Moderna has rejected claims that U.S. government scientists co-invented a critical part of its coronavirus vaccine, escalating what's become a messy dispute between the company and its longtime research partners at the National Institutes of Health.

The biotech on Wednesday said it disagrees that NIH scientists co-created the genetic sequence used in its COVID-19 shot, a key discovery that underlies the intellectual property covering the vaccine. That sequence was chosen "by Moderna scientists using Moderna technology" and NIH scientists weren't involved until after a patent request had been filed, the 

• The statement comes as the year-long disagreement between the NIH and Moderna could reportedly soon be headed to court. Moderna's shot, one of the world's most lucrative COVID-19 vaccines, has mainly been bought by wealthier nations — an inequity that critics argue partial government ownership could help address.

• Throughout much of last year, Moderna and Pfizer were locked in a race to develop the first mRNA vaccine for COVID-19.

  While both benefited from billions of dollars in advance purchase orders, Moderna scientists worked closely with their counterparts at NIH on early clinical research for the small biotech company's vaccine. Later, the NIH and other government agencies helped coordinate and fund the pivotal trial that supported the shot's emergency authorization.

  Pfizer, with its comparatively vast resources, ran its clinical testing independently.

  In the NIH's view, the contributions of its scientists are even more fundamental, deserving of co-inventor status on patents covering the technology behind Moderna's shot. That's been the case on some patents, but a filing by Moderna in July for one covering the genetic sequence itself left off several government scientists the NIH claims were involved, The New York Times reported earlier this week.

  The claim isn't just about professional reputation. Co-inventor status would give the government the power in extreme circumstances to take possession of the intellectual property if it believes the owner isn't making drugs accessible.

  The government has never invoked these so-called march-in rights, but many advocacy groups have argued that it should when drug prices are too high. Likewise, in a public health emergency the government could theoretically use that power to transfer the patent to another drugmaker if it believes Moderna isn't taking practical steps to make its vaccine accessible. While the shot is widely available in the U.S., many of the supply contracts signed by the company have involved developed countries rather than lower-income nations, something which the drugmaker has been criticized for.

  Moreover, industry critics claim drugmakers routinely fail to disclose the NIH's contribution to their intellectual property.

  In its Thursday statement, Moderna argues that "strict rules" under U.S. patent laws restrict who can be listed as a co-inventor, and that NIH scientists' listing on some of the vaccine's patents doesn't mean that they should be claimed on all of them.

  "We do not agree that NIAID scientists co-invented claims to the mRNA (modified nucleotide) sequence of our COVID-19 vaccine, Moderna said. "The mRNA sequence was selected exclusively by Moderna scientists using Moderna’s technology and without input of NIAID scientists, who were not even aware of the mRNA sequence until after the patent application had already been filed."

  Moderna's statement followed The New York Times story and a Reuters interview with NIH Director Francis Collins, who told that publication the biotech had made "a major mistake." Collins indicated then he expected "legal authorities" would become involved.

  For its part, Moderna said that, on Sept. 29, it offered to resolve the dispute by making the U.S. government co-owners of those patent applications that only listed Moderna scientists as inventors.