However, doctors questioned whether swine flu would have the same effect in the United States. Horvitz noted that reporting methods for influenza in Mexico are different from those here. Rutherford, meanwhile, noted that the more rural nature of the country means that older people living in more remote areas would not have gained the immunity that older Americans gained from previous strains of the virus that spread.
The number of younger people affected has been one of the driving forces behind concerns about swine flu.
"It's a very different calculation if any illness is killing people 80 years old instead of 8 years old," said Laurie Garrett, a senior fellow for global health at the Council on Foreign Relations.
She explained that even if the death toll is lower than that of other years, the number of years of life lost may be much higher.
But others said H1N1 needs to be compared to other hazards of daily life.
"While 4,000 deaths seem like a lot more than 1,200, and each death is a tragedy, it still appears that the effects of H1N1, although widespread are quite mild," said Dr. Gabe Kelen, director of the department of emergency medicine at Johns Hopkins.
He said that most of the deaths in younger people, while upsetting, were in those who had underlying conditions -- a similar pattern to deaths in the elderly during annual flu seasons.
"We also need to put the deaths in perspective," said Kelen. "Society seems to accept deaths from drunk drivers, and shootings without the type of alarm that H1N1 engenders. Dying from H1N1 is less likely than being hit by a drunk driver or being shot in many parts of the country." However, unfortunately, he concluded, "There's no vaccine to protect against impaired drivers or for acute lead poisoning."
"If I had my vaccine I'd be vaccinating them right now," said Horovitz, saying he does not know why some hospitals were able to get their supplies of swine flu vaccine sooner, calling it "a mystery to me."
"I'd just like everyone who has high risk patients to have their vaccine, and certainly the seasonal flu vaccine is a good idea for everyone now, if there's any left," he said.
Despite protective effects of seasonal flu vaccine, it remains unclear if it has any effect in protecting people from H1N1, because the strains are so different.
Ultimately, however, swine flu may have a lower death toll because of the attention it has brought to the ways flu spreads.
"I suspect that the death rate will be lower than the seasonal influenza rate," said James. "Every effort is being made both socially and medically to limit the spread of the disease and those actions have been effective. We have never fielded such a response to influenza with vaccine, antivirals and social interventions such as covering your cough, washing your hands, staying home if you are sick so effectively."
ABC's Dan Childs contributed reporting.