S1 File -

<div><p>Smoking is a leading cause of preventable morbidity and mortality globally. During the COVID-19 pandemic, Smoking Cessation (SC) services faced many challenges, including lockdown and social distancing restrictions. Consequently, SC services had to adapt to the challenges in different ways or halt delivery. This research evaluated the impact of COVID-19 on the delivery and outcomes of SC services. This was achieved by comparing service delivery and outcomes pre-COVID-19 and during the pandemic and drawing insights for the delivery of SC services post-pandemic. Secondary analysis was performed on the data of 11,533 participants who attended the One Life Suffolk (OLS) SC services pre- and during the COVID-19 pandemic. A total of 4923 and 6610 participants attended SC services pre-COVID-19 and during COVID-19 respectively. Fifty-four percent of participants achieved quit status at week-4 while attending the SC services during the COVID-19 pandemic, compared with 46% pre-COVID-19, (<i>X</i><sup>2</sup>(1) = 38.2, <i>p-</i>value<0.001). Participants who attended the SC services during the COVID-19 period were 1.7 times more likely to achieve quit status at week-4 than pre-COVID-19. However, the proportion of participants lost-to-follow-up (LTF) was significantly higher during the COVID-19 period (11%) compared to pre-COVID-19 (7%), (<i>X</i><sup>2</sup>(1) = 51.4, <i>p-</i>value <0.001). There was an increased participation and quit rate during the pandemic for modified, remotely delivered SC services indicating successful delivery of remote services during the pandemic. Although switching from face-to-face to online helped some smokers to access the service at a time of motivational readiness, despite the COVID-19 restrictions, some smokers could not access or use some aspects of the remote delivery due to a lack of internet access, poor digital literacy, no peer support and no commitment to a group during face-to-face sessions, contributing to an increased rate of LTF. Posing a major challenge to SC services delivery, COVID-19 compelled OLS SC services to adapt and be more innovative in their delivery. SC services need to continue to evolve and adapt by applying the lessons learnt during the pandemic in terms of flexibility and person-centered delivery given what did and did not work well for different demographics within the population.</p></div>