Johnson and Johnson says can provide 20M US doses

J&J disclosed the figure in written testimony ahead of a Congressional hearing on Tuesday looking at the country's vaccine supply. White House officials cautioned last week that initial supplies of J&J's vaccine would be limited. 

The company reiterated that it will have capacity to provide 100 million vaccine doses to the US by the end of June. That supply will help government officials reach the goal of having enough injections to vaccinate most adult Americans later this year. On a global scale the company aims to produce 1 billion doses this year. 

US health regulators are still reviewing the safety and effectiveness of the shot and a decision to allow its emergency use is expected later this week. J&J''s vaccine would be the first in the US that requires only a single shot. 

Currently available vaccines from Pfizer and Moderna require two doses spaced several weeks apart. Executives from both companies and two other vaccine makers will also testify at Tuesday's hearing.