Most people are suffering from the H1N1 virus, which is the most prevalent strain of the flu this year, and now, one of the top treatments made for children, Tamiflu, is in short supply.

CBS News medical contributor Dr. David Agus told the “CBS This Morning” co-hosts that currently 45 states are “rampant” with flu, but he said hopefully it will not be as bad as last year, where there were up to 40,000 deaths from the disease.

“It’s not too late for a flu shot,” said Agus. “It takes about 10 to 14 days for a flu shot to kick in and give you immunity … whether it’s your doctor or your pharmacist – get that flu shot, get prepared and be aware of the symptoms.”

Agus said that since the flu season could go as late as May, it’s definitely not too late to get a flu shot to prevent illness. The Centers for Disease Control estimates that only 40 percent of Americans have been vaccinated so far this season.

However, if there is a shortage of Tamiflu in your area, Agus said physicians can take adult capsules and grind them down into smaller doses and mix them with a flavored liquid to give to younger patients.

“The flu classically starts with fever and chills, and then if you have it for more than three days, you have to go to your doctor,” said Agus. “If you have it for more than three days, you can get a bacterial infection, or it could be something serious, so go to your doctor.”