Can I mix and match my booster dose? All of your questions about COVID right now, in one place.

COVID-19 has been cropping up a lot more in the headlines lately.

With cases continuing to rise during winter, Aussies are now being urged to work from home where possible, wear masks in crowded areas and get our booster shots. 

"This third Omicron wave for 2022 is proving to be a very, very significant one," said Health Minister Mark Butler.

"We are seeing hundreds and hundreds of thousands of Australians infected every single week in this wave." 

Watch: A thank you to masks. Post continues below.

As the country faces a third Omicron wave, we decided to round up all the questions you have about the virus, in one place.

Here's everything you need to know. 

1. What do we know about the new Omicron variants?

When Omicron spread across the globe in late 2021, the BA.1 variant quickly overtook Delta as the dominant strain. Here in Australia, we saw cases peak at more than 100,000 a day thanks to the new strain. 

A second wave of Omicron BA.2 later struck in February, which saw cases peak at 60,000 a day in April. 

Now we're hearing about two new variants sweeping across the country; BA.4 and BA.5.

These variants are more infectious than previous strains and are threatening a third wave of Omicron in Australia. 

As Professor Adrian Esterman, Chair of Biostatistics and Epidemiology at the University of South Australia, told The Quicky, there are two ways strains can become more infections. 

"One is by being better able to latch on to the human cells... and the second way is by mutating so that the virus particle can evade our immune system. In the case of BA.4 and BA.5, the huge number of genetic mutations allows it to do both those things."

On top of variants BA.4 and BA.5, we're also being told to keep an eye on another strain nicknamed 'Centaurus'.

This variant, also known as BA.2.75, was first identified in India and has already spread in Australia, New Zealand Japan, Germany, the UK and the US.

Earlier this month, the European Centre for Disease Prevention and Control (ECDC) designated it a "variant under monitoring". 

2. Can I get a fourth COVID shot? 

Last week, millions more Aussies became eligible for a second COVID-19 booster.

The Australian Technical Advisory Group said those aged between 30 and 49 can now receive a fourth COVID-19 shot if they chose to, but this is not a formal recommendation.

Instead, they recommend an additional shot to those over 50.

Previously only those over 65, in aged or disability care, or immunocompromised were able to get a fourth dose. 

Sydney GP Dr Brad McKay says it's "really important" to get a booster, if you are eligible. 

"If its been over three months since having your last vaccine, or if it's been over three months since getting COVID itself, then your immunity will be waning quite a bit, and you'll be vulnerable to infection," he told The Quicky. 

"It's really important to get [a booster]. It will keep you out of hospital a little bit more, it will stop you from being able to get COVID and spreading it to your relatives, which is also super important if our hospitals are full."

He also said he's "frustrated" that more than 30 per cent of Aussies haven't had their third dose yet. 

"People who are out there trying to get their fourth dose, good on you... If you're in that 30 per cent, who have just had two doses, please go out and get your third dose."

Listen to Professor Adrian Esterman and Dr Brad McKay's full interview on The Quicky. Post continues below. 

3. Can I mix and match my booster dose? 

Pfizer and Moderna are recommended for booster shots for people 18 and over, regardless of which vaccine you had for your first two doses. 

Those aged 16 to 17 can only get the Pfizer vaccine. 

AstraZeneca or Novavax can also be used if you can't have a mRNA vaccine (such as Pfizer or Moderna). 

There is limited data on how mixing vaccines for your second booster dose specifically impacts protection. 

However, leading infectious diseases expert Professor Sharon Lewin previously told Mamamia that while there is a "theoretical benefit" to mixing shots for your first booster, she doesn’t believe it makes a difference.

Referring to a large UK study which tested nine different boosters on top of AZ/AZ or Pfizer/Pfizer, Professor Lewin continues, "All the vaccines that used mRNA, in either Pfizer or Moderna, gave the biggest boost of antibodies for both people that had AZ/AZ or had Pfizer/Pfizer."

4. What is a 'multi-demic'? 

You may have heard the word 'mult-demic' floating around lately.  

This refers to the number or respiratory viruses currently sweeping across the country. 

"We're facing a multi-demic of respiratory viruses," Sydney University infectious disease expert Professor Robert Booy told the Courier-Mail.

"There's three or four of them causing trouble - influenza, RSV, para-influenza, adenovirus, HMPV... there are a lot.

"Because [we] were locked down for two years, the level of natural immunity dropped off against flu and COVID, so we have a lot of cases and deaths due to Omicron and the opening of a society with less natural immunity."

As such, our health care system has been placed under additional pressure. 

"Our hospitals are full of patients coming in now with COVID. It was already full with people coming in with influenza. And this is influenza where people haven't had vaccinations for the past couple of years... So often people are feeling pretty lousy from flu," said Dr McKay. 

"On top of that, we've got all of the regular cases coming in, so just normal health problems. We've also got disasters everywhere with floods, and people becoming homeless from flooding, people getting injuries from being in floodwaters... So it's just a horrible sort of mess of potential medical problems that are happening all around the country at the moment."

5. Will mask mandates come back?

Right now, we're hearing talk amongst several states and territories about the possibility of reintroducing some COVID-19 restrictions, namely mask mandates. 

Last week, Victoria knocked back official COVID-19 health advice for mask mandates to return in schools, early childhood centres, retail stores and hospitality venues. 

Acting Chief Health Officer Ben Cowie advised Health Minister Mary-Anne Thomas to reinstate the mandates, but she instead opted to strongly recommend Victorians wear masks indoors and in crowded outdoor spaces.

"I made a decision based on the advice that I had received that further mandating masks was not the most effective way to get the message out about the importance of mask wearing," she told reporters on Tuesday. 

In NSW, Chief Health Officer Dr Kerry Chant urged people to consider wearing masks in enclosed spaces to curb the spread of the virus. 

Professor Esterman told The Quicky he would like to see mask mandates return around the country. 

"I was really concerned when various state and territory governments removed the face mask mandates... I think face masks should be worn inside places like retail settings [and] public transport, I'm not talking about just generally going out for a walk or anything."

Masks are still compulsory to wear in some settings, including on public transport in states like New South Wales, Victoria, Western Australia, ACT and Queensland.

There hasn't been any suggestion of any of the other COVID restrictions being re-considered, as of yet. 

6. What do I need to know about the new changes to the reinfection windows?

Last week, NSW and Victoria revised their COVID-19 reinfection periods from 12 weeks down to four.

This means people who have previously had COVID-19 should test for the virus after 28 days since their isolation ended if they are experiencing symptoms.

People who test positive again will need to follow the relevant health advice and will be reported as new cases.

Dr Kerry Chant said the reduced reinfection period was due to the new Omicron variants BA.4 and BA.5.

"They are more able to evade immunity gained from previous infection and vaccination reinfection is more likely and possible just weeks after a prior infection," she said.

"We’re urging people who have recently had COVID-19, even if they left isolation in the past four weeks, not to be complacent. If you develop symptoms again, make sure to test and isolate."

WA and the ACT have also enacted the new measures.

7. Can I access anti-viral medication? 

Last week, it was announced more Aussies will be able to access potentially lifesaving COVID-19 antiviral treatments.

People over 70 who test positive to the virus can now access antivirals on the Pharmaceutical Benefits Scheme. 

Access has also been expanded to people over 50 with two or more risk factors for severe disease and Aboriginal or Torres Strait Islander people over 30 with two or more risk factors. Anyone 18 or over and immunocompromised may also be eligible.

More than 73,000 Aussies have already benefited from the antiviral treatments, which are taken as a tablet or capsule, and help stop infection from becoming severe.

- With AAP. 

This article was originally published on July 13, 2022 and was updated on July 20, 2022.

Feature Image: Getty.

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