Your responsibility: The best advice on vaccines

What can we do as individuals to combat the winter COVID-19 wave? In the second in a series, The Age’s health team asks experts for the best advice on vaccinations.

With vaccine mandates behind us, ensuring you have sufficient immunity to weather the incoming tide of the third Omicron wave rests in your hands.

The decisions each of us make have implications, particularly for the healthcare system, which is buckling under demand. The new, highly transmissible Omicron subvariants have fuelled an 83 per cent spike in COVID-19 hospitalisations in just three weeks in Victoria.

Professor Sharon Lewin, director of the Doherty Institute.

Ahead of an expected peak in early August, the federal government has lowered the age of eligibility for a fourth dose from those aged 65 and above to people over the age of 50, alongside those with serious immune or health conditions.

People aged 30-49 are now also eligible, but health authorities stopped short of explicitly recommending they get the jab.

It can be difficult to keep up with the rapidly changing health advice. So, we asked Doherty Institute for Infection and Immunity director Sharon Lewin what the best research tells us.

Lewin cited data from Israel showing a fourth dose for people over the age of 60 provides a four-fold reduction in the risk of hospitalisation — an effect that lasts for at least six weeks.

The vaccine is less effective at protecting against infection, however, giving only a two-fold reduction in the risk of catching the virus. The immunity boost peaks at four weeks but disappears after eight, Lewin said.

“The vaccines are not as good against these new variants. They continue to protect well against severe illness, and this is enhanced with each dose. But they’re less and less effective against infection.”

Health authorities now accept that the coronavirus is endemic – that is, consistently present – so are less focused on limiting the number of infections. The key priority for now is stopping people dying or needing hospitalisation.

While those aged 30-49 are allowed to get the fourth jab, the absence of studies showing the second booster’s clinical benefits for this age group explains why it has not been specifically recommended.

Lewin said those in this age bracket should consider the timing of their previous infection and vaccination, and their vulnerability to severe illness, in deciding whether to get the shot. But there was no downside to getting another vaccine, she said.

“I would anticipate that your immune response is enhanced with that extra dose at a younger age, it’s just how much clinical benefit it gives, and we don’t know the answer to that,” Lewin said.

Moderna and Pfizer supply the fourth doses and Lewin said there was no difference between the benefits of these vaccines, despite what you have had previously.

She said the country’s take-up of the third vaccine needed improvement, with only 70 per cent of eligible people receiving three or more doses in Australia.

Mounting evidence shows the benefits of getting a third dose. A new study on 2 million adults in NSW reveals a third vaccine provided 65 per cent more protection against hospitalisation or death from Omicron than two vaccine doses.

COVID-19 vaccination has not been recommended for babies and children under the age of five, while third doses are not at this stage recommended for kids aged 12-15 who not immunocompromised, as they are at less risk of serious illness.

The Morning Edition newsletter is our guide to the day’s most important and interesting stories, analysis and insights. Sign up here.