Prevention of Breakthrough Varicella and Outbreaks by Two Dose Vaccination

Abstract

Among viral infections, one of the known human herpes viruses, Varicella-Zoster Virus (VZV) causes latent infection. The VZV causes two distinct diseases, varicella (chickenpox) and after latency shingles (herpes zoster). Although safe and effective vaccine is available, it is not widely used in many geographic areas mainly because of non-inclusion in the routine immunization schedule. Over the years, many countries have reported more than 90% reduction in number of varicella infections mainly due to vaccination. In developing countries estimated 15–16 cases per thousand are reported of which 2–4% develop complications. An effective surveillance to detect cases of varicella and introduction of vaccination are essential to control and prevent varicella infections. Since humans are only reservoir for this virus, it is possible to eradicate this disease by effective vaccination program. Sometimes it is possible to get chicken pox with wild type of Varicella-Zoster virus after varicella vaccination and is termed as modified or breakthrough varicella infection. A coverage of two doses provides maximum protection. A number of studies conducted across the globe emphasis the need to implement two vaccine doses to maintain a high level of immunity, to prevent breakthrough varicella and epidemics.

Keywords: Varicella-Zoster virus, chicken pox, shingles, breakthrough varicella, vaccination, infection, varicella vaccine