Varicella (Chickenpox) Vaccine:
Why We Don't Just "Let Kids Get It"

"Just let them get it naturally — it builds immunity." This is one of the most common things I hear from parents about chickenpox. And while I understand the logic, the evidence tells a more complicated story.

Chickenpox Is Not Always Mild

Most cases in otherwise healthy children are unpleasant but manageable. Some are not. Complications from chickenpox include:

• Bacterial superinfection — scratched spots become infected with Group A Streptococcus or Staphylococcus, occasionally causing necrotising fasciitis (flesh-eating infection)
• Viral encephalitis — brain inflammation, occurring in ~1–2 per 10,000 cases
• Cerebellar ataxia — temporary loss of coordination, can be alarming though usually resolves
• Pneumonia — more common in adults who get chickenpox
• Reye's syndrome — if aspirin is given during chickenpox (never give aspirin to children with viral illness)

Death from chickenpox occurs in approximately 1–2 per 100,000 cases — mostly in otherwise healthy children, not just immunocompromised individuals.

How Contagious Is It?

Extremely. Varicella has a basic reproduction number (R0) of approximately 10 — meaning one infected child can spread it to 10 others in a susceptible population. An infected child is contagious from 1–2 days before the rash appears until all spots have crusted over (~5–7 days). In a preschool or childcare setting, chickenpox spreads rapidly.

The Hidden Legacy: Shingles

Here is the fact that most "just let them get it" advocates overlook: the varicella-zoster virus (VZV) never fully leaves the body. After the chickenpox rash resolves, the virus retreats into sensory nerve ganglia and lies dormant for decades. In approximately 1 in 3 people, it reactivates as shingles (herpes zoster) — a painful, blistering rash along a nerve distribution, which can cause post-herpetic neuralgia (chronic severe nerve pain lasting months to years) and, if the ophthalmic branch is affected, permanent vision loss.

Children vaccinated with varicella have significantly less latent viral burden — and therefore lower lifetime shingles risk. Deliberate natural infection gives your child the illness and a lifelong nerve hitchhiker.

The Vaccine

• Varilrix (GSK): Live attenuated Oka-strain. Standard in Singapore clinics.
• Varivax (MSD): Alternative using Oka/Merck strain
• ProQuad/MMRV (MSD): Combined MMR + Varicella — reduces the number of injections at 15 months

Schedule: 2 doses — at 12 months and 15 months.