At one point, demand for vaccines was so great that, at one Port Melbourne medical clinic, staff decided to hire out a local football club to cater for more people.
Staff were administering up to 300 COVID-19 vaccine doses each day, with both booster shots and vaccines for children in the mix, but that flow of people has since slowed to a trickle.
A weekend blitz to get kids vaccinated recently fizzled, forcing the clinic to stop administering doses altogether.
Sarah Lewis, a doctor at the clinic, said she was concerned that so many children aged between five and 11 years remained unvaccinated, despite becoming eligible early in January.
"We initially had a huge demand, there were a lot of parents who were really, really keen to get their children vaccinated but, once that initial wave passed, we saw the demand really drop off," she said.
"We set up to be able to do 200 vaccines a day over a weekend and we did 67 and 28 on Saturday and Sunday respectively."
The problem is not unique to the Port Melbourne clinic, with data showing that, across the state, vaccination rates among children are lower than expected.
In January, the Victorian government predicted that more than 80 per cent of children aged five to 11 years would have received at least one COVID-19 vaccine dose by mid-February.
But that number sits at just 52 per cent.
Nationally, many states are lagging behind in vaccinating primary school-aged children, with only 47.87 per cent of children having received a first dose, on average.
The ACT is leading the way, with 75.86 per cent of the group vaccinated.
Meanwhile, in Queensland, only 41.34 per cent of children aged between five and 11 years have received at least one vaccine dose.
'Some children get quite sick'
Dr Lewis said she believed the drop-off in vaccinations for children was partly because the Omicron variant of COVID-19 was known to be milder than previous variants.
"Parents feel quite secure that, if their children catch Omicron, that they're not going to be affected, they'll be just suffering from a mild illness and that will pass," Dr Lewis said.
"However, they're not seeing that there are some children who get quite sick.
Dr Lewis said COVID increased the risk of type 1 diabetes and multi-inflammatory syndrome in children after infection.
She said it should be better known that such outcomes can play out for children who get sick, and that vaccination provided extra protection.
"It also helps protect the whole school community because it makes your child less likely to spread the virus to someone else."
Since schools returned late last month, COVID-19 infections have spread among staff and students.
In the past week, 10,000 positive Omicron infections were recorded in Victorian schools alone.
Best outcome to avoid infection, expert says
Margie Danchin, an immunisation expert at the Murdoch Children’s Research Institute, said the messages parents had taken in about Omicron had affected vaccination rates.
"We know that this is the age group with the lowest risk of severe disease, but severe disease does happen and it is particularly more common in children with underlying medical conditions," she said.
Dr Danchin said the fact that different countries across the world had taken different approaches had potentially confused parents.
"The UK has recommended a high-risk program only, with medically at-risk children to be vaccinated, and, for example, Sweden has recommended against vaccination [for younger children]," she said.
"I think we need very clear messaging on the reasons why children need to be vaccinated, for parents.
"That messaging needs to be tailored to different groups."
Dr Danchin said it was important to clearly communicate that the best outcome was preventing children from catching the virus.
She said about 1 per cent of children who caught COVID-19 needed to be admitted to hospital.
