key: cord-0726224-iyr6ow7y
authors: SmithPhD, Louise E.; SimPhD, Julius; AmlôtPhD, Richard; CuttsMSc, Megan; DaschMSc, Hannah; SevdalisPhD, Nick; RubinPhD, G. James; ShermanPhD, Susan M.
title: Side-effect expectations from COVID-19 vaccination: Findings from a nationally representative cross-sectional survey (CoVAccS – wave 2)
date: 2021-11-17
journal: J Psychosom Res
DOI: 10.1016/j.jpsychores.2021.110679
sha: e02a98fac3061b0fd1ecabf41e48d98729b077d6
doc_id: 726224
cord_uid: iyr6ow7y

Objectives Concern about side effects is one of the most common reasons for refusing vaccination. Side-effect expectations are also known to predict perception of side effects. We aimed to investigate the percentage of people who thought side effects from COVID-19 vaccination were likely and investigate factors associated with side-effect expectation. Methods Online cross-sectional survey of 1470 UK adults who had not been vaccinated for COVID-19 (conducted 13 to 15 January 2021). We asked participants how likely they thought side effects from COVID-19 vaccination were. Linear regression analyses were used to investigate associations with side-effect expectations. Results Most participants were uncertain whether they would experience side effects from a COVID-19 vaccine; only a minority reported that side effects were very likely (9.4%, 95% CI 7.9% to 10.9%, n = 138/1470). Personal and clinical characteristics, general, and COVID-19 vaccination beliefs and attitudes explained 29.7% of the variance in side-effect expectation, with COVID-19 vaccination beliefs alone accounting for 17.2%. Side-effect expectations were associated with: older age, being clinically extremely vulnerable to COVID-19, being afraid of needles, lower perceived social norms for COVID-19 vaccination, lower perceived necessity and safety of COVID-19 vaccination, and perceived lack of information about COVID-19 and vaccination. Conclusions Side-effect expectation was associated with believing that COVID-19 vaccination was unsafe, ineffective and that others would be less likely to approve of you having a COVID-19 vaccination. Communications should emphasise the safety, effectiveness, and widespread uptake of vaccination, while promoting accurate perceptions of the incidence of vaccination side effects.

Fears about vaccine side effects are among the most common reasons for refusal of vaccinations, including during the H1N1 influenza pandemic. [1] [2] [3] In the UK, three COVID-19 vaccines have been approved for use: the Pfizer/BioNTech (approved 2 December 2020), AstraZeneca (30 December 2020) , and Moderna (8 January 2021) vaccines. [4] [5] [6] Clinical trial data indicate that injection site adverse events are very common (up to 83% Pfizer/BioNTech, 67% AstraZeneca, 89% Moderna). [7] [8] [9] Common systemic adverse effects include fatigue (Pfizer/BioNTech up to 59%, AstraZeneca 70%), headache (Pfizer/BioNTech up to 52%, AstraZeneca 68%), and fever (Pfizer/BioNTech up to 16%, AstraZeneca 18%). [7, 8, 10] Older people experience fewer adverse effects. [8, 9] There is some evidence that side effects may be more common (Pfizer/BioNTech) and severe (Moderna) following the second dose of the vaccine. [8] [9] [10] The cause of adverse effects from vaccination is not always clear. While some may be caused by biological mechanisms of the vaccine, psychological factors also play a part. Sideeffect expectations are important, fuelling the 'nocebo effect', a phenomenon whereby the expectation of symptoms is self-fulfilling. The association between side-effect expectations and subsequent reporting of side effects has been found for a range of medications, including cancer treatments, rheumatoid arthritis medication, and child vaccination. [11] [12] [13] A systematic review of factors associated with expectations of side effects from medical interventions found some evidence that negative beliefs about medications was associated with greater side-effect expectations. [14] The aim of this study was to estimate the percentage of the UK population who expected side effects from the COVID-19 vaccine, and to investigate associations between side-effect expectations and personal and clinical characteristics, general vaccine beliefs and attitudes, and COVID-19 vaccination beliefs and attitudes. 

This study reports data from the second wave of the COVID-19 vaccination acceptability study (CoVAccS) . Full methods of the study have been reported elsewhere. [15] Design Cross-sectional online survey hosted on Qualtrics. Data were collected from 13 to 15 January 2021. Participants 1,500 participants were recruited through Prolific's UK online research panel.

Participants were eligible for the study if they were aged eighteen years or over, lived in the UK, and had not completed our previous survey (n>31,000 eligible participants). [16] We used quota sampling based on age, sex, and ethnicity so that participant characteristics were broadly reflective of those in the UK population. Participants provided informed consent to take part in the study before being able to commence the survey. Upon completion of the survey, participants were paid £2.

For this study, we included participants if they indicated that they had not yet received a COVID-19 vaccine (n=1470).

Full survey materials are available online. [17] Side-effect expectation was measured by a single item asking participants how likely they thought it was that they "would get side effects from a coronavirus vaccine" on an 11point scale, from "extremely unlikely" (0) to "extremely likely" (10).

To measure general vaccination beliefs and attitudes, we asked participants to what extent they agreed that vaccination is a good thing in general and that they were afraid of needles, on an 11-point scale from "strongly disagree" (0) to "strongly agree" (10).

We measured COVID-19 vaccination beliefs and attitudes using 21 statements investigating: perceived effectiveness and safety of COVID-19 vaccination; barriers and facilitators to vaccination; perceived information sufficiency about COVID-19 and the vaccine; social norms about vaccination; beliefs about profiteering; and beliefs concerning the impact of vaccination on restrictions. Participants were asked to what extent they agreed with the statements from "strongly disagree" (0) to "strongly agree" (10) . Sixteen of these items were included in a principal components analysis, which identified five components accounting for 68% of the variance in the original items: social norms regarding vaccination, necessity of vaccination, safety of the vaccine, adequacy of information about the vaccine, and freedom from restrictions through the vaccine. [15] We asked participants for their age, sex, ethnicity, religion, highest level of qualification, and employment status. Participants were asked whether they, or someone they lived with, had a medical condition that made them extremely clinically vulnerable to COVID-19.

[18] We also asked participants if they worked or volunteered in roles critical to COVID-19 ("key worker" J o u r n a l P r e -p r o o f Journal Pre-proof Analysis We categorised respondents as expecting side effects from COVID-19 vaccination using a priori cut offs on the likelihood scale (zero to two = very unlikely, three to seven = uncertain, eight to ten = very likely). [15, 16] To investigate factors associated with side-effect expectations we used a linear regression model, using the original 0 to 10 scale as the outcome measure. Variables were entered into the model in blocks: personal and clinical characteristics (block 1); general beliefs and attitudes relating to vaccination (block 2); and beliefs and attitudes relating to COVID-19 vaccination (block 3).

To control the rate of Type 1 errors, we set statistical significance at p≤.01 and therefore calculated 99% confidence intervals (CIs) for regression coefficients.

The 1470 participants included in analyses were broadly representative of the UK population (50.8%, n=746 female; 85.2%, n=1246 white ethnicity; mean age 45.5 years, SD=15.5, range 18 to 80 years).

Most participants were uncertain about the likelihood of side effects from COVID-19 vaccination, with the midpoint of the scale being the most selected (modal) response. When using our a priori cut-offs, a minority of participants reported that side effects from a COVID-19 vaccine were very likely (9.4%, 95% CI 7.9% to 10.9%, n=138/1470; Figure 1 ).

One-third of participants thought that side effects were very unlikely (33.1%, 95% CI 30.7% to 35.5%, n=486/1470), while 57.6% (95% CI 55.0% to 60.1%, n=846/1470) were uncertain.

J o u r n a l P r e -p r o o f (Table 1 ). shown that coverage of medication side effects in the news media increases symptom reporting. [22] Preliminary evidence suggests that coverage of a possible link between the AstraZeneca vaccine and blood clots may have affected side-effect expectations. [23] However, these data remain important by virtue of quantifying the prevalence of side-effect expectations and associated factors in the absence of much information at the start of the vaccine rollout in the UK.

Unsurprisingly, poorer perceived safety of COVID-19 vaccination was associated with greater side-effect expectations. [11] In line with research finding that negative beliefs about vaccinations were associated with increased side-effect expectations,[20] we also found that lower perceived necessity of COVID-19 vaccination was associated with greater side-effect AstraZeneca vaccine may be linked to unusual blood clots related to low blood platelets (published 7 April 2021). [23] Providing reassurance about the typically transitory and nonharmful nature of side-effects may be a useful strategy in increasing initial vaccine uptake and reducing long-term attrition among those offered booster jabs (offered in the UK since October 2021).

As this study is cross-sectional, we cannot infer direction of causality between attitudes and beliefs and side-effect expectations. Further, the survey methodology used cannot rule out self-selection bias affecting the study results. To the best of our knowledge, there is no validated measure of side-effect expectation. We used a single item to measure side effect expectation, with regard to the established psychometric properties of a 0 to 10 numerical rating scale format. [30] This item was based on previous research conducted by our group. [11] Not all potential variables that could have been associated with side effect expectations were investigated due to space limitations in the survey.

At the start of the COVID-19 vaccine rollout in the UK, most people were unsure whether side effects from vaccination were likely. Media coverage of side effects and seeing people experience side effects as the vaccine rollout continues may heighten side-effect expectations. COVID-19 vaccination beliefs and attitudes were associated with side-effect expectations. In particular, side-effect expectations were associated with poorer perceived safety and effectiveness of the vaccine, thinking that others were less likely to approve if you

Factors associated with uptake of vaccination against pandemic influenza: A systematic review

A systematic review of factors affecting vaccine uptake in young children

Factors associated with the uptake of seasonal influenza vaccination in adults: a systematic review

Medicines and Healthcare products Regulatory Agency: Regulatory approval of

Pfizer/BioNTech vaccine for COVID-19

Medicines and Healthcare products Regulatory Agency: Regulatory approval of COVID-19 Vaccine AstraZeneca

Safety and immunogenicity of the ChAdOx1

Efficacy and Safety of the mRNA-1273

SARS-CoV-2 Vaccine

Vaccine side-effects and SARS-CoV-2 infection after vaccination in users of the COVID Symptom Study app in the UK: a prospective observational study

Parental expectation of side effects following vaccination is self-fulfilling: a prospective cohort study

Prediction of nonspecific side effects in rheumatoid arthritis patients by beliefs about medicines

The relationship between anticipated response and subsequent experience of cancer treatment-related side effects: A meta-analysis comparing effects before and after treatment exposure

A systematic review of factors associated with side-effect expectations from medical interventions. Health Expect

COVID-19 vaccination acceptability in the UK at the start of the vaccination programme: a nationally representative cross-sectional survey (CoVAccS -wave 2). Public Health

COVID-19 vaccination intention in the UK: 18. NHS: Who is at higher risk of coronavirus

Cabinet Office, Department for Education: Children of critical workers and vulnerable children who can access schools or educational settings

How does the side-effect information in patient information leaflets influence peoples' side-effect expectations? A cross-sectional national survey of 18-to 65-year-olds in England. Health Expectations

Impact of television coverage on the number and type of symptoms reported during a health scare: a retrospective pre-post observational study

Covid-19 vaccines: confidence, concerns and behaviours

A systematic review of factors that contribute to 26

Face-to-face interventions for informing or educating parents about early childhood vaccination

European Centre for Disease Prevention and Control: Catalogue of interventions addressing vaccine hesitancy

The effect of format on parents' understanding of the risks and benefits of clinical research: a comparison between text, tables, and graphics

Readability of medicinal package leaflets: a systematic review

Response scale selection in adult pain measures: results from a literature review