Two new studies suggest mouth to mouth is not key to CPR, which is just as effective as with. While, two years ago the American Heart Association reiterated the same, however, this latest research published in the New England Journal of Medicine is the most compelling evidence to date.

NPR reports the study involved over 3,200 people who required CPR after going into cardiac arrest; 911 dispatchers issued directions to bystanders to either administer hands-only CPR or mouth to mouth. The survival rate for victims of both types were roughly the same, indicating chest compressions to be the most important element of CPR.

According to NPR, mouth to mouth resuscitation is only needed in cases where someone has stopped breathing after choking or nearly drowning, and can be safely skipped in suspected heart attacks.

The first proposal for CPR was received around 50 years ago, when researchers suggested external chest compression after a heart attack could provide blood circulation to the brain and heart. It was only later that mouth to mouth got added on.

This is good news for those who worry about the risk of disease transmission in mouth to mouth resuscitation on a stranger, though the risk is low. As well, chest compression is also easier for most people to perform, rather than mouth to mouth.

However, those attending a CPR course can still expect to be taught the rescue breathing technique, since it may be necessary in other situations.