Despite strong oppositions from international nonprofit group Médecins Sans Frontières and local company Panacea Biotec, India's patent office has granted Pfizer a patent for its blockbuster pneumococcal vaccine Prevnar 13.

The Indian patent, originally filed by Wyeth in 2007, would block other companies from selling cheaper versions of the vaccine in India or manufacturing one in the country for exports until 2026.

"The method Pfizer is trying to patent is too obvious to deserve a patent under Indian law, and is just a way to guarantee an extended market monopoly for the corporation for many years to come," Leena Menghaney, South Asia head for MSF’s Access Campaign, said in a statement.

Pfizer’s patent involves the methods of conjugating 13 serotypes of streptococcus pneumoniae into a single carrier protein. An equivalent patent was revoked by the European Patent Office in 2014 and is being challenged in South Korea and before the U.S. Patent Trial and Appeal Board, MSF said.

Pfizer is currently offering the shot at as low as $3.05 per dose in a four-dose presentation to GAVI through UNICEF, which provides access to vaccines in the world’s least resourceful countries, including India. But that is still higher than the $6 per course (three doses) price MSF said the Serum Institute of India had agreed to offer.

In a statement to FiercePharma, Pfizer says that the multidose presentation reduces the cold-chain requirements, shipping and storage costs by 75% compared to the standard presentation in mass immunization settings.

"Pfizer remains committed towards further enhancing access of this vaccine in India, both in the market as well as through partnership with the Government to expand introduction in the public program," the big pharma said in a statement. "We are committed to creating an affordable and sustainable program to support the availability of Prevenar 13."

Launched in India in 2010, Prevnar was recently included in India’s public immunization program in select states, but Reuters reported that under this phased program, currently only about 2.1 million of the 25 million eligible people in the country will get it this year. Outside of the GAVI-supported government program, which gives out the vaccine free of charge, a full course of the vaccine costs about $170 on India’s private market, according to Reuters.

Last March, MSF filed a pre-grant opposition against what it called an "unmerited" patent application after "years of fruitless negotiations with Pfizer to lower the vaccine’s price for use in its projects." MSF now worries that manufacturers will have to find new ways to develop noninfringing pneumococcal vaccines, delaying availability of cheaper, competing shots.

MSF and Pfizer are constantly at odds with each other over Prevnar 13, the world’s best-selling vaccine, but whose sales have dropped dramatically in recent years.

Back in 2015, MSF dumped $17 million in fake cash in front of Pfizer’s New York headquarters as the initiation of its "A Fair Shot" campaign that called for Pfizer and GlaxoSmithKline to lower the prices of their pneumococcal vaccines in emerging markets to $5 per child for the entire course. Last October, the charity group rejected Pfizer’s offer of a million free Prevnar doses, arguing that accepting such donations can "undermine long-term efforts to increase access."

Perhaps the only break to that growing tension happened last November, when Pfizer offered a discount to Prevnar for children caught in humanitarian emergencies, following GSK’s footsteps. A Pfizer spokeswoman told FiercePharma that "Pfizer will donate all sales proceeds from this program to selected humanitarian groups undertaking the difficult work of reaching vulnerable populations facing humanitarian emergencies."