How long will the COVID vaccines last? Here’s what we know so far

Next week, the Pfizer vaccine rollout will begin and the first COVID-19 jab on Australian soil will take place.

The Pfizer option will be given to priority groups (which includes quarantine workers and people living in aged care facilities) but most Australians will get the yet-to-be-approved Oxford-AstraZeneca jab.

Health Minister Greg Hunt yesterday announced Australians would begin receiving the vaccine from February 22, with 60,000 doses to be rolled out across the country by the end of the month.

But how long will these vaccines last?

Can Australians expect to roll up their sleeves every year or so to get a booster shot?

Here’s what we know — and don’t know — about how long the Pfizer and AstraZeneca vaccines will protect us after we’ve been inoculated.

How long do vaccinations usually remain effective?

There’s no “typical” timeframe that a vaccine will protect us for — it’s different for every vaccine.

To recap, vaccines help your develop an immunity to a virus without you having to contract it and get sick.

“Most vaccines, and we hope the COVID vaccine, produce a much higher level of immunity than natural infection,” Burnet Institute professor of international health Michael Toole said.

But not all vaccines do this in the same way or protect us for the same period of time.

The two-dose measles-mumps-rubella (MMR) vaccine, for example, contains a weak, live version of the viruses and works so well that it offers lifelong protection.

“Measles — the protection is lifelong, smallpox lifelong, other vaccines needs boosters after a while, typhoid fever, hepatitis,” Professor Toole said.

How long will the COVID vaccines remain effective?

It’s too early to tell. There’s a lot more research about the efficacy of COVID-19 vaccines — meaning how well a vaccine prevents someone from getting the virus — than about the lifespan of the vaccines themselves.

As University of Sydney professor of medical microbiology James Triccas explained, this is because we’re only a year into the pandemic and researchers are tracking the longevity of people’s immune responses in “real time”.

In December, Moderna published a study that showed their COVID-19 vaccine still showed good immune responses four months after the date of vaccination — results which Professor Triccas said were encouraging.

“That’s the best I’ve seen in terms of how far they’ve measured out,” he said.

Research also shows the Pfizer and AstraZeneca COIVD vaccines protect against disease, hospitalisation and death, Professor Triccas added.

Both Professor Triccas and Professor Toole said we simply don’t know how long the COVID-19 vaccines will last — although we may have a clearer picture by mid-year.

“That’s the short and only answer really because we just don’t know,” Professor Toole said.

Why do some vaccines need a booster and others don’t?

This depends on how our bodies respond to the vaccine. For example, the MMR vaccine offers lifelong protection against measles.

Professor Toole says this is because live vaccines are “more of less the same as being infected” and it’s been proven that people don’t get measles twice.

Measles is also a stable virus and doesn’t mutate — unlike COVID-19, which has already evolved into different variants.

Professor Triccas says it’s difficult to predict which vaccines will be longer-lasting, but it is helpful to look at what happens following infection with the virus itself, because vaccines “tend to mimic” that response.

That’s because vaccines aim to induce the same immune response your body develops when fighting off the actual virus.

But not all immune responses are as strong as one which fights off measles.

“For other viruses and bacteria, just the nature of the immune response that develops after the infection or after the vaccination does not last as long and you need to boost it,” Professor Triccas said, which is why some vaccines need a booster shoot to keep you protected.

If the Pfizer and AstraZeneca COVID-19 vaccines don’t last long, Professor Toole says the most “likely outcome” is we’ll need a booster jab or an annual shot that’s adapted to fight off different variants.

Will I feel sick after the COVID vaccine?

According to clinical trials, yes, you may feel a bit unwell after the jab — especially after the second one.

The US Centers for Disease Control describes these as “normal signs that your body is building protection”.

Think of it as a positive sign — the vaccine is doing what it’s meant to and helping your body develop immunity to the virus.

“One in 100 will get more severe side-effects after the second dose — nausea, poor appetite — maybe some gastric upset.”

It’s also important to remember these side effects are temporary, most last no more than a couple of days and patients recover without any problems.

Will the vaccine protect from COVID straight away?

No. You will need two doses of the vaccine to be properly protected.

And it’s worth remembering that the vaccine won’t necessarily stop you from getting COVID and spreading it, but will help your body not to get sick if you do contract it.