News Your vaccine questions: How long is it effective, which is best, and what happens with new strains?
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Your vaccine questions: How long is it effective, which is best, and what happens with new strains?

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The first phase of Australia’s vaccination program has begun, hailing the  next stage in our fight against COVID-19.

Most of us are experiencing this first phase as onlookers, watching as our vulnerable peers and front-line workers get those initial precious injections.

There’s still a lot of questions about the vaccine – how it works, when you’ll get it, and what’s in it.

We asked you for all your vaccine-related questions, and you responded en masse.

And while we couldn’t answer every single one – we noticed some trends in your questions so we put those to vaccine experts.

Answering them today is the dream team from the Burnet Institute: director Professor Brendan Crabb, vaccine development expert Professor Heidi Drummer, and infectious diseases clinician Assistant Professor Joe Doyle, who also works at The Alfred hospital.

We’ll leave you with them.

I’m allergic to egg. Do any of the vaccines contain egg and, if so, am I still able to have it?

Yes, there are no egg products in the COVID vaccines, so there is no problem there.

Are the current vaccines effective against the emerging British and South African variants?

Studies are ongoing to monitor real-world effectiveness of vaccines against these variants.

What we know so far is the efficacy of current vaccines is only slightly reduced against the dominant strain circulating in Britain (reduction of up to ~15 per cent).

A greater reduction in efficacy has been reported against the strain circulating in South Africa, with efficacy reduced to between ~10-60 per cent so far, depending on the vaccine.

The good news is that current vaccines still provide very good protection against severe disease and reduce the number of people requiring hospital treatment against the variants.

Manufacturers are currently updating their vaccines to match current circulating strains of COVID-19.

Am I able to have the COVID-19 vaccination and the flu vaccine in the same year?

Yes, no problem. They are unrelated illnesses caused by unrelated viruses and are protected by unrelated vaccines.

As a general principle, you could receive any other vaccine that you would normally receive in the same year as the COVID vaccine.

People often receive many vaccines concurrently or close to each other. The current advice is the COVID vaccine should be given alone and no other vaccine for 14 days afterwards.

What do we know about the long-term side effects of the vaccines?

Increased life expectancy is likely to be the main one. That really is what vaccines deliver.

Life expectancy has been going up in pretty much every country every year for each of the past 40 to 50 years. It’s largely because of a huge decline in vaccine-preventable diseases.

For COVID vaccines, it depends on what is meant by long term because it can’t be answered at this stage beyond six months or so.

So far there are no reports of anything notable in that regard. In line with all other vaccines licensed for use in Australia, there is a very low risk, if any risk at all, of a long-term negative effect of COVID vaccine.

How long is the vaccine effective for? Will I have to have a new dose every year?

As we have only been using the vaccines in humans for a relatively short time, we do not yet know how long immunity after vaccination will last.

Two factors determine how long immunity lasts.

One is the emergence of variants that reduce vaccine efficacy.

The second is our immune system’s ability to remember to respond to infection after vaccination.

Ongoing monitoring of people that have received vaccines will help us to understand how long we maintain “immunological memory” against COVID-19. Given the emergence of variants, it is likely that we will need periodic updates to boost and broaden our immunity in any case.

Aged-care resident Jane Malysiak received the first COVID-19 vaccine in Australia on Sunday.

Is the AstraZeneca vaccine effective enough and why can’t we all have the Pfizer?

Both vaccines are highly effective at preventing symptomatic COVID-19, and at preventing severe disease. But we are still learning.

As an example of that, very recent research has shown that the AstraZeneca vaccine efficacy is better (82 per cent) when doses are spaced three months apart.

As we are able to manufacture the AZ vaccine in Australia, it means we can rapidly vaccinate our population.

The Pfizer vaccine cannot be made here, we don’t have the technological capability. It is in high demand globally and we will not have access in the short term for widespread vaccine coverage.

With the efficacy of some vaccines under scrutiny, will it be possible, at a later date, to ‘top up’ a less-effective vaccine with one that provides a wider protection? 

Firstly, despite all you read, it is not yet clear that some vaccines are substantially inferior to others.

Having said that, we are learning more all the time. If it turns out that one vaccine is significantly superior to another in some endpoints (preventing transmission for example), then there is no barrier to receiving that ‘superior’ vaccine at a later date – apart from availability of the vaccine, of course.

Are there people who should not be vaccinated? 

Individuals with specific concerns or health problems should seek specific advice about their suitability for vaccination.

Anyone with existing allergies to any vaccine component is advised to avoid vaccination.

There are no groups of potentially immunosuppressed patients that should be excluded from receiving the vaccine based on their treatment or disease alone.

Specific studies are needed to determine if the vaccines are safe and effective in children and pregnant women.

There is every likelihood they will be, but these clinical trials need to be completed before there is a strong recommendation for these groups.

What happens if there is a new strain after being vaccinated? 

If new strains emerge that reduce efficacy after being vaccinated, booster shots of new vaccines may be necessary to broaden our immunity against variants of concern.

Booster shots will likely represent prevalent pandemic strains of COVID-19. In the same way, each year the influenza vaccine is modified to represent the prevalent circulating pandemic strains of virus.

This will be an ongoing area of investigation and whether this is required will depend on how quickly variants of concern emerge and spread around the world.

Scott Morrison holds a vial of AstraZeneca vaccine at the CSL serum lab in Melbourne. Photo: AAP

I believe I’m high risk. How do I make sure I’m in a priority vaccination group?

Each jurisdiction is currently developing local procedures for delivering vaccine to the community, starting with those at highest risk.

At this stage, we know hospitals are the first to receive the vaccine to deliver to those in the first priority group; each health service will have guidelines to ensure their frontline staff or highest-priority members of the community are vaccinated as soon as possible.

The Commonwealth Department of Health have a COVID-19 vaccine website listing the priority groups for each phase of the vaccine rollout. See: https://www.health.gov.au/initiatives-and-programs/covid-19-vaccines.

You can check your eligibility at each phase of the rollout here: https://covid-vaccine.healthdirect.gov.au/eligibility