• Self-Reported Mood- Affective Slider [ Time Frame: Baseline, immediately post- intervention (15- 20 minutes post baseline) ]
  Self-reported mood will be measured using three validated patient-reported outcome measures to determine changes in mood from before to after usual care/ intervention arms. One of the three outcome measures includes the Affective Slider (AS), which is a slider scale that is measures a single value on a continuous normalised scale ranging from 0-1, with a central, default thumb position value equal to 0.5, where 0 is low and 1 is high.
• Self-Reported Mood- Scale of Positive and Negative Experience [ Time Frame: Baseline, immediately post- intervention (15- 20 minutes post baseline) ]
  The second outcome measure of changes in mood will be the Scale of Positive and Negative Experience (SPANE), where participants rate 12 emotion words from 1 to 5, where 1 is Not at all and 5 is Very. The overall affect is then determined using these scores and can also be divided out into positive and negative feelings scales.
• Self-Reported Mood- Happy-Sad and Alert-Sleepy Dynamic Visual Analogue Mood Scales [ Time Frame: Baseline, immediately post- intervention (15- 20 minutes post baseline) ]
  The third and final measure of changes in mood will be the Happy-Sad and Alert-Sleepy Dynamic Visual Analogue Mood Scales (DVAMS), which is a morphing image scale that is gender specific and changes when the participant moves the slider scale. The scale ranges from 0 to 100, where 0 is low and 100 is high. The central, default thumb position value is 50.

• Influenza vaccination-specific antibody responses- Haemagglutination inhibition assay [ Time Frame: Baseline, 4 weeks post-vaccination ]
  Antibody levels specific to antigens contained in the influenza vaccination will be assessed in sera taken immediately prior to vaccination and at 4 weeks post-vaccination. This will be assessed using the haemagglutination inhibition (HAI) assay that allows for the determination of the quantity of influenza virus present based of HAI units by carrying out serial dilutions. A larger number of HAI units equates to a high quantity of influenza virus.
• Influenza vaccination-specific antibody responses- IgG-specific enzyme-linked immunosorbent assay [ Time Frame: Baseline, 4 weeks post-vaccination ]
  The concentration of influenza specific antibody will be measured using a IgG- specific enzyme linked immunosorbent assay (ELISA).
• Number of participants who experience flu-like symptoms and self care [ Time Frame: 6 months ]
  Participants who experience cold and flu-like symptoms will a complete flu-like symptoms diary and self-care behaviours for occasions of flu-like illnesses during the 6 months post-vaccination.
• Number of participants who do not follow up with trial procedures- Attrition [ Time Frame: Baseline, immediately post- intervention, 4 weeks post-vaccination, 6 months post-vaccination ]
  Loss to follow-up will be noted for participants who do not complete the intervention, do not attend the post-vaccination follow-up, and who do not return flu-like symptom diaries at 6 months post-vaccination.
• Recruitment [ Time Frame: From the time of recruitment to the start of the Randomised Control Trial ]
  The number and proportion of participants who consent to participate in the trial from the total number of the population approached.

Infectious diseases are important causes of morbidity and mortality worldwide, and vaccinations are vital to reducing the risk of disease. Vaccine efficacy, however, is dependent on the immune system's ability to respond to vaccination antigens. Influenza vaccines play an important role in combating influenza. However, some populations, such as older adults, respond poorly to vaccination due to their compromised immune systems, with efficacy at 17-53% (compared to 70-90% in young adults).

Behavioural and psychological influences have been shown to alter immune responses. An observational study looking into behavioural and psychological effects, which have been identified as immune modulators (stress, physical activity, nutrition, mood and sleep) found greater positive mood on the day of vaccination predicted significantly greater antibody responses to influenza vaccination. Following this, a feasibility study carried out on 110 older adults demonstrated the ability to enhance positive mood prior to influenza vaccination using a brief digital intervention.

The clinical trial will be the next phase of this research, where the cohort will consist of 650 participants, aged over 65 years, who will receive the quadrivalent, cell-grown influenza vaccination, immediately after one of three conditions. These conditions include: the control arm of usual participant care for vaccination; participants watching a 15-minute digital intervention via a tablet that does not allow content selection; and a personalised digital intervention that allows for participant selection of content they would like to view for 15 minutes. The purpose of these digital interventions is to enhance positive mood of patients prior to vaccination.

The primary aim of this trial is to explore which of two brief interventions has the largest effect on positive mood, compared with usual care. The secondary aim is to measure vaccine specific antibody responses, with the hypothesis that individuals with enhanced positive mood will present larger vaccine specific antibody responses.

This trial will also allow data collection on exploring recruitment, attrition, intervention engagement, and practicality of collecting clinical data available through electronic records and self-report measures to inform the design of a future definitive trial.

• Vaccination
• Infection

• Other: Standardised Digital Intervention
  Video intervention designed to induce an increase in positive mood in older adults. Includes comedy clips, uplifting music and positive imagery. Intervention approximately 15-20 minutes in length. This includes 3 short comedy clips (fork handles sketch, the two Ronnie's; A room with a view - faulty towers; Tim Vine Live stand-up extract), uplifting music (Jailhouse Rock - Elvis Presley; Happy Together - The Turtles), jokes and positive imagery. The content of the intervention has been informed by patient and public involvement, focus groups with older adults, and pilot testing.
• Other: Individualised Digital Intervention
  Similar to the standardised digital intervention, however, participants will be able to individualise the intervention by choosing video clips from a limited menu of choices. Intervention approximately 15-20 minutes in length. The 4 categories include stand-up comedy (Michael McIntyre, Tim Vine and Victoria Wood), sit-com (Fawlty Towers, Only Fools and Horses and Two Ronnies), music (Elvis Presley, Last Night at the Proms, Roy Orbison) and variety (Britain's Got Talent, Strictly Come Dancing, Terry Wogan). Participants are able to select 3 of the videos, which are roughly 5 minutes in length, to reach a total of 15-20 minutes of content.

• No Intervention: Usual care, control arm
  Usual care in which participants will not see a video intervention. This group will attend their influenza vaccination appointment as usual, without intervention. Participants will receive Northern Hemisphere Influenza Vaccine 2019/20 (Delivered as part of Standard Care).
• Experimental: Standardised Digital Intervention
  Video intervention designed to induce an increase in positive mood in older adults. Includes comedy clips, uplifting music and positive imagery. Intervention approximately 15-20 minutes in length. Following intervention, participants will receive the Northern Hemisphere Influenza Vaccine 2019/20 (Delivered as part of Standard Care).
  Intervention: Other: Standardised Digital Intervention
• Experimental: Individualised Digital Intervention
  Similar to the standardised digital intervention, however participants will be able to individualise the intervention by choosing video clips from a limited menu of choices. Intervention approximately 15-20 minutes in length. Following intervention, participants will receive the Northern Hemisphere Influenza Vaccine 2019/20 (Delivered as part of Standard Care).
  Intervention: Other: Individualised Digital Intervention

• Ayling K, Fairclough L, Tighe P, Todd I, Halliday V, Garibaldi J, Royal S, Hamed A, Buchanan H, Vedhara K. Positive mood on the day of influenza vaccination predicts vaccine effectiveness: A prospective observational cohort study. Brain Behav Immun. 2018 Jan;67:314-323. doi: 10.1016/j.bbi.2017.09.008. Epub 2017 Sep 18.
• Andre FE, Booy R, Bock HL, Clemens J, Datta SK, John TJ, Lee BW, Lolekha S, Peltola H, Ruff TA, Santosham M, Schmitt HJ. Vaccination greatly reduces disease, disability, death and inequity worldwide. Bull World Health Organ. 2008 Feb;86(2):140-6. Review.
• Goodwin K, Viboud C, Simonsen L. Antibody response to influenza vaccination in the elderly: a quantitative review. Vaccine. 2006 Feb 20;24(8):1159-69. Epub 2005 Sep 19. Review.
• Moynihan JA, Larson MR, Treanor J, Duberstein PR, Power A, Shore B, Ader R. Psychosocial factors and the response to influenza vaccination in older adults. Psychosom Med. 2004 Nov-Dec;66(6):950-3.
• Betella A, Verschure PF. The Affective Slider: A Digital Self-Assessment Scale for the Measurement of Human Emotions. PLoS One. 2016 Feb 5;11(2):e0148037. doi: 10.1371/journal.pone.0148037. eCollection 2016.
• Barrows PD, Thomas SA. Assessment of mood in aphasia following stroke: validation of the Dynamic Visual Analogue Mood Scales (D-VAMS). Clin Rehabil. 2018 Jan;32(1):94-102. doi: 10.1177/0269215517714590. Epub 2017 Jun 27.

Inclusion Criteria:

• Males and Females aged 65-85 years (inclusive)
• Received influenza vaccination for the 2018/19 season
• Eligible to receive 2019/20 influenza vaccination as part of usual care
• Ability to give informed consent

Exclusion Criteria:

• Males and Females aged less than 65 or over 85 years (exclusive)
• Did not receive influenza vaccination for the 2018/19 season
• Ineligible to receive 2019/20 influenza vaccination as part of usual care
• Unable to provide informed consent
• Deemed by health care provider to be:
• Too physically frail to participate
• Diagnosed with dementia or other cognitive condition which would make participation difficult
• Insufficient command of English language
• Influenza vaccination contraindicated
• Sufficiently impaired of hearing or vision that exposure to the intervention video content as intended would be compromised
• Those for whom the collection of blood samples is contraindicated
• Those who have participated previously in the pilot study (NCT03144518).