b'CARES Annual Report 2020 | 43Temporal Trends in Patient Outcomes Survival from OHCA may have been significantly impacted by the COVID-19 pandemic. Potential contributing factors include fewer arrests occurring in public locations, decreased presenting shockable rhythms, lower rates of bystander CPR and defibrillation, changes in patterns of care and post-resuscitation interventions, as well as delays in time-sensitive interventions by bystanders and 911 responders. Figure 30 highlights monthly trends in survival rates for 2019 and 2020. Similar to other observed metrics, 2020 survival rates remained stable in the first three months of the year, closely mirroring 2019 rates. However, overall survival from April 2020 onwards was considerably lower than in 2019, decreasing from a rate of 9.8% in March to a yearly low of 7.1% in December. Notably, the sharpest decrease occurred between March and April, during the onset of the pandemic.The second graph (Figure 31) visualizes monthly trends in Utstein survival for 2019 and 2020. While month-to-month variability occurred in both years, Utstein survival was lower in 2020 compared with 2019 for every month except January. Between February and April 2020, the rate of Utstein survival decreased from 30.6% to 27.2%, increasing again in July to 32.3%, and eventually declining to an annual low of 24.7% in December.Figure 30. Overall survival by month (2019 vs 2020). Figure 31. Utstein survival by month (2019 vs 2020).'