Viewpoint: Rotavirus disease, seasonality and vaccination

An interview with Philip Spandorfer, MD, a practicing pediatrician at North Atlanta Pediatrics and a pediatric emergency medicine specialist at the Children's Healthcare of Atlanta Scottish Rite Hospital.

Rotavirus Resource Center: Which patients are more likely to experience severe rotavirus disease?

Rotavirus is the most common cause of infectious gastroenteritis. Although rotavirus can infect people of any age, about half the patients are between 4 and 24 months old. These children are at higher risk for contracting severe disease for several reasons: They have never been exposed to rotavirus, they have no protection against rotavirus, and viral loads are higher in this age group. Furthermore, once these children contract the disease, their metabolic demands increase, making them more likely to become symptomatic. The children are dependent on others to give them fluids and nutrition, and they have less capacity to increase their cardiac output, placing them at greater risk for hypovolemic shock.

Philip Spandorfer

RRC: How does rotavirus spread?

Rotavirus is known to spread by the fecal-oral route. Interestingly, rotavirus can be found on toys and other hard surfaces, indicating that fomites may play a role, and there may be a respiratory route of transmission as well. Contaminated water supplies are not considered to be a common source for the spread of rotavirus.

RRC: What is the seasonality of the disease?

The rotavirus season in the United States typically starts between late November and early January depending on location. The season starts in the West, followed by the South, and then the North and Midwest. However, since the introduction of the two new rotavirus vaccines, beginning in 2006 with the first vaccine, the start of the season has been delayed by about 12 weeks. Even more exciting is that the season is still ending at the same time it did previously –specifically the season is shortened by about 12 weeks and is still ending in mid-June.

RRC: The CDC’s National Respiratory and Enteric Virus Surveillance System recently reported that the 2007-2008 rotavirus season was milder than previous seasons. What are your thoughts on this finding?

This report is consistent with what we are seeing clinically in pediatric emergency departments and pediatricians' offices. The season started later, was not as intense and ended at the same time. Not only did we have a shortening of the season by about three months but we also had a less severe season. The children we saw last season were less dehydrated and we were using less parenteral hydration.

RRC: What was your experience with the 2008-2009 season?

The 2008-2009 season was comparable to the 2007-2008 season. Although the report recently published in the August edition of Pediatrics was only able to compare the 2000-2006 seasons to one post-vaccination season, 2007-2008, I believe that the data shown for that one year are consistent with what we also saw this past season.

RRC: What are your predictions for the 2009-2010 season? Do you think that increased rates of vaccination will alter seasonality?

I suspect that the 2009-2010 season will be similar to the two previous seasons if not even more mild. I am hopeful that with increased vaccination coverage, the rotavirus season may be further shortened — or eliminated entirely. However, there are other causes of viral gastroenteritis, but I have not seen an increase clinically in a replacement for rotavirus as a cause.

RRC: What are your thoughts on the suggestion that unvaccinated children indirectly benefit from increasing vaccine coverage?

Vaccination is a sensitive subject with parents today. I firmly believe in vaccinations and that there is not a connection between vaccines and autism. However, I understand why parents are nervous given the prominence that the “controversy” holds in the media. Hence there remains a large unvaccinated population. Children with poor access to medical care may also remain unvaccinated or inadequately vaccinated. The recent report from the CDC’s National Respiratory and Enteric Virus Surveillance System has shown that there is a reduction in rotavirus disease even in the unvaccinated population. I like this herd immunity effect, but I am concerned that the unvaccinated will act as a reservoir for the virus.

RRC: WHO’s Strategic Advisory Group of Experts recently recommended that all national immunization programs include rotavirus vaccination. What is your perspective on this recommendation? Do you recommend vaccination?

I highly recommend vaccination. The data clearly show a reduction in the severity of illness with rotavirus vaccination. This reduction benefits individual patients as well as society by decreasing resource utilization and costs.

For more information:

Pitzer VE, Viboud C, Simonsen L, et al. Science. 2009;325(5938):290-294.
WHO. Weekly Epidemiological Record. 2009;84:213-236.
Centers for Disease Control and Prevention (CDC). Morb Mortal Wkly Rep. 2008;57:697-700.
Tate JE, Panozzo CA, Payne DC, et al. Pediatrics. 2009;124(2):465-471.