Effectiveness of natural immune protection against COVID-19 reinfection: systematic review with meta-analysis


Abderrahmane Moundir
Abderrahmane Errami
Jalila El Bakkouri
Ahmed Ben Abdelaziz
Ahmed Aziz Bousfiha


Introduction: The future of the COVID-19 pandemic depends on the evolution of the virus and immune protection stimulated by vaccination
or upon exposure to natural infection. While most research focuses on vaccine efficacy, data remain unclear on the efficacy and duration of
natural immune protection against infection. In this article, we aim to determine the efficacy of natural immune protection against reinfection with
COVID-19 or severe COVID-19.
Methods: We performed a systematic review of available studies in electronic databases followed by a meta-analysis to determine the efficacy
of natural immune protection against COVID-19 reinfection and severe infection.
Results: Of the 414 studies identified for the full review, 8 studies met the inclusion criteria and were analyzed. The total number of individuals
participating in the 8 studies included 19,837,147 people. Individuals with a history of SARS-CoV-2 infection (1,9% [0,6%-3,1%]) had a lower rate
of infection than individuals without a history of infection (7,1% [3,9%-10,1%]). The mean efficacy of natural immune protection against reinfection
was 84,7% [78,5%-90,9%], while the mean efficacy of natural immune protection against severe COVID-19 infection was 96,9% [94%-99,6%].
Conclusion: These results indicate that natural immune protection against reinfection is high, particularly against severe COVID-19. However,
further research is needed to determine the duration of natural immune protection and the impact of different variants of SARS-CoV-2.


COVID-19, Natural immune protection , Effectiveness, Reinfection, Systematic review, Meta-analysis.



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