As most Australians were still receiving their third dose of the COVID-19 vaccine in early 2022, Israel had already started injecting its residents with a fourth jab.
The Middle Eastern nation became the first place in the world to offer its adult citizens a second booster in January, just as the Omicron wave charged across the globe.
Any Israeli over the age of 18 was able to get the jab, as long as five months had passed since they received their previous booster or had recovered from the illness.
More than 830,000 Israelis — mostly the elderly, health workers and immunocompromised residents — have so far taken up that offer.
Senior citizen Annette Bellows was one of them.
"Oh yes, I wanted to get it," she said.
"I felt much safer and better about my chances with another booster. I still got COVID, but presumably, I got it lighter, I don't know."
The World Health Organization is yet to give an official recommendation on the efficacy of a fourth COVID-19 dose.
Australia last week expanded access to the second booster.
While the nation's expert vaccine advisory body recommended jabs for Australians over 50, it also gave those aged 30 and older the option to get one if they wanted to.
Experts are divided on the efficacy of a second booster for younger people.
But Israeli researchers say Australia's most vulnerable residents will benefit from the expanded rollout.
Who benefits from a fourth shot?
Earlier this year, researchers studied the effects of a fourth shot on the immune responses of young Israeli health workers.
The results suggest the effectiveness of the fourth dose is no different from the effectiveness of a third dose.
While the jury may be out on the benefits for younger people, Israeli researchers say one age group clearly receives significant additional protection.
Results of a newly published study by Tel Aviv University and Ben-Gurion University of the Negev showed the fourth COVID-19 vaccine reduced the risk of death by 72 per cent among Israel's elderly.
"This is a huge step forward to control the spread of COVID in Australia and other countries, that plan to introduce the fourth dose," lead researcher Khitam Muhsen said.
The study of 40,000 nursing home residents found those vaccinated with a fourth dose of the Pfizer vaccine had a 34 per cent reduced risk of contracting the Omicron variant.
They also had a 64 to 67 per cent reduced risk of requiring hospitalisation.
"When there was a variant that had so many mutations, there was a lot of questions about whether the vaccine would be protective, or effective," Dr Muhsen said.
Another study of over-60s, published in May, found while the fourth dose's protection against catching COVID-19 waned after about a month, the additional booster gave three times higher protection from severe disease, compared to having three doses.
The available vaccines on the market were based on the original SARS-CoV-2 strain first detected in China in 2020.
But Dr Muhsen said the fourth shot still appeared to have some protection against variants such as Omicron.
"We have demonstrated that by enhancing the levels of neutralising antibodies, we can provide cross-protection against new variants that have so many mutations," she said.
Another consideration for young people contemplating whether to get a fourth shot is the looming possibility of an Omicron-specific vaccine.
Moderna and Pfizer both say they are close to releasing new booster shots that target the BA.1 sub-variant of Omicron.
However, so-called "sticky" sub-variants of Omicron, BA.4 and BA.5, are considered highly infectious and are racing around the globe.
Pfizer said it should be able to adapt its Omicron booster to provide protection against the new sub-lineages by October.
Have vaccines tamed Israel's COVID-19 waves?
Israel has long placed itself at the forefront of the world's vaccination schedule, becoming the first country to approve the third and fourth COVID-19 vaccine doses.
In the next few weeks, it will become one of the few countries to vaccinate some of its youngest citizens — those aged between six months and five years old.
Health officials have also scrapped a number of restrictions including mask mandates, COVID-19 tests at airports and lockdowns.
But the country is by no means out of the woods.
Cases there appear to be rising again, with more than 70,000 infections recorded in the past week, according to Johns Hopkins University.
But the number of deaths associated with the virus has been stable and in single digits for several months.
The vaccine rollout has had a significant impact on daily life in Israel, according to infectious diseases specialist Eyal Leshem from Sheba Medical Centre.
"Israel was very rapid in achieving high coverage in the adult population," Professor Leshem said.
Professor Leshem said vaccines have had a huge impact on reducing severe disease, hospitalisation and deaths.
"Compared to other countries of our size, we've seen a lower mortality rate," he said.
