The chickenpox vaccine is a shot that can protect nearly everyone who gets it from catching chickenpox. It’s also called the varicella vaccine because chickenpox is caused by the varicella-zoster virus. The vaccine is made from the live but weakened, or attenuated, virus.
Viruses that have been attenuated are less virulent than viruses that are not. Although the virus in the chickenpox vaccine is generally incapable of causing a disease, it still stimulates a response from the body’s immune system. That response is what gives someone who’s had a shot for chickenpox immunity from the illness.
Why Do People Need a Chickenpox Vaccine?
Most cases of chickenpox are relatively mild and run their course in five to 10 days. But it can be very serious, even life threatening, in a small percentage of cases. Before the varicella vaccine was licensed in the U.S. in 1995, there were approximately 100 deaths and more than 11,000 hospitalizations a year from chickenpox. Most of the people who died were healthy before they got chickenpox.
The risk of serious, life-threatening complications is greatest among infants, adults, and people with weakened immune systems. But anyone can develop serious complications and there is no way to predict who will.
There’s another reason for getting a shot for chickenpox. The illness is highly contagious and can be spread by direct contact or through the air by sneezing or coughing. Also, someone can get it by coming in contact with fluid from chickenpox blisters. For that reason, children with chickenpox need to be kept out of school or day care for about a week or more; parents may need to miss work as a result. Also, the illness causes an itchy rash that usually forms between 200 and 500 blisters over the entire body, headaches, coughing, and fussiness. So even if the illness is mild, it still means five to 10 days of being uncomfortable.
Are Children Required to Get a Chickenpox Vaccination?
Most states require that children entering child care and school show evidence of immunity to chickenpox or evidence of having been given the chickenpox vaccine.
Who Should Get Vaccinated With the Chickenpox Vaccine?
The chickenpox vaccine is recommended for all children under the age of 13 who have not had chickenpox. It is also recommended for all adolescents and adults who have not been vaccinated and have not had chickenpox.
If you have had chickenpox there is no need for you to get the vaccine.
Since 2005, the vaccine has also been available as part of a combination vaccine called MMRV, which offers protection against measles, mumps, rubella, and varicella.
How Many Shots of the Chickenpox Vaccine Are Needed?
The varicella vaccine is given in two doses. A child should have the first shot at the age of 12-18 months. The second shot should be given at the age of 4 to 6 years. Older children and adults should have two shots, with four to eight weeks between the first and second shot.
Are There Side Effects Associated With the Chickenpox Vaccine?
All medicines have potential side effects. But the side effects associated with the varicella vaccine are generally mild. The most common are pain, redness, or swelling at the injection site. A small percentage of people develop a mild rash, usually around the spot where the shot was given. Severe side effects are very rare.
Are There People Who Should Not Get a Chickenpox Shot?
Anyone who is moderately to severely ill when a chickenpox shot is scheduled should wait until the illness passes before getting the shot. Also, anyone who had an allergic reaction to the first shot should not get the second shot.
Other people who should not get the shot include:
- Pregnant women, because the vaccine’s effect on the fetus is not known.
- Anyone allergic to gelatin; a gelatin-free version of the varicella vaccine is available.
- Anyone allergic to neomycin.
- Anyone with an immune system disease.
- Anyone receiving high doses of steroids.
- Anyone being treated for cancer with X-rays, drugs, or chemotherapy.
- Anyone who had a transfusion or received blood products within five months prior to the shot.
If the Virus in Chickenpox Vaccine Is Live, Can It Cause Chickenpox?
About 2% of the children who are vaccinated develop a very mild case of chickenpox, usually with no more than five to six blisters.
It is also possible for a person who has been vaccinated for chickenpox to develop chickenpox at some later point in life. When that happens, the disease is almost always milder and the recovery more rapid than for people who have not had the shots.
But it’s important to keep in mind that up to 90% of the people who get the vaccine will not catch chickenpox.