Cúm là gì?

Rotaviruses belong to the genus Rotavirus (in the family Reoviridae) which comprises eight species, referred to as A, B, C, D, E, F, G and H. Group A rotaviruses are responsible for most rotavirus infections in humans, although people have also been infected with groups B and C. Like in influenza viruses, the structure of rotaviruses enables them to mutate rapidly to produce new strains.

Rotavirus infections are the leading cause of dehydrating gastroenteritis in young children.

Cần để ý những gì

Rotavirus disease can present with a spectrum of symptoms, from asymptomatic or mild infection to severe disease. Clinical signs can include:

  • sốt
  • vomiting
  • abdominal pain
  • watery diarrhoea.

Severe cases, if left untreated, can result in significant dehydration leading to electrolyte imbalance, hypotensive shock and death.

The incubation period for developing disease is usually between 24 and 72 hours. The diarrhoea usually lasts from 3 to 7 days.

Bệnh lây truyền qua đường nào

Rotaviruses are mainly transmitted through the faecal–oral route, through close person-to-person contact, contaminated food and water, and via fomites (e.g. toys and other surfaces contaminated by faeces). Rotaviruses are also transmitted through respiratory droplets (e.g. through coughing, sneezing, talking). Spread is common in families, hospitals and childcare settings.

Viral replication occurs in the villous epithelium of the small intestine.  The virus can be transmitted during the acute illness. Excretion for more than 30 days has been reported to occur.

Asymptomatic infected individuals can transmit the virus unknowingly.

Dịch tễ học

Worldwide, rotaviruses are the most common cause of dehydrating diarrhoea among children under 5 years of age. Despite the availability of a vaccine, rotavirus continues to result in over 200,000 deaths per year. Deaths due to rotavirus are rare in Australia due to access to health care services.  

Rotavirus vaccines were added to the Australian National Immunisation Program (NIP) in 2007. Since then, there has been an estimated 64% decrease in hospitalisations for children aged under 3 years, and case numbers have fallen. In 2022, notification rates were lowest in Tasmania (at 11 per 100,000) and highest in the Northern Territory and Queensland (at 47 per 100,000). 

Compared with their non-Indigenous peers, Aboriginal and Torres Strait Islander infants and children are hospitalised with rotavirus gastroenteritis about 3 to 5 times more often, and are younger at age of hospitalisation. 

Without vaccination, most children will experience at least one rotavirus infection before the age of 3 years. Repeated infections can occur.  

In temperate areas of Australia infections are more common in the winter months. However, in the tropical/arid regions of Australia there is no seasonal pattern.  

Phòng ngừa

Rotavirus spread can be mitigated through: 

  • effective hand hygiene measures 
  • effective decontamination of fomites 
  • vaccination.

Vắc-xin

Vaccination is approximately 88% effective in preventing rotavirus infection. There are 2 vaccines registered for use in Australia: 

  • Rotarix  
  • Rotateq. 

Both rotavirus vaccines are live-attenuated vaccines requiring oral administration (by mouth). A 2-dose course of Rotarix is currently provided on the NIP at 6 weeks and 4 months of age.  

There is limited data on the safety and efficacy of rotavirus vaccination when given outside of specific age groups. For this reason, rotavirus vaccines must be administered within the recommended timeframe, with particular attention paid to the upper age limits. If adherence to the recommended timeframes for administration is not possible, vaccination should be withheld indefinitely.  

Infants who receive a first dose of either vaccine should complete the entire course of vaccination using the same oral rotavirus vaccine. However, if an infant inadvertently received one of each, give a 3rd dose of either rotavirus vaccine. The upper age limits and minimum intervals between doses must still be met.

WordPress Tables Plugin

* Preterm infants are recommended to receive vaccines based on chronological age, not corrected age.
^Dose 2 is ideally administered before turning 28 weeks to allow for dose 3 to be given 4 weeks later (before the infant turns 33 weeks). If dose 2 is administered later than 28 weeks, a 4 week interval is not possible, and dose 3 must not be administered.
shaded boxes indicate live-attenuated vaccines.
Rotateq is not routinely used in Australia.

Considerations

If an infant spits out a small amount of the dose of vaccine, it is still considered a valid dose and does not need repeating. If they spit out most of the dose of vaccine within minutes of receiving it, a repeat dose should be administered at the same visit.

Infants who have an enteral feeding tube (e.g. orogastric, nasogastric, gastrostomy, or jejunal tube) can receive rotavirus vaccines via their tube. Rotavirus vaccines should never be injected.

Rotavirus vaccination is not required for a child to be considered up to date with their routine vaccines. It is not bắt buộc for the purposes of the No Jab No Pay or No Jab No Play legislation.

Tác dụng phụ của vắc-xin

Several large studies have showed that vaccinated infants had no increase in vomiting, diarrhoea or fever compared with unvaccinated infants. However, anecdotally, infants may be more fussy or gassy within the first 7 days following vaccination. Supportive therapies such as paracetamol and additional fluids (breastmilk/formula) can help manage symptoms.  

Good hand hygiene practices are particularly important when handling soiled nappies during this period to minimise the risk of transmission as the virus can shed in stools for 7 to 10 days following immunisation. 

Some Australian and international studies have shown a very small increase in risk of intussusception post rotavirus vaccine. The baseline risk of intussusception for Australian infants is around 80 cases per 100,000 infants. A 2013 study found 6 additional cases of intussusception for every 100,000 infants vaccinated. This equates to 14 more cases per year in Australia.

Intussusception is a rare condition where the bowel slides or telescopes inside itself causing a blockage. Infants with intussusception may show signs of lethargy, intermittent pain or distress, associated with episodes of pallor. They may pull up their legs, vomit and/or have diarrhoea. Jelly-like or bloody stools is a late sign. Immunisation providers should inform parents and carers to be alert for symptoms and the very rare risk of intussusception.

Precautions and contraindications

There is a theoretical risk of vaccine-associated gastroenteritis if vaccines are administered to infants with immunocompromise. However, for some infants with less severe immunocompromise (including those with HIV who are asymptomatic and have adequate CD4+ count) the benefits of vaccine-induced protection may outweigh this risk. Further clarification on the degree of immunocompromise may be sought from dịch vụ tiêm chủng chuyên khoa 

Infants living in households with persons who have an immunodeficiency disorder or impaired immune status can still be vaccinated. Counselling on hand hygiene and disposing of soiled nappies to minimise the risk of vaccine virus transmission is recommended.  

Infants with severe combined immunodeficiency (SCID) must not receive rotavirus vaccines due to the risk of vaccine-associated gastroenteritis.  

Infants born to mothers who received bDMARDs (biological disease-modifying anti-rheumatic drugs) during pregnancy can receive rotavirus vaccines. Refer to MVEC: Immunosuppression in pregnancy để biết thêm thông tin.  

Rotavirus vaccines must not be given to any infant with a previous history of intussusception or a congenital bowel abnormality which predisposes them to intussusception.

Phối hợp với các loại vắc-xin khác

Rotavirus vaccines can be safety administered with other vaccines including other live-attenuated vaccines, such as BCG.

Các tác giả: Georgie Lewis (Giám đốc lâm sàng SAEFVIC, Viện nghiên cứu trẻ em Murdoch) và Rachael McGuire (Y tá nghiên cứu SAEFVIC, Viện nghiên cứu trẻ em Murdoch)

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

Ngày: May 2024

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