Five reasons NSW Covid case numbers have stayed low since reopening - The Guardian Australia

When New South Wales exited lockdown in October, the premier, Dominic Perrottet, warned that with extra freedoms would likely come extra cases and hospitalisations.

Health experts name five key reasons why NSW has managed to keep case numbers so low while reopening its economy to the world.

Gregory Dore, an infectious disease physician and epidemiologist at the Kirby Institute, said the main reason case numbers were much lower than predicted was the effectiveness of the vaccine at containing outbreaks had been underestimated.

A vaccination blitz in hard-hit hotspots in NSW pushed some LGAs in south-west and western Sydney from having the lowest first-dose rate in the city to the fastest vaccination pace nationwide. On 1 August, just 33% of south-west Sydney had received a vaccination dose. Just two months later, the figure was 91.8%.

Optimal immunity after vaccination comes around a fortnight after receiving a second dose. But protection against severe disease may only require a lower level of immune response, and clinical trials have found the Pfizer vaccine provides partial protection just two weeks after the first vaccination dose.

With a large proportion of recently vaccinated people circulating in the population, immunity levels were high, as was protection against severe infection.

Dore said as well as underestimating the effectiveness of the vaccine, modelling may also have overestimated the severity of the Delta strain.