Introduction: Childhood immunisation is the most cost effective method to prevent vaccine preventable diseases and decrease childhood morbidity and mortality. COVID-19 pandemic has affected routine immunisation of children due to various reasons. We aimed to study the attendance to immunisation clinic at our tertiary care hospital prior and during COVID-19 pandemic. Methods: Retrospective data of monthly attendance to the immunisation clinic at our tertiary care hospital was collected for a study period of 30months, sub-grouped into - January 2019 to March 2020 (pre-COVID) and April 2020 to June 2021 (during COVID). The clinic caters to children from first day of life till 18 years, as per National Immunisation Schedule (NIS). Trends in attendance across the months were studied. Statistical analysis were employed to test whether there was a significant reduction in immunisation clinic attendance. Results: Attendance to the immunisation clinic during the 30 month study period was 37418 children. Among these, 29879 children received birth dose vaccines. This cohort was excluded from further analysis as deliveries continued at our maternity centre in both periods of study. Comparing vaccine recipients above the age of 6weeks till 18years across the months, 6222 and 1502 children received immunisation in the pre-COVID and during COVID pandemic respectively. No child received immunisation from April 2020 to July 2020 during national lockdown. Unpaired t-test showed highly significant reduction in attendance to immunisation clinic during the COVID pandemic in comparison to pre-COVID period (p<0.001). The reduction in immunisation attendance had greatest affection among recipients of pentavalent vaccine at our centre. Conclusion: Immunisation among children is significantly hampered during this COVID-19 pandemic as highlighted by our study findings. Vaccination delay leaves young children vulnerable and there is an acute need to increase awareness and catch-up drives to prevent resurgence of vaccine preventable diseases.