Iranian Journal of Nursing and Midwifery Research1735-906631420260809555568ENHealth Information Technology Research Center, Isfahan University of Medical Sciences, Isfahan, Iran,Department of Community Health Nursing, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran,Department of Community Health and Geriatric, School of Nursing and Midwifery, Iran University of Medical Sciences, Tehran, Iran,Department of Medical Informatics, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran,1. Department of Nursing, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran, 2.Social Determinants of Health Research Center, Social Health Research Institute, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran,Nursing and Midwifery Care Research Center, Health Management Research Institute, School of Nursing and Midwifery, Iran University of Medical Sciences, Tehran, Iran2026080320260803<p><strong>Background: </strong>The COVID‑19 pandemic has resulted in a severe shortage of nurses in health care systems worldwide. The first and acute phase of COVID‑19 was challenging for health systems due to the unknown nature and complexity of the disease. This study aimed to extract the factors that influenced the shortage of nurses during the first and the acute phase of COVID‑19. <strong>Materials and Methods: </strong>Based on the PRISMA guidelines, a systematic search was conducted in PubMed, ScienceDirect, Cochrane, Scopus, and Web of Science databases from the start of the COVID‑19 outbreak to 2021. Studies were screened separately; the inclusion criteria were applied. The risk of bias was assessed with the Hoy tool, and data extraction was conducted. Factors were extracted and categorized by thematic analysis. <strong>Results: </strong>In total, 1035 studies were found. Finally, 11 original papers met the eligibility criteria. Most studies (seven) were cross‑sectional. After thematic analysis, the results showed that the nursing shortage during the COVID‑19 outbreak can be attributed to three main categories: 1) <em>The pandemic perceived threat</em>, 2) <em>Internal and External Factors</em>, and 3) <em>Professional and Psychosocial Support. </em><strong>Conclusions: </strong>This study highlighted the need for the healthcare system to switch from reactive crisis management to proactive and resilient strategies. To prevent nurse burnout and attrition and guarantee the continuity of care in future emergencies, it is essential to plan to address perceived threats and strengthen support systems in addition to implementing multilevel interventions in organizational and psychological domains. This integrated strategy will convert vulnerability into readiness and resilience.</p><p> </p>http://ijnmr.mui.ac.ir/index.php/ijnmr/article/view/2408http://ijnmr.mui.ac.ir/index.php/ijnmr/article/download/2408/70707995