Washington (CNN) -- More than half of all adult Americans say they don't want to get the H1N1 flu vaccine, according to a new national poll.
The CNN/Opinion Research Corporation survey released Wednesday also indicates that the number of adults who have tried to get the vaccine but were turned away is higher than the number of adults who have gotten a swine flu shot.
According to the poll, 55 percent of adults don't want to get the swine flu vaccine and don't plan to get a shot. Another one in five say they want to get inoculated but haven't taken any steps to do so; 14 percent want a shot and have tried to get it but have been unsuccessful. Just 7 percent have been inoculated for H1N1.
Why are more than half of all Americans shunning the vaccine?
"The perception that the vaccine has dangerous side effects is the top reason," says CNN polling director Keating Holland. "Roughly half of those who don't want a swine flu shot say that the possibility of side effects is one reason why they don't plan to get the vaccine. That works out to 28 percent of the adult population who don't plan to get inoculated due to the risk of dangerous side effects."
So far officials of the National Institutes of Health say they've seen no serious side effects in clinical trials and that study subjects who have been immunized have generated a good response.
The Centers for Disease Control and Prevention recommends the vaccine for certain high-priority groups because they are more likely to have serious complications if they develop swine flu. These groups include: pregnant women; caregivers and household contacts of children younger than 6 months; everyone between the ages of 6 months and 24 years; and people ages 25 to 64 with existing health problems.
One in four American adults say they don't plan on getting a shot because they are not in a high-risk group, with 21 percent indicating they don't plan on getting vaccinated because they only go to a doctor when they are sick. Most of those respondents are men.
What about the 14 percent who have unsuccessfully tried to get the vaccine?
"Some say they don't know where to go. That works out to 4 percent of the total adult population who want to get inoculated but haven't been able to locate a medical facility that is giving swine flu shots," Holland said. "A bigger group, 5 percent of the total population, say that they found a facility with the vaccine but were turned away because they were not in a high-risk group or for some other reason. And 3 percent of all adults say they found a facility that had the vaccine but it ran out before they got there."
Add together those last two groups, and the number of Americans who actively sought the vaccine but were turned away for some reason is 8 percent of the total adult population, roughly the same number as the 7 percent who have been inoculated so far.
The CNN/Opinion Research Corporation poll was conducted November 13-15, with 1,014 adult Americans questioned by telephone. The survey's overall sampling error is plus or minus 3 percentage points.
CNN deputy political director Paul Steinhauser and senior medical correspondent Elizabeth Cohen contributed to this report