Hoping to increase the number of coronavirus tests, the Austrian capital Vienna has a new weapon: instead of pizzas, bike couriers are now delivering Covid-19 tests.

"In the city we're speedier than cars, because we can get through dense traffic faster and don't need to look for ," said Marcus Hanauld, a 25-year-old messenger bike courier who until three weeks ago was delivering takeaways.

To test and trace potential cases faster, more than 100 bike messengers working for courier service Veloce are now delivering the city's free "gargle tests" to around 1,000 people every day.

Like many countries across Europe, Austria is battling to contain a surging number of coronavirus cases, with Vienna currently accounting for about a third of the country's overall infections.

Donning a mask, goggles and a fresh pair of surgical gloves, Hanauld hands each of the five members of the Mihailovic family a cup of saline solution, instructs them to gargle for at least half a minute, then spit the solution into test tubes which he'll take to a lab at the end of his eight-hour shift.

Veloce's bike messengers have been delivering Covid-19 tests since the beginning of October, in part due to heavy criticism that testing and contract tracing in the city of 2 million has been slow and inefficient, allowing the virus to spread rapidly.

By the end of the month, the city wants to scale up to about 200 couriers, in addition to other types of tests, such as drive-through sites and ordinary testing teams being dispatched to those who have to quarantine.

"It tastes like when we took a holiday by the sea," the family's 12-year-old daughter, who tested positive in a wide-scale testing drive at her school last week, tells her younger siblings.

Hanauld was trained to administer and correctly store the test samples in his insulated backpack as well as how to protect himself from contracting Covid-19, but refers patients to the city's free health hotline when it comes to medical questions.

"I recognised right away that he must have arrived by bike, because he carries the same backpack I had when I worked as a pizza delivery boy," the family's father, Mihalo, said.