It's just more than a year since the start of the COVID-19 pandemic and worldwide vaccinations are already under way.
Unsurprisingly, after all the upheavals of 2020, some people are wondering how these vaccines will work and whether they are safe.
Although the technology being used to make COVID-19 vaccines is relatively new in terms of vaccine production, it has already been used for some time to develop medicines to fight important diseases such as various kinds of cancer.
Humans are really walking germ factories.
Although most germs help to keep us healthy and perform useful functions like helping us digest our food and protect our skin, a few germs - called antigens - can make us sick.
When our body identifies an unfamiliar antigen, such as COVID-19, it sets about protecting us from it by making antibodies.
Vaccine scientists use bits of these germs to get our bodies to make antibodies.
Most people are now familiar with the image of a COVID-19 virus resembling a ball with spikes on it.
The virus uses these spikes to attach to our cells, to break in, multiply, and make us ill.
Scientists used the genetic code for COVID-19's spikes (called mRNA) to make vaccines which cause our body create antibodies. In fact, people make better antibodies through vaccination than by recovering from COVID-19 disease, which is a very good reason to be vaccinated.
Although these vaccines have been created in a very short time, like all new medicines, COVID-19 vaccines have been rigorously tested using three stages of clinical trials.
At each trial stage, the vaccine must prove safe, must not cause illness and must cause the recipient to make the right protective antibodies.
The first trials involve small groups of healthy adults, progressing until the vaccine is considered safe to be given to whole populations.
A fourth monitoring stage keeps a very close eye on how they work in the general population, who are not necessarily all healthy.
In Australia, all vaccines are also carefully vetted by two expert groups - the Australian Technical Advisory Group on Immunisation (ATAGI), and a special Therapeutic Goods Administration (TGA) committee.
All vaccines were once new and used new technology.
Thanks to vaccines, in Australia there is no more paralysis from polio, suffocation from diphtheria, or death from smallpox; all because of advances in vaccine technology.
Dr Priscilla Robinson is an Adjunct Associate Professor in the School of Public Health at La Trobe University.
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