NEW YORK, May 6, 2014 /PRNewswire/ -- Last winter's flu season was fairly typical of other winters over the last decade, with the prevalence of the flu and the number of people who had flu shots both fairly close to the averages for that time period. The effectiveness of flu vaccines also seems to have been fairly typical.
These are some of the results of The Harris Poll of 2,300 adults surveyed online between April 16 and 21, 2014 (Full findings, including data tables, available here). Some of the main findings of this Harris Poll are:
- 44% of all adults report that they had flu shots. This compares with 40%, 39%, 44%, 40% and 44% over the five previous winters.
- 13% of adults believe that they had the flu last winter, compared to 18%, 12%, 11%, 11% and 14% over the five previous winters.
- As in most of the Harris Polls on this topic over the last ten years, the numbers of people who believe they had the flu was almost the same for people who had flu shots (12%) and those who did not (13%). However, it would be a mistake to conclude from this that the vaccine was ineffective. There is clear evidence in this poll that people who were more vulnerable were also more likely to have received shots (see below).
- There seem to be have been wide variations in the effectiveness of the flu vaccines used in different years, based on the numbers of people who were and were not vaccinated who think they got the flu. The vaccines seem to have been most effective in the winters of 2003-2004 and 2004-2005, and much less effective in the winter of 2010-2011.
- Because flu symptoms are sometimes confused with symptoms of other conditions, people who said they had had the flu were asked if they had visited a doctor who had diagnosed flu. About half (47%) of those had flu shots and who also believe that they had the flu report that their flu was diagnosed by a doctor.
- Efforts to vaccinate the elderly, who are more vulnerable to flu, seem to have been quite effective. Fully 76% of people aged 65 and over were vaccinated, and only 7% of seniors report that they had the flu. People aged 25 to 29 were the least likely (16%) to be have had flu shots, and they were the most likely (19%) to believe that they had the flu.
- White adults were somewhat more likely to have had flu shots than African-Americans and Hispanics (46% compared to 40% and 38%), but this gap was smaller than in the previous year. As in the winter before, Hispanics were more likely to believe they had the flu than whites or African-Americans (16% compared to 11% and 12%).
- Almost half of all adults (47%) think they will get flu shots next winter. This includes the great majority (92%) of people who had one last winter and only a few (10%) of those who did not.
Reasons for caution
This is a complicated subject and there are several reasons for caution in interpreting these findings - for example, it would be a mistake to conclude that the flu vaccines used last winter had no effect. However, it is probably safe to conclude that the flu vaccines used to protect people over the last five winters were less effective than the vaccines used to protect people in the winters of 2006-07, 2004-05, and 2003-04. In each of those winters, people who received shots were significantly less likely (especially in 2004-05) to get the flu (or to believe they got it) than were those who did not have flu shots.
"The diagnosis, and particularly self-diagnosis, of the flu is not very reliable, as other infections can produce flu-like symptoms," points out Harris Poll Chairman Humphrey Taylor. "This raises the question of whether some people who report having had the flu may have been mistaken." This year's survey finds that about three quarters of these people are "certain" they had the flu (74%) and two thirds spent one or more days in bed (66%). However, only 47% visited a doctor who diagnosed the flu.
"Furthermore," continues Taylor, "the absence of a direct correlation between those who had flu shots and those who did not get the flu does not mean that the flu shots had no effect, because those who are more likely to get the flu may also be more likely to get flu shots." The Harris Poll suggests that this happened. Fully 76% of people aged 65 and over - a high risk group - had flu shots, and 51% of people aged 50-64 did so. Far fewer adults under 50 were vaccinated. The particularly high incidence of flu shots among those 65 and older probably explains why this group was less likely to get the flu than younger people.
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This Harris Poll was conducted online within the United States between April 16 and 21, 2014 among 2,300 adults (aged 18 and over). 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 sample surveys and polls, whether or not they use probability sampling, are subject to multiple sources of error which are most often not possible to quantify or estimate, including sampling error, coverage error, error associated with nonresponse, error associated with question wording and response options, and post-survey weighting and adjustments. Therefore, The Harris Poll avoids the words "margin of error" as they are misleading. All that can be calculated are different possible sampling errors with different probabilities for pure, unweighted, random samples with 100% response rates. These are only theoretical because no published polls come close to this ideal.
Respondents for this survey were selected from among those who have agreed to participate in Harris Poll surveys. The data have been weighted to reflect the composition of the adult population. Because the sample is based on those who agreed to participate in our panel, no estimates of theoretical sampling error can be calculated.
These statements conform to the principles of disclosure of the National Council on Public Polls.
The results of this Harris Poll may not be used in advertising, marketing or promotion without the prior written permission of The Harris Poll.
Product and brand names are trademarks or registered trademarks of their respective owners.
The Harris Poll® #45, May 6, 2014
By Humphrey Taylor, Chairman, The Harris Poll
About Nielsen & The Harris Poll
On February 3, 2014, Nielsen acquired Harris Interactive and The Harris Poll. Nielsen Holdings N.V. (NYSE: NLSN) is a global information and measurement company with leading market positions in marketing and consumer information, television and other media measurement, online intelligence and mobile measurement. Nielsen has a presence in approximately 100 countries, with headquarters in New York, USA and Diemen, the Netherlands. For more information, visit www.nielsen.com.
The Harris Poll
SOURCE The Harris Poll