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A varicella vaccine for children has been readily available in Canada since 2000, but some parents and physicians doubt the need for it. The Immunization Monitoring Program, ACTive (IMPACT) network of pediatric hospitals tabulated 1900 varicella-related hospitalizations and seven varicella-related deaths from 2000 to 2005. The present report describes these fatal cases, demonstrating the unpredictable and avoidable nature of life-threatening varicella complications. The knowledge that healthy children can die of chickenpox could influence parents to accept the recommended vaccination. Deaths from varicella should cease to occur, given the safe alternative of, and free access to, vaccination in current provincial programs.
Il existe un vaccin antivaricelleux au Canada depuis 2000, mais certains parents et certains médecins remettent son utilité en question. Le réseau d’hôpitaux pédiatriques du Programme de surveillance active des effets secondaires associés aux vaccins (IMPACT) a dénombré 1 900 hospitalisations attribuables à la varicelle et sept décès associés à cette infection entre 2000 et 2005. Le présent rapport décrit ces cas fatals et démontre la nature imprévisible et évitable des complications de la varicelle pouvant mettre la vie en danger. Le fait de savoir que des enfants en santé peuvent mourir de la varicelle pourrait inciter des parents à accepter le vaccin recommandé. Il ne devrait plus y avoir de décès causés par la varicelle, compte tenu de la disponibilité de vaccins sécuritaires et de leur accès gratuit dans le cadre des programmes provinciaux actuels.
At present, all provinces and territories have included varicella-zoster (VZ) vaccine in their routine childhood programs. The uptake of VZ vaccine is increasing rapidly but there are still some parents and physicians who doubt the need to avoid chickenpox because they perceive it as a benign illness. Quoting the serious complication rate of one in 200 cases may not convince them otherwise because the risk sounds remote. However, knowing that healthy children can die of chickenpox can alter parents’ perception of risk, despite the rarity of the event.
Between 2000 to 2005, the Immunization Monitoring Program, ACTive (IMPACT) surveillance network of 12 Canadian paediatric referral centres tabulated 1900 varicella-related admissions and seven varicella-related deaths. Three fatalities occurred in 2000, two in 2001, one in 2002 and one in 2005. No fatal cases were detected in 2003 or 2004. The present report emphasizes the unpredictability of severe complications and the feasibility of avoiding them using VZ vaccine, as illustrated by seven varicella-related fatalities.
A seven-year-old girl with seizure disorder, developmental delay and apparently normal immune function acquired chickenpox from an unknown source. She was admitted to hospital nine days after the onset of rash with septic shock caused by Streptococcus pneumoniae, complicated by disseminated intravascular coagulopathy, adult-type respiratory distress syndrome and thrombocytopenia. Varicella rash was still evident but resolving. She died soon after admission despite receiving intensive care. Although eligible, she did not receive VZ vaccine. Vaccination of other susceptible children in her circle of contacts would have reduced her risk of exposure.
A 13-year-old girl had surgically corrected congenital heart disease and developmental delay but apparently normal immune function. She developed chickenpox following exposure at school. She was admitted 13 days after the onset of rash with bilateral nodular lung infiltrates consistent with varicella pneumonia. She died from pulmonary hemorrhage and subsequent cardiorespiratory arrest, despite antiviral treatment. Although eligible, she did not receive VZ vaccine. Vaccination of other susceptible children at school would have reduced her risk of exposure.
A one-year-old girl had chronic lung disease requiring supplemental oxygen therapy and nonimmunosuppressive doses of corticosteroids by aerosol and by mouth. She developed chickenpox following household exposure. She was not given VZ immune globulin. She developed a rash while in hospital for respiratory support and was promptly given antiviral medication. Despite this, she developed bilateral nodular lung infiltrates and progressive respiratory failure, from which she died. Autopsy confirmed the presence of varicella pneumonitis. She did not receive VZ vaccine but appeared to be eligible while receiving low-dose corticosteroid medication. Alternatively, the susceptible household member(s) could have been vaccinated to reduce her risk of exposure.
A nine-year-old boy had cerebral palsy, seizure disorder and apparently normal immune function. He developed chickenpox following exposure at school. He was admitted four days after the onset of rash, with multiple complications that included shock, adult-type respiratory distress syndrome, thrombocytopenia, hepatitis, bilateral nodular lung infiltrates and seizures. He died despite intensive care and antiviral medication. He did not receive VZ vaccine despite being eligible. Vaccination of other susceptible children at school would have reduced his risk of exposure.
A four-month-old boy was in good health before developing chickenpox. He was exposed at home to an adult with chickenpox. He was admitted five days after the onset of rash with staphylococcal scalded skin syndrome and septic shock. He died despite intensive care. He was too young to receive VZ vaccine and too old to receive VZ immune globulin. Vaccination of the susceptible adult household member would have reduced his risk of exposure.
A nine-month-old boy was in good health before developing chickenpox. He was exposed at home to a child with chickenpox. He was admitted on day 5 of the rash illness with group A streptococcal sepsis and shock. Complications included thrombocytopenia, hepatic injury and hemorrhagic varicella. He died in the emergency department shortly after arrival. He was too young to receive VZ vaccine. Vaccination of the susceptible older child in his household would have reduced his risk of exposure.
A four-year-old boy had congenital heart disease with apparently normal immune function. He contracted chickenpox from an unknown source. He presented to hospital on day 6 of rash illness with group A streptococcal septic shock, complicated by thrombocytopenia and hepatitis. He developed cardiac arrest and died soon after admission to intensive care. He was eligible for VZ vaccine but lived in the one province where it was not routinely provided in 2005.
With the exception of one child (case 3), all of the children were thought to have normal immune function. Each of the five children older than one year of age had a chronic health problem not associated with immunodeficiency, although a subtle immune defect cannot be excluded. In our previous review of 861 VZ cases (1), children with chronic conditions more often required intensive care and died than did previously healthy children (4% versus 0.2%, respectively). The children with health problems in the present report were most likely in frequent contact with health professionals; despite this, however, none of the children received VZ vaccine. The two children younger than one year of age (ie, too young to immunize) would have been spared if susceptible older household members had received VZ vaccine instead of developing chickenpox. All seven cases occurred before implementation of the routine VZ vaccination program in their home province. Thus, although VZ vaccine was available, a lack of public funding limited uptake (2). Greater uptake of vaccine in public programs in 2003 and 2004 may account for the absence of fatal cases during these years.
Bacterial sepsis was the fatal complication in four of the seven cases, involving S pneumoniae, group A streptococcus and Staphylococcus aureus. The pneumococcal infection occurred before the availability of pneumococcal conjugate vaccine and is a reminder that VZ virus replication in the upper airway predisposes to otitis media, pneumonia and bacteremia with pathogens carried in the airway. Streptococcal and staphylococcal infections are more likely to occur through secondary infection of vesicles but they can also invade from the upper airway. Bacterial exotoxins may contribute to injury, as exemplified by the case of staphylococcal scalded skin syndrome and the two cases of streptococcal infection. The Canadian Paediatric Society Surveillance Program identified varicella as the predisposing factor in 16 of 26 cases (61%) of necrotizing fasciitis caused by group A streptococci, emphasizing the common association of streptococcal and varicella infections (3).
The viremic phase of chickenpox ordinarily distributes virus to the skin without causing injury to other tissues. With high-grade viremia, visceral lesions can develop, most commonly in the lungs and liver. Three children in this series died of varicella pneumonitis, one of whom also had multiorgan injury. The hallmark of varicella pneumonitis is bilateral nodular lung infiltrates on radiological examination of the chest. All three children with pneumonitis had such lung infiltrates.
It is jarring to speak of deaths in relation to a common childhood infection like chickenpox. The complete Canada-wide varicella case fatality count from 2000 to 2005 is not yet available but likely exceeds the seven cases summarized in the present report. In the United States (US), six of the eight varicella-related deaths reported in 2003 and early 2004 involved children (4). Routine vaccination in the US is substantially reducing varicella hospital admissions and deaths. By 2001, the US hospitalization rate for varicella among young children had declined 84% from prevaccine rates (5). With improving VZ vaccination rates, the situation will approach that of measles, which was once as common as varicella but has not caused a death in Canada in the past decade and only rarely causes hospital admissions. Deaths from other former childhood killers such as tetanus, diphtheria and polio have ceased to occur as a result of widespread immunization. Deaths from varicella should be equally intolerable given a safe alternative.
Some physicians have been slow to accept VZ vaccine for a variety of reasons. For those who consider chickenpox a benign illness, we have described seven reasons to reconsider that view. With rapidly advancing bacterial or viral complications, antimicrobial treatment may not be sufficient to avoid unfortunate outcomes, even with intensive care. Prevention through vaccination is the better approach.
Earlier questions about some of the properties of the VZ vaccine have been extensively addressed:
In short, the benefits of VZ vaccination substantially outweigh the risks and remaining unknowns attached to it. The Canadian Paediatric Society recommends routine VZ vaccination (8), which is in agreement with national guidelines and has the full support of the authors.
This IMPACT project was sponsored by the Public Health Agency of Canada and coordinated by the Canadian Paediatric Society. IMPACT members and participating centres include the following: R Morris (MD), Janeway Children’s Health and Rehabilitation Centre, St John’s, Newfoundland and Labrador; S Halperin (MD), IWK Health Centre, Halifax, Nova Scotia; P Déry (MD), Centre Mère-Enfant de Québec (CHUL), Sainte-Foy, Québec; M Lebel (MD), Hôpital Sainte-Justine, Montréal, Québec; D Moore (MD), Montreal Children’s Hospital, Montreal, Quebec; N Le Saux (MD), Children’s Hospital of Eastern Ontario, Ottawa, Ontario; E Ford-Jones (MD), The Hospital for Sick Children, Toronto, Ontario; B Law (MD), Winnipeg Children’s Hospital, Winnipeg, Manitoba; J Embree (MD), Winnipeg Children’s Hospital, Winnipeg, Manitoba; B Tan (MD), Royal University Hospital, Saskatoon, Saskatchewan; T Jadavji (MD), Alberta Children’s Hospital, Calgary, Alberta; W Vaudry (MD), Stollery Children’s Hospital, Edmonton, Alberta; D Scheifele (MD), BC Children’s Hospital, Vancouver, British Columbia; MA Davis, Canadian Paediatric Society, Ottawa, Ontario; T Tam (MBBS), Public Health Agency of Canada, Ottawa, Ontario.