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Chickenpox

652 Paediatrics doctors in Hong Kong →

Also known as: Varicella ·

Chickenpox is an acute infectious disease caused by the varicella-zoster virus, mostly affecting children under twelve. The incubation period is ten to twenty-one days, usually fourteen to sixteen, and recovery generally takes two to four weeks. Vaccination is effective: about nine in ten of those vaccinated develop immunity.

Hong Kong has 652 registered Paediatrics doctors.

Source: Medical Council of Hong Kong register · read 2026-09-20

ok.med editorial team ·
Compiled by the editorial team from the sources listed below. Not reviewed by an individual doctor.

What is chickenpox?

The Centre for Health Protection describes chickenpox as an acute infectious disease caused by the varicella-zoster virus, occurring mostly in children under twelve.

Fever and an itchy rash are the usual presentation. The rash emerges over about five days, starting on the trunk and spreading to the face and limbs. It is flat at first, then raised into small blisters which last three to four days before drying and crusting. Recovery generally takes two to four weeks.

Almost everyone is immune for life after chickenpox, but the virus can lie dormant in the body and reactivate years later as herpes zoster — shingles, 生蛇 in Cantonese. Childhood chickenpox and adult shingles are therefore not two unrelated illnesses but two stages of the same virus.

How long is the incubation and contagious period?

The Centre for Health Protection gives an incubation period of ten to twenty-one days, usually fourteen to sixteen. A patient is infectious from one to two days before the rash appears until all the blisters have dried, and is most infectious in the early days of the rash.

The chickenpox timeline, and what each stage means for a parent
StageTimingWhat it means for a parent
Incubation10 to 21 days, usually 14 to 16A rash two weeks after exposure is normal; there is no way to be sure in between
Becomes infectious1 to 2 days before the rashThe child can pass it on before anyone sees a rash
Most infectiousThe early days of the rashThe Centre for Health Protection calls chickenpox extremely infectious
No longer infectious / may returnWhen all blisters have dried, usually about a week after the rashThe test is the state of the blisters, not a number of days

Medical Council of Hong Kong register

652 Paediatrics doctors in Hong Kong

All 652 ›

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How does chickenpox vaccination work here?

The Centre for Health Protection states that vaccination effectively prevents chickenpox, with about nine in ten of those vaccinated developing immunity. Under the Hong Kong Childhood Immunisation Programme children receive two varicella-containing doses in total.

The varicella vaccine was brought into the Hong Kong Childhood Immunisation Programme on 2 July 2014. The exact schedule differs by the child’s date of birth; parents can check with a Department of Health Maternal and Child Health Centre or their family doctor.

Someone vaccinated can still catch chickenpox — a breakthrough infection. The Centre for Health Protection notes these are usually milder or less typical, with fewer blisters, a rash that is mostly maculopapular rather than vesicular, and a shorter course than in the unvaccinated. A rash after vaccination therefore does not mean the vaccine failed.

How should a home be cleaned, and will an alcohol rub do?

For chickenpox the Centre for Health Protection accepts a hand rub containing 70 to 80 per cent alcohol. This is not the case for hand, foot and mouth disease, and the difference is worth keeping separate in mind.

Washing remains first choice: liquid soap and water, rubbing for at least twenty seconds. For surfaces, household bleach diluted 1 to 99 is left fifteen to thirty minutes then rinsed and wiped dry; metal surfaces can be disinfected with 70 per cent alcohol. Keep rooms well ventilated.

Why the advice differs comes down to the organism. Chickenpox is caused by the varicella-zoster virus; hand, foot and mouth disease is caused by enteroviruses, and the Centre for Health Protection states plainly that alcohol does not effectively kill enterovirus 71. The same bottle of hand rub is adequate in one case and not in the other.

At a glance

Chickenpox timeline: incubation 10 to 21

Chickenpox timeline: incubation 10 to 21 days, infectious from 1 to 2 days before the rash, blisters lasting 3 to 4 days, and return to school only once all blisters have dried — usually about a week after the rash.
Data: Centre for Health Protection · Read the original ›

When can a child return to school?

The Centre for Health Protection’s test is the state of the blisters: a child with chickenpox should stay home until all the blisters have dried, usually about a week after the rash appears.

This applies to schools, kindergartens, kindergarten-cum-child care centres and child care centres. The Centre for Health Protection also reminds parents to watch other children in the household for symptoms — because the infectious period begins before the rash, siblings have usually already been exposed.

Who is at higher risk of chickenpox?

The Centre for Health Protection describes chickenpox as a mild, self-limiting illness, but notes that people with weakened immunity and pregnant women face a higher chance of serious complications such as pneumonia and encephalitis.

Chickenpox in a newborn can be severe and even life-threatening, and infection in early pregnancy can cause congenital defects in the foetus. The Centre for Health Protection therefore advises patients to avoid contact with pregnant women and people with weakened immunity — advice aimed not only at the patient but at the adults living with them.

What are the arrangements in Hong Kong?

Chickenpox is one of the few childhood infections here with a subsidised vaccine, and the return-to-school rule is set out explicitly. Both are what local parents most often look up.

  • Under the Hong Kong Childhood Immunisation Programme children receive two varicella-containing doses in total, and about nine in ten of those vaccinated develop immunity.Centre for Health Protection: Chickenpox · read · (source)
  • The Department of Health brought the varicella vaccine into the Hong Kong Childhood Immunisation Programme with effect from 2 July 2014.HKSAR Government Press Release (24 June 2014) · read · (source)
  • The return-to-school rule is set out explicitly: a child with chickenpox should not attend school, kindergarten, a kindergarten-cum-child care centre or a child care centre, and should stay home until all blisters have dried — usually about a week after the rash appears.Centre for Health Protection: Chickenpox · read · (source)
  • The schedule differs according to the child’s date of birth; the Family Health Service directs parents to a Department of Health Maternal and Child Health Centre or their family doctor for details.Family Health Service, Department of Health: Hong Kong Childhood Immunisation Programme · read · (source)

When should a child be seen promptly?

  • Persistent fever — one of the signs the Centre for Health Protection asks parents to watch for.
  • Refusing food, or drinking noticeably less.
  • Vomiting, or unusual sleepiness.
  • Redness, pus or increasing pain around the blisters — the skin may have become infected.
  • Where a pregnant woman, a newborn or someone with weakened immunity has been exposed, seek medical advice early.

Each has its own page and doctor list

Conditions related to Chickenpox

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Which districts have Paediatrics doctors?

Frequently asked questions

Can you get chickenpox twice?
The Centre for Health Protection states that almost everyone is immune for life after having chickenpox. The virus does remain dormant, however, and may reactivate years later as shingles — another stage of the same virus rather than a second bout of chickenpox.
Why did my vaccinated child still get it?
This is a breakthrough infection. The Centre for Health Protection notes such cases are usually milder or less typical, with fewer blisters, a mostly maculopapular rash and a shorter course. The vaccine reduces the chance and the severity rather than guaranteeing prevention.
Is an alcohol hand rub enough?
For chickenpox the Centre for Health Protection accepts a hand rub containing 70 to 80 per cent alcohol. The same does not hold for hand, foot and mouth disease: the Centre states that alcohol does not effectively kill enterovirus 71, so soap and water is required there.
When can the child go back to school?
When all the blisters have dried — usually about a week after the rash appears. The test is the state of the blisters, not a number of days, so it cannot be worked out from the calendar alone.
What if someone in the household is pregnant?
The Centre for Health Protection notes that pregnant women face a higher chance of serious complications such as pneumonia and encephalitis, and that infection in early pregnancy can cause congenital defects. Patients should avoid contact with pregnant women, and a pregnant woman who has been exposed should seek medical advice early.
How can scarring be avoided?
The Centre for Health Protection suggests clean cotton gloves at night so blisters are not scratched open, which can lead to skin infection and scarring. Itch should be managed with medicines as a doctor directs.

Sources

  1. Centre for Health Protection health topic: chickenpox — cause, incubation, infectious period, symptoms, complications, management and prevention. Centre for Health Protection, Department of Health ()
  2. Centre for Health Protection communicable disease leaflet: chickenpox — breakthrough infection, the return-to-school rule and what parents should watch for. Centre for Health Protection, Department of Health ()
  3. Family Health Service, Department of Health: the Hong Kong Childhood Immunisation Programme schedule. Family Health Service, Department of Health ()
  4. Government press release: the Department of Health brings varicella vaccine into the Childhood Immunisation Programme from 2 July. HKSAR Government Press Release (24 June 2014) ()

This page is compiled from the Hong Kong official sources listed above. It is general information only — not a diagnosis, a treatment recommendation or medical advice, and no substitute for seeing a doctor. If you are unsure or your condition changes, consult a registered doctor.