Just as many of us have had to relearn how to wash our hands properly when the pandemic hit (the rule of thumb is 20 seconds of scrubbing, or enough time to sing “happy birthday” twice, from start to finish), it turns out that sanitizer requires similar attention. The CDC study revealed that rubbing for exactly 30 seconds was proven to kill coronavirus, but doing less could leave traces of active virus, making you vulnerable to infection. As the study explains, this amount of time is “recommended but not routinely performed in practice,” meaning many of us have been at risk of transmission without knowing it.ae0fcc31ae342fd3a1346ebb1f342fcb RELATED: For more up-to-date information, sign up for our daily newsletter. The good news is that when it’s used properly, sanitizer is very effective in fighting COVID. “We found that SARS-CoV-2 was efficiently inactivated by WHO-recommended formulations, supporting their use in healthcare systems and viral outbreaks,” explained the researchers. It should be noted that these “WHO-recommended formulations” only include sanitizers with an alcohol content of 70 percent or more. So, the next time you use hand sanitizer, make sure it’s doing its job by rubbing it in for a full 30 seconds. Apply a generous amount all over your hands (including between the fingers, and on the backs of your hands), and don’t forget to sing “happy birthday” three times before stopping. And to make sure your sanitizing routine is up to code, The No. 1 Thing To Know About Hand Sanitizer.