Reports

This report is based on medical evidence presented at sanctioned medical congress, from peer reviewed literature or opinion provided by a qualified healthcare practitioner. The consumption of the information contained within this report is intended for qualified Canadian healthcare practitioners only.

PRIORITY PRESS - 9th Canadian Immunization Conference (CIC)

Quebec City, Quebec / December 5-8, 2010

Rotavirus (RV) infection is associated with a substantial disease burden in Canadian children, as demonstrated by Dr. Nicole Le Saux, Children’s Hospital of Eastern Ontario, London. In a Toronto-based study carried out by Ford-Jones et al. (Arch Pediatr Adolesc Med 2000;154(6):586-93), approximately 400 children were recruited from either child care centres or primary care physicians’ (PCPs’) offices. Over an 8-month interval, 23% of the diarrheal illness seen in children was due to RV infection and much higher rates approaching 55% have been reported among children attending PCPs across Canada. Between 9 and 17% of the children required emergency room (ER) care, and on average, 6% required hospitalization or received intravenous hydration in the ER for RV gastroenteritis (GE).

Another 37% of children hospitalized for diarrhea in 18 Toronto hospitals tested positive for RV according to another study—“and RV testing was not consecutively done on all patients so 37% is probably an underestimate of what the true RV rate was,” observed Dr. Le Saux.

When RV testing was encouraged as it was in a 7-hospital study carried out in Quebec, RV was felt to cause over 71% of the diarrhea disease seen in hospitalized children. IMPACT (Immunization Monitoring Program, ACTive) data from 12 pediatric hospitals in which nurse monitors actively sought target disease found that over a period of 3 years (2005-2007), 1856 children had laboratory-confirmed RV infection; 1359 of these cases were community acquired, the rest were hospital-acquired.

“These are mainly healthy children—they have no underlying illnesses—but are only admitted for their RV disease,” Dr. Le Saux told delegates. Some 70% of those who were admitted in the IMPACT study had the “typical triad” of RV symptoms including diarrhea, vomiting and fever. Dr. Le Saux also emphasized that many of the hospital admissions were not for some transient GE event but included diagnoses of clinical sepsis, seizure and hypotension.

Symptoms of RV GE typically last between 6 and 8 days, “so this is not just a simple, 2-day GI infection, it is a very significant infection that is also systemic in many cases,” she noted. RV also occurs “almost endemically” in most pediatric hospitals and it is very difficult to prevent, she added: In fact, RV is the most common hospital-acquired infection in most hospitals.

Verhagen et al. presented data here at the CIC on children with chronic medical conditions who require frequent or prolonged hospitalizations. Investigators reported that 214 nosocomial RV GE cases occurred in a single Canadian tertiary-care pediatric hospital over a 10-year period, with no real decline in rates over time. The median duration of diarrhea was 4 days, while the median length of hospital stay was 23 days. Of the two-thirds of patients who developed nosocomial RV GE requiring rehydration, 46% required intravenous rehydration and 12% of the group required readmission because of the RV GE, where the median duration of hospital stay was 4 days.

Major Impact on RV Disease

If there were any doubt that a publicly-funded RV vaccination campaign would not have a major impact on RV disease, that doubt was dispelled by experiences in the US and Australia. The US licensed the pentavalent vaccine in February 2006 and the monovalent vaccine in April 2008; both vaccines were approved for universal childhood vaccination programs. By March 2009, the Centers for Disease Control and Prevention (CDC) estimated that about 71% of infants had received one of the vaccines, and by the fall of 2010, it was estimated about 80% of infants had been vaccinated against RV.

As reported by epidemiologist Daniel Payne, PhD, CDC, Atlanta, Georgia, the number of RV-positive tests from 25 reporting laboratories from 2006 when the pentavalent oral vaccine was introduced through to 2010 has been precipitously and continually dropping. In fact, case numbers were so low in 2010 that the RV season technically did not exist. According to data provided by reporting laboratories to the CDC, 51% of hospitalizations for diarrhea, vomiting and fever were due to RV infection in 2006; in 2007, this number was the same but by 2008, only 6% of hospitalizations due to the same triad of symptoms were due to RV and in 2010, this was down to 4%.

“This is a disease that once plagued every emergency department and every hospital and it’s now virtually gone,” Dr. Payne confirmed. Indeed, according to findings from 9 independent, US hospital-based studies, there was an 84 to 95% reduction in RV cases in 2008 compared with the previous year. Again in 2010, “we are hitting an all-time low,” Dr. Payne told delegates, “and this is the first time in reported history in the US that there has never been an RV season.”

Importantly as well, there has been a significant herd immunity effect following the introduction of the RV vaccines. Regarding the decline in RV acute GE hospitalization rates in 2008 vs. 2006, unpublished data from Dr. Payne’s own group found that there was an 87% reduction in RV GE rates in infants between the ages of 6 and 12 months (the last dose of the RV vaccine is given at 8 months); a 96% reduction in infants and toddlers between 1 and 2 years of age; and a 92% reduction in toddlers between 2 and 3 years of age.

Estimates from the American Committee on Immunization Practices on RV disease events prevented by vaccination in a 2009 birth cohort out to 5 years of age include 21 deaths; 52,706 hospitalizations; 160,402 ED visits; and 276,257 clinic visits. “We are also seeing that there are really significant cost savings as a result of this decline so the cost benefit from the vaccination program looks very solid as well,” Dr. Payne remarked.

Findings from Australia

A very similar picture has been documented in Australia following its introduction of a publicly funded RV vaccination program. As discussed by Prof. Kristine Macartney, National Centre for Immunisation Research and Surveillance, Sydney, Australia, the publicly funded RV vaccine campaign was launched in July 2007 as part of the National Immunisation Program; within 1 year, “we reached 85% coverage nationally,” she reported. Compared to pre-vaccine years, hospitalizations due to RV infection dropped in infants <12 months from approximately 400/100,000 to approximately 200/100,000 in 2007-2008 and to approximately 100/100,000 in 2008-2009.

Among infants and children between 12 and 23 months of age, RV hospitalization rates declined from approximately 500/100,000 in pre-vaccine years, to approximately 300/100,000 in 2007-2008 and 100/100,000 in 2008-2009. In 2010, only about 17% of samples sent to the Queensland Public Health laboratory tested positive for RV, Dr. Macartney noted. “We’ve also had a reduction in nosocomial RV episodes,” she added, “and overall, these 2 vaccines have been incredibly well accepted by providers and parents. We feel the benefit:risk ratio is very positive.”

Summary

As the Canadian Paediatric Society (CPS) note in their position statement, the RV vaccines may not prevent all causes of RV diarrhea but will prevent severe disease and significantly decrease the risk of dehydration and the need for hospitalization in vaccinated infants. Both vaccines have been proven to be safe and efficacious; however, since there are no interchangeability data, the CPS note that whenever possible, the RV vaccination series should be completed with the same product. “Canadian physicians should advocate for universal funding and integration of this vaccine into provincial programs to ensure equitable access for all,” the CPS also state in their recommendations for RV vaccination.