Major Finding: Of 200 hospitalized children tested for rotavirus before approval of the vaccine, 27% tested positive. Of 161 and 180 hospitalized children tested in the subsequent 2 years after vaccine approval, 12% and 14% tested positive for rotavirus infections.
Data Source: A retrospective cohort study of 1,996 children admitted to a single hospital.
Disclosures: Dr. Hamwi said he had no relevant financial conflicts of interest. One of the coinvestigators, Dr. David DiJohn, disclosed that he is on the speakers bureau for both GlaxoSmithKline and Sanofi-Aventis.
PHILADELPHIA — The introduction of the rotavirus vaccine was associated with a significant decrease in the number of children admitted to a New York City hospital for rotavirus infections, as well as a decline in the severity of the rotavirus season.
The annual percentage of admitted patients who tested positive for the virus decreased from more than 12% before the vaccine was available to 3% afterward, Dr. Haytham Hamwi said at the annual meeting of the Eastern Society for Pediatric Research.
Dr. Hamwi of the Flushing (N.Y.) Hospital Medical Center discussed a retrospective study of rotavirus testing and admissions spanning three time periods: September 2004 through August 2005 (before the vaccine was available), and after the vaccine was available, September 2007 through August 2008 and September 2008 through August 2009. The hospital database and the New York City vaccine registry provided the data for the study.
Dr. Hamwi and his colleagues included in their study all patients aged 0–6 years who were admitted to the hospital during those periods, except any child who had received the rotavirus vaccine within 3 weeks of a hospital admission.
“The vaccine can cause shedding of antigen in the stool, leading to a false-positive result,” Dr. Hamwi said.
During the first study period (2004–2005), 442 patients aged 0–6 years were admitted to the hospital; 200 of those were tested for rotavirus.
Of these, 55 (27%) tested positive for the virus. Patients with rotavirus infections comprised 12% of all hospital admissions among 0–6 year olds.
During the second study period (2007–2008), 744 children aged 0–6 years were admitted to the hospital.
The surge in admissions occurred because several neighboring hospitals had closed, Dr. Hamwi said.
Of the admissions, 161 were tested for rotavirus and 20 (12%) tested positive. Rotavirus accounted for 2.6% of admissions for 0- to 6-year-old children during that time.
In the third study period (2008–2009), there were 810 admissions. Of these, 180 were tested for the virus and 26 (14%) tested positive. Children with rotavirus accounted for 3% of the admissions.
A vaccination history was available for 76 children who tested positive for the virus in the study.
Of these, 75 were unvaccinated against rotavirus and 1 had been incompletely vaccinated, Dr. Hamwi said. No rotavirus was found in unvaccinated children.
The investigators also examined the relationship between the vaccine and rotavirus seasonality.
In the prevaccine study periods, rotavirus appeared in November, peaked in February, and had a second peak in April.
In both postvaccination study periods, the disease appeared later and did not show the typical winter peak.
A smaller peak occurred in March and April of the second of the two study periods.