KEY POINTS

  • 9-year-old twins Alejandra and Marisol were the first to receive Pfizer vaccine shots in children under 12
  • Pfizer's vaccine has a 100% efficacy rate in children ages 12 to 15
  • The drugmaker is making plans to study the vaccine's effectiveness in children as young as six months

Pfizer this month has fully inoculated 9-year-old twins Alejandra and Marisol Gerardo as part of an initial study to evaluate the safety of its COVID-19 vaccine in younger children. 

The study, which includes 144 children who will all receive the vaccine, had given the shots to the twins two weeks ago, making them the first participants under 12 to receive the Pfizer vaccine. 

The Gerardo twins said the only side effect they experienced was a sore arm. Their parents, who are both doctors, enrolled them in the study after reviewing the Pfizer vaccine’s safety profile. 

The first phase of the trials for children under age 12 aims to evaluate the safety of the shots and determine the dose that should be given in the next phases. Pfizer is conducting these trials in four medical centers, including Duke Health.

Minnesota’s top epidemiologist, Dr. Ruth Lynfield, on Tuesday revealed that Pfizer is expanding its trial to children ages 2 to 11 after it found its vaccine 100% effective in protecting children between ages 12 and 15 against COVID-19. 

Pfizer CEO Albert Bourla in late March said the company plans to submit the results of the vaccine study to the FDA and other regulators soon, with hopes of vaccinating children ages 12 to 15 before the next school year. 

“We share the urgency to expand the authorization of our vaccine to use in younger populations and are encouraged by the clinical trial data from adolescents between the ages of 12 and 15,” Bourla said in a press release

The trial enrolled 2,260 participants in the U.S. Researchers confirmed there were 18 coronavirus infections seen in the placebo group, but no participant in the vaccine group became infected with COVID-19. 

The drugmaker is now making plans to include kids as young as six months. 

"Trials for the Pfizer vaccine have now begun in 2- to 11-year-olds and plans are being made for children down to six months of age," Dr. Lynfield said

Moderna and Johnson & Johnson also are testing their coronavirus vaccines in younger children. Moderna had finished enrolling kids ages 12 to 17 in its trials. J&J is currently holding a vaccine trial involving kids ages 12 to 18. 

Concerns have risen that more transmissible coronavirus variants such as the one first detected in South Africa or another in Britain are more resistant to existing vaccines such as the one developed by Pfizer-BioNTech Concerns have risen that more transmissible coronavirus variants such as the one first detected in South Africa or another in Britain are more resistant to existing vaccines such as the one developed by Pfizer-BioNTech Photo: AFP / Luis ROBAYO