A systematic review of 81 studies across 20 countries found that healthcare service utilisation decreased by about a third during the COVID-19 pandemic, with considerable variation. The median reduction in services was 37%, with the largest reductions in visits (42%), admissions (28%), diagnostics (31%), and therapeutics (30%). Among 35 studies reporting secondary outcomes, 45% showed larger reductions in utilisation among people with milder illness, while 55% found no difference. The review highlights the need to address unmet health needs and reduce unnecessary care in the post-pandemic recovery. The study also notes that while some people may have avoided unnecessary care, others missed essential services, such as vaccinations and cancer treatments. The review emphasizes the importance of learning from this 'natural experiment' to improve healthcare systems and reduce low-value care. The findings suggest that the pandemic may have led to both underutilization and overutilization of healthcare services, with significant implications for future healthcare planning and resource allocation. The study also points out the limitations of the review, including potential publication bias and the exclusion of some data sources. Overall, the review provides valuable insights into the impact of the pandemic on healthcare utilisation and highlights the need for further research to understand the long-term effects of these changes.A systematic review of 81 studies across 20 countries found that healthcare service utilisation decreased by about a third during the COVID-19 pandemic, with considerable variation. The median reduction in services was 37%, with the largest reductions in visits (42%), admissions (28%), diagnostics (31%), and therapeutics (30%). Among 35 studies reporting secondary outcomes, 45% showed larger reductions in utilisation among people with milder illness, while 55% found no difference. The review highlights the need to address unmet health needs and reduce unnecessary care in the post-pandemic recovery. The study also notes that while some people may have avoided unnecessary care, others missed essential services, such as vaccinations and cancer treatments. The review emphasizes the importance of learning from this 'natural experiment' to improve healthcare systems and reduce low-value care. The findings suggest that the pandemic may have led to both underutilization and overutilization of healthcare services, with significant implications for future healthcare planning and resource allocation. The study also points out the limitations of the review, including potential publication bias and the exclusion of some data sources. Overall, the review provides valuable insights into the impact of the pandemic on healthcare utilisation and highlights the need for further research to understand the long-term effects of these changes.