccination in Europe - Malta's strategies

BACKGROUND

COVID-19 vaccines reduce morbidity and mortality, but mass vaccination faces multiple challenges leading to different vaccination rates in different countries. Malta, a small European country, has achieved a very rapid vaccination rollout. This paper presents a narrative review of Malta's vaccination strategy and its impact on the country's COVID-19 situation.

METHODS

Data was obtained through a literature review of Maltese newspapers and from Malta's COVID-19 government dashboard. A comprehensive summary of vaccination operations was provided by Malta's COVID-19 vaccination team.

RESULTS

Malta comprised part of the European Commission joint procurement and obtained the maximum vaccines that were eligible from all manufacturers. Four tier priority population groups were set up, with both vaccine doses (where applicable) allocated and stored for each individual. Multiple hubs were set up to simultaneously administer first and eventually second doses accordingly. To date (August 9, 2021) 398,128 of the population are fully vaccinated and 405,073 received the first dose, with both morbidity and mortality declining progressively as vaccination coverage progressed.

CONCLUSION

Malta has successfully implemented a COVID-19 strategy that rapidly covered a substantial proportion of the population over a short period of time, with herd immunity reached by end of May 2021. Low population vaccination hesitancy and high vaccine doses availability were two major factors in this success.

Optimal Immunity Control and Final Size Minimization by Social Distancing for the SIR Epidemic Model

The aim of this article is to understand how to apply partial or total containment to SIR epidemic model during a given finite time interval in order to minimize the epidemic final size, that is the cumulative number of cases infected during the complete course of an epidemic. The existence and uniqueness of an optimal strategy are proved for this infinite-horizon problem, and a full characterization of the solution is provided. The best policy consists in applying the maximal allowed social distancing effort until the end of the interval, starting at a date that is not always the closest date and may be found by a simple algorithm. Both theoretical results and numerical simulations demonstrate that it leads to a significant decrease in the epidemic final size. We show that in any case the optimal intervention has to begin before the number of susceptible cases has crossed the herd immunity level, and that its limit is always smaller than this threshold. This problem is also shown to be equivalent to the minimum containment time necessary to stop at a given distance after this threshold value.

COVID-19 zugzwang: Potential public health moves towards population (herd) immunity

COVID-19 is pandemic, and likely to become endemic, possibly returning with greater virulence. Outlining potential public health actions, including hygiene measures, social distancing and face masks, and realistic future advances, this paper focuses on the consequences of taking no public health action; the role of natural changes such as weather; the adverse public health consequences of lockdowns; testing for surveillance and research purposes; testing to identify cases and contacts, including the role of antibody tests; the public health value of treatments; mobilising people who have recovered; population (a synonym for herd) immunity through vaccination and through natural infection; involving the entire population; and the need for public debate. Until there is a vaccine, population immunity is going to occur only from infection. Allowing infection in those at very low risk while making it safer for them and wider society needs consideration but is currently taboo. About 40–50% population immunity is sufficient to suppress an infection with a reproduction number of about 1 or slightly more. Importantly, in children and young people COVID-19 is currently rarely fatal, roughly comparable with influenza. The balance between the damage caused by COVID-19 and that caused by lockdowns needs quantifying. Public debate, including on population immunity, informed by epidemiological data, is now urgent.

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The long-term solution to the COVID-19 pandemic is population immunity through natural infection or vaccination.

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40-50% population immunity is sufficient to suppress and eliminate this pandemic.

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New vaccines may not work well in the older age groups and those with underlying conditions and may not be safer than the infection for children and youth.

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Immunity is currently being acquired by infection and we need safer strategies for managing this.

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Open, honest, factual and sensitively conducted public dialogue is now urgent.

Optimal voluntary and mandatory insect repellent usage and emigration strategies to control the chikungunya outbreak on Reunion Island

In 2005, a chikungunya virus outbreak devastated the tropical island of Reunion, infecting a third of the total population. Motivated by the Reunion Island case study, we investigate the theoretic potential for two intervention measures under both voluntary and mandatory protocols to control a vector-borne disease when there is risk of the disease becoming endemic. The first measure uses insect repellent to prevent mosquito bites, while the second involves emigrating to the neighboring Mauritius Island to avoid infection. There is a threshold on the cost of using repellent above which both voluntary and mandatory regimes find it optimal to forgo usage. Below that threshold, mandatory usage protocols will eradicate the disease; however, voluntary adoption leaves the disease at a small endemic level. Emigrating from the island to avoid infection results in a tragedy-of-the-commons effect: while being potentially beneficial to specific susceptible individuals, the remaining islanders paradoxically face a higher risk of infection. Mandated relocation of susceptible individuals away from the epidemic is viable only if the cost of this relocation is several magnitudes lower than the cost of infection. Since this assumption is unlikely to hold for chikungunya, it is optimal to discourage such emigration for the benefit of the entire population. An underlying assumption about the conservation of human-vector encounter rates in mosquito biting behavior informs our conclusions and may warrant additional experimental verification.

Heterogeneity in SIR epidemics modeling: superspreaders and herd immunity

Deterministic epidemic models, such as the Susceptible-Infected-Recovered (SIR) model, are immensely useful even if they lack the nuance and complexity of social contacts at the heart of network science modeling. Here we present a simple modification of the SIR equations to include the heterogeneity of social connection networks. A typical power-law model of social interactions from network science reproduces the observation that individuals with a high number of contacts, "hubs" or "superspreaders", can become the primary conduits for transmission. Conversely, once the tail of the distribution is saturated, herd immunity sets in at a smaller overall recovered fraction than in the analogous SIR model. The new dynamical equations suggest that cutting off the tail of the social connection distribution, i.e., stopping superspreaders, is an efficient non-pharmaceutical intervention to slow the spread of a pandemic, such as the Coronavirus Disease 2019 (COVID-19).

Forecasting of the SARS-CoV-2 epidemic in India using SIR model, flatten curve and herd immunity

In this paper, we are presenting an epidemiological model for exploring the transmission of outbreaks caused by viral infections. Mathematics and statistics are still at the cutting edge of technology where scientific experts, health facilities, and government deal with infection and disease transmission issues. The model has implicitly applied to COVID-19, a transmittable disease by the SARS-CoV-2 virus. The SIR model (Susceptible-Infection-Recovered) used as a context for examining the nature of the pandemic. Though, some of the mathematical model assumptions have been improved evaluation of the contamination-free from excessive predictions. The objective of this study is to provide a simple but effective explanatory model for the prediction of the future development of infection and for checking the effectiveness of containment and lock-down. We proposed a SIR model with a flattening curve and herd immunity based on a susceptible population that grows over time and difference in mortality and birth rates. It illustrates how a disease behaves over time, taking variables such as the number of sensitive individuals in the community and the number of those who are immune. It accurately model the disease and their lessons on the importance of immunization and herd immunity. The outcomes obtained from the simulation of the COVID-19 outbreak in India make it possible to formulate projections and forecasts for the future epidemic progress circumstance in India.

Responding to the COVID-19 Pandemic in Developing Countries: Lessons from Selected Countries of the Global South

Reviewing selected policy responses in Asia and South America, this paper draws pragmatic lessons for developing countries to better address the COVID-19 pandemic. It argues that not acting quickly and adequately incurs much higher costs. So-called ‘best practices’, while useful, may be inappropriate, especially if not complemented by effective and suitable socio-economic measures. Public understanding, support and cooperation, not harsh and selective enforcement of draconian measures, are critical for successful implementation of containment strategies. This requires inclusive and transparent policy-making, and well-coordinated and accountable government actions that build and maintain trust between citizens and government. In short, addressing the pandemic crisis needs ‘all of government’ and ‘whole of society’ approaches under credible leadership.

Does education about local vaccination rates and the importance of herd immunity change US parents' concern about measles?

It is unclear how broadly aware parents are of the concept of herd immunity and whether parents consider community benefits of vaccination when making decisions about their child’s vaccinations. We aimed to determine whether educating parents about community-level benefits of measles, mumps, and rubella (MMR) vaccination and local vaccination rates would impact concern about their child’s risk of measles and risk of a measles outbreak.

We conducted an electronic survey among Minnesota parents of children aged 6–18 years in August 2016. We assessed baseline knowledge of herd immunity, asked participants to estimate MMR vaccination coverage in their county, and asked participants to estimate the minimum coverage needed to prevent measles outbreaks. We then delivered a short, educational intervention via the survey to inform participants about the benefits of herd immunity, the actual MMR vaccination coverage in their county, and that at least 95% MMR vaccination coverage is needed to prevent measles outbreaks. Pre- and post-intervention, participants were asked to report how concerned they were that their child might get measles. We used logistic regression models to assess factors associated with awareness of herd immunity, change in concern about one’s child’s measles risk, and overall concern for a measles outbreak.

Among 493 participants, 67.8% were aware of herd immunity at baseline. Post-intervention, 40.2% (n = 198) of parents learned that MMR vaccination rates in their county were higher than they expected. All participants found out that their county MMR rates were lower than the measles herd immunity threshold of 95%. Overall, 27.0% (n = 133) of participants reported an increase in concern that their child might get measles after learning about local vaccination coverage and the coverage needed to achieve herd immunity.

We found that our short, educational intervention aimed to increase awareness about herd immunity and local vaccination led to an increase in concern about disease risk among less than a third of parents.

The COVID-19 pandemic through eyes of a NYC fertility center: a unique learning experience with often unexpected results

Affecting basic tenets of human existence such as health, economic as well as personal security and, of course, reproduction, the COVID-19 pandemic transcended medical specialties and professional disciplines. Yet, six months into the pandemic, there still exists no consensus on how to combat the virus in absence of a vaccine. Facing unprecedented circumstances, and in absence of real evidence on how to proceed, our organization early in the pandemic decided to act independently from often seemingly irrational guidance and, instead, to carefully follow a quickly evolving COVID-19 literature. Here described is the, likely, unique journey of a fertility center that maintained services during peaks of COVID-19 and political unrest that followed. Closely following publicly available data, we recognized relatively early that New York City and other East Coast regions, which during the initial COVID-19 wave between March and May represented the hardest-hit areas in the country, during the second wave, beginning in June and still in progress, remained almost completely unaffected. In contrast, south western regions, almost completely unaffected by the initial wave, were severely affected in the second wave. These two distinctively different infectious phenotypes suggested two likely explanations: The country was witnessing infections with two different SARS-CoV-2 viruses and NYC (along with the East Coast) acquired during the first wave much better immunity to the virus than south western regions. Both hypotheses since have been confirmed: East and West Coasts, indeed, were initially infected by two distinctively different lineages of the virus, with the East Coast lineage being 10-times more infectious. In addition, immunologists discovered an up to this point unknown long-term anti-viral innate (cellular) immune response which offers additional and much broader anti-viral immunity than the classical adaptive immunity via immobilizing antibodies that has been known for decades. Consequently, we predict that in the U.S., even in absence of an available vaccine, COVID-19, by September-October, will be at similarly low levels as are currently seen in NYC and other East Coast regions (generally < 1% test-positivity). We, furthermore, predict that, if current mitigation measures are maintained and no newly aggressive mutation of the virus enters the country, a significant fall-wave of COVID-19, in combination with the usual fall wave of influenza, appears unlikely. To continue serving patients uninterrupted throughout the pandemic, turned for all of our center's staff into a highly rewarding experience, garnered respect and appreciation from patients, and turned into an absolutely unique learning experience.