Global control of COVID-19: good vaccines may not suffice

The COVID-19 pandemic has unveiled health and socioeconomic inequities around the globe. Effective epidemic control requires the achievement of herd immunity, where susceptible individuals are conferred indirect protection by being surrounded by immunized individuals. The proportion of people that need to be vaccinated to obtain herd immunity is determined through the herd immunity threshold. However, the number of susceptible individuals and the opportunities for contact between infectious and susceptible individuals influence the progress of an epidemic. Thus, in addition to vaccination, control of a pandemic may be difficult or impossible to achieve without other public health measures, including wearing face masks and social distancing. This article discusses the factors that may contribute to herd immunity and control of COVID-19 through the availability of effective vaccines and describes how vaccine effectiveness in the community may be lower than that expected. It also discusses how pandemic control in some countries and populations may face vaccine accessibility barriers if market forces strongly regulate the new technologies available, according to the inverse care law.

Rotational worker vaccination provides indirect protection to vulnerable groups in regions with low COVID-19 prevalence

As COVID-19 vaccines become available, different model-based approach have been developed to evaluate strategic priorities for vaccine allocation to reduce severe illness. One strategy is to directly prioritize groups that are likely to experience medical complications due to COVID-19, such as older adults. A second strategy is to limit community spread by reducing importations, for example by vaccinating members of the mobile labour force, such as rotational workers. This second strategy may be appropriate for regions with low disease prevalence, where importations are a substantial fraction of all cases and reducing the importation rate reduces the risk of community outbreaks, which can provide significant indirect protection for vulnerable individuals. Current studies have focused on comparing vaccination strategies in the absence of importations, and have not considered allocating vaccines to reduce the importation rate. Here, we provide an analytical criteria to compare the reduction in the risk of hospitalization and intensive care unit (ICU) admission over four months when either older adults or rotational workers are prioritized for vaccination. Vaccinating rotational workers (assumed to be 6,000 individuals and about 1% of the Newfoundland and Labrador (NL) population) could reduce the average risk of hospitalization and ICU admission by 42%, if no community spread is observed at the time of vaccination, because epidemic spread is reduced and vulnerable individuals are indirectly protected. In contrast, vaccinating all individuals aged 75 and older (about 43,300 individuals, or 8% of the NL population) would lead to a 24% reduction in the average risk of hospitalization, and to a 45% reduction in the average risk of ICU admission, because a large number of individuals at high risk from COVID-19 are now vaccinated. Therefore, reducing the risk of hospitalization and ICU admission of the susceptible population by reducing case importations would require a significantly lower number of vaccines. Benefits of vaccinating rotational workers decrease with increasing infection prevalence in the community. Prioritizing members of the mobile labour force should be considered as an efficient strategy to indirectly protect vulnerable groups from COVID-19 exposure in regions with low disease prevalence.

Case study of COVID 19 from August to end of December 2020 in Babylon, Iraq

Objectives: The aim of study is to study Case study of COVID 19 in Babylon Province in Iraq. Method: In January 2021 we started searching for the official source for the numbers of people infected with COVID19 within the borders of Babylon Governorate, where the Babylon Health Department was reviewed, and after that we were directed with official authorization to the Public Health Department in Babylon Governorate / Department of Communicable Diseases / Respiratory Diseases Unit (weekly periodic visit). Where the official numbers were obtained for the number of infected people and the number of deaths that occur due to complication with this infection, as well as the number of recovery cases from the date of 01/08/2020 to 01/01/2021. Results: related to the number of infected cases we see decrease the no. of infected with corona virus in Babylon Governorate from beginning the study to become lest at the end of 2020 with the significant decrease (P < 0.05) (The highest infected cases were notices in first month (1/8 – 31/8) while the lowest cases were seen in last month (1/12 – 31/12)) that may be due to: The main cause may be the most people may have gained herd immunity or population immunity, is the indirect protection from an infectious disease that happens when a population is have immunity developed through previous infection, that may refer to the end of first wave of this pandemic which start from the June. Conclusion: Knowing the pathogenesis of the virus and risk factors, increasing the experience of doctors and working cadres, increasing clinical capacity, providing specialized treatments, increasing the number of ICU beds, in addition to increasing the number of respiratory ventilators and increasing the number of tests.

Mathematical modeling of endemic cholera transmission

Mathematical modeling can be used to project the impact of mass vaccination on cholera transmission. Here, we discuss two examples for which indirect protection from mass vaccination needs to be considered. In the first, we show that non-vaccinees can be protected by mass vaccination campaigns. This additional benefit of indirect protection improves the cost-effectiveness of mass vaccination. In the second, we model the use of mass vaccination to eliminate cholera. In this case, a high population level of immunity, including contributions from infection and vaccination, is required to reach the “herd immunity” threshold needed to stop transmission and achieve elimination.

Institutional guarantees for the protection of human rights and freedoms: experience of foreign countries

The article examines the main existing institutional guarantees that ensure the protection of human and civil rights and freedoms in foreign countries. Analyzed are judicial protection mechanisms, the activities of prejudicial bodies, as well as mechanisms of extrajudicial protection. The author emphasizes that the protection of human rights and freedoms is a constitutional obligation of the state. Special attention is paid to specialт mechanisms for the protection of human rights, such as the Commissioner for Human Rights, the activities of various bodies of constitutional control; indicates the importance of extrajudicial mechanisms for the protection of rights and freedoms. The author analyzes methods of direct protection of rights and freedoms, as well as the role of executive and legislative authorities as elements of indirect protection.

Levels of pneumococcal conjugate vaccine coverage and indirect protection against invasive pneumococcal disease and pneumonia hospitalisations in Australia: An observational study

Background There is limited empiric evidence on the coverage of pneumococcal conjugate vaccines (PCVs) required to generate substantial indirect protection. We investigate the association between population PCV coverage and indirect protection against invasive pneumococcal disease (IPD) and pneumonia hospitalisations among undervaccinated Australian children. Methods and findings Birth and vaccination records, IPD notifications, and hospitalisations were individually linked for children aged <5 years, born between 2001 and 2012 in 2 Australian states (New South Wales and Western Australia; 1.37 million children). Using Poisson regression models, we examined the association between PCV coverage, in small geographical units, and the incidence of (1) 7-valent PCV (PCV7)-type IPD; (2) all-cause pneumonia; and (3) pneumococcal and lobar pneumonia hospitalisation in undervaccinated children. Undervaccinated children received <2 doses of PCV at <12 months of age and no doses at ≥12 months of age. Potential confounding variables were selected for adjustment a priori with the assistance of a directed acyclic graph. There were strong inverse associations between PCV coverage and the incidence of PCV7-type IPD (adjusted incidence rate ratio [aIRR] 0.967, 95% confidence interval [CI] 0.958 to 0.975, p-value < 0.001), and pneumonia hospitalisations (all-cause pneumonia: aIRR 0.991 95% CI 0.990 to 0.994, p-value < 0.001) among undervaccinated children. Subgroup analyses for children <4 months old, urban, rural, and Indigenous populations showed similar trends, although effects were smaller for rural and Indigenous populations. Approximately 50% coverage of PCV7 among children <5 years of age was estimated to prevent up to 72.5% (95% CI 51.6 to 84.4) of PCV7-type IPD among undervaccinated children, while 90% coverage was estimated to prevent 95.2% (95% CI 89.4 to 97.8). The main limitations of this study include the potential for differential loss to follow-up, geographical misclassification of children (based on residential address at birth only), and unmeasured confounders. Conclusions In this study, we observed substantial indirect protection at lower levels of PCV coverage than previously described—challenging assumptions that high levels of PCV coverage (i.e., greater than 90%) are required. Understanding the association between PCV coverage and indirect protection is a priority since the control of vaccine-type pneumococcal disease is a prerequisite for reducing the number of PCV doses (from 3 to 2). Reduced dose schedules have the potential to substantially reduce program costs while maintaining vaccine impact.

Vaccination is Australia's most important COVID-19 public health action, even though herd immunity is unlikely

The Australian National Cabinet four-step plan to transition to post-pandemic re-opening begins with vaccination to achieve herd protection and protection of the health system against a surge in COVID-19 cases. Assuming a pre-vaccination reproduction number for the Delta variant of 5, we show that for the current Mixed program of vaccinating over 60s with AstraZeneca and 16-60s with Pfizer we would not achieve herd immunity. We would need to cover 85% of the population (including many 5-16 year-olds to achieve herd immunity). At lower reproduction number of 3 and our current Mixed strategy, we can achieve herd immunity without vaccinating 5-15 year olds. This will be achieved at a 60% coverage pursuing a strategy targetting high transmitters or 70% coverage using a strategy targetting the vulnerable first. A reproduction number of 7 precludes achieving herd immunity, however vaccination is able to prevent 75% of deaths compared with no vaccination. We also examine the impact of vaccination on death in the event that herd immunity is not achieved. Direct effects of vaccination on reducing death are very good for both Pfizer and AstraZeneca vaccines. However we estimate that the Mixed or Pfizer program performs better than the AstraZeneca program. Furthermore, vaccination levels below the herd immunity threshold can lead to substantial (albeit incomplete) indirect protection for both vaccinated and unvaccinated populations. Given the potential for not reaching herd immunity, we need to consider what level of severe disease and death is acceptable, balanced against the consequences of ongoing aggressive control strategies.

Pneumococcal conjugate vaccine coverage and indirect protection against invasive pneumococcal disease and pneumonia hospitalisations in Australia: a retrospective record linkage cohort study

Background: There is limited empiric evidence on the coverage of pneumococcal conjugate vaccines (PCV) required to generate substantial indirect protection. We investigate the association between population PCV coverage and indirect protection against invasive pneumococcal disease (IPD) and pneumonia hospitalisations among under-vaccinated Australian children. Methods: Birth and vaccination records, IPD notifications and hospitalisations were individually linked for children aged < five years, born between 2001 and 2012 in two Australian states (New South Wales and Western Australia; 1.37 million children). Using Poisson regression models, we examined the association between PCV coverage, in small geographical units, and the incidence of (1) 7-valent PCV (PCV7)-type IPD, (2) all-cause pneumonia and (3) pneumococcal and lobar pneumonia hospitalisation in under-vaccinated children. Under-vaccinated children received < two doses of PCV at < 12 months of age and no doses at ≥ 12 months of age. Potential confounding variables were selected for adjustment a priori with the assistance of a directed acyclic graph. The main limitations of this study include the potential for differential loss to follow-up, geographical misclassification of children (based on addressed at birth only) and unmeasured confounders. Findings There were strong inverse associations between PCV coverage and the incidence of PCV7-type IPD (adjusted incidence rate ratio [aIRR] 0.967, 95% CI 0.958-0.975, p-value <0.001), and pneumonia hospitalisations (all-cause pneumonia: aIRR 0.991 95% CI 0.990-0.994, p-value<0.001) among under-vaccinated children. Subgroup analyses for children < four months old, urban, rural and Indigenous populations showed similar trends, although effects were smaller for rural and Indigenous populations. Fifty-percent coverage of PCV7 among children < five years of age prevented up to 72.5% (95% CI 51.6-84.4) of PCV7-type IPD among under-vaccinated children, while 90% coverage prevented 95.2% (95% CI 89.4-97.8). Conclusions In this study we observed substantial indirect protection at low PCV coverage, challenging assumptions high vaccine coverage is required.

The real-life impact of vaccination on COVID-19 mortality in Europe and Israel

OBJECTIVES: This study aimed at estimating the real-life impact of vaccination on COVID-19 mortality, with adjustment for SARS-CoV-2 variants spread and other factors across Europe and Israel. METHODS: Time series analysis of daily number of COVID-19 deaths was performed using non-linear Poisson mixed regression models. Variants' frequency, demographic, climate, health and mobility characteristics of thirty-two countries were considered as potentially relevant adjustment factors between January 2020 and April 2021. RESULTS: The analysis revealed that vaccination efficacy in terms of protection against deaths was equal to 72%, with a lower reduction of number of deaths for B.1.1.7 versus non-B.1.1.7 variants (70% and 78%, respectively). Other factors significantly related to mortality were arrivals at airports, mobility change from the pre-pandemic level and temperature. CONCLUSIONS: Our study confirms a strong effectiveness of COVID-19 vaccination based on real-life public data, although lower than expected from clinical trials. This suggests the absence of indirect protection for non-vaccinated individuals. Results also show that vaccination effectiveness against mortality associated with the B.1.1.7 variant is slightly lower compared with other variants. Lastly, this analysis confirms the role of mobility reduction, within and between countries, as an effective way to reduce COVID-19 mortality and suggests the possibility of seasonal variations in COVID-19 incidence.