Perceptions of pandemic influenza vaccines

Abstract

Pandemic influenza A (H1N1) (pH1N1) was first identified in North America in early 2009. The pandemic flu outbreak during the 2009–2010 influenza season demonstrated how rapidly a new strain of flu can emerge and spread. Vaccination is the most effective method to prevent influenza, and vaccination during a pandemic is critical in limiting morbidity and mortality. Unfortunately, reports of vaccination rates for pH1N1 vaccines during the 2009–2010 influenza season indicated low rates for various demographic groups, including pregnant women, health care workers, child care workers, college students, and the general public. Furthermore, when asked about perceptions of pH1N1 vaccines, respondents in a variety of studies from the pH1N1 pandemic indicated common and universal misconceptions about influenza vaccines, especially in regard to perceptions of need, efficacy and safety. Therefore, if vaccination rates are to increase, an important outcome especially during pandemics, the psychological characteristics underpinning perceptions of influenza vaccines need to be understood better.

Vaccination is the most effective method to prevent influenza.¹ When a new pandemic virus emerges, vaccination is the most cost effective means of preventing serious illness or death from influenza infection.² The 2009 pandemic influenza A (H1N1) (pH1N1) was first identified in Spring 2009, which provided researchers a unique opportunity to examine perceptions of pandemic vaccines during the 2009–2010 influenza season among various populations during a period of extensive media coverage and heightened vigilance. While influenza immunization provides the best preventative strategy against the influenza virus, influenza vaccination rates prior to the pandemic were typically low among several populations.^3-5 Therefore, researchers understood the imperative to gather information about vaccination rates and vaccine perceptions during time periods when vaccination gains heightened importance, such as during a pandemic. Unfortunately, reports from specialized groups targeted to receive the pH1N1 vaccine, as well as the general public, indicate that vaccination rates were low for pH1N1, with individuals reporting distrust of the pH1N1 vaccine during the 2009–2010 influenza season.

The 2009–2010 pH1N1 Pandemic

Death rates during an influenza pandemic can exact a terrible toll on the world’s population. Historians estimate that the 1918–1920 pandemic took 100 million people’s lives; or 5% of the world’s population.⁶ Given a 3-fold population increase since the 1918 pandemic, a pandemic on a similar scale today would kill 300 million people. Thus, when a new pandemic virus emerges, resources are quickly mobilized, with vaccination becoming central to preventing a catastrophe.⁷ In Spring 2009, pH1N1 was first identified and, as experts predicted, spread quickly resulting in widespread influenza activity. The burden of pH1N1 in the US alone has been estimated to be approximately 61 million cases, with 274,000 hospitalizations and 12,500 deaths. Higher rates of hospitalizations and deaths among children and adults under 65 y of age revealed that pH1N1 placed a burden on younger age groups, compared with seasonal influenza in past seasons.⁸ Initial doses of the pH1N1 vaccine were available in early October 2009.^2,9 At that time, target groups for priority vaccination were identified by the Centers for Disease Control and Prevention’s Advisory Committee for Immunization Practices (ACIP).³ Target groups differed considerably from those targeted for seasonal influenza vaccine, given a different illness susceptibility for pH1N1. The ACIP recommended that the 2009 pH1N1 vaccine be given first to pregnant women, healthcare workers, individuals age 6 mo to 24 y, individuals age 25–64 y with health conditions with higher risk of influenza complications, and caregivers of children younger than 6 mo of age.³ In an ideal world, the majority of the individuals in these target groups would have received the pH1N1 vaccine, since they were at greatest risk. However, that did not occur, with negative public perception about the pH1N1 vaccine being a significant factor.

Perceptions of pH1N1 Vaccines in Pregnant Women

Pregnant women with pH1N1 influenza were at increased risk for hospitalization and death. Moreover, infants born during their mother's influenza hospitalization were more likely to be delivered preterm. Thus, pH1N1 had severe effects on both pregnant women and their infants.^10,11 Several worldwide reports indicated variable pH1N1 vaccine uptake rates for pregnant women ranging from 25–80% of pregnant women. However, it did appear that pH1N1 vaccination levels were higher than previous years’ annual influenza vaccination coverage among pregnant women.^12-16 Despite the highest immunization rates for pH1N1 for all demographic groups, studies indicate that pregnant women were not well informed about the importance of the pH1N1 vaccine. Pregnant women often reported feeling pressured to get the vaccine from health care providers while harboring significant concerns for their health and the health of their fetus arising from taking the vaccine during pregnancy.^17-19 However, the promising levels of pH1N1 vaccinations in pregnant women indicate that the message of the importance of these vaccines was largely understood by this demographic group. Unfortunately, similar positive outcomes were not observed for other demographic groups also targeted to receive the pH1N1 vaccine.

Perceptions of Pandemic Vaccines in Health Care Workers

Since influenza is highly contagious, medical personnel receive substantial education regarding the importance of influenza vaccines, especially during a pandemic. Studies indicate that pH1N1 vaccination rates during the 2009–2010 influenza season for health care workers ranged from 13–41%. Healthcare workers who did not receive the pH1N1 vaccine stated that they did not get the vaccine because they were concerned about side effects and/or they had concerns about the AS03-adjuvants.^20,21 In summary, health care workers, who should be especially aware of the importance of pandemic influenza vaccines still appeared to have negative perceptions about these vaccines, resulting in low vaccination rates.

Perceptions of pH1N1 Vaccines in College Students

College students were highly susceptible to the pH1N1 virus, due to close living conditions in residence halls, social contact in and out of the classroom, and the fact that younger people were more likely to get the pH1N1 flu.^22-25 Data from laboratory-confirmed cases of pH1N1 flu suggested higher infection rates in younger age groups, which was the reason that people under the age of 25 were one of the key groups recommended by the CDC to receive the 2009 pH1N1 vaccine.²² However, college students perceived themselves at low risk for the flu. When researchers examined the likelihood of receiving a pH1N1 vaccination and perceptions of pH1N1 flu risk, the results indicated that only 16% of college students stated that they would get vaccinated. Moreover, the students appeared unconcerned about pH1N1, despite exposure to an extensive public health campaign for pH1N1. Alarmingly, many students reported that they would still attend class even if they were sick with the flu. Misconceptions about vaccine safety and usefulness were common. Top reasons for refusing the H1N1 vaccine included questioning vaccine safety and concerns about side effects.⁹

Perceptions of Pandemic Vaccines in Day Care Workers

In the US, over 1.3 million people are employed in child day care settings. Young children lack the skills to practice effective hygiene, which contributes to the rapid transmission of influenza among children and caregivers in child day care settings. During the pH1N1 pandemic, researchers surveyed child care workers and reported that only 11% of workers reported having received the pH1N1 vaccine. When queried why they had not been vaccinated against pH1N1, the most common reasons included thinking the vaccine was unnecessary, thinking that the vaccine was ineffective in preventing the pH1N1 flu, and thinking that the vaccine was unsafe. For the small proportion of workers who did receive the pH1N1 vaccine, the most endorsed reason included wanting to protect oneself/one’s family. The authors concluded that the low rates of pH1N1 vaccination stemmed from misconceptions about the efficacy and need for these vaccines.²⁶

Perceptions of Pandemic Vaccines in Community Samples

During a pandemic, it is imperative that the general public is receptive to influenza vaccines to limit the spread of the disease. Unfortunately, pH1N1 vaccine uptake was low in the general population, ranging from 17–20% for adults in the US and abroad.^27-29 These rates were lower than seasonal vaccine uptake, despite the fact that pH1N1 had crowded out other influenza viruses. Similar to the studies above, pH1N1 vaccines were perceived as unsafe by the general public.^27,28

Conclusions and Future Directions

The above research clearly illustrates that specific target groups and the general public had substantial misunderstandings about pH1N1 vaccines during the 2009–2010 pandemic, which contributed to the low vaccination rates. Even though immunization provides the best preventive strategy against the influenza virus, a vaccine is ineffective if people are not willing to get themselves vaccinated. Although the supply of pH1N1 vaccine was initially limited in the beginning of the 2009–2010 influenza season, in no study was lack of supply a major cited reason for not getting vaccinated.^9,26 Instead, the main reasons for low pH1N1 vaccination rates included misperceptions about need, efficacy of the vaccine, and safety. It is notable that the misperception regarding need is quite at odds with the actual data suggesting a 20% estimate of population-wide clinical rate of pH1N1 symptomatic cases.⁸ The findings from the pH1N1 studies are consistent with the broader literature suggesting that public confidence in vaccines, lauded as one of the greatest public health interventions, has declined to the point of being a crisis. While rigorous evidence of vaccine efficacy and safety is provided by scientists, the vaccine community has somewhat neglected the psychological and social factors that drive perceptions of these vaccines, which makes the use of vaccination programs less effective than they could be.³⁰

It is fortunate that the 2009–2010 H1N1 pandemic was not nearly as devastating as other pandemics, such as the 1918–1920 influenza pandemic. However, the findings from the pH1N1 studies illustrate common concerns that need to be addressed before a ruinous pandemic does occur. When critical, wide-scale vaccination programs are publicized in the future, common misconceptions regarding influenza vaccines need to be addressed. In particular, the need for vaccines, the efficacy of vaccines, and the safety of vaccines appear to be key concerns that should be addressed and emphasized. Importantly, psychological characteristics, such as feelings of fear, negative attitudes and poor perceptions about influenza vaccines coincide with actual vaccination levels in a population. If vaccination rates are to increase, an important outcome especially during pandemics, these psychological characteristics should be central to plans that build public confidence in influenza vaccines.