Novavax (NVAX 5.30%) is behind the leaders in the race to develop a coronavirus vaccine to prevent COVID-19, but the biotech continues to trot along. On the heels of positive phase 1 data earlier this month, the biotech started the phase 2 portion of its phase 1/2 clinical trial testing its coronavirus vaccine NVX-CoV2373.

The new study will enroll up to 1,500 subjects, substantially more than the 131 subjects enrolled in the phase 1 study. The phase 2 portion also expands the potential ages of participants from a range of 18 to 59 in phase 1 to a range of 18 to 84 for the phase 2 study.

Since older adults are especially vulnerable if they catch COVID-19, its important for a vaccine to be both safe and able to generate an immune response in the older adults. To get the answer quickly, Novavax plans to enroll half of the clinical trial with older adults, aged 60 to 84.

Pfizer (PFE 3.64%) and BioNTech (BNTX 11.11%) recently demonstrated that their coronavirus vaccine, BNT162b2, was able to generate antibodies in older adults 65 to 85. The levels weren't as high as younger subjects, but the antibody levels were still higher than levels seen in patients who had recovered from COVID-19.

Gloved hands giving an injection into a shoulder

Image source: Getty Images.

Novavax's investors will have to wait until the fourth quarter for interim data on antibody levels and safety of the vaccine from the phase 2 study. That's around the same time Pfizer and BioNTech, AstraZeneca, and Moderna expect to have initial phase 3 data, putting Novavax a few months behind the current leaders.

How much Novavax's slower pace hurts the biotech will ultimately be determined by the safety and efficacy of all the vaccines, as well as how quickly the front-runners can ramp up manufacturing to meet global demand.