How much immunity you have after getting Covid

You’ve had Covid – now what? Are you immune? Do you get out of isolating if re-exposed again? Here is what you need to know.

More and more Australians are testing positive to Covid-19, sparking questions over immunity and isolation rules for people who have recovered from the virus.

People reporting they feel glad they’ve got their isolation period over and done with before holidays, weddings or other big plans have been swirling the internet, and the idea of a natural immunity after infection became an even hotter topic of conversation after tennis great Novak Djokovic’s recent court battle to stay in Australia without being vaccinated.

But the reality is that in four states, whether you’ve had Covid or not, if you’re exposed to the virus again you’ll face the same isolation rules.

The good news is that after recovering you’re unlikely to catch the virus again any time soon.

Only some Australian states and territories’ isolation rules recognise this short-term protection.

Here is what you need to know.

How do isolation rules change after I’ve had Covid?

In NSW and the ACT, for one month after you are released from isolation, if you come into contact with someone with Covid (even a household contact) you do not need to isolate again if you don’t have symptoms.

In Victoria and South Australia, if you are re-exposed to Covid as a close contact within a month (specifically 30 days in Victoria) of your positive test result you do not need to isolate.

In the Northern Territory, once someone with Covid has completed their required isolation period, they are not considered to be a close contact if another member of the household tests positive and there is no specified time limit for this.

In some states if you test positive to Covid you do not need to isolate if re-exposed as a close contact within a month. Picture: NCA NewsWire / Josh Woning

All other state health department’s told news.com.au the same isolation rules applied whether you had Covid previously or not.

So, what’s with the 30 days?

What immunity do I have after I’ve recovered from Covid?

According to NSW Health, people who have recovered from Covid have a low risk of getting it again in the month after infection as most people develop some immunity.

SA Health also believes people will have some immunity to prevent reinfection at least for this long.

Infectious diseases physician and microbiologist Professor Peter Collignon, from Australian National University, told news.com.au because we don’t have all the answers, it’s likely the 30 days was a conservative recommendation.

He said we can be confident that natural infection gives you a reasonable level of immunity, but how long that period of protection lasts is still undecided.

“Does it mean you’re completely protected? No it doesn’t because people do get second infections but relatively not that commonly, so generally whether it’s after a vaccination or after a natural infection you’ll have reasonable levels of antibodies and protection for a period of time,” Prof Collignon explained.

“Provided you’ve already at least had two shots and you then get infected you are likely to have reasonable levels of protection for quite a while.”

Professor Peter Collignon believes governments are taking a conservative approach to isolation exemptions because we don’t have all the answers. Picture: AAP / Mick Tsikas

Infectious disease specialist Associate Professor Sanjaya Senanayake, from ANU, predicts this immunity could be “many months”.

“We don’t really know much about Omicron itself in terms of immunity but we know from Delta and various other strains, if you’ve had the infection you’re unlikely to get another infection – unless a new variant appears – for many months, and even the risk of that occurring is very small,” Associate Prof Senanayake told 2GB radio.

The federal department of health told news.com.au that the protection someone gains from having Covid varies from person-to-person.

“Because SARS-COV-2 (the virus which causes Covid-19) is relatively new and because lineages of concern continue to emerge, experts don’t yet know how long any natural immunity might last,” a spokeswoman said.

“People who have had Covid-19 should still be vaccinated and Australians should not rely on assumed immunity from previous infection.”

It is recommended people who have Covid still get their booster. Picture: NCA NewsWire/ David Crosling

Should I get my booster if I’ve already had Covid?

Australians are encouraged to still get their booster dose even if they’ve had Covid.

The federal department of health said evidence suggested that boosters increase protection against contracting Omicron and transmitting it.

“If a patient tests positive for Covid-19 between their first and second doses, or between their second and booster dose the patient should delay their second dose or their booster dose until they have recovered from the acute illness,” a spokeswoman said.

How long am I infectious for with Covid?

The number of days a person is infectious with Covid varies.

Prof Collignon said an immunosuppressed person can transmit the virus for quite a while, but generally people would drop off from having high levels of the virus pretty quickly.

“It’s harder when they’re asymptomatic but you usually get symptoms for a day or so, have your test and then your infectivity drops fairly rapidly three to four days after that,” he said.

It is expected that for the vast majority by seven days people would have no virus or very low levels.