WASHINGTON (Reuters) - Moderna Inc, looking to boost production of its COVID-19 vaccine, met with Nexus Pharmaceuticals to discuss manufacturing the shot at the company’s new plant in Wisconsin, which has the capacity to process and fill 30 million doses a month, sources with knowledge of the matter said. The meeting between Moderna and the maker of specialty drugs took place on Tuesday, the sources said. Senior White House and administration officials, including David Kessler, chief science officer for Covid response and Tim Manning, COVID-19 supply coordinator, have facilitated introductions and discussions between Nexus, Moderna and Johnson & Johnson, according to two sources. Even though President Joe Biden has said there would be enough vaccines for all adults in the United States by May, there could still be supply concerns later in the year, particularly if people require a booster shot at some point to protect against concerning virus variants that may be circulating. It remains unclear if the meeting will result in a deal to manufacture vaccines at the Nexus plant, the sources said. Funding from the Defense Production Act will be essential for a deal to work, one of the sources said. “Moderna is looking to produce more vaccines ... and Nexus has the capacity to do it,” one of the sources said. Illinois-based Nexus does not currently manufacture COVID-19 vaccines but has built capacity to ramp up production at their new plant in Wisconsin, one of the sources said. The White House declined comment on the meeting. Nexus and Moderna also declined comment. On Tuesday, Moderna said it was on track to deliver 300 million doses to the United States by the end of July, in line with its commitments. Moderna delivered 45 million vaccines to U.S. states in March. Moderna’s chief executive on Wednesday said the company was unlikely to markedly speed up its vaccine production in the next few months, though it expects the output to have increased significantly by 2022. The Biden administration has previously brokered commitments among rival drugmakers to boost COVID-19 vaccine production. In March, Biden announced that Merck & Co will help manufacture Johnson & Johnson’s single-shot coronavirus vaccine. Despite its efforts there have been significant setbacks. For example, some 15 million doses of J&J’s vaccine were wasted due to contamination with ingredients from AstraZeneca’s shot at a Baltimore plant that was producing both. That Emergent BioSolutions facility will now produce only the J&J shot. Separately, U.S. federal health agencies on Tuesday recommended pausing use of the J&J COVID-19 vaccine while it looks into six cases of rare brain blood clots in women under age 50 who received the shot.