Efficacy and effectiveness of inactivated vaccines against symptomatic COVID-19, severe COVID-19, and COVID-19 clinical outcomes in the general population: a systematic review and meta-analysis

How well do different COVID-19 vaccines protect against different viral variants? A systematic review and meta-analysis

While the efficacy of coronavirus disease 2019 (COVID-19) vaccines has been evaluated in numerous trials, comprehensive evidence on how protection by different vaccines has varied over time remains limited. We aimed to compare protective effects of different vaccines against different viral variants. To achieve this, we searched Medline, Cochrane Library and Embase for randomized controlled trials assessing the efficacy of COVID-19 vaccines. Forest plots using Mantel-Haenszel and random-effects models were generated showing risk ratios (RRs) and 95% CIs by vaccines and variants. We included 36 studies with 90 variant-specific primary outcomes. We found a RR of 0.26 (95% CI 0.21 to 0.31) against all variants overall, with the highest protective effects against the wild-type (RR 0.13; 95% CI 0.10 to 0.18), followed by Alpha (RR 0.26; 95% CI 0.18 to 0.36), Gamma (RR 0.34; 95% CI 0.21 to 0.55), Delta (RR 0.39; 95% CI 0.28 to 0.56) and Beta (RR 0.49; 95% CI 0.40 to 0.62) variants. Nucleic acid vaccines showed the highest protection levels against all variants (RR 0.11; 95% CI 0.08 to 0.15), followed by protein subunit, inactivated virus and viral vector. In conclusion, we found high but heterogenous levels of protection for most COVID-19 vaccines, with decreasing protective effects for vaccines based on traditional technologies as SARS-CoV-2 variants emerged over time. Novel nucleic acid-based vaccines offered substantially higher and more consistent protection.

Factors associated with COVID-19 in-hospital death and COVID-19 vaccine effectiveness against COVID-19 hospitalization in the Philippines during pre-omicron and omicron period: A case-control study (MOTIVATE-P study)

COVID-19 vaccine effectiveness (VE) studies are limited in low- and middle-income countries. A case-control study was conducted among COVID-19 and other pneumonia patients admitted to a hospital in the Philippines during the pre-Omicron and Omicron periods. To elucidate factors associated with in-hospital death, 1782 COVID-19 patients were assessed. To estimate absolute VE for various severe outcomes, 1059 patients were assessed (869 [82.1%] COVID-19 cases; 190 [17.9%] controls). Factors associated with in-hospital death included older age, tuberculosis (adjusted odds ratio [aOR] 2.45 [95% confidence interval {95% CI} 1.69-3.57]), HIV (aOR 3.30 [95% CI 2.03-5.37]), and current smokers (aOR 2.65 [95% CI 1.72-4.10]). Pre-Omicron, the primary series provided high protection within a median of 2 months (hospitalization: 85.4% [95% CI 35.9-96.7%]; oxygen requirement: 91.0% [95% CI 49.4-98.4%]; invasive mechanical ventilation (IMV): 97.0% [95% CI 65.7-99.7%]; death: 96.5% [95% CI 67.1-99.6%]). During Omicron, the primary series provided moderate-high protection within a median of 6-9 months (hospitalization: 70.2% [95% CI 27.0-87.8%]; oxygen requirement: 71.4% [95% CI 29.3-88.4%]; IMV: 72.7% [95% CI -11.6-93.3%]; death: 58.9% [95% CI -82.8-90.8%]). Primary series VE against severe COVID-19 outcomes was consistently high for both pre-Omicron and Omicron in a setting where approximately half of the vaccinees received inactivated vaccines.

Multiplex molecular assays for the laboratory-based and point-of-care diagnosis of infections caused by seasonal influenza, COVID-19, and RSV

INTRODUCTION

SARS-CoV-2, seasonal influenza, and respiratory syncytial virus (RSV) are major causes of acute respiratory infections in all age groups and responsible for an enormous socio-economic burden. The recently coined term 'tripledemic' describes co-circulation of these three viruses, a novel epidemiological paradigm that poses profound public health implications.

AREAS COVERED

Real-time reverse transcription polymerase chain reaction (RT-PCR) is now considered the reference method for the diagnosis of SARS-CoV-2, influenza, and RSV infections. Syndromic-based multiplex RT-PCR panels that simultaneously detect several respiratory viruses have become increasingly common. This review explores available molecular diagnostics (MDx) platforms for the diagnosis of SARS-CoV-2, influenza, and RSV in the same biological sample. Within some limitations of the published validation and diagnostic accuracy studies, both laboratory-based and point-of-care multiplex panels proved highly performant in identifying SARS-CoV-2, influenza A, influenza B, and RSV. Improved operational efficiency and faster turnaround times make these assays potentially cost-effective or even cost-saving.

EXPERT OPINION

The adoption of multiplex MDx assays for the contemporary detection of SARS-CoV-2, influenza, RSV, and other respiratory pathogens will likely increase in the next few years. To maximize the clinical usefulness and cost-effectiveness of these assays, locally issued guidelines and protocols on their implementation should be adopted.

Biases in COVID-19 vaccine effectiveness studies using cohort design

Observational studies on COVID-19 vaccine effectiveness (VE) have provided critical real-world data, informing public health policy globally. These studies, primarily using pre-existing data sources, have been indispensable in assessing VE across diverse populations and developing sustainable vaccination strategies. Cohort design is frequently employed in VE research. The rapid implementation of vaccination campaigns during the COVID-19 pandemic introduced differential vaccination influenced by sociodemographic disparities, public policies, perceived risks, health-promoting behaviors, and health status, potentially resulting in biases such as healthy user bias, healthy vaccinee effect, frailty bias, differential depletion of susceptibility bias, and confounding by indication. The overwhelming burden on healthcare systems has escalated the risk of data inaccuracies, leading to outcome misclassifications. Additionally, the extensive array of diagnostic tests used during the pandemic has also contributed to misclassification biases. The urgency to publish quickly may have further influenced these biases or led to their oversight, affecting the validity of the findings. These biases in studies vary considerably depending on the setting, data sources, and analytical methods and are likely more pronounced in low- and middle-income country (LMIC) settings due to inadequate data infrastructure. Addressing and mitigating these biases is essential for accurate VE estimates, guiding public health strategies, and sustaining public trust in vaccination programs. Transparent communication about these biases and rigorous improvement in the design of future observational studies are essential.

COVID-19 vaccination and major cardiovascular and haematological adverse events in Abu Dhabi: retrospective cohort study

The widespread administration of COVID-19 vaccines has prompted a need to understand their safety profile. This investigation focuses on the safety of inactivated and mRNA-based COVID-19 vaccines, particularly concerning potential cardiovascular and haematological adverse events. A retrospective cohort study was conducted for 1.3 million individuals residing in Abu Dhabi, United Arab Emirates, who received 1.8 million doses of the inactivated BBIBP CorV (by SinoPharm) and mRNA-based BNT162b2 (Pfizer-BioNTech) vaccines between June 1, 2021, and June 30, 2022. The study's primary outcome was to assess the occurrence of selected cardiovascular and haematological events leading to hospitalization or emergency room visits within 21 days post-vaccination. Results showed no significant increase in the incidence rates of these events compared to the subsequent 22 to 42 days following vaccination. Analysis revealed no elevated risk for adverse outcomes following first (IRR 1·03; 95% CI 0·82-1·31), second (IRR 0·92; 95% CI 0·72-1·16) and third (IRR 0·82; 95% CI 0·66-1·00) doses of either vaccine. This study found no substantial link between receiving either mRNA and inactivated COVID-19 vaccines and a higher likelihood of cardiovascular or haematological events within 21 days after vaccination.

Inactivated COVID-19 vaccination and SARS-CoV-2 infection among Chinese adults in the "living with COVID" era

The objective of this research was to examine the correlation between the status of inactivated COVID-19 vaccination and self-reported confirmed SARS-CoV-2 infection among adults after China entered the "living with COVID" era. A cross-sectional online survey was conducted among parents or guardians of students attending all 220 kindergartens and 105 primary or secondary schools in Longhua District of Shenzhen, China during March 1 to 9, 2023. The participating schools invited all parents or guardians of their students to complete the online survey. The study focused on a sub-sample of 68,584 participants who were either unvaccinated (n = 2152) or only receiving inactivated COVID-19 vaccination (n = 66,432). Logistic regression was employed for data analysis. Prior to the implementation of the "living with COVID" policy, 83.5% of the participants received three doses of inactivated COVID-19 vaccines; 63.0% reported being infected with the SARS-CoV-2 after the policy change. In a multivariate analysis, participants who had received a third dose within the past 6 months were less likely to be infected with SARS-CoV-2, as compared to those who had not completed the primary vaccination series (4-6 months: AOR: 0.84, 95%CI: 0.77, 0.92; ≤3 months: AOR: 0.82, 95%CI: 0.73, 0.92). Despite the high coverage, our results suggested that three doses of inactivated COVID-19 vaccines did not provide adequate protection against SARS-CoV-2 infection among Chinese adults.

MA, Tovar-Rosero YY, Oñate AA, O'Ryan M. Two centuries of vaccination: historical and conceptual approach and future perspectives

Over the past two centuries, vaccines have been critical for the prevention of infectious diseases and are considered milestones in the medical and public health history. The World Health Organization estimates that vaccination currently prevents approximately 3.5-5 million deaths annually, attributed to diseases such as diphtheria, tetanus, pertussis, influenza, and measles. Vaccination has been instrumental in eradicating important pathogens, including the smallpox virus and wild poliovirus types 2 and 3. This narrative review offers a detailed journey through the history and advancements in vaccinology, tailored for healthcare workers. It traces pivotal milestones, beginning with the variolation practices in the early 17th century, the development of the first smallpox vaccine, and the continuous evolution and innovation in vaccine development up to the present day. We also briefly review immunological principles underlying vaccination, as well as the main vaccine types, with a special mention of the recently introduced mRNA vaccine technology. Additionally, we discuss the broad benefits of vaccines, including their role in reducing morbidity and mortality, and in fostering socioeconomic development in communities. Finally, we address the issue of vaccine hesitancy and discuss effective strategies to promote vaccine acceptance. Research, collaboration, and the widespread acceptance and use of vaccines are imperative for the continued success of vaccination programs in controlling and ultimately eradicating infectious diseases.