There have been 13 Covid outbreaks in three months in Australia as Delta continues to spread havoc throughout the country.
The infectiousness of the virus is outpacing the test-and-trace procedures that states like NSW have previously used to keep cases under control, forcing every jurisdiction into lockdown at some point except Tasmania and the Australian Capital Territory.
Melbourne University clinical epidemiologist Professor Nancy Baxter said Delta was about five times more infectious than the original Wuhan strain, which was making it difficult to control.
Delta is also showing up the weaknesses in Australia’s hotel quarantine, with several Queensland breaches in recent weeks, despite the halving of overseas arrivals.
The continuing number of high cases in NSW has some experts worried the state has lost its chance to get cases down to zero and Greater Sydney may need to be in lockdown until Christmas.
However, NSW Premier Gladys Berejiklian has pinned her hopes on vaccination, saying the city may be able to emerge from the current lockdown on August 28 if vaccination rates hit 50 per cent of adults over 16 years.
So far around 19 per cent have been fully vaccinated.
The infectiousness of the Delta variant is being described as a “game changer” in management of the pandemic and means vaccination is increasingly being seen as the key to exiting lockdowns.
But leaked data in the United States has pointed to the limitations of vaccination and the possibility that measures including mask wearing may need to continue until higher rates of immunity are achieved.
About 70 per cent of adults in the United States have now been vaccinated (making up about 50 per cent of the total population) but there has been a resurgence of the virus in recent weeks, something’s that’s been blamed on Delta.
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A leaked Centres for Disease Control and Prevention (CDC) slide presentation, obtained by The Washington Post, suggests Delta spreads as easily as chickenpox, and is more transmissible than the common cold or ebola.
It also appears to be causing more severe illness than earlier variants, with concerns that officials must “acknowledge the war has changed”.
In the wake of the report, the CDC again recommended mask wearing in high-risk areas, even for those who have been vaccinated.
However, US scientist Anthony Fauci has said the US is unlikely to be sent back into lockdown despite the recent surge in cases, although noted that America is in for “some pain and suffering in the future”.
We won’t be able to do whatever we want
Prof Baxter said the CDC finding showed Australians can’t think they will be able to do whatever they want once 50 per cent of the population is vaccinated.
“You can’t think of vaccination as the only thing between us and freedom,” she said.
Last week it was revealed that lockdowns in Australia would begin to be phased out once 70 per cent of adults were vaccinated, with further freedoms once 80 per cent were vaccinated.
This is equivalent to around 56 per cent and 64 per cent of Australia’s total population when children are included.
Prof Baxter said vaccination was highly protective against severe illness and hospitalisation but was not as effective at preventing someone from getting Delta, compared to previous strains.
She said one of the most significant findings in the CDC document was data showing that if someone does get infected with Delta, they appear to be just as contagious as those who aren’t vaccinated.
“It’s more infectious and more deadly if you get it,” Prof Baxter said.
“Those who are vaccinated could get a mild disease but they are infectious and are certainly capable of transmitting it.”
The CDC slide set also indicates breakthrough infections among vaccinated people are not as rare as previously thought, with about “35,000 symptomatic infections per week among 162 million vaccinated Americans”.
A review of findings from other countries shows that while the original Covid strain was as contagious as the common cold, each person with Delta infects on average eight others, making it as transmissible as chickenpox but still less than measles.
Reports from Canada and Scotland also suggest Delta might be more severe, with higher odds of hospitalisation. In Singapore, too, it raised the odds of ICU admission and death.
While data around vaccine efficacy varies across different countries, the CDC has estimated being vaccinated is about 90 per cent effective against severe disease and death, and at least 67 per cent effective against infection.
‘It is nowhere near over’
One of the superspreading events that has shocked authorities the most has been an outbreak in one of the country’s most vaccinated towns.
More than 95 per cent of Provincetown’s permanent residents have been vaccinated but it still played host to a huge outbreak that has been linked to 900 cases.
It’s thought the outbreak began when high numbers of visitors flocked to the tourist town in Massachusetts over the July 4 weekend, partying in clubs and at house parties in a return to pre-Covid life.
But weeks later the town was grappling with a serious outbreak that included about 200 permanent residents testing positive.
Roughly three-quarters of people were vaccinated, a preliminary report on the outbreak released on Friday by the CDC said.
“Now it is clear, as clear as day, that you can be vaccinated and still get Covid,” Provincetown resident Susan Peskin told The New York Times.
“Bottom line, we have to really watch ourselves and not think it is over. It is nowhere near over.”
In more positive news, being vaccinated did seem to prevent people getting seriously ill, with only seven people hospitalised and no deaths yet reported.
Infectious diseases physician Professor Celine Gounder of New York University said this was part of the reason why the CDC changed its guidance.
“It’s not really so much for your own protection — as a vaccinated person if you have one of these breakthrough infections, you may have mild symptoms, you may have no symptoms, but based on what we’re seeing here you could be contagious to other people,” she told AFP.
— with AFP