Children between five and 11 years old can now be vaccinated against Covid-19 after the Food and Drug Administration issued emergency use authorisation on Friday.
The Pfizer's Covid-19 vaccine is the first one authorised in the United States for younger children.
However, the administration is waiting for the Centre for Disease Control and Prevention to issue guidance on how to use the vaccine in this age group, based on the findings.
The CDC’s Advisory Committee on Immunization Practices will meet next week before the roll out is done.
Findings from the paediatric clinical trial investigation involving about 4,500 children aged 5 to 11 stated that the vaccine is almost 91 per cent effective in preventing Covid-19 in that age group.
Given to children, the FDA has authorised 10-microgram doses a third of the size of the adults which is always 30 micrograms. The children too require two shots given on the same schedule as the vaccine for adolescents and adults.
According to data from a Phase 2/3 trial Pfizer submitted in September, the two-dose, 10-microgram vaccine generated a "robust" antibody response in younger children. In a research document posted last week.
The vaccine is said to be safe and 91 per cent effective against symptomatic Covid-19 in children ages 5 to 11 years.
At higher doses tested in the trials, scientists saw a few more minor side effects, nothing severe but with the 10-microgram dose, researchers saw fewer issues with chills and fever than the other groups that were earlier tested.
Dr Paul Offit, a member of the independent FDA vaccine committee who directs the Vaccine Education Centre at Children's Hospital of Philadelphia says it is reassuring that children are getting lower doses.
One goal of vaccine trials for any age is to find the smallest level of antigen, the part that triggers an immune response to maximize protection without side effects.
Dr James Versalovic, Texas Children's Hospital interim paediatrician-in-chief said that considering that the children are developing and reacting differently, there was a need to treat them differently.
“This is why we considered testing Pfizer in younger children and immediately after we did the adolescents, we took a step back and we looked at the dosing, because we thought that we may be able to use a lower dose and be able to get the same immune response," said Dr Robert Frenck
After testing, "we got just as good an immune response as the 30-microgram dose and there were less side effects."
Moderna vaccine has also released preliminary results showing that its low-dose vaccine is safe and produces a strong immune response in children ages six to 11 years though it has not be reviewed by the FDA
Recently, Modena released its findings indicating that for children, they require half the size of the company's vaccine for adults.
However, in as much as drug companies are coming up with Covid-19 doses for children, several studies have shown that their bodies' immune systems are able to clear the infection much faster than adults, less likely to be infected and less likely to spread the virus.
One of the studies published in the journal Nature Immunology by scientists from Columbia University in New York, showed that their bodies react to the disease in a subtle way than adults and produce fewer antibodies to fight the disease.
Dr Francis Ndung’u, a microbiologist explains this phenomenon. “Children haven’t had a lot of immunological responses that would kill them like adults, whom a cytokine storm (exaggerated inflammatory responses) makes very sick, and it is not common in children,” he says.
Dr Anthony Etyang, who specialises in adult medicine and epidemiology, also says the difference in severity of the disease in adults and children could be linked to the cytokine storm. “Children don’t seem to generate a cytokine storm as big as adults,” he says.
“It causes inflammation in many different organs of the body: lungs, kidneys, the heart. It is a disorganised form of inflammation and that is why it is called a storm. It causes the organs to fail and in the worst case scenario, it leads to death,” adds Dr Etyang.