UPDATED: Pfizer's Prevenar 13 patent challenged in India as MSF continues its price fight

The medical charity Médecins Sans Frontières is taking its fight with Pfizer over the cost of top-selling vaccine Prevenar 13 to a new level. It is challenging the drugmaker's request for a patent on the vax in India.

MSF said today that it had filed its "patent opposition," a form of citizen challenge, after years of fruitless negotiations and trying to convince the New York company to discount the vaccine deeply in poor countries. It claims that the technology Pfizer is trying to patent is "too obvious to deserve a patent under Indian law."

In a statement Pfizer said it had not yet received notice of MSF's pregrant opposition, but that it is committed to an affordable program. It said it is in "talks with Indian government health officials to understand local needs and government priorities with the goal of meeting their needs in their recently announced expanded immunization program."

MSF has for years battled both Pfizer and GlaxoSmithKline ($GSK), which make the only two pneumonia vaccines, Prevnar 13, known as Prevenar in India, and Synflorix, saying the two having been sticking it to developing countries for years. MSF said the lowest price currently available is $10 a child, which is provided through GAVI, while one Indian supplier could do it for $6 for the required three doses. Some countries reportedly pay in excess of $60 per child.

They point out that pneumonia is the leading cause of death for children under 5, killing almost a million children each year. They claim that pneumonia vaccines account for about 45% of the cost of fully vaccinating a child against 12 diseases, and that vaccination costs are now 68 times higher than in 2001, in large part because of pneumonia vaccine prices.

Both companies defend their prices based on the complexity of making the jabs. Pfizer has pointed out its takes "more than two years to create a batch of Prevnar 13, encompassing some 500 quality control tests … multiple facilities and hundreds of trained professionals." Glaxo calls Synflorix "one of the most complex" vaccines it has ever manufactured.

Both companies also make big bucks from the products. Sales of Prevnar 13 topped $6 billion last year. In 2014, it got a huge boost when the Centers of Disease Control's Advisory Committee on Immunization Practices recommended the shot for adults aged 65 and older in the U.S. That was expected to add about $2 billion in sales. It is projected by EvaluatePharma to be the fifth best-selling drug in the world in 2020 at $6.9 billion. GSK had 2015 sales of about $548 million for Synflorix.

- here's the announcement

Special Report: The top 20 drugs in 2020--worldwide sales - Prevnar 13

Editor's note: The story was updated to include a comment from Pfizer.