Vaccinations can be upsetting to babies — and their parents. But babies are less upset and calm down much faster from the sting of an injection when they're soothed with a quick series of comforting measures dubbed the five S's. The first S is for swaddling.

Babies who had been vaccinated and comforted by their parent were still crying one minute later. But fewer than 10% who had been comforted by a trained resident using the five S's were still crying one minute after their injections.

One minute after vaccination, the pain scores of infants who were comforted by their parent averaged nearly four, while those of babies comforted by the five S's were under two.

The method was described by Dr. Harvey Karp in his 2003 book, The Happiest Baby on the Block. And while it can certainly be helpful at other times, such as with a colicky baby, it really shines after vaccinations.

It all starts with swaddling, followed by holding the baby to your side or stomach and gently swinging her back and forth while whispering, "Shush" into her ear. The final S, offering the baby a pacifier to suck on, is usually the least important one. And while this may sound like a lengthy procedure, residents were trained to do it in under 30 seconds.

A one-minute video of the five S's (without pacifier) in action shows just how quickly they can soothe a crying baby. It's like flipping a switch.

The study looked at 230 two- and four- month old babies during visits for standard vaccinations. Half of the babies were comforted after injections by their parent as they normally would be. The other half was comforted by a resident who had been trained to perform the five S's quickly and efficiently.

Another resident acted as timer, and a third recorded a pain score every 15 seconds for the first two minutes and every thirty seconds afterwards until five minutes after the vaccination. The pain score was based on three observations: quality of cry (whimpering to screaming), facial grimace and infant body movement.

One minute after vaccination, the pain scores of infants who were comforted by their parent averaged nearly four, while those of babies comforted by the five S's were under two. A lower score means less pain.

The study also looked at how helpful a drink of sugar water given before the vaccination was. All babies received either 2 ml (less than half a teaspoon) of a 24% sucrose solution or 2 ml of water two minutes before their injections. The sugar did help reduce the pain scores of infants who were comforted by their parent but was nowhere near as effective as comforting with the five S's was. Neither did it add to the effectiveness of the five S's--pain score and crying time did not differ between children comforted by the five S's who received sugar and children comforted by the five S's who received water. Sugar is not the sixth S.

The study authors were initially skeptical that the five S's would prove particularly effective. So were many of the parents. They're not skeptical anymore.

An article on the study was published online before print by Pediatrics on April 16, 2012 and is freely available. The article will also appear in the May print edition of the journal.