Global Prevalence of Varicella-Associated Complications: A Systematic Review and Meta-Analysis.

Introduction: Varicella (chickenpox) is an infectious disease caused by the varicella zoster virus affecting children, adolescents, and adults. Varicella symptoms are usually self-limiting; however, different complications with widespread and systemic manifestations can occur. This systematic literature review aims to explore and quantify varicella-associated complication rates.

Combined measles-mumps-rubella-varicella vaccine and febrile convulsions: the risk considered in the broad context.

Introduction: Studies on quadrivalent measles, mumps, rubella, and varicella (MMRV) vaccines have indicated a twofold increased relative risk of febrile convulsion (FC) after the first dose compared to MMR and V administered at the same medical visit (MMR+V).

Areas Covered: This narrative review contextualizes FC occurrence after the first MMRV vaccine dose from a clinical perspective and outlines approaches to attenuate FC occurrence post-vaccination.

Expert Opinion: While the relative FC risk increases after the first dose of MMRV compared to MMR+V vaccine in measles-naïve infants, the attributable risk is low the overall FC risk in the pediatric population triggered by other causes, like natural exposure to pathogens or routine vaccination.

Clinical trials show similar safety outcomes including febrile convulsion rates for GSK's and Merck's measles-mumps-rubella (MMR) vaccines.

Combined measles-mumps-rubella (MMR) vaccines produced by GSK (GSK-MMR) and Merck (Merck-MMR) have demonstrated effectiveness and an acceptable safety profile, as documented over decades of post-licensure use in various regions worldwide. In the United States, 2 doses of the MMR vaccine are recommended at the ages of 12-15 months and 4-6 years. All-cause febrile convulsions have the highest incidence at 12-18 months of age, when the first MMR vaccine dose is administered.

No Consistent Evidence of Decreased Exposure to Varicella-Zoster Virus Among Older Adults in Countries with Universal Varicella Vaccination.

Background: Universal varicella vaccination might reduce opportunities for varicella-zoster virus (VZV) exposure and protective immunological boosting, thus increasing herpes zoster incidence in latently infected adults. We assessed humoral and cell-mediated immunity (CMI), as markers of VZV exposure, in adults aged ≥50 years.

Methods: We repurposed data from placebo recipients in a large multinational clinical trial (ZOE-50).

Randomised controlled trial showed long-term efficacy, immunogenicity and safety of varicella vaccines in Norwegian and Swedish children.

Aim: Several countries, such as Norway and Sweden, have not implemented universal varicella vaccination. We present data for Norway and Sweden that were generated by a paediatric multi-country Phase III study over a 10-year period. This assessed the efficacy, antibody persistence and safety of two varicella vaccines containing the same Oka strain.

A randomized trial assessing the efficacy, immunogenicity, and safety of vaccination with live attenuated varicella zoster virus-containing vaccines: ten-year follow-up in Russian children.

In Russia, a universal varicella vaccination (UVV) program has not been implemented, and varicella vaccination coverage is low. We assessed the efficacy, antibody persistence, and safety of one- and two-dose varicella vaccination schedules in Russian children with a ten-year follow-up period, as part of an international phase IIIB, observer-blind, randomized, controlled trial (NCT00226499). Children aged 12-22 months were randomized (3:3:1) to receive two doses of tetravalent measles-mumps-rubella-varicella vaccine (V2 group), one dose trivalent measles-mumps-rubella (MMR) vaccine and one dose of varicella vaccine (V1 group), or two doses of MMR vaccine (V0 [control] group), 42 days apart.

Measles, mumps, rubella prevention: how can we do better?

Introduction: Measles, mumps, and rubella incidence decreased drastically following vaccination programs' implementation. However, measles and mumps' resurgence was recently reported, outbreaks still occur, and challenges remain to control these diseases.

Areas Covered: This qualitative narrative review provides an objective appraisal of the literature regarding current challenges in controlling measles, mumps, rubella infections, and interventions to address them.

Ten-year follow-up on efficacy, immunogenicity and safety of two doses of a combined measles-mumps-rubella-varicella vaccine or one dose of monovalent varicella vaccine: Results from five East European countries.

Background: We assessed the 10-year efficacy, immunogenicity and safety of two doses of a combined measles-mumps-rubella-varicella vaccine (MMRV) or one dose of a monovalent varicella vaccine (V) in children from Czech Republic, Lithuania, Poland, Romania and Slovakia.

Methods: This was a phase IIIB follow-up of an observer-blind, randomized, controlled trial (NCT00226499). In phase A, healthy children aged 12-22 months from 10 European countries were randomized in a 3:3:1 ratio to receive two doses of MMRV (MMRV group), one dose of MMR followed by one dose of V (MMR + V group), or two doses of MMR (MMR; control group), 42 days apart.

Epidemiological Impact and Cost-Effectiveness of Varicella Vaccination Strategies in the United Kingdom.

Background: Despite the burden of varicella, there is no universal varicella vaccination (UVV) program in the United Kingdom (UK) due to concerns that it could increase herpes zoster (HZ) incidence. We assessed the cost-utility of a first-dose monovalent (varicella [V]) or quadrivalent (measles-mumps-rubella-varicella [MMRV]) followed by a second-dose MMRV UVV program. GSK and MSD varicella-containing vaccines (VCVs) were considered.

Varicella vaccination in Italy and Germany - different routes to success: a systematic review.

Introduction: Italy (in pilot regions) and Germany (nationwide) were the first European countries to introduce universal varicella vaccination (UVV) programs.

Areas Covered: A systematic review was performed to assess varicella epidemiology before UVV programs and the impact of 1-dose and 2-dose UVV programs in Italy and Germany.

Expert Opinion: Italy implemented 1- or 2-dose UVV programs successively in eight pilot regions between 2003 and 2011 and nationwide in 2017.

Herpes zoster in the context of varicella vaccination - An equation with several variables.

Background: Varicella and herpes zoster (HZ), diseases both caused by the varicella zoster virus (VZV), are vaccine-preventable. However, the hypothesis that childhood varicella vaccination may increase the incidence of HZ hinders varicella universal routine vaccination (URV) implementation in many countries.

Methods: This non-systematic and narrative review of the literature considers the burden of varicella and HZ, and the effectiveness of the respective vaccines.

A New Combined Vaccine Against Measles, Mumps, Rubella and Varicella in India.

A quadrivalent MMRV (measles-mumps-rubella-varicella) combination vaccine has recently been launched in India. This vaccine is highly immunogenic, with seroconversion rates against all antigens reaching 96.6-100% at 42 to 56 days after the second vaccine dose in unvaccinated children or in those previously vaccinated with MMR+/-V.

Varicella vaccination - the global experience.

Varicella, although a frequently benign childhood disease, nevertheless represents a considerable health burden. WHO recommends including varicella vaccines in universal routine vaccination programs, and maintaining coverage >80%. Many countries have successfully introduced varicella vaccination and have benefited from lower disease burden, but many others have not adopted the vaccine.