Varicella (Chickenpox)

Symptoms

The classic symptom of chickenpox is the appearance of an irritable, itchy rash of red spots. These spots are fluid-filled blisters that eventually dry up and turn into scabs. They usually appear on the face, chest, and back before spreading to other regions in the body. 

Symptoms² that may appear 1-2 days prior to the rash include:

Complications

Though chickenpox is a mild disease, one may experience severe health issues that can lead to death. Those who are at high risk include newborn infants, adolescents, adults, pregnant women, and individuals with a weakened immune system. Common complications include: 

How long do symptoms last?

Varicella is self-limited (resolves spontaneously); any crusted scabs developed from the rash will disappear within 7 to 10 days.

After initial exposure, the virus remains in your body and may be reactivated, causing a different disease known as Shingles. Shingles is a contagious infection that is primarily indicated by heightened pain and may be accompanied by an irritable rash similar to chickenpox.

The Varicella Vaccine

There are currently two Varicella-containing vaccines licensed for use in the U.S:

• Varicella Vaccine (Varivax) 
• Measles-mumps-rubella-varicella, MMRV Vaccine (ProQuad)

Varicella Vaccine Safety

Figure 1.³ Incidence rates of breakthrough varicella per 1000 PY (person-years) from 1995-2008. Overall rate of lesions decreased overtime after implementation of Varicella vaccine in 1995. 

Lesion: an area of abnormal tissue

Breakthrough: Varicella that occurs in vaccinated individuals after 42 days

1000-PY (person-years): for every 1,000 people observed within 1 year, you would expect 1 breakthrough Varicella case

Table 1.⁴ Mild and severe adverse events provided by the World Health Organization (WHO). This table uses data derived from a literature search on PubMed in 2008 using keywords "vaccine antigen", "safety", and "adverse events"

Varicella Vaccine Effectiveness

Figure 2.⁵ In 4 states that have been reporting Varicella cases annually since before the vaccine implementation, incidence (occurrences) declined an average of 97.4% from 1993-1995 to 2013-2014. Decreases can be noticed with recommendation of the 1st-dose and 2nd-dose.

Herd Immunity: How It Works

Communities that have very high rates of vaccination further benefit from herd immunity, conferring increased protection to those unable to receive the vaccination.

Varicella Vaccine Schedule⁶

Table 3. 

Table 4. 

• Recommended for all adolescents and adults without evidence of immunity 
• For persons with HIV, the minimum interval between the two doses should be 3 months
• Varivax has no upper age limit

How do I know if I am protected against Varicella?⁷

Types of Varicella Vaccines

Both contain live, attenuated (weakened) viral strains

Vaccine Side Effects

Side effects⁸ from the vaccine are more likely to occur after the first dose than after the second, and go away after a few days

 Table 2.⁹ 

The Bottom Line

As mentioned before, chickenpox is a mild disease that can lead to severe health issues--including the onset of Shingles at a later age or death. The best way to avoid these complications and chickenpox in general is vaccination.