Varicella, more commonly known as chickenpox, is a common childhood disease that is caused by the varicella-zoster virus and characterized by a blistering, itchy rash. It is highly contagious and easily spread to others through coughing, sneezing and talking. While the varicella vaccine has gone a long way toward eradicating the disease, there are still 91 million cases worldwide, 238,000 varicella-associated hospitalizations, and 2,000 varicella-related deaths each year. These cases most often occur in persons who were not able get vaccinated or in children not yet old enough to receive both doses.
Aside from getting the varicella vaccine, the most effective way you can prevent spreading chickenpox to others, or contracting it yourself, is to familiarize yourself with the virus’s patterns. More specifically, you must familiarize yourself with how the virus spreads and for how long a person is contagious.
The varicella-zoster virus is highly contagious to persons who have either never had the disease or who have not been vaccinated for it. In fact, if one person has the disease, as much as 90% of the people close to him or her and who do not have immunity will also become infected. The virus spreads through close contact between an infected and non-immune person, such as through coughing, sneezing and touch.
Most people are contagious with varicella before they even know they have it. An infected person can transmit the virus to others one to two days before the onset of the rash.
Contagion continues until the chickenpox lesions have crusted, and until no new lesions have appeared for at least 24 hours.
Vaccinated individuals who end up contracting varicella-zoster virus despite the immunization may not develop lesions that crust. In these people, their contagious continues until no new lesions have developed for at least 24 hours.
Following the onset of the rash, varicella blisters typically scab over within five to seven days. While a person has blisters, he or she should stay home and away from others for those five to seven days and until the blisters have fully scabbed over.
The latency period for varicella is roughly two weeks, though persons can develop symptoms within as few as 10 days of exposure or as many as 21 days after exposure. It is important to note that vaccinated persons who contract the virus can still spread it to others. Most people who lived through the virus have immunity for life. It is possible, however, for a person to contract varicella twice, though this is not common.
As much as 90% of non-immune persons who come into contact with an infected person will also contract the virus. That said, persons who are most at risk of contracting varicella are those who have never had chickenpox before. If you or a loved one has a weakened immune system — whether because of HIV, an organ transplant, an autoimmune disorder, cancer treatment or another reason — it is imperative that you protect yourself and/or him or her.