Covid-19 vaccine efficacy not as strong with Delta variant - The Australian

Vaccinologists are downplaying the significance of an Israeli study that showed the Pfizer vaccine has reduced efficacy against symptomatic infection caused by the Delta variant.

But they say the evidence indicates vaccines are still highly protective against severe disease from most Covid variants.

Israel’s Health Ministry released data showing the Pfizer vaccine appears to largely prevent hospitalisation and serious illness from Delta, but has only 64 per cent efficacy in preventing symptomatic infection from it. Three months ago, when the Delta variant was less prevalent, Pfizer’s efficacy against symptomatic infection was 94.3 per cent.

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The Israeli government has ordered studies into the need for booster shots in the wake of the data.

Nikolai Petrovsky, a Flinders University coronavirus vaccine developer and chairman of biotech company Vaxine, said the Israeli findings were not a surprise.

“What we consistently see across the board is that all of the current vaccines are not providing the same level of protection against the variants collectively as they did against the original strain,” Professor Petrovsky said.

“We don’t want to imply that vaccines are not working because they are still protecting against severe disease. But if we are talking about protection against asymptomatic infection or prevention of transmission, then it is increasingly clear the existing vaccines are not effective in these situations, particularly when they are dealing with the variants.

“Of course, just like flu vaccines, we know these vaccines protect mostly against hospitalisation and death. So it should come as no surprise that with Covid-19 we see the same thing.

“Currently, the main rationale for vaccinating people against Covid-19 is to reduce the number getting extremely sick, thereby taking the pressure off hospitals. This will remain the case until we have vaccines that can better block infection and transmission than the current generation of vaccines – this is what my own research is directed to.”

Jamie Triccas, a professor of medical microbiology at the University of Sydney, said the Israeli study was the latest in many studies that had shown vaccines’ reduced efficacy against variants.

Public Health England in May found the protection of two doses of Pfizer against the variant was 88 per cent, and just 66 per cent for AstraZeneca.

“But the really critical thing is that all of the real-world studies we’ve seen so far with the variants show that the vaccines hold up very well against preventing severe infection and hospitalisation and death,” he said.

Professor Triccas said boosters were likely to be the key to strong immunity against variants. Moderna is working on a multivalent booster shot, of which Australia has ordered 15 million doses, and Pfizer and AstraZeneca are also developing boosters. “The evidence suggests that the immunity induced by current vaccines holds up quite well over time, but it looks like there is a decay or reduction in immunity over time.

“So it may be that if you have reduced immunity against the variants, a booster could bring you back up to a very high level or above the level you were with the previous vaccine. And … give you that extra level of protection.”

Health Editor

Sydney

Natasha Robinson began her career at The Australian in 2004. A Walkley awards finalist and a Kennedy Awards winner, she was appointed Health Editor in 2019, and has covered rounds including national affairs, in... Read more

Vaccine efficacy not as strong with Delta

10:47 AMNATASHA ROBINSONVaccinologists are downplaying the significance of an Israeli study that showed the Pfizer vaccine has reduced efficacy against symptomatic infection caused by the Delta variant.

Push for kids to receive the Pfizer jab

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https://news.google.com/__i/rss/rd/articles/CBMijgFodHRwczovL3d3dy50aGVhdXN0cmFsaWFuLmNvbS5hdS9zY2llbmNlL2NvdmlkMTktdmFjY2luZS1lZmZpY2FjeS1ub3QtYXMtc3Ryb25nLXdpdGgtZGVsdGEtdmFyaWFudC9uZXdzLXN0b3J5LzFmYTczMzE5ZTNmM2RiYTc2YjdkYWY4OGZiODliNDZm0gGOAWh0dHBzOi8vYW1wLnRoZWF1c3RyYWxpYW4uY29tLmF1L3NjaWVuY2UvY292aWQxOS12YWNjaW5lLWVmZmljYWN5LW5vdC1hcy1zdHJvbmctd2l0aC1kZWx0YS12YXJpYW50L25ld3Mtc3RvcnkvMWZhNzMzMTllM2YzZGJhNzZiN2RhZjg4ZmI4OWI0NmY?oc=5

2021-07-06 12:59:00Z
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