In the first week of March, 24 states were still reporting widespread cases of flu, with 20 more reporting increases in some areas of the state. Experts warn that many healthy people are still susceptible because they did not get shots this year following warnings of a pending vaccine shortage.

Since many workplaces didn’t offer the vaccinations, health officials say it’s even more important this year to make sure employees wash their hands regularly and stay home if they have symptoms of the virus.

A recent survey by the University of Arizona found that germs thoroughly invade offices. Researchers tested samples from 328 surfaces — from cubicles to conference rooms — in office buildings in New York, Chicago, San Francisco, Atlanta and Tucson, Ariz. The study, funded by a grant from The Clorox Co., recorded the highest levels of the human parainfluenza 1 virus (HPIV1) — a virus that causes respiratory infections like bronchiolitis and pneumonia and can live on surfaces for up to three days — on the desktops of cubicles and offices. They also found the virus on telephones, door handles and light switches.