Protective immunity elicited by measles vaccine exerts anti-tumor effects on measles virus hemagglutinin gene-modified cancer cells in a mouse model

Measles vaccine effectiveness in African children: a systematic review and meta-analysis

INTRODUCTION

Measles is an extremely contagious viral disease that can be prevented through vaccination. It is caused by the measles virus and presents with symptoms such as high fever, cough, runny nose, conjunctivitis, and a distinctive rash. Complications may include pneumonia, diarrhoea, and neurological issues. The disease spreads through respiratory droplets and continues to pose a significant public health challenge, especially in Africa, despite vaccination efforts.

OBJECTIVE

This systematic review and meta-analysis aim to estimate the pooled vaccine effectiveness of measles vaccines among African children, providing insights into immunization program success and informing policy decisions on vaccine distribution and resource allocation.

METHODS

Following PRISMA guidelines, search was conducted in databases including PubMed/Medline, Science Direct, HINARI, Cochrane/Wiley library, Europe PMC, and grey literatures like Google Scholar up to March 2024. Cross-sectional studies assessed measles vaccine effectiveness in African children aged nine months and above were included. Data was extracted using JBI extraction tool and entered into microsoft excel and analysed via STATA version 20.1 using random effect model.

RESULTS

From 5295 identified articles, 18 met the inclusion criteria, encompassing 26,470 children from 13 African countries. The pooled measles vaccine effectiveness was 68.58%, with significant heterogeneity (I2 = 99.66%, p < 0.001). Subgroup analysis showed variability in vaccine effectiveness by study period, with higher effectiveness in studies conducted after the Global Vaccine Action Plan (GVAP) in 2012.

CONCLUSION

Measles vaccine effectiveness varies in African regions, ranging from 98.4% in Nigeria to 36.5% in Mozambique, with an overall effectiveness of 68.58% and high heterogeneity among studies. Optimizing vaccine distribution, increasing coverage, and prompt administration are important for enhancing effectiveness. Continued support for GVAP strategies and further research is needed to understand factors affecting vaccine performance and improve immunization efforts in Africa.

Development and application of oncolytic viruses as the nemesis of tumor cells

Viruses and tumors are two pathologies that negatively impact human health, but what occurs when a virus encounters a tumor? A global consensus among cancer patients suggests that surgical resection, chemotherapy, radiotherapy, and other methods are the primary means to combat cancer. However, with the innovation and development of biomedical technology, tumor biotherapy (immunotherapy, molecular targeted therapy, gene therapy, oncolytic virus therapy, etc.) has emerged as an alternative treatment for malignant tumors. Oncolytic viruses possess numerous anti-tumor properties, such as directly lysing tumor cells, activating anti-tumor immune responses, and improving the tumor microenvironment. Compared to traditional immunotherapy, oncolytic virus therapy offers advantages including high killing efficiency, precise targeting, and minimal side effects. Although oncolytic virus (OV) therapy was introduced as a novel approach to tumor treatment in the 19th century, its efficacy was suboptimal, limiting its widespread application. However, since the U.S. Food and Drug Administration (FDA) approved the first OV therapy drug, T-VEC, in 2015, interest in OV has grown significantly. In recent years, oncolytic virus therapy has shown increasingly promising application prospects and has become a major research focus in the field of cancer treatment. This article reviews the development, classification, and research progress of oncolytic viruses, as well as their mechanisms of action, therapeutic methods, and routes of administration.

Repurposing Infectious Diseases Vaccines Against Cancer

Vaccines used to prevent infections have long been known to stimulate immune responses to cancer as illustrated by the approval of the Bacillus Calmette-Guérin (BCG) vaccine to treat bladder cancer since the 1970s. The recent approval of immunotherapies has rejuvenated this research area with reports of anti-tumor responses with existing infectious diseases vaccines used as such, either alone or in combination with immune checkpoint inhibitors. Here, we have reviewed and summarized research activities using approved vaccines to treat cancer. Data supporting a cancer therapeutic use was found for 16 vaccines. For 10 (BCG, diphtheria, tetanus, human papillomavirus, influenza, measles, pneumococcus, smallpox, typhoid and varicella-zoster), clinical trials have been conducted or are ongoing. Within the remaining 6, preclinical evidence supports further evaluation of the rotavirus, yellow fever and pertussis vaccine in carefully designed clinical trials. The mechanistic evidence for the cholera vaccine, combined with the observational data in colorectal cancer, is also supportive of clinical translation. There is limited data for the hepatitis B and mumps vaccine (without measles vaccine). Four findings are worth highlighting: the superiority of intravesical typhoid vaccine instillations over BCG in a preclinical bladder cancer model, which is now the subject of a phase I trial; the perioperative use of the influenza vaccine to limit and prevent the natural killer cell dysfunction induced by cancer surgery; objective responses following intratumoral injections of measles vaccine in cutaneous T-cell lymphoma; objective responses induced by human papillomavirus vaccine in cutaneous squamous cell carcinoma. All vaccines are intended to induce or improve an anti-tumor (immune) response. In addition to the biological and immunological mechanisms that vary between vaccines, the mode of administration and sequence with other (immuno-)therapies warrant more attention in future research.