COVID-19 vaccination and case surveillance

NCIRS in collaboration with NSW Health conducted an analysis of COVID-19 case surveillance data during the Delta outbreak in New South Wales for the period 16 June to 7 October 2021. The aim was to describe the vaccination status of cases who had been diagnosed with COVID-19 during the outbreak. 

Our analysis found that vaccinated people were substantially less likely to become infected or have serious disease. Among the 61,800 COVID-19 cases with onset of infection during the period, the vast majority were unvaccinated, with only 6.1% of cases having had two doses of vaccine. In the peak fortnight of the outbreak, the COVID-19 case rate among unvaccinated people compared with those vaccinated with 2 doses was 10-times higher, and rates of serious infection (ICU or death) in unvaccinated people compared with those vaccinated with 2 doses was more than 16-times higher.   

The effect of the vaccine was found to be greatest against severe disease but vaccination also protected against infection.

The results of this analysis have been published in a report “In focus: Vaccination among COVID-19 cases in the NSW Delta outbreak Reporting period: 16 June to 7 October 2021”.

Read the full report here

See also COVID-19 vaccination highly effective during Delta outbreak in NSW