(CNN) � It looks like booster shots will likely be recommended for people who got the Johnson & Johnson COVID-19 vaccine.
The company says phase two studies show people who received boosters six months after the initial dose showed a nine-fold increase in antibodies from a month after the first shot.
This data comes days after the Biden administration recommended booster shots for people who got Pfizer and Moderna's vaccine.
Recipients of those shots become eligible for a booster eight months after receiving their second dose.
Health officials believe immunity from the vaccines eventually starts to wane, leaving recipients more vulnerable to infection if they don't get boosters.
Johnson & Johnson's single shot vaccine came out in February, a couple months after Pfizer and Moderna's version.
The first people to receive it are just now starting to hit the six month mark.
About 14 million Americans have been vaccinated with J&J's shot.
