This is Dr Jamie Pearce from Elite Medical Centre.
Thesedays we have been asked by many of our patients regards to AstraZeneca and Pfizer Vaccines, the recommended gap between the 1st and the 2nd doses etc.
I created this FAQs based on the latest announcement of Victorian government and statistics we got so far.
Will it be less effective if I get the second dose 6 weeks later instead of 12?
In initial clinical trials for the vaccine it looked like the majority of the immune response from the first dose had occurred by about 4 weeks. However, later studies
showed that a longer gap may be better. They studied how effective the vaccine was at preventing an infection with symptoms:
- Efficiency in those who waited less than 6 weeks = 55.1%
- Efficiency in those who waited 12 weeks or more = 81.3%
However, this study was based on the initial COVID strain.
Is the vaccine less effective against the delta variant of COVID?
A newer study has looked at the delta strain. They studied how effective the vaccine was at preventing symptomatic disease in people who had 2 doses 12 weeks apart:
The first dose on it´s own was only around 30% effective, but this rose to nearer 70% effectiveness after the second dose.
The effectiveness at preventing hospitalisation or death from COVID may be much higher than the numbers above which are about preventing any form of symptoms from infection (mild or severe).
Why has the recommended gap between my doses changed from 12 to 6 weeks?
The low effectiveness of just one dose, coupled with rising case numbers in Melbourne shows how important it is to get the second dose. The benefit from getting the second dose sooner might outweigh
the risk of not giving the first dose as long to work.
Unfortunately, there isn’t any data showing how effective the vaccine is against delta when given 6 weeks apart – so guidance is being made on ‘our best guess’ at the moment.
It’s also worth remembering that the second dose needs time to work too, as a rough guide this might be 2-3 weeks after each vaccination.
Can I choose when I get my second dose?
Absolutely. The boxes on the next page might help you decide. You’re eligible to receive your second dose any time from 4 to 12 weeks after the first. If it’s already been more than 12 weeks since your first
dose, don’t worry, ring us to book in as soon as you can.
Pro´s of getting a second dose sooner:
✓ Boosting your immunity to covid
✓ A good idea for people who:
- Are at risk of exposure eg
those who can’t work from
- Those with health conditions
like lung disease putting them
at higher risk of severe
disease from COVID.
- Need to travel to higher risk
places eg NSW or abroad.
Con’s of getting a second dose sooner:
✓ There’s a worry the vaccine may
not be as effective.
✓ This may be a better option for:
- Those who are working
from home or able to
considerably reduce their
- Those who are young,
otherwise well and at less
risk of severe covid
Are there any other risks from getting the second dose?
The great news is that in Australia, after more than 9 million doses administered, there hasn’t been a single case of blood clotting (TTS) after the second dose.
Meaning it’s extremely safe to go ahead and get your second dose.
I’m now eligible for Pfizer, can I get that as my second dose?
Apart from for the very very few patients who had a severe reaction to the first dose, patients are only able to receive the same vaccine for their second dose. This is a national policy and so won’t change if you attend a different vaccination centre. As discussed though, the second dose is safe and incredibly important to boost your immunity.
Will there be a booster available?
You may have read that Moderna is in the pipeline and whilst we’ve not had any confirmation yet, we suspect there will likely be an accelerated booster jab plan which might further help to make up for any
reduced immune response from shortening the dose interval.
I still have more questions, can I speak to a doctor?
Yes, please let reception know and they can arrange an appointment – we ask that this is a telephone appointment wherever possible. We particularly suggest anyone taking immunosuppressant medication or planning chemotherapy to speak to us or your specialist.
You can always read more and get the latest news about the vaccine rollout here.