@book{3790,
	author = {Hansen, Christian Holm },
	title = {Assessment of protection against reinfection with  SARS-CoV-2 among 4 million PCR-tested individuals in  Denmark in 2020: a population-level observational study /},
	url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7969130/}
}