One of Victoria’s few positive coronavirus cases reported this week could be Australia’s first case of reinfection.
If confirmed, it’s not surprising, health officials say. There has been murmurs of second infections since the pandemic began, and the first official case was confirmed in August. Still, there’s only been six confirmed worldwide.
In Victoria’s case, the man first tested positive to COVID-19 in July. He was then counted as one of the state’s positive cases on Tuesday.
On Wednesday, Victorian Premier Dan Andrews told his daily press conference it was more likely to be a second infection, rather than a lingering initial infection.
Final medical tests are underway for absolute confirmation.
“There have been very few reported cases of reinfection around the world. It is also the case that persistent shedding over a long period of time can be a feature of this virus,” Mr Andrews said.
“This is understandably frustrating for everyone involved, whether this is in fact a positive case or not, but we do take a very cautious approach, and I think that is the best way to go.”
Overall, medical experts say it’s no great reason to panic – in fact, it can help us learn more about the virus and how to best overcome it.
La Trobe University epidemiology associate professor Hassan Vally said it was accepted knowledge that some viruses provide life-long immunity, while others only cover a short term.
And since COVID-19 is less than one year old, we’re not sure which camp it falls into just yet.
“So far … there have been very few cases of reinfection reported,” Associate Professor Vally said.
Associate Professor Vally said sheer mathematics came into play: The law of truly large numbers says when the numbers are big enough, improbably events happen.
“We have obviously seen a very large number of infections now around the world and so we will start to see unlikely events occur,” he said.
Understanding reinfections in COVID-19 will have implications for how effective vaccines are developed, he said.
Patient zero – version two
The first confirmed case of a second reinfection was a 33-year-old man in Hong Kong.
He was infected during Hong Kong’s first wave and was discharged from hospital after he recovered in April.
About four months later he tested positive again after returning from a trip to Spain via Britain on August 15.
It was determined the second infection was a different strain from the first – he had definitely caught the virus twice.
The man’s second infection was only picked up due to routine testing, he was asymptomatic.
This could be the sticking point in how serious and common reinfections are, respiratory diseases expert Brian Oliver said.
“What we know from other cases of reinfection is that the second infection is very mild, and sometimes occurs without causing any symptoms at all,” Professor Oliver said.
“I don’t think that we need to be worried about the possibility of reinfection. When we are vaccinated it doesn’t mean that an infection will not occur, it just means that our body is primed to deal with the infection and so the effects of the infection are reduced.”