Dr. Jo Anne Passalacqua, an infectious disease specialist at Saint Vincent's Medical Center, says the Johnson & Johnson announcement that its COVID-19 booster shot is 94% effective when administered two months after the first dose is promising.

"Johnson & Johson has looked at data for two months out and they have also looked at data for as much as six months out, and basically both of those data points show significant levels of immunity for people who received the J&J vaccine," Passalacqua says.

She says the data is very promising, but reviews from the Food and Drug Administration and Advisory Committee on Immunization Practices will be verified prior to booster recommendations.

Should federal officials give the green light to a booster shot, Passalacqua says it might make those who still need to get vaccinated more comfortable with choosing J&J - especially with the delta variant spreading.

"This is absolutely what we need. We need a significant portion of the population to be vaccinated. But we also need high levels of protection for our vaccinated people and particularly for our high-risk people," she says.