Australian and international researchers carried out a systematic review of all data published on COVID-19 vaccine first doses.

They found there were notable differences between the sexes.

Vaccine efficacy in the first jab was consistently found to be higher in males than females, lead author from the University of Melbourne Professor Cassandra Szoeke said.

It was also more common for females to experience negative side effects, specifically blood-clotting symptoms from the AstraZeneca and Janssen vaccines.

"The real point is there are sex differences in health, both in terms of the treatments we use and also in terms of disease," Prof Szoeke told AAP.

"Despite the fact there's been a lot about this, people still aren't reporting their results by sex."

All international studies on the COVID-19 vaccines collected data on the person's sex but only 30 per cent reported that information in their findings, Prof Szoeke said.

"The people who bother to look, although they were very much in the minority, did find differences," the Healthy Ageing Program director said.

"The more you can personalise and tailor treatment to the individual, the better. If we can't even start with the obvious 50 per cent, we're really struggling."

Breaking down the data by sex to determine differences in efficacy and symptoms won't only improve health outcomes but also increase confidence in the vaccines, Prof Szoeke said.

"Vaccines are great," she said. "The impact of vaccination has vastly reduced what COVID would have done to the global population.

"One of the number one reasons why people are hesitant is because it hasn't been around long enough and they don't know enough about it.

"The more information you can give them, the better."

More than 98 per cent of Australians aged over 16 have had at least one dose of a COVID-19 vaccine, while close to 69 per cent have had three jabs.

Australian Associated Press