Chickenpox vaccine
The chickenpox vaccine, known as Varivax, is a live, attenuated vaccine designed to provide immunity against the varicella-zoster virus (VZV), which is responsible for causing chickenpox. This vaccine was first licensed in the United States in 1995 and has since become part of routine childhood immunizations, initially requiring a single dose and later a second dose introduced in 2006. Chickenpox is a highly contagious viral disease characterized by a blister-like rash, fever, and fatigue, with complications that can arise in a small percentage of cases, including pneumonia and encephalitis.
The vaccine has proven to be highly effective in reducing the incidence of varicella, with cases in the U.S. declining by 85 to 90 percent since its introduction. Side effects are typically mild, including fever and a rash, but the vaccine is contraindicated for certain individuals, such as those with specific allergies, immunosuppression, or during pregnancy. Additionally, administering the vaccine shortly after exposure to the virus can prevent the disease in children, although this effectiveness has not been shown in older adolescents and adults.
Overall, the chickenpox vaccine has significantly decreased the burden of the disease, contributing to fewer hospitalizations and fatalities associated with varicella, while also reducing the incidence of shingles later in life.
Chickenpox vaccine
Also known as: Varicella-zoster vaccine
Definition
The chickenpox vaccine is a live, attenuated vaccine producing CD4 and CD8 effectors and memory T cell antibody immunity to the varicella-zoster virus (VZV), which causes chickenpox.
Pathogenicity and Clinical Significance
Varicella is a highly contagious viral illness caused by VZV, a human herpes virus of the Alphaherpesvirinae subfamily. Transmission is by respiratory droplets or by direct contact with the virus-containing vesicle fluid. Household transmission rates approach 90 percent.
During the ensuing week, the virus spreads to various parts of the body, including the skin, liver, central nervous system, lymphatic system, and spleen. The majority of affected persons have symptoms that include fever, malaise, and inflamed, pruritic vesicles, which resolve in two to three weeks.
Approximately one in fifty persons exhibit complications that include encephalitis, pneumonia, and hepatitis. Secondary bacterial skin infections can occur as open skin lesions provide an entry portal. Varicella virus can be transmitted through the placenta to the fetus if the disease is acquired by the girl or woman during pregnancy. The fetus may be born with congenital varicella syndrome and demonstrate skin, extremity, ocular, and brain abnormalities.
Herpes virus remains dormant in the spinal and cranial sensory ganglia. It reactivates typically in later life as the person’s antibody level wanes or the person experiences immune suppression, like that seen in cancer. Reemergence of the herpes virus is called shingles and can lead to extremely painful postherpetic neuralgia, which lasts from weeks to years.
Disease Prevention
The vaccine Varivax was licensed in the United States in 1995. In 1996, the Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention recommended Varivax as part of routine childhood immunizations. Initially a single dose, a second dose was added in 2006. The combination vaccine ProQuad, which contains mumps, measles, rubella, and varicella antigens, was approved in 2005. The vaccine Zostavax has been effective in boosting cell-mediated immunity (antibody production) and in providing partial immunity. It is approved for use in persons at age sixty years.
The most common side effects of varicella vaccine include fever, injection-site complaints, and a varicella-like rash. The vaccine is not recommended for persons with hypersensitivity to its ingredients, which include gelatin and neomycin; for persons with immunosuppression or with active tuberculosis; or for women or girls who are pregnant.
Postexposure Vaccine
Post-varicella-exposure vaccination in children has shown some effectiveness in preventing disease if administered within three days of exposure. Protection has not been demonstrated in adolescents and adults.
Impact
Before the development of a chickenpox vaccine, four million people in the United States acquired varicella annually, leading to ten thousand hospitalizations and one hundred deaths. After the development of a vaccine, these numbers were reduced by 85 to 90 percent. The initial vaccine dose reduced varicella infection by 64 percent, and the second dose further reduced infection by 90 percent. According to the Centers for Disease Control and Prevention, in 2020, there were less than 150,000 cases of chickenpox, resulting in only 1400 hospitalizations and less than thirty deaths. Research has shown that the administration of varicella vaccine in childhood reduces the incidence of herpes zoster in adulthood as well.
Bibliography
Campos-Outcalt, Doug. “ACIP Immunization Update.” Journal of Family Practice 59, no. 3 (2010): 155-158.
Centers for Disease Control and Prevention. “Recommended Immunization Schedules for Persons Aged 0-18 Years—United States, 2008.” Morbidity and Mortality Weekly Report 57 (2008): Q1-Q4. Available at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5701a8.htm.
“Chickenpox Vaccine Saves Lives Infographic.” Centers for Disease Control and Prevention, 20 Oct. 2022, www.cdc.gov/chickenpox/vaccine-infographic.html. Accessed 28 Feb. 2023.
‗‗‗‗‗‗‗. “Varicella (Chickenpox) Vaccination.” Available at http://www.cdc.gov/vaccines/vpd-vac/varicella.
Macartney, K., and P. McIntryre. “Vaccines for Post-exposure Prophylaxis Against Varicella (Chickenpox) in Children and Adults.” Cochrane Database of Systematic Reviews (2008): CD001833.Available through EBSCO DynaMed Systematic Literature Surveillance at http://www.ebscohost.com/dynamed.
Marin, M., H. C. Meissner, and J. F. Seward. “Varicella Prevention in the United States.” Pediatrics 122 (2008): 744-751.
Roush, Sandra, et al. “Historical Comparisons of Morbidity and Mortality for Vaccine-Preventable Diseases in the United States.” Journal of the American Medical Association 298, no. 18 (2007): 2155-2163
Smith, Candace, and Ann Arvin. “Varicella in the Fetus and Newborn.” Seminars in Fetal and Neonatal Medicine 14 (2009): 209-217.
Tyring, S. K. “Management of Herpes Zoster and Postherpetic Neuralgia.” Journal of the American Academy of Dermatology 57, no. 6 (December, 2007): S136-S142.
Ward, Mark A. “Varicella.” In Conn’s Current Therapy 2011, edited by Robert E. Rakel, Edward T. Bope, and Rick D. Kellerman. Philadelphia: Saunders/Elsevier, 2010.
Whitley, Richard J. “Varicella-Zoster Virus.” In Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases, edited by Gerald L. Mandell, John F. Bennett, and Raphael Dolin. 7th ed. New York: Churchill Livingstone/Elsevier, 2010.