A government decree will soften legal clauses around negligence, remove a reference to "fraudulent maneuvers" and create a fund to compensate people harmed by a vaccine.
The prior language had hampered negotiations with vaccine firms, and the changes could help Argentina step up its vaccine program as it faces cases and deaths among the highest in the world.
"This regulation will facilitate and favor the possibility of accessing more vaccines," Health Minister Carla Vizzotti said late on Friday, adding it would allow better access via the WHO/Gavi-led COVAX program and from donations, especially from the United States.
The United States recently announced donations of Pfizer and Johnson & Johnson (JNJ.N) vaccines to Peru and Colombia respectively.
Argentina, currently facing a second wave of COVID-19, has recorded some 4.5 million cases of the virus and 95,382 deaths.
Its vaccine program has been largely built around Russia's Sputnik V vaccine, China's Sinopharm and the AstraZeneca (AZN.L) vaccine developed with Oxford University.
Vilma Ibarra, legal and technical secretary with the presidency office, said the decree was a "result of conversations and concessions with the laboratories that supply the vaccines" over legal obstacles.
"We arrived at a text that we understand facilitates and contains the possibility of acquiring vaccines for children and expanding the spectrum of vaccines for the general population," Ibarra said.
Argentine authorities have carried out 21.6 million inoculations with some 4.3 million people having received two doses. The South American county has a population of around 45 million people. Reporting by Maxi Heath; Editing by Adam Jourdan and Cynthia Osterman