"It is too early to tell if this strain is associated with more severe norovirus disease but likely lower population immunity is the reason for the early surge of an otherwise seasonal increase of this virus," Jan Vinjé, head of the CDC's CaliciNet system, told CBS News in an email.

The cases mark the fourth norovirus outbreak on Holland America ships since early December, following others on its Eurodam, Rotterdam and Zuiderdam vessels. Other companies, including Cunard Line and Princess Cruises also saw outbreaks in recent weeks.

No. Hand sanitizer is simply not as effective against norovirus as it at killing other pathogens due to the virus's firm shell, Dr. William Schaffner, professor of infectious diseases at Vanderbilt University Medical Center, told TODAY.com recently.

New data from the Centers for Disease Control and Prevention (CDC) has found that cases of norovirus, the very contagious stomach bug, are on the rise acro

Drivers of the increase in norovirus cases may include a new strain, but continued precautions, good hygiene, can help reduce risk.

You can also get norovirus by touching objects or surfaces that are contaminated and then putting your hands in your mouth without washing them first. Hand-washing with soap and water is key, as hand sanitizer will not do the trick in the case of norovirus, experts say.

Don gloves. It is necessary to wear gloves while cleaning during and after a bout of norovirus, and to wash your hands after removing and disposing of the gloves. “Even if you are wearing gloves, wash your hands for a full 20 seconds with soap and water after cleaning,” Ek says.

As cold and flu season runs rampant this winter, there's an extra virus to residents may have to work to avoid.Norovirus, a highly contagious stomach bug, is s

Hand sanitizer alone isn't enough to protect you from norovirus, experts say. So it's important to know how to stay safe and wash your hands properly.