He said the body needed on average about three weeks to work with the vaccine to activate strong protective measures against the virus.
He said delays in getting vaccinated worked against suppression efforts.
“The vaccine needs this time to start activating with the body and the underlining message is for people to get vaccinated as soon as possible,” Dr Grenfell said.
“Every eligible person should be getting the vaccine and anyone over the age of 60 still waiting for the Pfizer vaccine needs to get vaccinated and as soon as possible.
“There is plenty of AstraZeneca vaccine, which has proven to be safe and in some studies more effective in reducing hospitalisation and providing long-lasting immunity than Pfizer. My 22-year-old daughter has had the AstraZeneca vaccine.”
Dr Grenfell, who has done much of his work as part of an Australian role in vaccination while based at Natimuk, has joined Grampians Public Health Unit to help in a regional vaccination program.
He said a critical observation people should make when absorbing day-to-day figures regarding the virus in Victoria was how many people in a serious condition in hospital with COVID-19 had received their two doses of vaccination.
“None! It’s a profound message. None of the patients in hospital with COVID-19 are people who have been fully vaccinated,” he said.
“I like to use a saying that for every fully vaccinated person it means there is another person less that will need to be admitted to hospital with COVID-19.
“There has been a great response from the community regarding vaccination, but we need to keep going.”
Dr Grenfell has been CSIRO health and biosecurity director since mid 2016.