Coronavirus: Two jabs needed for Delta coverage

Australians who’ve had one vaccine dose have little protection against Delta variant; immunity only rises substantially after two jabs.

People line up to receive their COVID-19 vaccination at the NSW Health Vaccination hub in Sydney. Picture: NCA NewsWire/Bianca De Marchi.

Australians who have received one Covid-19 vaccine dose have relatively little protection against the Delta variant, with immunity only rising substantially after two doses.

As health chiefs in Australia warned the Delta variant was transmitted as the result of “inadvertent” contact between people sometimes lasting only seconds, UK authorities have estimated the ability of vaccines to protect against illness from the Delta variant after one dose to be low.

Public Health England estimated the Pfizer vaccine offers only about 36 per cent protection against the Delta variant after one dose, while AstraZeneca offered around 30 per cent protection after one dose. Protection from the Delta variant rose to 88 per cent for Pfizer and 67 per cent for AstraZeneca after two doses.

Only about 5 per cent of the population in Australia have received two vaccine doses.

Queensland’s chief health officer outlined the difficult scenario facing authorities as the Delta variant continues to escape quarantine.

“If you remember at the start of this pandemic, I spoke about 15 minutes of close contact being a concern. Now, it looks like it’s five to 10 seconds that’s a concern,” Dr Young said. “So it’s just the risk is so much higher now than it was only a year ago.”

NSW Health Minister Brad Hazzard said he was as concerned as he has been since the start of the pandemic because of the transmissibility of the Delta variant, which is estimated to be about 50 per cent more infectious than the original Wuhan strain.

The Delta variant continues to spread in NSW, with 16 new cases announced on Wednesday. A superspreader event at a West Hoxton Park birthday party resulted in eight infections.

Public Health England’s weekly Covid-19 variant cases data showed that numbers of the Delta variant rose by 33,630 during the past week to a total of 75,953 cases. The Delta variant now accounts for 99 per cent of sequenced and genotyped cases across the UK.

Of the 806 people during the past week who caught the Delta variant who were hospitalised, 84 had received two doses of a Covid-19 vaccine.

The Delta variant is spreading the most rapidly among young age groups in the UK, with rates of vaccination much lower in younger people. Public Health England has said there is evidence the Delta variant causes more severe disease in unvaccinated people and is more likely to infect children.

The US Centers for Disease Control and Prevention has warned the Delta variant will likely become predominant strain in the US in the coming months.

Scientists at King’s College London who are running a project called the Zoe COVID Symptom Study have reported that individuals infected with the Delta variant display a slightly different set of symptoms to those infected with the original strain.

More people infected with the Delta variant were reporting “cold-like symptoms” such as having a headache and a runny nose. Some people infected with the Delta variant simply believed they had a cold.

Meanwhile in India, where the Delta variant first emerged last October, health authorities announced that a new mutation of the variant dubbed “Delta plus” has been recorded in 22 cases in three states, and they suspect Delta plus had again increased its transmissibility. That variant has also now been recorded in the US, the UK, Portugal, Switzerland, Japan, Poland, Russia and China.