INTRODUCTION

Vaccines and immunization remain one of the most cost-effective ways of preventing disease and it is estimated to avert 2–3 million deaths annually¹.Vaccines have resulted in the eradication of deadly illnesses, turning once devastating diseases to distant memories. For vaccination campaigns to be successful from a public health perspective, enough people must take them to achieve herd immunity^2,3. Widespread vaccine hesitancy is therefore a public health crisis and has been listed as one of the top ten threats to global health. Defined by the World Health Organization (WHO) as the reluctance or refusal to vaccinate despite the availability of vaccine, vaccine hesitancy is not necessarily new⁴. The reasons for vaccine hesitancy are complex and not confined to complacency and lack of confidence in vaccines⁵. However, the COVID-19 vaccine hesitancy demands special attention because this is by far the largest, most destructive, and most sustained public health disaster in the past many decades.

COVID-19 was declared a global pandemic on 11 March 2020, allowing the rapid deployment of resources including manpower and necessary non-pharmacological interventions to prevent further spread. In the US, the urgency of COVID-19 paved way for one of the fastest vaccine development and approval timelines, facilitated in no small part by a dynamic public–private partnership initiated by the US government known as ‘Operation WARP Speed’⁶. This speedy process, while facilitating access to vaccines to those in critical need, has also raised skepticism in the general population regarding whether due process was followed and whether the vaccine is safe. In an international study of G7 countries, only 12% of Americans strongly agreed that if the public authorities propose a vaccination against COVID-19, they would be confident that the proposed vaccine will not be dangerous. Furthermore, 22% said they were worried about the safety of COVID-19 vaccines because of the speed with which they are being developed and produced⁷.

Studies have been conducted at the national level to examine prevalence and determinants of vaccine hesitancy. For example, Fisher et al.⁸ found that vaccine hesitancy was higher among younger adults, females, people with high school education level or less, lower annual household income, people living in rural settings, persons who declined the influenza vaccine in the past year, and those who live in the Southern US⁸. A Pew survey report released on 3 December 2020, showed that with respect to political affiliation, 50% of republican-leaning persons compared with 69% of democratic-leaning persons would accept the COVID-19 vaccine when it became available⁹.

Less is, however, known about state-specific variations in vaccine hesitancy; this is important as vaccine rollout in the US is decentralized and at the state level. State-specific data can therefore inform public health planning, programs, and policy. Furthermore, given that wide variations exist in the burden of COVID-19 incidence and mortality rates across states, we were interested in examining whether this variation was associated with vaccine hesitancy. In line with the Health Belief Model which posits that an individual’s course of action with regard to health-related behavior is determined by among other factors, the perceived severity of the condition and their perceived susceptibility to it, not only the perceived benefits or harms.

METHODS

RESULTS

Population characteristics

Within the pooled sample, mean age was 47.2 years (46.9–47.5). By age categories, 10.5%, 35.3%, 34.2%, 2% were 18–24, 25–44, 45–64, and ≥ 65 years, respectively. Overall, 48.4% were male, and 51.6% were female. By race/ethnicity, 62.6%, 11.3%, 5.3%, 17.2%, and 3.8%, were non-Hispanic White, non-Hispanic Black, non-Hispanic Asian, Hispanic, and non-Hispanic other race. Most (55.1%) were married, while 18.3% were either widowed, divorced, or separated, and 26.7% identified as never married. Only 8.5% had less than high school education, 30.6% graduated from high school, 21.3% had some college education, 26.7% had a college degree, and 12.9% had a professional degree. Furthermore, 14.4%, 24.4%, 31.1%, 22.1%, and 8.0%, had annual household income (US$) less than 25000, 25000–50000, 50000–100000, 100000–200000 and >200000, respectively (Table 1).

Past COVID-19 diagnosis and receipt of COVID-19 vaccine

Overall, 14.6% reported they had ever been diagnosed with COVID-19 (range: 0.04% in Vermont to 14.8% in California) and 7.7% reported that they had ever received a COVID-19 vaccine (range: 0.2% Wyoming to 11.8% in Texas). Consistent patterns (or reverse patterns as the case might be) were seen in the groups most likely to be diagnosed with COVID-19 versus those most likely to have received a vaccine. The top 10 states in terms of self-reported COVID-19 diagnosis were: California 14.8%, Texas 9.5%, Florida 5.8%, New York 5.7%, Illinois 4.4%, Ohio 4.4%, Georgia 3.8%, Pennsylvania 3.4%, Indiana 2.6%, and Arizona 2.4%. The top 10 states in terms of receipt of a COVID-19 vaccine were: Texas 11.8%, California 8.4%, Florida 6.1%, New York 6.0%, Pennsylvania 3.6%, Illinois 3.4%, Ohio 3.3%, Georgia 3.0%, North Carolina 2.9%, Michigan 2.9% (Table 2).

Intent to decline COVID-19 vaccine and associated reasons

Of those who had not received any COVID-19 vaccine, 50.95% would receive the COVID-19 vaccine when it is available, 39.52% said they were unsure if they would or would not get the vaccine, and 9.53% said they would not get the vaccine. By state, the percentage who indicated intent to decline the vaccine was lowest in the following 10 states: Rhode Island 11.7%, Massachusetts 13.9%, California 16.2%, Connecticut 17.0%, District of Columbia 17.3%, Washington 17.5%, Delaware 17.6%, New Hampshire 18.0%, New Jersey 18.1%, and Virginia 18.4%. Conversely, this percentage was highest in the following 10 states: Louisiana 40.2%, Mississippi 35.9%, Idaho 34.8%, Alabama 34.7%, Wyoming 34.1%, Montana 33.5%, South Carolina 32.1%, Arizona 30.8%, Indiana 30.7%, and Oklahoma 30.7% (Table 3).

Within the pooled national sample, the 3 most common reasons for vaccine hesitancy were: ‘I plan to wait and see. If it is safe, I will get it later’ (22.1%); ‘I think others need it more than me’ (17.8%), and ‘I do not trust the government’ (18.0%). Only about 9.3% in the pooled national were concerned about the side effect of the vaccine, and 2.4% did not believe they needed a vaccine at all. The most common reasons cited for not believing the vaccine was needed were: ‘I plan to use masks and other precautions’ (25.9%), ‘COVID-19 is not a serious illness’ (25.4%), and ‘I am not a member of high-risk group’ (23.8%). Within republican and democratic-leaning states, the top 3 reasons cited for vaccine hesitancy were identical, and reflective of the general population: ‘I plan to wait and see. If it is safe, I will get it later’ (22.8% democratic vs 21.4% republican), ‘I think others need it more than me’ (18.0% democratic vs 17.5% republican), and ‘I do not trust the government’ (16.8% democratic vs 17.1% republican) (Table 4).

Sociodemographic characteristics associated with vaccine hesitancy

Within the pooled national sample, factors associated with increased likelihood of being vaccine hesitant included: being Black than White (APR=1.63; 95% CI: 1.53–1.73); having already tested positive for COVID-19 versus never having tested positive (APR=1.18; 95% CI: 1.12–1.25); being female versus male (APR=1.15; 95% CI: 1.11–1.20); and living in a republican versus democratic-leaning state (APR=1.26; 95% CI: 1.20–1.32). Conversely, the likelihood of vaccine hesitancy was lower among people aged 45–65 years (APR=0.85; 95% CI: 0.76–0.95), and ≥65 years (APR=0.35; 95% CI: 0.31–0.40), compared to those 18–24 years; living in a multi-unit dwelling ≥5 apartment building (APR=0.63; 95% CI: 0.57–0.69), compared to those in detached mobile unit (APR=0.78; 95% CI: 0.72–0.84); those with a professional degree (APR=0.51; 95% CI: 0.45–0.58) versus less than a high school education; and annual household income more than $200000 (APR=0.44; 95% CI: 0.39–0.50) compared with less than $25000. Persons living in the South (APR=1.12; 95% CI: 1.04–1.21), Midwest (APR=1.16; 95% CI: 1.07–1.25), and West (APR=1.18; 95% CI: 1.09–1.26), compared to the Northeast (all p<0.05) (Table 5). For details on vaccine hesitancy among people who have not received any COVID-19 vaccine by age, gender, race/ethnicity, see Supplementary file.

DISCUSSION

This study examined variations across states in the percentage showing COVID-19 vaccine hesitancy. We found that vaccine hesitancy varied widely with a difference of close to 30 percentage points between the state with lowest prevalence (Rhode Island, 11.7%), and that with the highest prevalence (Louisiana, 40.2%). This state-specific variation is a novel finding from our study that state programs can use to plan for their vaccine campaigns. Our study also confirmed findings from other studies, including key sociodemographic factors that directly impact intent to decline the COVID-19 vaccination. For example, Black race and female gender were strongly associated with vaccine hesitancy, consistent with other studies^11,12. A possible explanation for the higher likelihood of vaccine hesitancy among females is perception of reduced risk, since some studies have shown that females have less risk of acquiring the infection and experiencing COVID-19 related mortality¹³. Another factor that may be contributing to vaccine hesitancy among females is the unknown effects of COVID-19 vaccine on reproductive capability, fetus in pregnant females, and breastfeeding children in lactating women. However, it must be noted that despite female gender being a seemingly protective factor, individual-based risk factors such as the presence of lower socioeconomic status, inability to physical distance due to housing conditions, chronic medical conditions including obesity, and asthma, are associated with increased risk of acquiring COVID-19 infection and developing severe disease. Identifying as Black, was the strongest determinant of vaccine hesitancy, a finding that aligns with well documented mistrust in government and research^14-16. That one in four of the general population reported hesitancy is likely attributable to the widespread climate of mistrust about the origins of COVID-19, mistrust in government, and for some, mistrust in vaccines in general, all of which have dovetailed to engender conspiracy theories with resultant higher levels of vaccine skepticism, and hesitancy especially among racial minorities. Research studies have also shown that people who believe conspiracies about COVID-19 report that they will be less likely to access a COVID-19 vaccine once one becomes available, they are also more likely to indicate less support for COVID-19 public health policies^17,18. Data show that Blacks are more likely to get infected and experience severe COVID-19 disease and mortality when compared with other races^19,20. However, our study shows that they are also the group with the highest odds of declining the vaccine. Interventions to address this multifaceted distrust must first acknowledge and address issues of social inequity and promote transparent partnerships to vaccine confidence and acceptance.

Education level can influence the ability of an individual to comprehend scientific information²¹, and this plays a pivotal role in vaccine acceptance and uptake. In our study, having a high school education or less was also associated with vaccine hesitancy. The ability to comprehend scientific information such as what vaccines are, how they work, and what efficacy of the vaccine means, for example, is directly impacted by literacy. Lack of access to internet and internet connectible devices can also negatively impact vaccine attitudes. While information about the vaccines is present on the websites of public health agencies such as the Centers for Disease Control and Prevention, and the Food and Drug Administration, the style and language of information can also be a barrier if it is difficult to understand. Anti-vaccination contents are readily available and accessible on social media platforms^22,23, to increase vaccine acceptance, information about vaccines need to be just as easily accessible and understandable by lay audience.

Our results showed a bipartisan distinction in attitudes towards vaccines. Republican-leaning states had higher likelihood of vaccine hesitancy, while states with democratic-leaning showed more vaccine receptivity. This can be partly explained by the politicization of public health measures including facemask wearing, policies on state shutdowns, and physical distancing measures. These attitudes have carried over into public sentiments about the COVID-19 vaccine. Our study did not highlight systematic differences between democratic-leaning versus republic-leaning states in reasons for vaccine hesitancy. Our study, like other, has shown that vaccine acceptance is higher in populations who perceive that they are at higher risk of contracting the infection and having more severe disease²⁴. Our study also highlighted that person who reside in larger apartment buildings are less vaccine hesitant; one possible explanation may be perception of higher risk due to less ability to physical distance since they are constantly exposed to their co-tenants while sharing common high-contact areas such as mail, laundry, and exercise rooms. We also noted that vaccine hesitancy was higher among those with a previous diagnosis of COVID-19. Vaccine hesitancy in this subpopulation may be due to perception of reduced risk of reinfection. However, this may be an incorrect assumption since case reports have highlighted serologically confirmed reinfection in an individual with previous diagnosis of COVID-19^25,26. Knowledge about the longevity of natural COVID-19 immunity is still evolving. The perception of reduced risk due to innate immunity also has public health significance since some individuals may become less compliant with non-pharmacological interventions such as facemask wearing and physical distancing.

CONCLUSIONS

One in four Americans indicated vaccine hesitancy, especially women, Blacks and those living in republican-leaning states. Enhanced and sustained efforts are needed to boost trust and confidence in the COVID-19 vaccines. Knowledge of state-specific information can have significant impact on how clinicians, frontline workers, public health professionals, state departments of health, and overseeing agencies tailor specific campaigns to promote vaccine confidence and uptake, while also encouraging non-pharmacological interventions²⁷.