These are some of the results of a nationwide Harris Poll of 2,563 U.S. adults surveyed online by Harris Interactive(R) between April 10 and 16, 2007.
All of these results should be treated with some caution. People's memories of whether they had flu shots may not be completely accurate. This is not a double-blind clinical trial, which is the gold standard for measuring the effectiveness of drugs. Furthermore, experts on the flu say that it is easy to confuse it with other infections, so some people who believe that they had the flu may not actually have had it. However, a large 71 percent majority of those who received flu shots and who believe they had the flu say they are certain they had it; but only just over a third (39%) visited a doctor who diagnosed the flu. The techniques used in this year's survey are the same as those used in previous years.
The main findings of this survey include:
- Approximately one-third (35%) of all adults claim to have had a flu shot
before the winter of 2006/2007. This includes a much higher proportion
(73%) of people aged 65 and over, who are regarded as more seriously at
risk from the flu if they catch it;
- Fifteen percent of all adults believe they had the flu, somewhat below
the 18 percent and 21 percent who believe they had the flu in the
winters of 2003/2004 (18%) and 2004/2005 (21%);
- The proportion of adults who had received flu shots who believe they
subsequently caught the flu (13%) was only somewhat lower than the
proportion of those who had not received flu shots who subsequently
caught the flu (17%).
The difference between these numbers (13% and 17%) is smaller than the differences found after the winters of 2003/2004 (14% and 21%) and 2004/2005 (13% and 23%). However the survey contains some good news. Fewer people (15%) caught the flu this last winter than in the two previous winters we studied (18% and 21%).
TABLE 1
THOSE WHO HAD FLU SHOTS AND THOSE WHO GOT THE FLU THIS WINTER
"Thinking back to this winter just ending ...
Did you get the flu this winter?
Did you have a flu vaccine shot before this winter?"
Base: All Adults
March March April
2004 2005 2007
% % %
Percentage of all adults who had
a flu shot before this winter 35 27 35
Percentage of all adults who got
the flu this winter 18 21 15
TABLE 2
HOW MANY OF THOSE WHO GOT OR DID NOT HAVE FLU SHOTS GOT THE FLU?
"Thinking back to this winter just ending ...
Did you get the flu this winter?
Did you have a flu vaccine shot before this winter?"
Base: All Adults
March March April
2004 2005 2007
% % %
Percentage of all adults who
had a flu shot who got the flu 14 13 13
Percentage of all adults who did
not have flu shots who got the flu 21 23 17
How much less likely were people
with flu shots to get the flu
than those who were not vaccinated? 33 43 24
TABLE 3
THE EXPERIENCES OF THOSE WHO BELIEVE THEY GOT THE FLU
AFTER HAVING HAD A FLU SHOT
"Did you spend one or more days in bed with the flu?"
"Did you visit a doctor who diagnosed the flu?" "How certain are you that you got the flu, and that it was not just a cough or
a cold?"
Base: All adults who had a flu shot and believe they had the flu
March March April
2004 2005 2007
% % %
Spent one or more days in bed 79 85 74
Visited a doctor who diagnosed flu 51 53 39
Certain I got the flu 80 82 71
TABLE 4
DEMOGRAPHICS OF THOSE WHO HAD FLU SHOTS AND OF THOSE WHO GOT THE FLU
"Did you get the flu this winter?
Did you have a flu vaccine shot before this winter?"
Base: All adults
Got the Flu Had a Flu Shot
% %
All Adults 15 35
Sex
Male 13 36
Female 17 34
Age
18-24 20 26
25-29 24 15
30-39 19 21
40-49 16 22
50-65 10 43
65+ 9 73
Race/Ethnicity
White 14 36
African-American 15 33
Hispanic 24 32
Methodology
This Harris Poll(R) was conducted online within the United States between April 10 and 16, 2007 among a nationwide cross section of 2,563 (aged 18 and over) of whom 899 got a flu shot before the winter of 2006/2007. Figures for age, sex, race/ethnicity, education, region and household income were weighted where necessary to bring them into line with their actual proportions in the population. Propensity score weighting was also used to adjust for respondents' propensity to be online.
All surveys are subject to several sources of error. These include: sampling error (because only a sample of a population is interviewed); measurement error due to question wording and/or question order, deliberately or unintentionally inaccurate responses, nonresponse (including refusals), interviewer effects (when live interviewers are used) and weighting.
With one exception (sampling error) the magnitude of the errors that result cannot be estimated. There is, therefore, no way to calculate a finite "margin of error" for any survey and the use of these words should be avoided.
With pure probability samples, with 100 percent response rates, it is possible to calculate the probability that the sampling error (but not other sources of error) is not greater than some number. With a pure probability sample of 2,563 adults one could say with a ninety-five percent probability that the overall results have a sampling error of +/- two percentage points. However that does not take other sources of error into account. This online survey is not based on a probability sample and therefore no theoretical sampling error can be calculated.
These statements conform to the principles of disclosure of the National Council on Public Polls.
J29951
Q 756, 760, 765, 770
The Harris Poll(R) #37, May 2, 2007
By Humphrey Taylor, chairman of The Harris Poll(R), Harris Interactive.
About Harris Interactive
Harris Interactive is the 12th largest and fastest-growing market research firm in the world. The company provides innovative research, insights and strategic advice to help its clients make more confident decisions which lead to measurable and enduring improvements in performance. Harris Interactive is widely known for The Harris Poll, one of the longest running, independent opinion polls and for pioneering online market research methods. The company has built what it believes to be the world's largest panel of survey respondents, the Harris Poll Online. Harris Interactive serves clients worldwide through its United States, Europe and Asia offices, its wholly-owned subsidiaries Novatris in France and MediaTransfer AG in Germany, and through a global network of independent market research firms. More information about Harris Interactive may be obtained at http://www.harrisinteractive.com. To become a member of the Harris Poll Online and be invited to participate in online surveys, register at http://www.harrispollonline.com
Press Contact:
Tracey McNerney
Harris Interactive
585-214-7756
(1) This statement refers to Harris Poll #26 Flu Shots Effective Half the
Time For Winter 2004/2005, According to New Poll of U.S. Adults, April
6, 2005 and Flu Shots Appear to Have Provided Limited Protection
Against Flu Last Winter, May 26, 2004.
