I pull up to the garage, in the backstreets of North Melbourne, just as the sun starts to sink. I make the call as instructed and the garage door rolls open. A gloved hand waves me inside. Then the door slides shut and a squeaky metal tray is wheeled over to my car window. I tilt my head back. Time for my coronavirus test.

This all feels strangely clandestine for a medical examination but, in the new world built to combat COVID-19, testing “‘drive-throughs” have been hastily set up all over Australia – and beyond – sometimes with the promise of results pinged back to your phone within 48 hours.

So what does the coronavirus test involve? Is it as brain-scrambling as people say? What are antibody tests? And will we all be tested soon?

Why do I have to be tested?

To track a virus you can't see with the naked eye, that can spread by stealth even without symptoms, the World Health Organisation says countries must test and test often. But this virus also moves fast – it had morphed into a pandemic before global stores of testing kits could catch up, so at first many nations, including Australia, rationed tests to only those with known exposure risks. We've since opened up testing to anyone with symptoms. With more than 1 million tests already processed, Australia now boasts one of the highest testing rates in the world.

In early April, when infections were still climbing, NSW's biggest COVID-19 testing lab, NSW Health Pathology in Sydney, was running more than 2000 tests a day. The lab's director, Professor Bill Rawlinson, says testing is now critical to charting Australia's path out of lockdown, helping guide decisions such as when to reopen schools and businesses. "If we can find the cases – and we think we are finding most of them – we can get on top of this... though there are a lot more out there." Right now, less than 1 per cent of tests in Australia come back positive for COVID-19.

I don't have any of the tell-tale signs of the illness – no shortness of breath, fever, cough nor loss of smell. But do I have a sniffle, and in Victoria that's now enough to put me straight into the drive-through testing queue. I’m the last patient of the day. The garage is almost empty of cars.

“We usually do this kind of thing in a clinic, hey,” the nurse laughs as I cast a wary eye over the swab in her hand. “Open up.”

What does the test involve?

To find the virus you need to catch it in the act, either by swabbing a sample directly or by singling out the body’s immune response to the infection in a blood test. I’m here for the swab or PCR (polymerase chain reaction) test, the “gold standard” in diagnosis.

It’s considered accurate and minimally invasive (we'll see) but the actual testing part has to be done back at a lab where the sample can be examined for signs of the virus’ unique genetic code, often taking many hours to process.

Healthcare workers take swabs from where the germ is known to live – the back of the nose, the throat and sometimes from phlegm coughed up from the lungs. It can make you gag or your eyes water as the wand goes in your mouth then your nostril but it only lasts a few seconds. The problem is that if the virus is breeding further down in the lungs or elsewhere in the body, the test might miss it altogether.

That’s why, despite all the grim warnings from friends who've already faced the Q-tip – and compared the nasal portion of the test to everything from an alien probe to the Egyptian mummification process – I find myself saying these daring words: “Get as much as you can. Really ram it in there."

What does it feel like?

Have you ever accidentally shoved your toothbrush too far down your throat? That's worse than a coronavirus test. The nurse is quick, efficient and gentle. With the swab pushing into the very back of my nasal cavity, my eyes at last start to water, but by then she's already drawing it out and sealing it away for the lab.

I tell her it feels a little anticlimactic. She tells me she's impressed. "You're the only person I've done who hasn't cried. Some people sob. I've made grown men cry.”

Two days later, as promised, my phone dings. The results are negative. Still, I have a lingering suspicion – what if that cough that kept me sealed away at home two months ago was really COVID-19?

At the Walter and Eliza Hall Institute of Medical Research, Professor Ivo Mueller tells me that if I had the virus back then, it wouldn’t show up on the PCR test now. The germ's genetic material breaks down fast once it stops replicating and usually vanishes from testing range within 10 days of symptoms appearing. An Australian government spokesman adds that while in some cases swabs will repeatedly pick up virus, even in patients deemed well again, that doesn't mean it's still infectious or "alive" – although caution should still be taken.

Can a blood test tell me if I’ve had the virus?

To find out my past exposure, Mueller says, I'd need the second kind of test – a blood sample to see if my immune system has produced antibodies against the virus. My doctor tells me I can't get one yet. "And they're not that accurate anyway right now," she says.

Successfully fighting off a virus leaves us armed with antibodies ready for round two should it come back. They tend to give us at least a period of immunity if not always a lifelong shield – common coronaviruses that cause colds, for example, go away for at least a few months or a year before we become susceptible again.

But in the case of COVID-19, Rawlinson says, there are still questions about how many antibodies patients produce and how much protection they offer. Antibodies take at least a week or two to appear in our system, meaning tests done too early will miss them. And, as Mueller explains, they also drop off in number within a few months of recovery, making them increasingly hard to find in the blood over time.

“We’re looking for the ghost of a past infection,” Mueller says. “We know people get immune responses because that’s how they recover. But to stay immune to something we don’t just need antibodies, we need long-term memory cells that produce the right kinds of antibodies, [the ones that] can fight the virus off, not just warn it’s there. Our bodies remember some infections [such as measles] better than others, like malaria.”

So are antibody tests accurate?

When it comes to the blood tests themselves, not all are created equal. Experts agree that blood tests run back at labs yield the best results but tend to take more time and money – rapid finger-prick tests, meanwhile, can offer results in minutes but are less sensitive and so tend to miss more infections.

"You're using 10 microlitres of blood versus [many] times that in a blood sample,” Rawlinson says.

Mueller explains a good rapid test needs to be highly specific (returning close to zero false positives) as well as sensitive. “There’s a lot of shonky tests out there so it’s important they're all [checked].”

Despite high-profile problems with rapid tests overseas, the Australian government has already spent millions of dollars on two different sets. Independent testing performed after they were bought and approved for use by Australia's drug regulator found their sensitivity was low and they could still return false positives – which shelved plans for a mass rollout to clinics.

Rawlinson, meanwhile, is checking new lab-run blood-test kits and those are “performing well so far”. A blood test in the lab allows scientists to dig deeper into the sample: are the antibodies showing up the "right kind", those that give protection? Have they been tailor-made by the body to fight COVID-19 or are they just our generic baseline defence, or even old antibodies left over from another more common coronavirus trying their luck – and confusing the results?

"There is some cross-reactivity with immunity for [another dangerous coronavirus] SARS," Mueller says. "But maybe less than 10,000 people in the world have had that. The coronaviruses we get that give us colds, they’re quite genetically different, so we don't think we're seeing much of that but it’s still unclear."

NSW Health confirmed that its Westmead pathology centre has just started retrospectively testing 3500 pathology samples left in the lab for COVID-19 antibodies in order to help map recent infection levels in Sydney and its surrounds. "[This blood] testing is significantly more accurate than the current rapid antibody tests," a spokeswoman said.

Meanwhile, Mueller and his team are using technology they've developed for malaria testing to improve existing lab tests – in a month or so they hope to have a first-generation blood test able to tell not just if someone has been infected but when. A longitudinal study, measuring the natural decline in immune memory in recovered patients over the next year or so, could then allow them to make what Mueller calls “software upgrades” to refine the test even further.

Still, official expert advice to the Australian government in April stressed both kinds of blood tests are limited in their usefulness while question marks remain around COVID-19 immunity – and neither should be used for diagnosis. That also casts a cloud over some other nations' plans to use antibody testing to issue "immunity passports" that would clear survivors to return to society.

Will everyone be tested in Australia?

Australia’s Health Minister, Greg Hunt, has defended the government’s spending on rapid tests as part of its preparation for "population screening" in the case of a big outbreak. The idea is that if cases can be found quickly and isolated, the tentacles of the virus will be hacked back before it can build into a dreaded second wave of infections.

To that end, China has now announced an ambitious plan to test all 11 million people in the city of Wuhan, where the virus first emerged late last year and where it has begun to stir again in lower numbers after being nearly stamped out during an initial lockdown.

But Rawlinson says constrained supplies of PCR test swabs and reagents make the maths of population screening daunting. "[Twenty-five] million people [in Australia] is a lot of tests, and sometimes you have to do a few tests each."

The Australian government has not indicated the testing blitz will slow down any time soon. Victoria, which is leading the charge alongside NSW, says testing will continue within its own borders until at least the end of 2020 - almost 400,000 tests have been done since January and a total of 311,000 are expected to be processed during the expanded testing blitz running over May.

Right now, the federal government says there's enough supply of testing kits to meet demand nationally: states still have existing deals with manufacturers and the Morrison government has now acquired extra stock, including a "secure supply line" for COVID-19 testing in private pathology labs. (Both Victoria's health department and NSW Health Pathology also say they have enough supply).

But, logistically, just testing people with symptoms and (some frontline workers without them) is already causing backlogs. Behind the scenes, private labs have also been pushing for more money for each test, which are subsidised by governments.

Mueller agrees scaling up either PCR or blood testing to everyone would be a challenge. “But just here at our lab, once we have our blood [test] fully functional, we can do about 500, 600 people a day, maybe 1000, at a cost of maybe $5 each.”

Finger-prick tests may prove their value in helping nations, particularly poorer ones, through the first level of population screening, Mueller says, as positive results could then be cross-checked in the lab.

“False positives when you have low numbers, like in Australia, could tell us we had outbreaks we never did ... But testing here in Victoria [and] Australia is good right now. I don't think we'll miss a major outbreak.”