Hospitalizations, deaths continue to decline after rotavirus vaccine introduction

Patel MM. Pediatr Infect Dis J. 2011;30(suppl 1):S1-S66.

Researchers continue to note declines in deaths and hospitalizations after the implementation of routine rotavirus vaccination. If this pattern holds, greater population protection than expected may be attained in developing country settings.

Twelve studies published as a special supplement to The Pediatric Infectious Disease Journal summarize data on the decline in the number of children who are hospitalized due to rotavirus in countries that include rotavirus vaccines as part of their routine immunization programs.

Anne Schuchat

“These studies add to the growing body of evidence that shows rotavirus vaccines are safe, effective, and most importantly, saving children’s lives,” Anne Schuchat, MD, who is director of the National Center for Immunization and Respiratory Diseases at the CDC, said in a press release about the studies. “Unfortunately, too many children around the world get severely ill or die from this preventable disease. We must continue to expand our efforts to ensure that children around the world have access to these vaccines.”

Study highlights

Lucia Helena de Oliveira, RN, MSc, and colleagues of the Comprehensive Family Immunization Project, Pan American Health Organization, in Washington, D.C., reported that 12 of 15 Latin American and Caribbean countries are using the vaccines, but “coverage levels need to increase to maximize the effect of the intervention,” they said. In this study, the researchers call for better rotavirus surveillance to “better assess the effect of vaccine use.”

In El Salvador, rotavirus hospitalization rates for children younger than 5 years declined by 69% to 81% in the 2.5 years after the introduction of rotavirus vaccine in October 2006. Led by Catherine Yen, MD, MPH, and colleagues from the CDC, the researchers compared all-cause diarrhea and rotavirus-specific hospitalization rates in seven sentinel surveillance hospitals during the prevaccine year of 2006 with the years after vaccine introduction. The research showed that among sentinel surveillance hospitals, rotavirus hospitalization rates among children younger than 5 years declined by 81% (95% CI, 78–84) in 2008 when two-dose rotavirus vaccine coverage was 50% among newborns. The decline was about 69% (95% CI, 65–73) in 2009 when the two-dose vaccine coverage grew to 61% among newborns. The researchers also observed declines of 48% and 35% in 2008 and 2009, respectively, in the national diarrhea-related health care visits.

“When a new vaccine is introduced, it generally takes some time for vaccine compliance to rise to levels comparable to other well-established vaccines. Thus, vaccine compliance with rotavirus vaccine was not expected to have reached full coverage at the time these vaccine impact studies were completed,” Yen said in an interview with Infectious Diseases in Children. “However, even at lower coverage levels, we were able to see a substantial positive impact of rotavirus vaccines on disease burden.”

In Mexico, which introduced rotavirus vaccine in May 2007, there was a 40% decline in diarrhea-related hospitalizations in children younger than aged 5 years in the 2 years after vaccine introduction. In this study, led by Manjari Quintanar-Solares, MD, and colleagues from the CDC, the researchers obtained data from 306 Ministry of Health hospitals on diarrhea-related hospitalizations between January 2003 and June 2009, and they compared the median number of diarrhea-related hospitalizations during the 2008 and 2009 rotavirus seasons with the median number of diarrhea-related hospitalizations from 2003 to 2006. A median number of 10,993 diarrhea-related hospitalizations occurred each prevaccine rotavirus season from 2003 to 2006, but that number dropped to 9,836 in 2008 and dropped again to 6,597 in 2009. The researchers noted no declines during 2008 or 2009 among unvaccinated children.

In Panama, Yadira Molto, MD, and colleagues from the CDC obtained monthly numbers of diarrhea-associated hospitalizations among children aged younger than 5 years in five health regions in Panama, representing 53% of the birth cohort. The researchers said during the prevaccine years of 2003-2006, diarrhea-associated hospitalizations averaged about 4,057 annually, but that number dropped to 3,159 in 2007 and to about 2,500 in 2008. This reduction in rotavirus coincided with increasing use of the rotavirus vaccine, from 63% at the end of 2006 to 94% by the end of 2008.

In the United States, Jacqueline Tate, PhD, and colleagues from the CDC reported there was a significant 58% to 86% reduction in rotavirus-related hospitalizations in the 3 years after vaccine introduction in July 2006. The researchers on that study concluded that: “Rotavirus vaccine has been widely accepted by pediatricians. Vaccine coverage is steadily increasing but remains lower than coverage levels of other routine infant immunizations.”

In an interview with Infectious Diseases in Children, Tate said, “There are many barriers for total compliance with rotavirus vaccines, and many of these are country specific. Individual countries need to assess what their particular barriers are and how best to address them.”

In Australia, Jim Buttery, FRACP, MSc, and colleagues from the Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, said after rotavirus vaccine introduction in July 2007, there was an 89% to 94% reduction in rotavirus-related hospitalizations in children younger than 5 years living in Queensland in the 2 years after vaccine introduction. Researchers in Australia also noted changes among dominating strains based on which vaccines were used in a specific location. In that study, the researchers noted, G1P[8] was the dominant genotype nationally, followed by G2P[4], G9P[8] and G3P[8].

“G2P[4] strains were more prevalent in states using Rotarix (GlaxoSmithKline), whereas G3P[8] strains were more prevalent in states using RotaTeq (Merck),” the researchers concluded.

The Australian studies also suggested that there were large reductions in rotavirus disease among older, unvaccinated children, suggesting herd immunity played a role.

Rotavirus recommendations

Diarrhea is one of the top two killers worldwide of children aged younger than 5 years, and rotavirus is the leading cause of severe diarrheal disease in children. Each year, rotavirus-related diarrheal disease takes the lives of more than 500,000 children younger than age 5 years and is responsible for millions more hospitalizations.

In 2009, WHO officials recommended that all countries include rotavirus vaccines in their national immunization programs. Prevention and treatment of diarrhea also includes oral rehydration therapy, exclusive breast-feeding, zinc treatment and improved hygiene and sanitation. Although most children in the world will be infected with rotavirus by their third birthdays, children in developing countries more often die of diarrhea caused by rotavirus because treatment for severe infections is often limited or inaccessible.

“Wherever we look, in both the developed and developing worlds, we see a rapid and impressive reduction in rotavirus infections following the roll-out of vaccine,” John Wecker, PhD, director of the Vaccine Access and Delivery Global Program at PATH, said about the studies in a press release. “Vaccine effectiveness often takes years to document; with rotavirus, there is an immediate dramatic impact — one which should compel decision-makers and donors to support and implement the WHO recommendation to introduce rotavirus vaccines today.” – by Colleen Zacharyczuk

Disclosures: Drs. Tate and Yen reported no relevant financial disclosures.

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