Australian CCTV footage suggests that “scarily fleeting” contact of “five to 10 seconds” with the COVID-19 Delta variant can infect, reports The Guardian.
Based on CCTV footage, health officials suspect it has been transmitted in encounters of roughly five to 10 seconds between people walking past each other in an indoor shopping area in Sydney in at least two instances.
There were no mask mandates in place in Sydney at the time, and the individuals were unlikely to have been vaccinated, given that less than 5% of the Australian population has received both doses. The city and some surrounding areas recently entered a strict two-week lockdown in an effort to curb the spread of the variant.
And scientists warn that unless countries escalate immunisation campaigns and practise caution, the transmission advantage of the Delta variant could tip the race between vaccination and the virus in favour of the latter.
The Delta variant, first detected in India, has been identified in at least 92 countries and is considered the “fittest” variant yet of the virus that causes COVID-19, with its enhanced ability to prey on the vulnerable – particularly in places with low vaccination rates. Research in the United Kingdom, where the variant accounts for 99% of new cases, suggests it is about 60% more transmissible than the previously dominant Alpha variant. It may also be linked to a greater risk of hospitalisation and is somewhat more resistant to vaccines, particularly after one dose.
Professor Catherine Noakes from the UKʼs Scientific Advisory Group for Emergencies (Sage) and an expert in airborne infections at the University of Leeds, suggested three possible reasons: that the people it infects have a higher viral load, meaning they would emit more particles; that people need to be exposed to less of the virus to become infected; or that a relatively short exposure time to an infected person is enough to spread the disease.
It is possible that a person could be infected by being close to a carrier for a few seconds, if the carrier were to exhale a load of virus particles and the person just happened to breathe in at exactly the wrong moment, she said. “What it doesnʼt necessarily mean is that it is transmitting that way all the time for everybody. It may well just be one of these really unlucky events.”
The World Health Organization is urging even fully vaccinated people to “play it safe” by continuing to wear masks, maintain social distance and practise other safety measures, to deal with the Delta variant. Israel, where about 55% of the population has been fully vaccinated, reimposed its mask mandate a week ago to combat the rapid rise in Delta cases just 10 days after having lifted it.
Infections more than quadrupled last week, attributed to two school outbreaks. Eligibility for the vaccine was extended to 12- to 15-year-olds last month, but take-up in the age group has been low. The rise in cases in Israel has not yet translated into an increase in hospital admissions and deaths, so the move is likely to be a precautionary one, Noakes said.
Full story in The Guardian (Open access)
See more from the MedicalBrief archives:
COVID-19 transmission – The global misuse of data
Coronavirus can survive on skin for nine hours, flu for less than two — Japan study
Israel delivers the world’s fastest COVID vaccination inoculation drive
COVID-19 in children: No room for complacency