Chickenpox and Varicella Vaccine
In the past, chickenpox was a common childhood illness in the United States, particularly for children under the age of 10. The development of a vaccine in the 1970s has led to a decline in cases. While most symptoms of this contagious disease can be managed at home without a stay at a health care facility, chickenpox can strike adults, in which case the symptoms can be more severe. In addition, approximately 10% of children who contract chickenpox may develop complications that require attention from a physician.
What is chickenpox?
Chickenpox is a viral infection caused by the varicella zoster virus (VZV). While the origin of the term chickenpox is unknown, some believe that it was derived from chickpeas due to the blisters’ resemblance to chickpeas. Others think the term is based on child pox or itching pox. Most typically, the illness appears in children, and a rash appears anywhere between 10 – 21 days after becoming infected with the virus. On average, a child may develop from 250 – 500 blisters, which are itchy and filled with fluid. The blisters first appear on the face, scalp or torso. After several days, the first blisters will form scabs; however, more blisters may develop later. Often, they affect the inside of the mouth and the eyelids. The rash usually heals completely without scarring. Chickenpox has also been observed in other primates like chimpanzees and gorillas.
Where does chickenpox come from?
While the recurrent infection with the varicella zoster virus, herpes zoster or shingles, has been recognized since ancient time, physicians had not differentiated chickenpox varicella from smallpox until the late 19th century. However, the first description of chickenpox was provided by Giovanni Filippo in the 16th century. William Heberden demonstrated in 1767 that smallpox was different from chickenpox. In 1875, Rudolf Steiner showed that chickenpox was caused by an infectious agent, while Von Bokay made the first clinical observations differentiating herpes zoster from varicella zoster in 1909. Thomas Weller isolated the varicella virus in 1954, and Michiaki Takahashi developed the first live, attenuated vaccine for varicella in 1972.
How is chickenpox transmitted?
The chickenpox virus spreads easily through the air when an infected person sneezes or coughs. In addition, the disease can be spread through breathing in or touching the virus particles shed by the body. It can also be transmitted by indirect contact with items that had been in direct contact with active blisters. Chickenpox may also be transmitted by people with an active outbreak of shingles caused by the herpes zoster virus, and the varicella zoster virus may cause shingles.
What are chickenpox symptoms?
The typical symptoms of chickenpox include a rash with itchy, fluid filled lesions that scab over when healing. The rash may first develop over the face, back and chest and subsequently over the entire body, and then progresses to blisters, small bumps and pustules. Later the pustules or lesions may develop on the eyelids, mouth and genital areas. Scabs will form over the lesions after approximately one week. Other classic symptoms that frequently appear about one to two days before a rash include fatigue, high fever, headache, loss of appetite, nausea, and muscle aches. The average length of the incubation period is about 14 – 16 days from first exposure, although the incubation can range from 10 – 21 days. Certain patients with compromised immune systems may experience longer incubation periods. The period of communicability begins from one to two days prior to the onset of the rash and lasts up to 6 days after that.
What is the Chickenpox Vaccine?
The chickenpox vaccine, also known as the varicella vaccine (Varivax, Merck), is a live, attenuated vaccine made from the Oka strain of the varicella zoster virus. The vaccine is derived from the isolated virus from the vesicular fluid from a healthy child, and is attenuated by passage 30 – 33 times in human diploid cells and guinea pig fibroblasts. While the weakened virus in the vaccine will not cause the disease itself, it will prompt the body’s immune system to create the antibody to the varicella zoster virus, which gives the person immunity from chickenpox. The CDC advises individuals to receive two doses of varicella vaccine for all ages. Two doses prove to be approximately 98 percent effective in preventing the infection. Vaccine has been administered to over 15,000 people in Japan and the U.S., including healthy children, healthy adults, children with acute lymphocytic leukemia (ALL), and other immunocompromised patients.
What are the Chickenpox Vaccine Side Effects?
While getting the chickenpox vaccine is generally very safe, some people experience side effects. Most people experience no side effects, and serious side effects are very rare. Generally, side effects will occur after the first vaccination rather than after the second dose. Possible reactions include fever, redness/soreness or swelling at the injection site, and several small bumps or a mild rash after vaccination. Serious side effects, such as low blood counts and severe brain reactions, from the varicella vaccine are very rare.
Who should not get the Chickenpox Vaccine?
While it is very save, some people should not get the chickenpox vaccine: people with a severe allergic reaction to a previous dose of chickenpox vaccine or any element of the vaccine (such as gelatin or Neomycin), people with a moderate or severe illness at the time of injection, pregnant women, people with HIV/AIDS or other autoimmune diseases, people under drug treatment that weakens the immune system (such as steroids) or people with cancer.