Background Seasonal influenza vaccination (SIV) uptake in healthcare workers (HCWs) across London has more than doubled since 2014/15 from 25% to 64% in 2018/19, but uptake is still less than the national average of 70%. Given the lack of certainty in the literature around interventions that work to improve uptake, particularly within the NHS and across a range of Trust types, the aim here is to determine which interventions have been effective (and ineffective) in increasing uptake in SIV in HCWs across the 36 acute, community, mental health and specialist trusts in London.

Methods The Delphi technique is a structured process that uses a series of questionnaires or ‘rounds’ to gather information until a group consensus is reached. An advantage of the methodology is that it can be used to collate expertise across diverse locations and indivdiuals anonymously. A modified Delphi method was utilised consisting of 2 rounds of self-adminstered questionnaires completed electronically and a third round of a meeting where paper questionnaires were distributed to infection control and influenza leads from the 36 London Trusts represented in the room. Round 1 was devised using generic open-ended questions and responses were categorised qualitatively into themes. These themes were converted into statements for Round 2 and respondents were asked to indicate their degree of agreement/disagreement on a Likert scale. Median and mode responses were reviewed to determine if there was a trend towards strong (dis)agreement or (dis)agreement for each item on the Likert scale. Round 3 was devised exploring areas of most uncertainty from Round 2. Consensus was defined as where ≥75% of responses showed strong (dis)agreement/(dis)agreement on a Likert scale.

Results There were 34, 33 and 24 responses to the rounds respectively. The most effective interventions in increasing uptake amongst HCWs across a wide-range of different Trusts across London were found to be:

1. The availability/accessibility of vaccination at work

2. Planned advertising/promotion/communications, including electronic communication

3. Peer vaccinators

4. Myth-busting; education and training

5. Strong, visible leadership and engagement.

Contrary to popular belief, update varied by teams rather than by health professional so targeting influencers in teams was deemed effective.

Conclusion The results of the delphi method were transformed into the ‘7 steps to success’ campaign, which was implemented during winter 2019/20. The summative evaluation has shown that uptake amongst health care workers has increased significantly on last year.