Parenting is becoming less smelly, and frightening, with a major decline in infant gastric infections. The release of a vaccine against the rotavirus has led to a 71 percent drop in hospitalizations in Ontario for the disease. The vaccine is protecting older children as well as those who have been vaccinated. In a province with an advanced medical system this means huge financial savings and the prevention of much pain; globally it could save many lives.

The rotavirus, often known as “stomach flu”, causes fever, diarrhea, and vomiting. As unpleasant as it is for adults, the severe dehydration that can follow is potentially much more serious for children. A paper published in 2000 found that one in every 160 Canadian children were hospitalized for rotavirus infection before the age of five, two-thirds of them before they turned two. The figure was probably an underestimate since a third of children admitted to hospital with symptoms of the condition were not tested.

In 2011, a vaccine against the rotavirus was added to Ontario's infant schedule (you know, that thing anti-vaxxers keep saying has too many vaccines on it). The effects have now been measured in PLOS ONE, and the benefits are overwhelming.

"We were very excited to see the significant impact of the rotavirus vaccine program. Hospitalizations in Ontario due to rotavirus infection were reduced by 71 percent, and emergency department visits dropped by 68 percent," said lead author Dr. Sarah Wilson of Public Health Ontario in a statement. The drop was even greater for babies less than a year old – those the virus is most likely to endanger.

The next part of Wilson's statement is even more important from a public health perspective: "We expected to see a drop for babies and toddlers who were vaccinated under this program. What's particularly interesting is we saw the drop even in older kids who were too old to receive the publicly-funded rotavirus vaccine, which means that protecting babies against illness also benefited older children." There was a 75 percent decrease in hospitalizations for children aged 5 to 19; even adult hospitalization fell by 38 percent.

This isn't all that surprising. Rotavirus is a highly transmissible infection. Many people get it from family members, or by sharing facilities. With the vaccine protecting the most vulnerable members of society from getting sick, opportunities for transmission fall. Nevertheless, this sort of herd immunity is central to the push to persuade reluctant parents to vaccinate their children, and is rejected by the opponents of vaccines, both rotavirus and others like measles.

"This research clearly shows how effective a public vaccination program can be at protecting babies and kids from getting sick and alleviating burden on the health care system," said co-author Dr. Shelly Deeks.

The pain and suffering avoided can't be measured, but the financial costs of hospitalization for rotavirus has been calculated to be around $4,000 per incidence in the U.S.