Larger-Than-Expected Impact of Rotavirus Vaccine

We're starting to see the first evidence that rotavirus disease rates are going down, perhaps even more than we expected, thanks to the vaccine.

Although rates of both respiratory syncytial virus and influenza were up this past winter, compared with the previous couple of years, it's been very gratifying for the infectious disease community to see, for the first time, a paucity of rotavirus cases.

As every practitioner who treats children knows, rotavirus is the most common cause of severe wintertime gastroenteritis among children younger than 5 years. The numbers have stayed consistent: Every year, approximately 3 million children get rotavirus disease, about 700,000 seek health care for it, 250,000 present to the emergency department, 50,000 are admitted, and a small number (20–60) die. A recent analysis from the Centers for Disease Control and Prevention (CDC) showed that the total annual cost to society from rotavirus in the United States (in 2004 dollars) was $893 million, $319 million of which was to the health care system (Pediatrics 2007;119:684–97).

A previous oral rotavirus vaccine—the tetravalent rhesus vaccine, RotaShield—was removed from the market in 1999 because of a detected increase in intussusception after about a half-million children had received one or more doses. In February 2006, Rotateq—a new live, oral pentavalent human-bovine reassortment rotavirus vaccine (Merck & Co.)—was licensed and recommended. I'm excited about preliminary numbers, which suggest that rotavirus immunization may be more successful than predicted.

Here at Children's Mercy Hospital in Kansas City (317 beds/14,000 annual admissions), we test only the sickest children for rotavirus. During the 2006 rotavirus season, we tested 1,009 and got 514 positives (51%). In 2007, we had 686 positives out of 1,271 tested (54%)—not much different. We wouldn't have expected an impact that soon after the vaccine was licensed.

This year, however, we saw a dramatic change. Only 495 children presented with gastroenteritis who were sick enough to prompt testing, and of those, just 93 (19%) were positive. Even more amazing, only 38 children were admitted to the hospital, which represented a 10-fold decrease, compared with previous years. What happened to all our rotavirus cases?

This finding is even more remarkable when you look at how consistent our rotavirus disease rates have been over time. Last year, we combined our rotavirus data for the years 2000–2005 with those from Children's Hospital of Philadelphia (CHOP) from 2004–2006 and reported that approximately half of children admitted with severe diarrhea were tested for rotavirus (47% of 2,552 children at Mercy and 56% of 779 at CHOP). Of those, 71% of our 1,197 and 55% of CHOP's 438 were positive (Pediatr. Infect. Dis. J. 2007;26:914–9).

We haven't changed anything about our testing or admitting practices since those data were collected, which strongly suggests that our new numbers represent a real drop.

Moreover, if you look at the CDC's rotavirus surveillance data (www.cdc.gov/rotavirus

If nationwide surveillance data continue to bear out what we've seen at my hospital, the vaccine's impact will have far exceeded expectations. In the CDC cost analysis I mentioned earlier, investigators estimated that if vaccine coverage were equivalent to current national estimates for other vaccines such as diphtheria-tetanus-acellular pertussis—which is probably a big overestimate—a routine rotavirus vaccination program would prevent 51% of all cases of rotavirus gastroenteritis and 64% of all serious cases, including rotavirus-related hospitalization and emergency department visits.

Our 86% decrease (93 cases this year vs. 686 in 2007) is far greater than predicted by the CDC's analysis. Although viral shedding of the rotavirus vaccine is nowhere near what we used to see with oral polio vaccine, there is evidence that it occurs. In one study, fecal shedding of vaccine-virus strains was found in 8.9% of 360 recipients after the first dose (Int. J. Infect. Dis. 2007;11[Suppl 2]:S36–42), which raises the question of possible herd immunity.

Now, with the recent approval of Rotarix (GlaxoSmithKline)—another oral rotavirus vaccine that is given in two doses, compared with Rotateq's three—I'm optimistic that there will be more good news in the battle against this common childhood infection. Can you imagine the day when a pediatric resident will not see a hospitalized child who has rotavirus infection during the winter months?

I have no financial relationships with either Merck or GSK.

We're starting to see the first evidence that rotavirus disease rates are going down, perhaps even more than we expected, thanks to the vaccine.

Although rates of both respiratory syncytial virus and influenza were up this past winter, compared with the previous couple of years, it's been very gratifying for the infectious disease community to see, for the first time, a paucity of rotavirus cases.

As every practitioner who treats children knows, rotavirus is the most common cause of severe wintertime gastroenteritis among children younger than 5 years. The numbers have stayed consistent: Every year, approximately 3 million children get rotavirus disease, about 700,000 seek health care for it, 250,000 present to the emergency department, 50,000 are admitted, and a small number (20–60) die. A recent analysis from the Centers for Disease Control and Prevention (CDC) showed that the total annual cost to society from rotavirus in the United States (in 2004 dollars) was $893 million, $319 million of which was to the health care system (Pediatrics 2007;119:684–97).

A previous oral rotavirus vaccine—the tetravalent rhesus vaccine, RotaShield—was removed from the market in 1999 because of a detected increase in intussusception after about a half-million children had received one or more doses. In February 2006, Rotateq—a new live, oral pentavalent human-bovine reassortment rotavirus vaccine (Merck & Co.)—was licensed and recommended. I'm excited about preliminary numbers, which suggest that rotavirus immunization may be more successful than predicted.

Here at Children's Mercy Hospital in Kansas City (317 beds/14,000 annual admissions), we test only the sickest children for rotavirus. During the 2006 rotavirus season, we tested 1,009 and got 514 positives (51%). In 2007, we had 686 positives out of 1,271 tested (54%)—not much different. We wouldn't have expected an impact that soon after the vaccine was licensed.

This year, however, we saw a dramatic change. Only 495 children presented with gastroenteritis who were sick enough to prompt testing, and of those, just 93 (19%) were positive. Even more amazing, only 38 children were admitted to the hospital, which represented a 10-fold decrease, compared with previous years. What happened to all our rotavirus cases?

This finding is even more remarkable when you look at how consistent our rotavirus disease rates have been over time. Last year, we combined our rotavirus data for the years 2000–2005 with those from Children's Hospital of Philadelphia (CHOP) from 2004–2006 and reported that approximately half of children admitted with severe diarrhea were tested for rotavirus (47% of 2,552 children at Mercy and 56% of 779 at CHOP). Of those, 71% of our 1,197 and 55% of CHOP's 438 were positive (Pediatr. Infect. Dis. J. 2007;26:914–9).

We haven't changed anything about our testing or admitting practices since those data were collected, which strongly suggests that our new numbers represent a real drop.

Moreover, if you look at the CDC's rotavirus surveillance data (www.cdc.gov/rotavirus

If nationwide surveillance data continue to bear out what we've seen at my hospital, the vaccine's impact will have far exceeded expectations. In the CDC cost analysis I mentioned earlier, investigators estimated that if vaccine coverage were equivalent to current national estimates for other vaccines such as diphtheria-tetanus-acellular pertussis—which is probably a big overestimate—a routine rotavirus vaccination program would prevent 51% of all cases of rotavirus gastroenteritis and 64% of all serious cases, including rotavirus-related hospitalization and emergency department visits.

Our 86% decrease (93 cases this year vs. 686 in 2007) is far greater than predicted by the CDC's analysis. Although viral shedding of the rotavirus vaccine is nowhere near what we used to see with oral polio vaccine, there is evidence that it occurs. In one study, fecal shedding of vaccine-virus strains was found in 8.9% of 360 recipients after the first dose (Int. J. Infect. Dis. 2007;11[Suppl 2]:S36–42), which raises the question of possible herd immunity.

Now, with the recent approval of Rotarix (GlaxoSmithKline)—another oral rotavirus vaccine that is given in two doses, compared with Rotateq's three—I'm optimistic that there will be more good news in the battle against this common childhood infection. Can you imagine the day when a pediatric resident will not see a hospitalized child who has rotavirus infection during the winter months?

I have no financial relationships with either Merck or GSK.

We're starting to see the first evidence that rotavirus disease rates are going down, perhaps even more than we expected, thanks to the vaccine.

Although rates of both respiratory syncytial virus and influenza were up this past winter, compared with the previous couple of years, it's been very gratifying for the infectious disease community to see, for the first time, a paucity of rotavirus cases.

As every practitioner who treats children knows, rotavirus is the most common cause of severe wintertime gastroenteritis among children younger than 5 years. The numbers have stayed consistent: Every year, approximately 3 million children get rotavirus disease, about 700,000 seek health care for it, 250,000 present to the emergency department, 50,000 are admitted, and a small number (20–60) die. A recent analysis from the Centers for Disease Control and Prevention (CDC) showed that the total annual cost to society from rotavirus in the United States (in 2004 dollars) was $893 million, $319 million of which was to the health care system (Pediatrics 2007;119:684–97).

A previous oral rotavirus vaccine—the tetravalent rhesus vaccine, RotaShield—was removed from the market in 1999 because of a detected increase in intussusception after about a half-million children had received one or more doses. In February 2006, Rotateq—a new live, oral pentavalent human-bovine reassortment rotavirus vaccine (Merck & Co.)—was licensed and recommended. I'm excited about preliminary numbers, which suggest that rotavirus immunization may be more successful than predicted.

Here at Children's Mercy Hospital in Kansas City (317 beds/14,000 annual admissions), we test only the sickest children for rotavirus. During the 2006 rotavirus season, we tested 1,009 and got 514 positives (51%). In 2007, we had 686 positives out of 1,271 tested (54%)—not much different. We wouldn't have expected an impact that soon after the vaccine was licensed.

This year, however, we saw a dramatic change. Only 495 children presented with gastroenteritis who were sick enough to prompt testing, and of those, just 93 (19%) were positive. Even more amazing, only 38 children were admitted to the hospital, which represented a 10-fold decrease, compared with previous years. What happened to all our rotavirus cases?

This finding is even more remarkable when you look at how consistent our rotavirus disease rates have been over time. Last year, we combined our rotavirus data for the years 2000–2005 with those from Children's Hospital of Philadelphia (CHOP) from 2004–2006 and reported that approximately half of children admitted with severe diarrhea were tested for rotavirus (47% of 2,552 children at Mercy and 56% of 779 at CHOP). Of those, 71% of our 1,197 and 55% of CHOP's 438 were positive (Pediatr. Infect. Dis. J. 2007;26:914–9).

We haven't changed anything about our testing or admitting practices since those data were collected, which strongly suggests that our new numbers represent a real drop.

Moreover, if you look at the CDC's rotavirus surveillance data (www.cdc.gov/rotavirus

If nationwide surveillance data continue to bear out what we've seen at my hospital, the vaccine's impact will have far exceeded expectations. In the CDC cost analysis I mentioned earlier, investigators estimated that if vaccine coverage were equivalent to current national estimates for other vaccines such as diphtheria-tetanus-acellular pertussis—which is probably a big overestimate—a routine rotavirus vaccination program would prevent 51% of all cases of rotavirus gastroenteritis and 64% of all serious cases, including rotavirus-related hospitalization and emergency department visits.

Our 86% decrease (93 cases this year vs. 686 in 2007) is far greater than predicted by the CDC's analysis. Although viral shedding of the rotavirus vaccine is nowhere near what we used to see with oral polio vaccine, there is evidence that it occurs. In one study, fecal shedding of vaccine-virus strains was found in 8.9% of 360 recipients after the first dose (Int. J. Infect. Dis. 2007;11[Suppl 2]:S36–42), which raises the question of possible herd immunity.

Now, with the recent approval of Rotarix (GlaxoSmithKline)—another oral rotavirus vaccine that is given in two doses, compared with Rotateq's three—I'm optimistic that there will be more good news in the battle against this common childhood infection. Can you imagine the day when a pediatric resident will not see a hospitalized child who has rotavirus infection during the winter months?

I have no financial relationships with either Merck or GSK.