Will I be immune after getting the vaccine?
Since early 2020, people have been banking on a safe, effective coronavirus vaccine to help secure a return to normal life. The rollout of Australia's first COVID-19 vaccine, the Pfizer-BioNTech jab, is now only a few weeks away.
All of the coronavirus vaccines currently in use around the world are given in two doses, a few weeks apart. But, the protection the jabs will give you isn’t instant.
RMIT immunologist Dr Kylie Quinn said it takes about two weeks for the body to start generating enough antibodies to protect itself against the virus, but ‘protection’ doesn’t necessarily mean ‘immunity’.
Dr Kylie Quinn, an immunologist from RMIT. Source: SBS / , RMIT
“There are different levels of efficacy,” she told SBS News. “Some vaccines are able to prevent infection altogether - that's what we would call sterilising immunity - but that's really hard to achieve with vaccines.”
“The next level of immunity is where we might not be able to prevent infection, but it might not progress to the point where it causes disease or makes us feel sick.
“And the next level below that is where we might be able to get infected, but we would be able to prevent that from developing into severe disease.”
Can I still spread the virus after I’ve been vaccinated?
It’s still too early to tell if Australia's vaccines will prevent infection altogether or just the severe disease that infection causes.
If the latter turns out to be true, it means the vaccine will stop you from getting sick, but it won’t necessarily stop you from hosting and spreading the virus to others.
But experts say that should not be cause for alarm. Dr Quinn says questions like these are very much a normal part of all vaccine rollouts.
“With transmission, you need to be making enough virus to be able to affect someone else in an efficient way, and we don’t have any read on that with these vaccines at the moment,” she said.
“With any vaccines, what happens after the rollout is phase four. Phase four is when the vaccine is now out in the community and we’re monitoring how people are responding to it, but also how the virus is responding to that increased level of immunity within our population. That’s quite normal.”
How long will the vaccine keep me safe?
This is another question that scientists can’t answer just yet, although trial results are all pointing to a good level of protection months after immunisation.
Vaccines work by introducing your immune system to a blueprint of a virus. The immune system - tricked into thinking it's the real virus - recognises that blueprint as a threat and begins to build antibodies to protect you against it.
That means if you become infected with the real virus in the future, your immune system will know how to fight it.
Dr Quinn says the lifespan of those antibodies all depends on our bodies’ immune memories.
“Immune memory is how our immune cells actually recognise and remember an infection, so they can respond to it months and years later,” she said.
“We don’t know how long that immune memory will last with the SARS-CoV-2 vaccines, but we’re getting a pretty good read from people who have been previously infected or vaccinated about eight or nine months ago and have still got really good levels of immune memory, so that’s boding really well.”
What if new variants keep developing?
Over the past few months, newer variants of COVID-19 have emerged in the UK, South Africa and Brazil.
These variants have different mutations that make the virus easier to spread from one person to the next, but there’s no evidence yet that they result in more severe sickness.
New variants do pose a challenge in that they make it harder for your immune system to recognise the virus and launch a fight against it. But Dr Quinn said that shouldn’t render our current vaccines useless.
“At that point, we could consider adapting our vaccines and changing them, just like we do with the flu, from year to year,” Dr Quinn said.
“We’ve got some really good vaccine designs for that. mRNA vaccines [which includes the Pfizer/BioNTech vaccine] and the Novavax vaccine are perfect for that.”
When will we reach herd immunity?
Herd immunity is when the whole community becomes protected from a virus because enough people have either been infected or vaccinated.
That makes it incredibly unlikely that the virus will continue to spread because not enough people are able to host it.
But how many people will need to get vaccinated for Australia to reach herd immunity?
Professor Sharon Lewin. Source: SBS / , The Peter Doherty Institute for Infection and Immunity
Professor Sharon Lewin, the director of The Peter Doherty Institute for Infection and Immunity, said that magic number will depend on whether Australia's vaccines can block infection entirely or just block severe disease.
“Assuming that the vaccination stops you becoming infected or dramatically reduces your chance of becoming infected, then, on average, about 60-70 per cent would need to be vaccinated,” she told SBS News.
“If the vaccine is modestly effective at blocking infection, then you would need to vaccinate more people.”
A Department of Health spokesperson said the government is “on track” to complete its vaccination program by October.
If it meets that deadline, herd immunity could be a real possibility by the end of the year - if enough people get vaccinated.
But the immunisation experts say we shouldn’t get too bogged down in the concept of herd immunity.
“What we do know is that we have a vaccine that stops people getting sick and going to hospital, and that's tremendously important because that's what we're really worried about here,” Professor Lewin said.
Can I stop social distancing once I’ve been vaccinated?
No, and not for a while yet.
In Australia and beyond, health authorities are recommending everyone still maintain social distancing and other safety measures after getting vaccinated.
Professor Lewin said those measures would likely have to stay in place until authorities have more data on the vaccines.
“You should still socially distance, wash your hands, stay home if you're sick and get tested if you have symptoms because we don't yet know whether or how effective the vaccines are in reducing infection and transmission,” she said.
“Therefore, you could be vaccinated, which means you'll be protected from going to hospital - we think to almost 100 per cent effectiveness - but you may still acquire the virus and therefore spread it to others.”
That means while you may not become unwell, the people you could potentially spread the virus to could if they haven’t been vaccinated yet.
When will I be allowed to travel overseas?
Unfortunately, it looks like Australia’s border closures will be one of the last things to change after the vaccine rollout.
SBS News asked the Department of Health what the threshold for restarting international travel would be after the vaccine rollout begins.
“Due to the current uncertainty as to whether vaccination would stop a vaccinated individual transmitting to others, and while COVID-19 is a significant disease in the world, the public health risk posed by international travel remains high,” a spokesperson said.
“While no formal decision has been made, the government's expectation would be that whilst COVID-19 continues to pose a significant threat to public health globally and within Australia, returning Australians will still be required to undertake appropriate risk mitigations, including returning a negative COVID-19 test prior to flying and mandatory quarantine on arrival, to minimise the risk to the community.”
While no official border reopening plans have been announced, Professor Lewin said a high uptake of coronavirus vaccines would undoubtedly be a key factor in the return of international travel.
“For Australians, travelling to a place [after] being vaccinated would give you great comfort that should you be exposed to the virus, you're not going to get sick and end up in hospital, so it'd be a great precaution to take,” she said.
“I think once you're vaccinated, there'll be less limitations on people leaving the country.”
But returning to Australia could be another matter entirely.
“Until we know that the vaccines protect against infection, there's always the chance that people who are vaccinated will be carrying the virus, which means they will likely require quarantine,” Professor Lewin said.
“But there may be changes to how extensive that quarantine is. At the moment, we quarantine absolutely everyone that comes from any country. That may change. We may have different levels of quarantine based on whether you’re vaccinated or based on which country you’ve been to.”
People in Australia must stay at least 1.5 metres away from others. Check your jurisdiction's restrictions on gathering limits.
If you are experiencing cold or flu symptoms, stay home and arrange a test by calling your doctor or contact the Coronavirus Health Information Hotline on 1800 020 080.
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