The Efficacy of SARS-CoV-2 Vaccination in the Elderly: A Systemic Review and Meta-analysis

Measuring Vaccine Responses in the Multiplex Era

Vaccine studies in psychoneuroimmunology (PNI) provide insight into biopsychosocial interactions and their role in infectious diseases. Methodologies to measure vaccine responses are therefore of critical importance for PNI researchers. In this chapter, traditional and modern immunoassays for the assessment of vaccine responses are discussed, highlighting how multiplex techniques provide researchers with greater capacity and opportunity for novel research relating to vaccine outcomes.

Feasibility and Effectiveness of Vaccines for COVID-19: An Umbrella Review

Introduction

In January 2020, WHO declared the 2019 Coronavirus Disease (COVID-19) a pandemic. Though COVID-19 vaccines are recommended, ongoing surveillance is crucial due to potential unforeseen events. Evaluation of long-term effectiveness and safety and addressing emerging variants are vital. This study integrates systematic reviews to assess COVID-19 vaccine efficacy, immunogenicity, and safety comprehensively.

Methods

This study was an umbrella review study on the feasibility and effectiveness of vaccines for COVID-19. We conducted a comprehensive search in PubMed, Web of Sciences, and Scopus, using MeSH terms and keywords related to COVID-19 vaccines. Inclusion criteria comprised peer-reviewed systematic reviews and meta-analyses in English, focusing on feasibility and effectiveness. Exclusion criteria targeted non-systematic reviews exclusively on vaccine safety and duplicates. Two independent reviewers screened and resolved discrepancies. Data extraction included key details. Methodological quality was assessed using the ROBIS tool. Data synthesis involves narrative and, if applicable, quantitative synthesis (meta-analysis). Reporting followed PRISMA guidelines.

Results

A total of 32 systematic reviews were included in the study, of which 20 also conducted a meta-analysis. The studies investigated in the included reviews ranged from 7 to 74. The included articles were conducted in various countries around the globe. The findings indicated that COVID-19 vaccines are generally safe and effective for individuals with various medical conditions. The overall risk of bias for the included studies was assessed as low risk.

Conclusion

The study outcomes indicated that mRNA vaccines exhibit a higher incidence of adverse events but demonstrate greater efficacy. Conversely, inactivated and protein subunit vaccines are safer but exhibit lower efficiency. Moreover, the vaccine is considered safe for individuals with specific conditions such as inflammatory bowel disease, solid organ transplant recipients, children, pregnant individuals, and those with hematologic problems. Ultimately, the acceptance of the COVID-19 vaccine among individuals is influenced by various factors, including geographic, socioeconomic, and pandemic-related considerations.

Long COVID Syndrome: A Narrative Review on Burden of Age and Vaccination

Background/Objective: The COVID-19 pandemic has led to the emergence of post-acute COVID-19 syndrome, also known as long COVID, which presents a significant challenge due to its varied symptoms and unpredictable course, particularly in older adults. Similar to COVID-19 infections, factors such as age, pre-existing health conditions, and vaccination status may influence the occurrence and severity of long COVID. The objective is to analyze the role of aging in the context of long COVID and to investigate prevalence rates and vaccination efficacy to improve prevention strategies and treatment in this age group. Methods: Four researchers independently conducted a literature search of the PubMed database to trace studies published between July 2020 and July 2024. Results: Aging influences both the likelihood of developing long COVID and the recovery process, due to age-related physiological changes, immune system alterations, and the presence of comorbidities. Vaccination plays a key role in reducing the risk of long COVID by attenuating the inflammatory responses associated with its symptoms. Conclusions: Despite the protection vaccines offer against severe infection, hospitalization, and post-infection sequelae, vaccine hesitancy remains a major obstacle, worsening the impact of long COVID. Promising treatments for this condition include antivirals although further research is needed.

Vaccines for the Elderly and Vaccination Programs in Europe and the United States

The share of the elderly population is growing worldwide as life expectancy increases. Immunosenescence and comorbidities increase infectious diseases' morbidity and mortality in older adults. Here, we aimed to summarize the latest findings on vaccines for the elderly against herpes zoster, influenza, respiratory syncytial virus (RSV), COVID-19, and pneumococcal disease and to examine vaccine recommendation differences for this age group in Europe and the United States. PubMed was searched using the keywords "elders" and "vaccine" alongside the disease/pathogen in question and paraphrased or synonymous terms. Vaccine recommendations were also sought in the European and US Centers for Disease Control and Prevention databases. Improved vaccines, tailored for the elderly, mainly by using novel adjuvants or by increasing antigen concentration, are now available. Significant differences exist between immunization policies, especially between European countries, in terms of the recipient's age, number of doses, vaccination schedule, and implementation (mandatory or recommended). Understanding the factors that influence the immune response to vaccination in the elderly may help to design vaccines that offer long-term protection for this vulnerable age group. A consensus-based strategy in Europe could help to fill the gaps in immunization policy in the elderly, particularly regarding vaccination against RSV and pneumococcus.

Sarcopenic patients "get even": The impact of COVID-19 vaccination on mortality

BACKGROUND

Coronavirus Disease-2019 (COVID-19), driven by the SARS-CoV-2 virus, has disproportionately affected the elderly, with comorbidities like sarcopenia worsening prognosis. Considering the significant impact of RNA vaccines on survival rates in this population, our objective is to investigate the impact of vaccination on the survival of hospitalized elderly patients with COVID-19, considering the presence or absence of sarcopenia.

METHODS

Prospective study conducted on 159 patients aged>65 years from September 2021 to March 2022. Data about clinical and body composition, and mortality at 12-months after discharge were recorded. Sarcopenia was diagnosed according to the 2019 European Consensus criteria.

RESULTS

At the twelfth month post-discharge, vaccinated sarcopenic individuals exhibited a mortality risk similar to vaccinated non-sarcopenic individuals, and lower than unvaccinated non-sarcopenic patients. Cox regression analysis, adjusted for age, gender, comorbidity, functional and vaccinal status, showed that the presence of sarcopenia did not significantly impact the risk of death within 12-months post-discharge.

DISCUSSION

Vaccination emerges as a protective measure for sarcopenic patients, countering the potential adverse effects of sarcopenia on COVID-19 outcomes, underscoring the importance of immunization in the frail elderly with a call for meticulous monitoring of its benefits.

CONCLUSIONS

Our study represents the first attempt to analyze the vaccine's effect on survival in sarcopenic hospitalized older adults with COVID-19. The administration of vaccination to sarcopenic patients proves pivotal, as its omission could lead to notably unfavorable outcomes within this specific population.

The mRNA Vaccination Rate Is Negatively and the Proportion of Elderly Individuals Is Positively Associated With the Excess Mortality Rate After 2020 in Japan

BACKGROUND

The impact of mRNA vaccines on excess mortality during the COVID-19 pandemic in Japan is not clear. This study aimed to verify the explanatory factors of excess mortality rate using officially published data by government and research institutions.

METHODS

Multiple regression analysis was performed using the excess mortality rate in Japanese prefectures as the objective variable and the mRNA vaccination rate, proportion of elderly individuals in the population, number of physicians per population, and medical expenditure per person as explanatory variables.

RESULTS

From July 2021 to April 2023, the independent determinants of the excess mortality rate were as follows: proportion of elderly individuals (regression coefficient (B) = 0.0097, p < 0.001), partial vaccination rate (B = -0.0034, p = 0.048), proportion of elderly individuals (B = 0.010, p < 0.001), and third-shot vaccination rate (B = -0.0025, p < 0.046). The stepwise method did not essentially change the results. However, the p-values were smaller. The other two indicators were not associated with the excess mortality rate.

CONCLUSIONS

mRNA vaccination was associated with a lower excess mortality in Japan during the period, whereas the proportion of elderly individuals was associated with an increase in excess mortality. Thus, a policy of aggressive recommendations for mRNA vaccination is justified.

Online COVID-19 diagnosis prediction using complete blood count: an innovative tool for public health

BACKGROUND

COVID-19, caused by SARS-CoV-2, presents distinct diagnostic challenges due to its wide range of clinical manifestations and the overlapping symptoms with other common respiratory diseases. This study focuses on addressing these difficulties by employing machine learning (ML) methodologies, particularly the XGBoost algorithm, to utilize Complete Blood Count (CBC) parameters for predictive analysis.

METHODS

We performed a retrospective study involving 2114 COVID-19 patients treated between December 2022 and January 2023 at our healthcare facility. These patients were classified into fever (1057 patients) and pneumonia groups (1057 patients), based on their clinical symptoms. The CBC data were utilized to create predictive models, with model performance evaluated through metrics like Area Under the Receiver Operating Characteristics Curve (AUC), accuracy, sensitivity, specificity, and precision. We selected the top 10 predictive variables based on their significance in disease prediction. The data were then split into a training set (70% of patients) and a validation set (30% of patients) for model validation.

RESULTS

We identified 31 indicators with significant disparities. The XGBoost model outperformed others, with an AUC of 0.920 and high precision, sensitivity, specificity, and accuracy. The top 10 features (Age, Monocyte%, Mean Platelet Volume, Lymphocyte%, SIRI, Eosinophil count, Platelet count, Hemoglobin, Platelet Distribution Width, and Neutrophil count.) were crucial in constructing a more precise predictive model. The model demonstrated strong performance on both training (AUC = 0.977) and validation (AUC = 0.912) datasets, validated by decision curve analysis and calibration curve.

CONCLUSION

ML models that incorporate CBC parameters offer an innovative and effective tool for data analysis in COVID-19. They potentially enhance diagnostic accuracy and the efficacy of therapeutic interventions, ultimately contributing to a reduction in the mortality rate of this infectious disease.

COVID-19 Vaccination Effectiveness in the General Population of an Italian Province: Two Years of Follow-Up

We carried out a cohort study on the overall population of the province of Pescara, Italy, to assess the real-world effectiveness of SARS-CoV-2 vaccination against infection, severe, or lethal COVID-19, two years after the start of the vaccination campaign. We included all the resident or domiciled subjects, and extracted the official demographic, vaccination, COVID-19, hospital and co-pay exemption datasets from 1 January 2021, up to 15 February 2023. Cox proportional hazards analyses were adjusted for gender, age, diabetes, hypertension, COPD, major cardio- and cerebrovascular events, cancer, and kidney diseases. Throughout the follow-up (466 days on average), 186,676 subjects received greater than or equal to three vaccine doses (of ChAdOx1 nCoV-19, BNT162b2, mRNA-1273, NVX-CoV2373, or JNJ-78436735), 47,610 two doses, 11,452 one dose, and 44,989 none. Overall, 40.4% of subjects were infected with SARS-CoV-2. Of them, 2.74% had severe or lethal (1.30%) COVID-19. As compared to the unvaccinated, the individuals who received greater than or equal to one booster dose showed a ≥85% lower risk of severe or lethal COVID-19. A massive impact of vaccination was found among the elderly: 22.0% of the unvaccinated, infected individuals died, as opposed to less than 3% of those who received greater than or equal to three vaccine doses. No protection against infection was observed, although this finding was certainly influenced by the Italian restriction policies to control the pandemic. Importantly, during the Omicron predominance period, only the group who received at least a booster dose showed a reduced risk of COVID-19-related death.