Amid a surge in Covid-19 cases, experts are warning Australians to remain vigilant and ensure their vaccination status is up to date.

Associate Professor James Trauer, Head of the Epidemiological Modelling Unit for the School of Public Health and Preventive Medicine, said the country is current experiencing a significant wave of transmission.

That is being reflected in the wastewater surveillance results and the increase in hospital admissions.

The government and ATAGI (Australian Technical Advisory Group on Immunisation) is recommending eligible people get a booster, with the latest vaccine (targeting common subvariants of the virus) available from mid December.

A 2023 COVID-19 vaccine dose is recommended for the following groups, to be given at least six months after their most recent vaccine:

• All adults aged  over 65 years
• Adults aged 18 64 years who have medical comorbidities that increase their risk of severe COVID-19, and
• Adults who have a disability with significant or complex health needs.

A 2023 dose may be considered for other adults aged 18 64 years, based on an individual risk-benefit assessment. You can discuss with your GP or pharmacist.

If you are eligible for a booster, you can take it six months following a previous dose.

New variants

"Overall, the severity of Covid cases has decreased, with fewer people admitted to ICU than in previous years. This is attributable to high levels of population immunity, which is contributed to by both natural immunity (from past infection) and vaccination-derived immunity," said Professor Trauer.

"Covid is now an 'endemic' infection, meaning that the infection cannot be eliminated and transmission occurs continuously.

"When immunity after infection is short-lived, endemic transmission occur in peaks and troughs as immunity from previous waves fades. This is an expected feature of endemic Covid.

"The emergence of new variants is also contributing to these ebbs and flows. Although a few current variants are being closely watched, none of the currently circulating strains seem to cause more severe disease than the preceding strains. Because new variants are contributing significantly to each wave of infection, it is more difficult than ever before to predict when they will peak."

With Christmas coming up, he said eligible people should consider a vaccine booster.

"Because immunity after infection is so short-lived, reducing transmission in the short-term will have little effect on the number of times people get infected with Covid over the course of several years.

"Therefore, our most important protection against the effects of Covid is immunity, which can be enhanced through vaccination," he said.

"As per ATAGI's recommendations, this is appropriately focused on the most vulnerable to severe outcomes, particularly those aged over 65 or those with risk factors (and especially those aged over 75).

"Anyone who meets ATAGI's current recommendations for receiving a booster vaccine should strongly consider this. This is particularly relevant as the recently ATAGI-approved monovalent vaccines become available, which induce stronger immunity against the current circulating variants.

"In addition to vaccination, taking precautions when visiting persons at high risk of severe outcomes (eg visiting aged care facilities) remains important.

"This includes testing in advance and wearing face masks during such interactions.

"Persons at risk of severe disease should also consider testing to ensure that antiviral medications can be provided as soon as possible after symptoms of Covid occur."

For more information, or to book a vaccination, visit www.betterhealth.vic.gov.au/covid-19/covid-19-vaccination