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Background The potential for a bioterrorist attack involving smallpox has led to a debate about what national precautions should be taken. What is unclear is the public's knowledge of smallpox and views about precautions.
Methods We conducted a national survey of 1006 adults selected by means of random-digit dialing. Respondents were asked about their knowledge of and beliefs about the smallpox virus and the vaccine, their possible reactions to a bioterrorist attack involving smallpox, and a number of proposed state emergency powers.
Results The majority of the respondents have a number of beliefs about smallpox and smallpox vaccination that are false. The majority believe that there is an effective treatment for smallpox, that there have been cases of smallpox in the past five years, and that there is not enough smallpox vaccine to vaccinate everyone in the United States. Thirty percent believe that vaccination earlier in their lives would protect them from the disease. The majority of respondents said they wanted to be vaccinated; however, only 21 percent would want to be vaccinated if physicians declined vaccination. There was strong support among the respondents for several proposed state emergency powers.
Conclusions Our results suggest the need for public education about smallpox. These data also point to the importance of a discussion in the medical community about the advisability of vaccination of individual physicians at this time.
What is not known is how the general public views these issues. Prior research has shown that public opinion can strongly influence policy decisions.15,16,17 Also, should there be an outbreak of smallpox, the public response will be based on people's current knowledge and beliefs.18 To aid public health officials and physicians in planning for a possible outbreak, we conducted a national survey of Americans to learn their views on each of these questions and to discuss their implications.
Methods
Study Design
We used random-digit dialing to select survey participants. A total of 1006 U.S. adults completed the survey, which was conducted by telephone by ICR/International Communications Research between October 8 and December 8, 2002. The response rate was 65 percent.19 The sampling error was 3.1 percentage points.
Survey Questionnaire
The questionnaire was pretested for length and comprehensibility. It consisted of 61 questions, 7 of which had multiple parts.
Respondents were asked about their knowledge of the smallpox virus and vaccine and about their beliefs about equitable distribution of the vaccine in the event of a bioterrorist attack involving smallpox. They were also asked whether they would be vaccinated (or revaccinated) if the vaccine were made available. Respondents were told that there was a risk of serious side effects, including death, from the smallpox vaccine.
Respondents were asked where they would seek treatment and how confident they were in their own physician's ability to recognize the symptoms of smallpox. They were asked about their views on six possible emergency powers, proposed by the Centers for Disease Control and Prevention, which the states could invoke in the event of a bioterrorist attack.20 Respondents were told that on the basis of these emergency powers, states could arrest those who refused to obey a quarantine or isolation order, be vaccinated, or undergo a medical examination.
To adjust for sampling biases due to sociodemographic differences between respondents and nonrespondents and to ensure that the sample was representative, we weighted the responses on the basis of the latest U.S. Census data for sex, age, race or ethnic group, level of education, number of people in the household, and number of land telephone lines.
Results
Concern about a Smallpox Attack
The majority of the respondents (64 percent) said they believed that an attack by terrorists using smallpox would be likely if the United States took military action against Iraq; 20 percent thought it would be very likely, and 44 percent thought it would be somewhat likely (Table 1).
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Eighty-nine percent of the respondents knew that smallpox is a contagious disease (Table 1). However, 30 percent believed that there had been a case of smallpox in the United States in the past five years, and 63 percent thought there had been a case somewhere in the world in the past five years (Table 1). Moreover, 78 percent believed that there was a medical treatment for smallpox that would prevent death or serious effects after symptoms of the disease developed.
Beliefs about Smallpox
A majority of the respondents believed it was likely that they would survive if they contracted smallpox (very likely, 50 percent; somewhat likely, 37 percent). Two thirds of the respondents (67 percent) thought it was likely that they would contract smallpox if they came within a few feet of someone who had the disease (very likely, 26 percent; somewhat likely, 41 percent). The respondents were split on the aftereffects of smallpox, with 48 percent reporting that most people who contracted the disease and survived would have a full recovery and 46 percent reporting that they would have permanent, serious aftereffects such as disfigurement and blindness.
The Smallpox Vaccine
Sixty-six percent of the respondents believed that they had previously been vaccinated against smallpox (Table 2). Forty-six percent of those who reported a prior vaccination (30 percent of all respondents) believed it would protect them from becoming seriously ill if there were an outbreak of smallpox.
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Respondents were asked to assess their own level of risk from the smallpox vaccine. Twenty-five percent said it was likely that they would die from the vaccine, although only 6 percent thought this was very likely. Forty-one percent believed it was likely that they would have a serious illness (very likely, 11 percent; somewhat likely, 30 percent). A majority of the respondents reported that it was likely that they would have a fever or feel extremely tired (very likely, 33 percent; somewhat likely, 47 percent) and would have a sore arm (very likely, 57 percent; somewhat likely, 34 percent). Only about one quarter of the respondents (27 percent) believed that someone who has physical contact with a recently vaccinated person could contract a serious infection.
Vaccination Policy
The respondents were asked about two of the policy issues currently being debated: vaccination of health professionals and vaccination of the general public. A strong majority (81 percent) of the respondents favored voluntary vaccination of doctors and nurses in preparation for a bioterrorist attack. Nearly two thirds (65 percent) were in favor of offering the smallpox vaccine to the general public now on a voluntary basis, in preparation for a possible attack.
Many respondents believed that they would not be able to get vaccinated quickly if cases of smallpox were detected in their community and that there would not be enough vaccine for everyone in the United States (Table 2). Moreover, 72 percent believed that if it was not possible to vaccinate everyone quickly, wealthy and influential people would get the vaccine first; 43 percent believed that the distribution of the vaccine would discriminate against the elderly, and 22 percent believed that it would discriminate against blacks.
The Vaccination Decision
Sixty-one percent of the respondents said they would choose vaccination (or revaccination) if it were offered as a precaution against a bioterrorist threat, whereas 36 percent said they would not. Seven percent reported having a health condition that led them to believe they should not be vaccinated.
If there were cases of smallpox in the United States, 75 percent of the respondents would choose to be vaccinated. If there were cases of smallpox in the community, the proportion of respondents who would be willing to be vaccinated increased to 88 percent.
The actions of physicians also influenced the decision to be vaccinated. Seventy-three percent of the respondents said that they would be vaccinated if their own physician and most other physicians were vaccinated, as compared with 21 percent if their own physician and many other physicians refused vaccination.
Only 33 percent of the respondents would choose to be vaccinated if they had heard that "some people" had died from smallpox vaccine. Only 44 percent would be willing to be vaccinated if they had to stay out of work for two weeks. A small proportion of the respondents (9 percent) said that they would not be vaccinated under any of these circumstances.
Possible Reactions to a Smallpox Attack
Approximately half the respondents (52 percent) said they would go to their own physician first for diagnosis and care if they thought they had smallpox, 40 percent would go to a hospital emergency room, and 7 percent would go to their local health department (Table 3). Most of the respondents were confident that their own physician would recognize the symptoms of smallpox (43 percent were very confident, and 40 percent were somewhat confident).
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Two thirds of the respondents (67 percent) said that they would stay in the community if cases of smallpox were reported there, and 32 percent said they would stay elsewhere until the outbreak was over. However, 91 percent reported that they would stay in the community if they thought they had been exposed to the virus.
State Emergency Powers
As shown in Table 3, there was a high level of support for legislation requiring hospitals and clinics to provide services to people who might have smallpox (87 percent of the respondents favored such legislation) and requiring people with smallpox to be isolated in a special health facility (73 percent). Two thirds of the respondents (67 percent) believed that state governors should be able to use National Guard troops to prevent people from leaving areas with reported cases of smallpox. A smaller majority favored quarantining people suspected of having smallpox (57 percent), and the respondents were divided on the question of whether a person should be required to undergo a medical examination or test to diagnose smallpox, with 51 percent favoring this requirement and 48 percent opposing it. The only proposal not favored by 50 percent or more of the respondents was the requirement that a person be vaccinated against smallpox (41 percent favored this proposal).
Discussion
This survey revealed substantial misinformation among Americans about smallpox and smallpox vaccination. Our data show that the majority of the public would agree to vaccination and other measures to control smallpox, but that they would not agree to be vaccinated if physicians declined vaccination.
Our results should be interpreted in the context of the limitations of this study. Respondents were interviewed about these issues in the absence of any recent experience with a smallpox outbreak or vaccination. The answers given might differ if there were an outbreak of the disease. The survey was administered at one point in time and the stability of the responses over time is not known. In addition, all surveys are subject to sampling errors. The size of the sampling error varies according to the number of people interviewed and the magnitude of the difference in the responses to each question. The results may differ from those that would have been obtained if all adults in the United States had been interviewed.
Our findings have several important implications for physicians and public health professionals. First, our data highlight the central part that physicians would play in providing advice and care related to smallpox vaccination and treatment. If the threat of a smallpox attack increases, Americans' individual decisions about vaccination will be strongly influenced by what practicing physicians choose to do. If physicians are reluctant to be vaccinated, large numbers of Americans will be unwilling to do it voluntarily. Also, if there are deaths from side effects of the vaccine, the public will be less willing to be vaccinated and will look to their physicians for advice. The majority of the survey respondents reported that they would go to their own doctor, rather than an emergency room or a public health department, if they thought they had smallpox. Thus, primary care physicians will be on the frontlines in helping their patients decide about vaccination and in the event of a smallpox outbreak.
Second, the survey results suggest the need for public education about smallpox, since many Americans have beliefs about the disease that are incorrect according to scientific views. Although many aspects of the disease remain unclear, there is general agreement in some important areas. The last case of smallpox was reported in the United States in 1949 and in the world in 1977,21 yet a substantial proportion of the respondents thought there had been cases in the past five years. There is no specific treatment for smallpox,21 but a majority of the respondents thought that the disease could be effectively treated. In many people, immunity from a prior vaccination is likely to be negligible after 20 years, and the U.S. vaccination program ended in 1972,12,22,23 yet almost half of the respondents who had been vaccinated believed they would be protected from the disease. A majority of the respondents did not know that vaccination within two to three days after exposure to smallpox can provide protection against the virus.21,24 Although serious adverse reactions to the vaccine are expected to be relatively rare in patients without contraindications to the vaccine,23,25 a substantial proportion of the respondents thought that serious complications from the vaccine, including death, would be likely. Government sources say there are enough doses of the vaccine for everyone in the United States,26 but the majority of the respondents did not believe that there would be enough doses for everyone.
Third, our results suggest that the current view held by many public health officials and leaders of the medical community — that the smallpox vaccine should not be widely available to the general public — is at odds with the public's desire for access to the vaccine. Health officials need to clarify to the public the basis for their judgment to limit access to the vaccine.
Finally, the recent statement by the Bush administration about the plan to begin vaccinating military personnel and health care and emergency workers against smallpox within weeks, with immunization of the public offered on a limited, voluntary basis in the future,27 may make this issue more salient to the public. As adverse reactions to the vaccine occur, members of the public may look to their physicians for guidance in weighing the risks of vaccination against the risk of a bioterrorist attack involving smallpox.
Supported by a grant from the Robert Wood Johnson Foundation.
Source Information
From the Department of Health Policy and Management, Harvard School of Public Health, Boston (R.J.B., C.M.D., J.M.B., K.T.-C., K.J.W.); and ICR/International Communications Research, Media, Pa. (M.J.H.).
This article was published at www.nejm.org on December 19, 2002.
Address reprint requests to Dr. Blendon at the Department of Health Policy and Management, Harvard School of Public Health, 677 Huntington Ave., Boston, MA 02115.
References
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