Five reasons why the number of NSW Covid cases has remained low since reopening | Health
When New South Wales emerged from lockdown in October, Prime Minister Dominic Perrottet warned that with additional freedoms there would likely be additional cases and hospitalizations.
Modeling predicted up to 1,900 daily cases during the state’s first easing and a second larger peak around Christmas. Burnet Institute forecasts hospitalizations peak between 2,286 and 4,016 in Sydney at the end of September.
Instead, daily cases continued to decline after ‘Freedom Day’ on October 11, when 446 cases were reported and 769 people were treated for Covid in hospital.
Almost a month later, NSW’s 14-day benchmark rate is below a, hospitalizations have fallen by more than two-thirds, and only 222 new cases of Covid were reported on Tuesday.
Health experts name five key reasons NSW has managed to keep the number of cases so low while reopening its economy to the world.
1. Underestimated vaccine efficacy
Gregory Dore, infectious disease physician and epidemiologist at the Kirby Institute, said the main reason the number of cases was much lower than expected was that the vaccine’s effectiveness in containing outbreaks had been underestimated .
Model of the Doherty Institute who informed the national plan predicted that even high levels of vaccination would not be enough to contain Covid, with 300-1,000 cases per day expected with “Average seedling” happening.
“The models underestimated the impact of vaccination on transmission and the vaccination rate in these early months, especially targeted vaccination which extends to larger geographic areas,” said Dore. âThere has been a phenomenal buy-in. “
A vaccination blitz in hard-hit New South Wales hotspots has pushed some LGAs in southwest and west Sydney to have the lowest first-dose rate in the city at the vaccination rate the fastest in the country. As of August 1, only 33% of southwest Sydney had received a dose of vaccination. Two months later, the figure was 91.8%.
2. Real-time protection
Researchers at the University of Sydney coined the term “Real-time protection” to explain how the rapid pace of vaccination may have offset the impact of declining immunity to the vaccine.
Optimal immunity after vaccination occurs about two weeks after receiving a second dose. But protection against serious illness may only require a lower level of immune response, and clinical trials have shown that the Pfizer vaccine provides partial protection just two weeks after the first dose of vaccination.
With a large proportion of recently vaccinated people circulating in the population, immunity levels were high, as was protection against serious infections.
Dore said the NSW government’s decision to keep the interval between doses of Pfizer short also allowed NSW Health to vaccinate quickly.
âThis maximized the impact in preventing infection,â he said. “In the first few months you get the best value for your money and reduce infectivity if breakthroughs occur.”
3. The severity of Delta overestimated
Dore said that in addition to underestimating the effectiveness of the vaccine, modeling may also have overestimated the severity of the Delta strain.
âI think we overestimated how much this affects your risk of developing serious illness and overestimated the length of stay in hospital. The range of hospitalized cases was less severe than they had originally imagined. “
Doherty modeling predicted that the Pfizer vaccine was 93% effective in reducing overall transmission of the Delta variant, and AstraZeneca was 86%. Later The data abroad has suggested that Pfizer and AstraZeneca are 94% to 96% effective in reducing hospitalizations.
âCompared to the original strainâ¦ we thought Delta would make it much more likely that you ended up in the hospital, putting the vaccination aside,â Dore said.
âThis is variable data, and it’s not easy. But it was thought that the virulence and severity of the strain was much greater, and that can have a marked impactâ¦ once you shorten the length of stay (in the hospital), it has a cumulative effect.
4. Maintenance of sanitary measures
University of NSW epidemiologist Dr Abrar Chughtai said NSW Health had been successful in bringing outbreaks under control by keeping key health measures in place after restrictions were eased.
Chughtai said continuing to impose masks in public places has prevented the spread of the virus. Testing rates, contact tracing and isolation requirements have also been maintained despite the lifting of caps for sites.
âWhile many models predicted a very high number of cases, NSW Health is still performing aggressive testing, tracing and isolation,â he said.
University of Sydney School of Public Health professor Alexandra Martiniuk cited the “gradual reopening of state government with vaccination a requirement for entry to most indoor locations and measures ‘social distancing’ as the key to reducing cases.
She said NSW had also maintained “excellent” testing rates, with low test positivity compared to other countries with similar vaccination levels. About 0.3% of tests came back positive in NSW, while tests had continued to exceed 50,000 per day.
Martiniuk said the warm spring weather likely encouraged people to socialize outdoors more than in other countries, but contact tracing was also key to the low positive rate.
âEighty-three percent of results are available within one day of sample collection, and 93% of positive cases surveyed by NSW Health within 24 hours of notification,â she said.
5. High vaccination rate
NSW has one of the highest vaccination rates in the world, with first doses exceeding 93% and second doses exceeding 90% on Tuesday.
The âphenomenalâ speed at which the nation has ramped up deployment runs counter to countries like the United States and the United Kingdom, which have stagnated after approaching the 50% mark.
The Doherty Institute final report, released this month, said ongoing public health measures including testing, tracing, isolation and quarantine, combined with public health and social measures, were “critical interventions” to achieve a low number of cases.
But the report also acknowledged that the pace of the vaccination rollout had “exceeded expectations”, particularly in New South Wales, the Australian Capital Territory and Victoria, which had high community transmission, placing the countries on track to meet targets 90% “much faster” than original simulations. predicted.
Martiniuk said the high vaccination rate in NSW, coupled with the stages he had emerged from the lockdown, had succeeded in keeping cases under control.
“The reopening of NSW has been fair and phased, as countries we often compare reopened much sooner and more restrictions were removed in one fell swoop, like England in July, âMartiniuk said.
“Singapore (where the number of cases is increasing) has a higher proportion of the fully vaccinated population (82%), but the majority of Singapore’s vaccines were given earlier.
“Singapore also had more reluctance to vaccinate among its older populations, hence greater severity of cases and hospitalizations.”