The bumpy road to achieve herd immunity in COVID-19

Core health system measures response to COVID-19 among East Asian countries

Objective

The purpose of this study is to summarize the health system response to COVID-19 in four East Asian countries, analyze the effectiveness of their health system response, and provide lessons for other countries to control the epidemic and optimize their health system response.

Methods

This study investigated and summarized COVID-19 data and health system response in four East Asian countries, China, Japan, Mongolia, and South Korea from national governments and ministries of health, WHO country offices, and official websites of international organizations, to assess the effectiveness of health system measures.

Result

As of June 30, 2022, all four countries are in a declining portion of COVID-19. China has two waves, and new cases increased slowly, with the total cases per million remaining within 4, indicating a low level. Japan has experienced six waves, with case growth at an all-time high, total cases per million of 250.994. Mongolia started the epidemic later, but also experienced four waves, with total cases per million of 632.658, the highest of the four countries. South Korea has seen an increasing number of new cases per wave, with a total case per million of 473.759.

Conclusion

In containment strategies adopted by China and Mongolia, and mitigation strategies adopted by Japan and South Korea, health systems have played important roles in COVID-19 prevention and control. While promoting vaccination, countries should pay attention to non-pharmaceutical health system measures, as evidenced by: focusing on public information campaigns to lead public minds; strengthening detection capabilities for early detection and identification; using technical ways to participate in contact tracing, and promoting precise judging isolation.

Hematological parameters to predict post-COVID-19 immune response among vaccinated and nonvaccinated individuals: a retrospective cross-sectional study

Background

This study finds the changes in the hematological parameters of healthy individuals to predict the immune status against coronavirus disease 2019 (COVID-19) among COVID -19 vaccinated and nonvaccinated individuals.

Methods

A comparative cross-sectional study among 210 healthy individuals was conducted. All individuals were divided into three groups, that is, IgG positive, IgG negative, and IgG and IgM positive, based on ELISA. Data analysis was done using SPSS version 25 for Windows.

Results

A statistically significant effect was found among the three groups in terms of mean levels of hemoglobin (Hb), hematocrit (Hct), mean corpuscular hemoglobin concentration (MCHC), red blood cells (RBC), RDW-CV, lymphocyte, neutrophil, eosinophils, and basophil count. The study also showed that 52.8% (n=74) had neither taken vaccination nor had any history of previous COVID-19 infection but were IgG antibody positive.

Conclusion

There was a statistically significant difference among hematological parameters between immune and nonimmune groups, and it can predict the COVID-19 immune status.

Pathways to Immunity: Patterns of Excess Death Across the United States and Within Closed Religious Communities

Public health officials promoted COVID-19 vaccines to limit burdens placed on the U.S. healthcare system and end the pandemic. People in some closed religious communities refused to vaccinate and likely acquired temporary immunity through infection. This paper compares the death rates in Amish, Old Order Mennonites, and conservative Mennonite groups to a rate estimated for the U.S. population. Approximately two-thirds of the U.S. population was immunized against COVID-19, while few in the Amish/Mennonite community were. We find divergent patterns. Once vaccines became available, excess deaths declined in the general population and remained elevated among Amish and Mennonites. Vaccination campaigns must consider and value the cultural beliefs of closed religious communities to be effective.

Understanding the challenges to COVID-19 vaccines and treatment options, herd immunity and probability of reinfection

Unlike pandemics in the past, the outbreak of coronavirus disease 2019 (COVID-19), which rapidly spread worldwide, was met with a different approach to control and measures implemented across affected countries. The lack of understanding of the fundamental nature of the outbreak continues to make COVID-19 challenging to manage for both healthcare practitioners and the scientific community. Challenges to vaccine development and evaluation, current therapeutic options, convalescent plasma therapy, herd immunity, and the emergence of reinfection and new variants remain the major obstacles to combating COVID-19. This review discusses these challenges in the management of COVID-19 at length and highlights the mechanisms needed to provide better understanding of this pandemic.

Indirect Dispersion of SARS-CoV-2 Live-Attenuated Vaccine and Its Contribution to Herd Immunity

It has been 34 months since the beginning of the SARS-CoV-2 coronavirus pandemic, which causes the COVID-19 disease. In several countries, immunization has reached a proportion near what is required to reach herd immunity. Nevertheless, infections and re-infections have been observed even in vaccinated persons. That is because protection conferred by vaccines is not entirely effective against new virus variants. It is unknown how often booster vaccines will be necessary to maintain a good level of protective immunity. Furthermore, many individuals refuse vaccination, and in developing countries, a large proportion of the population has not yet been vaccinated. Some live-attenuated vaccines against SARS-CoV-2 are being developed. Here, we analyze the indirect dispersion of a live-attenuated virus from vaccinated individuals to their contacts and the contribution that this phenomenon could have to reaching Herd Immunity.

Towards novel nano-based vaccine platforms for SARS-CoV-2 and its variants of concern: Advances, challenges and limitations

Vaccination is the most effective tool available for fighting the spread of COVID-19. Recently, emerging variants of SARS-CoV-2 have led to growing concerns about increased transmissibility and decreased vaccine effectiveness. Currently, many vaccines are approved for emergency use and more are under development. This review highlights the ongoing advances in the design and development of different nano-based vaccine platforms. The challenges, limitations, and ethical consideration imposed by these nanocarriers are also discussed. Further, the effectiveness of the leading vaccine candidates against all SARS-CoV-2 variants of concern are highlighted. The review also focuses on the possibility of using an alternative non-invasive routes of vaccine administration using micro and nanotechnologies to enhance vaccination compliance and coverage.

Quantifying Changes in Vaccine Coverage in Mainstream Media as a Result of the COVID-19 Outbreak: Text Mining Study

Background

Achieving herd immunity through vaccination depends upon the public's acceptance, which in turn relies on their understanding of its risks and benefits. The fundamental objective of public health messaging on vaccines is therefore the clear communication of often complex information and, increasingly, the countering of misinformation. The primary outlet shaping public understanding is mainstream online news media, where coverage of COVID-19 vaccines was widespread.

Objective

We used text-mining analysis on the front pages of mainstream online news to quantify the volume and sentiment polarization of vaccine coverage.

Methods

We analyzed 28 million articles from 172 major news sources across 11 countries between July 2015 and April 2021. We employed keyword-based frequency analysis to estimate the proportion of overall articles devoted to vaccines. We performed topic detection using BERTopic and named entity recognition to identify the leading subjects and actors mentioned in the context of vaccines. We used the Vader Python module to perform sentiment polarization quantification of all collated English-language articles.

Results

The proportion of front-page articles mentioning vaccines increased from 0.1% to 4% with the outbreak of COVID-19. The number of negatively polarized articles increased from 6698 in 2015-2019 to 28,552 in 2020-2021. However, overall vaccine coverage before the COVID-19 pandemic was slightly negatively polarized (57% negative), whereas coverage during the pandemic was positively polarized (38% negative).

Conclusions

Throughout the pandemic, vaccines have risen from a marginal to a widely discussed topic on the front pages of major news outlets. Mainstream online media has been positively polarized toward vaccines, compared with mainly negative prepandemic vaccine news. However, the pandemic was accompanied by an order-of-magnitude increase in vaccine news that, due to low prepandemic frequency, may contribute to a perceived negative sentiment. These results highlight important interactions between the volume of news and overall polarization. To the best of our knowledge, our work is the first systematic text mining study of front-page vaccine news headlines in the context of COVID-19.

Seroprevalence of anti-SARS-CoV-2 IgG antibodies: relationship with COVID-19 diagnosis, symptoms, smoking, and method of transmission

•

The most discriminating symptom of COVID-19 by far was the loss of smell/taste.

•

In smokers, the incidence of positive COVID-19 diagnoses was significantly lower.

•

There was a discrepancy between COVID-19 diagnosis and the presence of IgG antibodies.

Aims

The study of SARS-CoV-2 antibodies in the population is a crucial step towards overcoming the COVID-19 pandemic. Seroepidemiological studies allow an estimation of the number of people who have been exposed to the virus, as well as the number of people who are still susceptible to infection.

Methods

In total, 13 560 people from Arganda del Rey, Madrid (Spain) were assessed between January and March 2021 for the presence of IgG antibodies, using rapid tests and histories of symptoms compatible with COVID-19.

Results

24.2% of the participants had IgG antibodies and 9% had a positive COVID-19 diagnosis. Loss of smell/taste was the most discriminating symptom of the disease. The main transmitters of infection were found to be household members. Unexpectedly, in smokers, the incidence of positive COVID-19 diagnoses was significantly lower. Additionally, it was found that there was a discrepancy between COVID-19 diagnosis and the presence of IgG antibodies.

Conclusions

Rapid anti-IgG tests are less reliable in detecting SARS-CoV-2 infection at an individual level, but are functional in estimating SARS-CoV-2 infection rates at an epidemiological level. The loss of smell/taste is a potential indicator for establishing COVID-19 infection.

Immunogenicity evaluation after BNT162b2 booster vaccination in healthcare workers

Waning of the immune response upon vaccination in SARS-CoV-2 infection is an important subject of evaluation in this pandemic, mostly in healthcare workers (HCW) that are constantly in contact with infected samples and patients. Therefore, our study aimed to establish the specific humoral response of specific IgG and IgA antibodies upon vaccination, during the second year of pandemic and evaluating the booster shot with the same vaccine type. A group of 103 HCW with documented exposure to the virus were monitored for specific IgG and IgA levels prior to vaccination, after the first vaccination round, during the following 8 months and after the booster shot with the same vaccine type. After 8 months post-vaccination the humoral response in both IgG and IgA decreased, 2.4 times for IgG, and 2.7 times for IgA. Although the antibodies levels significantly decreased, no documented infection was registered in the group. After the booster shot, the entire group, displayed IgG increased levels, immediately after booster followed by the increase in specific IgA. IgG levels post-second round of vaccination are statistically higher compared to the first round, while IgA is restored at the same levels. Within the vaccination or booster routine for a multiple waves' pandemic that is generating new virus variants, populational immunity remains an important issue for future implementation of prevention/control measures.

Rifampicin for COVID-19

Vaccinations for coronavirus disease-2019 (COVID-19) have begun more than a year before, yet without specific treatments available. Rifampicin, critically important for human medicine (World Health Organization’s list of essential medicines), may prove pharmacologically effective for treatment and chemoprophylaxis of healthcare personnel and those at higher risk. It has been known since 1969 that rifampicin has a direct selective antiviral effect on viruses which have their own RNA polymerase (severe acute respiratory syndrome coronavirus 2), like the main mechanism of action of remdesivir. This involves inhibition of late viral protein synthesis, the virion assembly, and the viral polymerase itself. This antiviral effect is dependent on the administration route, with local application resulting in higher drug concentrations at the site of viral replication. This would suggest also trying lung administration of rifampicin by nebulization to increase the drug’s concentration at infection sites while minimizing systemic side effects. Recent in silico studies with a computer-aided approach, found rifampicin among the most promising existing drugs that could be repurposed for the treatment of COVID-19.

Influence of heterogeneous age-group contact patterns on critical vaccination rates for herd immunity to SARS-CoV-2

Currently, several western countries have more than half of their population fully vaccinated against COVID-19. At the same time, some of them are experiencing a fourth or even a fifth wave of cases, most of them concentrated in sectors of the populations whose vaccination coverage is lower than the average. So, the initial scenario of vaccine prioritization has given way to a new one where achieving herd immunity is the primary concern. Using an age-structured vaccination model with waning immunity, we show that, under a limited supply of vaccines, a vaccination strategy based on minimizing the basic reproduction number allows for the deployment of a number of vaccine doses lower than the one required for maximizing the vaccination coverage. Such minimization is achieved by giving greater protection to those age groups that, for a given social contact pattern, have smaller fractions of susceptible individuals at the endemic equilibrium without vaccination, that is, to those groups that are more vulnerable to infection.

Testing Antigens, Antibodies, and Immune Cells in COVID-19 as a Public Health Topic—Experience and Outlines

The current COVID-19 pandemic has triggered an accelerated pace in all research domains, including reliable diagnostics methodology. Molecular diagnostics of the virus and its presence in biological samples relies on the RT-PCR method, the most used and validated worldwide. Nonconventional tests with improved parameters that are in the development stages will be presented, such as droplet digital PCR or CRISPR-based assays. These molecular tests were followed by rapid antigen testing along with the development of antibody tests, whether based on ELISA platform or on a chemiluminescent microparticle immunoassay. Less-conventional methods of testing antibodies (e.g., lateral flow immunoassay) are presented as well. Left somewhere in the backstage of COVID-19 research, immune cells and, furthermore, immune memory cells, are gaining the spotlight, more so in the vaccination context. Recently, methodologies using flow-cytometry evaluate circulating immune cells in infected/recovered patients. The appearance of new virus variants has triggered a surge for tests improvement. As the pandemic has entered an ongoing or postvaccination era, all methodologies that are used to monitor public health focus on diagnostic strategies and this review points out where gaps should be filled in both clinical and research settings.

Nano-carriers of COVID-19 vaccines: the main pillars of efficacy

As the current COVID-19 pandemic illustrates, vaccination is the most powerful method of disease prevention and public confidence in vaccines depends on their safety and efficacy. The information gathered in the current pandemic is growing at an accelerated pace. Both the key vital protein DNA/RNA messengers and the delivery carriers are the elements of a puzzle including their interactions with the immune system to suppress SARS-CoV-2 infection. A new nano-era is beginning in the vaccine development field and an array of side applications for diagnostic and antiviral tools will likely emerge. This review focuses on the evolution of vaccine carriers up to COVID-19-aimed nanoparticles and the immune-related adverse effects imposed by these nanocarriers.

COVID-19 vaccine hesitancy and acceptance in Mexico: a web-based nationwide survey

OBJECTIVE

To identify factors associated with COVID-19 vaccine hesitancy and acceptance among the Mexican population.

METHODS

In a web-based nationwide survey in early December 2020, respondents were inquired about their sociodemographic characteristics and their willingness to accept a hypothetical COVID-19 vaccine given a 50% or 90% effectiveness. A logistic regression model was used to identify the factors associated with hesitancy and acceptance.

RESULTS

A total 3 768 responses were analyzed. A 90% effective vaccine was accepted by 85% of respondents, while only 46% would accept being vaccinated with a 50% effective vaccine. In univariate analysis, each age group (40-49, 50-59, and ≥60) was strongly associated with vaccine hesitancy for a 90% effective vaccine (OR 0.48, 95% CI 0.38, 0.63; OR 0.33, 95 CI 0.26, 0.41; and OR 0.28, 95 CI 0.21, 0.38, respectively) compared to the 18-39 age group. After multivariable adjustment, similar magnitudes of association were observed. Being female and higher socioeconomic status were also associated with higher vaccine hesitancy.

CONCLUSIONS

Vaccine hesitancy represents a major public health problem in Mexico and is driven by multiple factors. Our study provides relevant insights for the development of effective policies and strategies to ensure widespread vaccination in Mexico.

Attitudes, acceptance and hesitancy among the general population worldwide to receive the COVID-19 vaccines and their contributing factors: A systematic review

BACKGROUND

High rates of vaccination worldwide are required to establish a herd immunity and stop the current COVID-19 pandemic evolution. Vaccine hesitancy is a major barrier in achieving herd immunity across different populations. This study sought to conduct a systematic review of the current literature regarding attitudes and hesitancy to receiving COVID-19 vaccination worldwide.

METHODS

A systematic literature search of PubMed and Web of Science was performed on July 5th, 2021, using developed keywords. Inclusion criteria required the study to (1) be conducted in English; (2) investigate attitudes, hesitancy, and/or barriers to COVID-19 vaccine acceptability among a given population; (3) utilize validated measurement techniques; (4) have the full text paper available and be peer-reviewed prior to final publication.

FINDINGS

Following PRISMA guidelines, 209 studies were included. The Newcastle Ottawa (NOS) scale for cross-sectional studies was used to assess the quality of the studies.Overall, vaccine acceptance rates ranged considerably between countries and between different time points, with Arabian countries showing the highest hesitancy rates compared with other parts of the world.

INTERPRETATION

A variety of different factors contributed to increased hesitancy, including having negative perception of vaccine efficacy, safety, convenience, and price. Some of the consistent socio-demographic groups that were identified to be associated with increased hesitancy included: women, younger participants, and people who were less educated, had lower income, had no insurance, living in a rural area, and self-identified as a racial/ethnic minority.

Trust in Authorities and Demographic Factors Affect Vaccine Acceptance During the COVID-19 Pandemic in Cyprus

Abstract. The COVID-19 pandemic has had a devastating impact on all aspects of human life. Accurately measuring vaccine acceptance and understanding the factors that influence vaccine attitudes and behaviors is crucial to designing public-health interventions to reduce the impact of COVID-19 through vaccinations. The current study adapted the vaccine acceptance scale ( Sarathchandra et al., 2018 ) to the Greek language and assessed the relationship between key components of vaccine acceptance to COVID-19 vaccine beliefs and attitudes, personal and family vaccination history and attitudes, and demographic variables (age, sex, education, and having children). The adapted vaccine acceptance instrument was found to have high internal consistency reliability. Further analyses indicated that younger and less-educated individuals are more vaccine-hesitant, and that vaccine acceptance is influenced by trust in authorities. These findings may have implications for understanding vaccine hesitancy and for the design and implementation of vaccine-related public health policies.

COVID‑19 vaccination and IgG and IgA antibody dynamics in healthcare workers

Given the current outbreak of coronavirus disease 2019 (COVID‑19) and the development and implementation of mass vaccination, data are being obtained by analyzing vaccination campaigns. In the present study, 69 healthcare workers who were exposed to patients with severe acute respiratory syndrome coronavirus‑2 were monitored for specific immunoglobulin (Ig)G and IgA levels at different time periods. Prior to vaccination, after the first round of vaccination at 21 days (when the second dose of vaccine was administrated) and 24 days after the second round of vaccination, with an mRNA‑based vaccine. The basal IgG and IgA levels in previously infected subjects and non‑infected subjects notably differed. Vaccination increased the IgG and IgA levels after the first dose in most subjects from both groups, the levels of which further increased following the second round of vaccination. The associations between IgG and IgA levels following the first and second rounds of vaccination demonstrated that in the entire vaccination group, regardless of prior exposure to the infectious agent, the increment and levels of IgG and IgA were similar. Thus, the levels upon vaccination were statistically similar irrespective of the starting base line prior to vaccination. In the present study, seroconversion was achieved in all subjects following the second round of vaccination, with similar antibodies levels.

Evaluation of serological lateral flow assays for severe acute respiratory syndrome coronavirus-2

BACKGROUND

COVID-19 has resulted in significant morbidity and mortality worldwide. Lateral flow assays can detect anti-Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) antibodies to monitor transmission. However, standardized evaluation of their accuracy and tools to aid in interpreting results are needed.

METHODS

We evaluated 20 IgG and IgM assays selected from available tests in April 2020. We evaluated the assays' performance using 56 pre-pandemic negative and 56 SARS-CoV-2-positive plasma samples, collected 10-40 days after symptom onset, confirmed by a molecular test and analyzed by an ultra-sensitive immunoassay. Finally, we developed a user-friendly web app to extrapolate the positive predictive values based on their accuracy and local prevalence.

RESULTS

Combined IgG + IgM sensitivities ranged from 33.9 to 94.6%, while combined specificities ranged from 92.6 to 100%. The highest sensitivities were detected in Lumiquick for IgG (98.2%), BioHit for both IgM (96.4%), and combined IgG + IgM sensitivity (94.6%). Furthermore, 11 LFAs and 8 LFAs showed perfect specificity for IgG and IgM, respectively, with 15 LFAs showing perfect combined IgG + IgM specificity. Lumiquick had the lowest estimated limit-of-detection (LOD) (0.1 μg/mL), followed by a similar LOD of 1.5 μg/mL for CareHealth, Cellex, KHB, and Vivachek.

CONCLUSION

We provide a public resource of the accuracy of select lateral flow assays with potential for home testing. The cost-effectiveness, scalable manufacturing process, and suitability for self-testing makes LFAs an attractive option for monitoring disease prevalence and assessing vaccine responsiveness. Our web tool provides an easy-to-use interface to demonstrate the impact of prevalence and test accuracy on the positive predictive values.

Targets and assay types for COVID-19 diagnosis

The lack of complete information on the immune response dynamics to infection with severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) has led to the use of mainly molecular tests such as reverse transcription PCR (RT-PCR) to diagnose Coronavirus 2019 disease (COVID-19). Although remarkable progress has been made in developing effective RT-PCR kits, the lack of specific equipment required to perform this technique in all clinical laboratories limits its widespread use. In the case of COVID-19, these tests can be used for the triage of symptomatic patients, for testing the contacts of confirmed cases, and also for the analysis and monitoring of the situation. Along with molecular tests involving reverse transcription PCR, various laboratory tests can identify the specific anti-viral antibodies or viral antigens. This review seeks to describe the targets and diagnostic methods available or currently in development for SARS-CoV-2 infection, including reverse transcription PCR (RT-PCR), serologic immunoassays (SIA) and the protein microarray method (PMM). Knowing the specific targets and the sensitivity of each assay used for COVID-19 diagnosis can lead to more efficient detection of infected patients and it can provide better management of the pandemic status.

Herbal medicine, a reliable support in COVID therapy

At present, specific therapies for COVID-19 are not well established, being certain only that the immune system plays a decisive role in the initiation and progression of the disease. Plants have given and continue to give compounds with great efficiency and low toxicity, some of them being a starting point for extremely effective synthetic substances. Although herbal remedies are used mainly for preventive purposes, there are also guidelines issued by some countries that indicate the use of traditional remedies for different stages of COVID-19 disease.Europe has a long and strong tradition of using medicinal plants for therapeutic purposes, but clinical trials for this type of approach are scarce, compared to Asia. In this regard, a bridge between tradition and science, would have a strong impact on the capacity for prevention and treatment of COVID-19. The paper reviews compounds of plant origin that have previously proven effective in counteracting some coronaviruses but also some of their major effects - direct action on virus replicative apparatus (viral entry or replication, action on the viral enzymatic system), collateral action of natural compounds on the immune system and also the contribution of herbal medicine as vaccine adjuvants are tackled.