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Varicella (chickenpox) is a highly contagious disease caused by infection with the varicella-zoster virus (VZV). After a person recovers, the virus stays dormant (inactive) within the dorsal root ganglia of the spinal nerves and can later be reactivated, presenting as herpes zoster (shingles). 

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Symptoms begin 7 to 21 days after exposure to the virus. Fever, rhinorrhoea (runny nose) and lethargy lasting 1 to 2 days are the first signs of disease (prodromal period). This is followed by the appearance of a pruritic (itchy) rash which is initially maculopapular (flat discoloured areas and raised areas) then becomes vesicular (fluid-filled blisters). The vesicles rupture then crust over, usually within 10 to 14 days. The rash can cover any part of the body including inside the mouth, on the scalp, eyelids and genital area. Unvaccinated children may experience 200 to 500 lesions. Approximately 5% of cases will be subclinical (symptoms are so mild they remain undetected under clinical examination).  

Most cases of varicella are self-limiting (will resolve by itself), but complications can include secondary bacterial infections, septicaemia (blood infections), pneumonia, meningitis, encephalitis and acute cerebellar ataxia (uncoordinated muscle movements). 

Varicella infections during pregnancy can result in congenital varicella syndrome in the child. Symptoms of congenital varicella syndrome include skin scarring, eye anomalies, limb defects and neurological malformations. The risk of congenital varicella syndrome is higher when infection occurs in the second trimester. Infants who have been exposed to varicella through a maternal varicella infection can develop herpes zoster, but this is rare. 

Despite vaccination, some people may still develop disease if exposed to infection. This is known as breakthrough disease. Breakthrough varicella symptoms are usually mild. Patients are typically afebrile and develop fewer skin lesions. People experiencing breakthrough disease are contagious and can transmit disease to others. 

Bệnh lây truyền qua đường nào

Varicella is transmitted by inhaling respiratory droplets that are made airborne when an infected person coughs or sneezes. It can also be spread by direct contact with the fluid inside the vesicles or through contact with items that have been contaminated with vesicle fluid. 

A person with varicella is considered infectious for 1 to 2 days prior to the onset of the rash until all the lesions have crusted. 

Dịch tễ học

Varicella is highly infectious. More than 80% of non-immune household contacts of an infected individual will develop disease.  

Prior to the introduction of vaccination in Australia in 2005, there were 240,000 cases of varicella annually, resulting in 1,500 hospitalisations and an average of 7 to 8 deaths. The rate of hospitalisation for varicella infection was reduced to 2.1 per 100,000 people in 2013. Most of these children were aged under 18 months, the scheduled age for varicella vaccination. (NB: Children can be safely vaccinated from 9 months of age.) 

Infants less than 4 weeks of age, premature neonates, unimmunised adolescents, có thai women and immunosuppressed individuals are at các greatest risk of severe disease and complications if they become infected. 

Phòng ngừa

Vaccines can provide protection against varicella infection. 

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^ MMRV combination vaccines must not be given as the first dose of measles-containing vaccine in children < 4 years due to the higher rates of fevers (see precautions and contraindications below).
* Whilst not registered for use in those aged ≥ 12 years, ATAGI recommends it may be used up to 14 years. MVEC advises that its use may also be considered in older adults when protection against measles, mumps and rubella is also required.
shaded boxes – varicella vaccine is routinely offered on the NIP as a single dose at 18 months. AIR will consider vaccination from 12 months of age as a valid dose.
ô vuông tô màu không đăng ký để sử dụng ở nhóm tuổi này.
shaded boxes indicate live-attenuated vaccines.

khuyến nghị

A single dose of varicella vaccination (in combination with measles, mumps and rubella) is funded on the NIP at 18 months of age. (NB: Children can be safely vaccinated from 9 months of age.)

A second dose (not funded) is recommended for greater protection to reduce the incidence of breakthrough disease. A minimum interval of 4 weeks is recommended between doses of live-attenuated vaccines.

Anyone non-immune aged 14 years and over should receive a catch-up course of 2 doses (administered 4 weeks apart) for adequate protection.

Household contacts of suy giảm miễn dịch individuals are recommended to complete their immunisation schedule on time.

Common vaccine side effects

Phản ứng tại chỗ tiêm (occurring in the first 48 hours) and fever (occurring 5 to 12 days after vaccination) are common side effects.

A maculopapular or vesicular rash (with 2 to 5 lesions) occurring 5 to 26 days after vaccination will develop in approximately 5% of vaccine recipients. If this occurs, it is recommended that lesions should remain covered until they crust over to avoid potential transmission of the virus to others. Transmission of the vaccine virus to contacts is extremely rare. Worldwide there have only been 11 documented cases of virus transmission from a recently vaccinated person to unvaccinated individuals.

Precautions and contraindications

All varicella vaccines are live-attenuated vaccines and are therefore contraindicated in pregnancy and in those with immunocompromise.

Children and adults who have been diagnosed with IFNAR1 should seek advice from an immunisation specialist or immunologist prior to vaccination.

There are recommended intervals between immunoglobulins or other blood products and administration of injected live-attenuated vaccines. Refer to MVEC: Vắc xin sống giảm độc lực và globulin miễn dịch hoặc sản phẩm máu.

When administered as the first dose of an MMR-containing vaccine, MMRV vắc xinS have been associated with higher rates of fever in children. It is therefore recommended that MMRV vaccines are administered as the second dose only of the 2-dose course of MMR in children under 4 years of age.  

Phòng ngừa sau phơi nhiễm

Vaccination (first or second dose) can be provided within 3 to 5 days of exposure to varicella (provided it is not contraindicated). This can reduce the likelihood of varicella disease developing. 

Neonates (whose mother develops infection up to 7 days prior to delivery or within 2 days after delivery), infants under 1 month of age (if mother is seronegative), pregnant women, premature infants (while still hospitalised, regardless of maternal serology) or immunosuppressed individuals who are exposed to varicella disease should receive Zoster Immunoglobulin (ZIG). 

Repeat doses of ZIG may be given if a person is exposed to varicella again more than 3 weeks after the first dose of ZIG.

Tác giả: Rachael McGuire (Research Nurse, SAEFVIC, Murdoch Children’s Research Institute)

Đượcxem xét bởi: Rachael McGuire (MVEC Education Nurse Coordinator) and Katie Butler (MVEC Education Nurse Coordinator)

Ngày: October 2023

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You should not consider the information on this site to be specific, professional medical advice for your personal health or for your family’s personal health. For medical concerns, including decisions about vaccinations, medications and other treatments, you should always consult a healthcare professional.