Hymn singing most likely sparked an outbreak of SARS-CoV-2 infection through airborne transmission of the virus in a Sydney church last year, researchers say.

A team of public health physicians and epidemiologists have described in forensic detail how an 18-year-old choir singer positive for SARS-CoV-2 unwittingly spread the virus to church parishioners seated up to 15 metres away.

Although the Western Sydney Local Health District researchers did not identify the church, the description and exposure dates match the outbreak that occurred at the Our Lady of Lebanon Cathedral in Harris Park in July 2020.

At the time of the outbreak, NSW Health said a confirmed case linked to the larger Thai Rock restaurant cluster attended the church on four occasions prior to diagnosis.