A world without vaccines would be "hundreds of thousands of times worse" than the COVID-19 pandemic, Hunter Medical Research Institute Professor Josh Davis says.
"Vaccination has been the single most successful public health intervention in human history," said Professor Davis, an infectious diseases expert and researcher.
"If you look at the number of deaths that have occurred so far with this pandemic, that would be a drop in the ocean compared to a world in which no one was vaccinated."
In a world without vaccines, the total number of people who have died from COVID-19 in the last three months would be "dying every day".
Vaccines were one of the key reasons why life expectancy was now in the 80s, not the 40s, he said.
Vaccine deniers - so-called anti-vaxxer activists - have been using COVID-19 to spread misinformation and lies.
Professor Davis believes these people "don't trust or believe in the concept of science and evidence".
If vaccine deniers want life and work to return to normal, "they have to embrace vaccinations".
Before the pandemic, infectious disease specialists were "very concerned about vaccine denial". This concern has risen with the pandemic.
Deaths continue to occur from vaccine-preventable diseases around the world. This was also a problem in Australia, but less so than other parts of the world.
"There are deaths from things like pertussis [whooping cough] in under-vaccinated populations," he said, adding that cases of severe illness and hospitalisation were more common.
Mini-outbreaks of measles and chicken pox have also occurred.
Full immunisation among non-Aboriginal children aged five was 96.5 per cent in the Hunter-New England region last year. For Aboriginal children, this rate was 98.1 per cent.
However, there are concerns that anti-vaccination propaganda is spreading.
Professor Davis urged people to consider the credibility of claims about vaccinations.
"If people see a message or advice coming out on social or traditional media, think about the qualifications and training of the person that's giving you that information.
"Quite often if you look behind it, they actually are no more qualified than any other person on the street [to speak about vaccinations].
"There's very few if any people that are actually trained in science or medicine who believe all the conspiracy theories around vaccines."
Vaccine deniers tend to be ignorant of horrendous diseases such as smallpox that vaccines eradicated. Diphtheria is another example.
"They used to cause outbreaks and lots of death."
The polio vaccination was another breakthrough for humanity.
"Polio caused not only deaths but paralysis. There are people alive today who have one weak leg or can't walk properly because of polio 80 years ago. Tetanus has nearly 100 per cent mortality if you get it. It's easy to prevent by vaccination."
Vaccines for pneumococcal disease prevent meningitis and pneumonia.
"They're more common diseases because the vaccine has been around for 20 years or so, not over 50 years like some others"
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