None of Australia’s COVID-19 vaccines are approved for children, with the Pfizer option recommended for those aged 16 years and over and AstraZeneca shots are for adults only.
The main point:
- Children are less likely to get sick with COVID-19 as adults
- The children are included in phase three of Australia’s vaccine rollout
- It is important for them to be vaccinated to achieve herd immunity
So why weren’t children prioritized in the first phase of the coronavirus vaccine launch? And how are children involved in vaccine clinical trials?
Asha Bowen, a pediatric infectious disease specialist at the Telethon Kids Institute and Perth Children’s Hospital, said it was somewhat unusual that a specially approved vaccine was not tested on children.
“Most of our vaccination models prevent vaccine-preventable diseases as early as possible,” he said.
But with COVID-19, it’s a different story.
Children and COVID-19
Dr Bowen said it was not clear why the children were not the main source of transmission of COVID.
“I think that’s what our scientists are trying very hard to look for,” he said.
“This is unusual from a respiratory virus perspective, where we usually see children getting very sick, and also being very predominantly involved in viral transmission.”
Dr Bowen said children play a role in influenza transmission, which is why the annual launch of flu shots includes children.
Nicholas Wood, a pediatrician and researcher at the University of Sydney, explains that because children do not appear to have many infections or come in with too severe a disease, there is no “urgency” to develop a vaccine for COVID-19 in childhood.
How are children involved in clinical trials?
Before the Therapeutic Good Administration gives approval for a vaccine, it must be tested extensively – first in the laboratory, then in animals and, finally, in humans.
The first stage of a clinical trial usually involves healthy adult volunteers, with the last stage involving a wider range of participants, including children.
Robert Booy, a senior associate professor at the National Center for Immunization Research, said the trial started with the older children, then gradually included the younger cohort.
“Once there is evidence of good and safe protection in the older age group, whether they are young adults or older adolescents, then you will gradually descend at five or 10 years at a time,” he said.
Dr Bowen said trials involving different age groups were sometimes run concurrently if there was insufficient safety data available about the drug.
And while children were “very, very rarely” enrolled in treatment trials, Dr. Bowen explained, this is usually the opposite case with vaccines.
But given the epidemiology of COVID-19, he is satisfied that Australian vaccine producers have followed the “appropriate pipeline”.
“And then running those same clinical trials in children, to find out whether the vaccine is safe and also whether it has a benefit is very important.
“At this time, it is an absolute gift that children do not catch COVID, so we have the opportunity to wait.”
Dr. Wood agrees.
“If the opposite happens, and children are dying and thousands are infected, [researchers] will probably jump fairly quickly from an adult trial to a younger children’s trial, “he says.
Ethical considerations for child trials
Dr Wood said before taking part in clinical trials it was important to clearly communicate the potential risks to those taking part and their guardians.
Because children under 18 years did not meet Australia’s legal age limit, researchers asked adolescents and children in older age groups to agree to participate.
The older age group received specific information explaining what was going to happen, but for very young participants the responsibility rests with the parents.
“We can’t do that [provide information] for one or two year olds. It really depends on the parents, “said Dr. Wood.
Dr Bowen said before enrolling children, researchers needed to understand safety parameters.
This includes having a clear understanding of the side effects, because if something goes wrong, the consequences can last a child’s lifetime.
He said adults can provide consent and understand the potential risks and possible benefits.
And in general, he adds, it’s easier for researchers to predict how drugs might work in adults.
That’s because fully mature adults have a relatively stable physiology compared to children who are still growing.
So when will children be vaccinated?
If Pfizer and AstraZeneca’s testing goes well, Australia has included children in the third and final phase of vaccine rollout, which is slated to start between September and November this year.
Dr Bowen is optimistic the vaccine will be approved for use in children by the Therapeutic Goods Administration before that.
“We’ve seen this vaccine develop very, very fast, and the safety profile is very, very good,” he said.
“I hope that by the time we reach stage three, there will be safety data and efficacy data for children who will also be vaccinated.”
Dr Wood said although they were not as severe as parents, engaging children was important for developing herd immunity, as they likely played a role in transmitting the virus.
“If a vaccine succeeds in stopping transmission, then basically we want to give it to everyone to have a herd immunity effect so we can stop transmission of the virus,” he said.