Somalia experienced its first wave of COVID-19 infections in March 2020 and has experienced fluctuating infection levels since. Longitudinal data on suspected cases of COVID-19, attitudes, and behaviours were collected by telephone interviews of cash-transfer programme beneficiaries from June 2020–April 2021. A multi-media Social and Behaviour Change Communication (SBCC) campaign was designed and implemented from February 2021 to May 2021. Between the end of the first wave and the onset of the second the perceived threat from COVID-19 increased, with the proportion of respondents viewing it as a major threat increasing from 46% to 70% (p= 0.021). Use of face coverings increased by 24% (p< 0.001) and hand shaking and hugging for social greeting decreased, with 17% and 23% more people abstaining from these practices (p= 0.001). A combined preventative behaviour score (PB-Score) increased by 1.3 points (p< 0.0001) with a higher score in female respondents (p< 0.0001). During wave 2, vaccine acceptance was reported by 69.9% (95% CI 64.9, 74.5), overall. Acceptance decreased with increasing age (p= 0.009) and was higher in males (75.5%) than females (67.0%) (p= 0.015). Awareness of the SBCC campaign was widespread with each of the 3 key campaign slogans having been heard by at least 67% of respondents. Awareness of 2 specific campaign slogans was independently associated with an increased use of face coverings (aOR 2.31;p< 0.0001) and vaccine acceptance (aOR 2.36;p< 0.0001). Respondents reported receiving information on the pandemic from a wide range of sources with mobile phones and radio the most common. Trust in different sources ranged widely.