Dr. Betteker says that's why the World Health Organization is so concerned about the swine flu, compared to the yearly influenza.
Because people have no immunity, this strain may spread faster.
However, most cases in the US have been no worse than the winter flu.
Still, many people have wondered why the flu, which is traditionally a winter illness, showed up in Mexico, in warmer weather.
"In the tropical regions, there is less of a season for influenza. It's not just a winter time illness, so we see flu in these areas anytime during the year," Dr. Betteker said.
Dr. Betteker says there's no evidence yet that we need to change how we live our lives.
"We don't need to worry about being in groups. You can go to the baseball games, you can go to the Poconos on vacation," Dr. Betteker said.
But flu prevention should be constant and we need to get used to common sense germ-busting practices, such as washing hands and covering your mouth when coughing.
While we follow those practices, scientists around the world are working on potential vaccines.
The Protein Sciences Corporation is using what's called a purified protein.
It's much faster to make.
In fact, 1,700 doses were in the mail to Hong Kong, just weeks after an order came in for a bird flu vaccine.
The US government hasn't called the company yet.
But the CEO hopes the Mexican government will.
"In 6 weeks, we will be turning out 20 to 30,000 doses per week," Dan Adams, CEO of Protein Sciences said.
Get Action News on your website
