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Novartis AG's Bexsero vaccine helps protect toddlers against the most common cause of meningitis when used as a booster, the Swiss drugmaker said on Thursday, giving its meningitis franchise another lift.

A late-stage study showed toddlers who had three doses as infants were protected against the meningococcal serogroup B, or MenB, when later given extra doses, cutting their risk of catching the potentially deadly illness.

MenB is the most common cause of bacterial meningitis and no vaccine is yet available.
Meningitis is an inflammation of the lining around the brain and spinal cord, and can kill within hours.

Novartis has filed for approval in Europe and other countries, such as Canada, and is working with U.S. authorities to design a U.S.-specific phase III trial.

"I am more confident than I have ever been," Andrin Oswald, head of Novartis' vaccines unit, told Reuters when asked about how likely approval was.

"We submitted the vaccine for approval in December, in Europe. It normally takes 12-18 months for a vaccine to be approved. In this case, this is a highly innovative technology so it may take closer to 18 months than 12," Oswald said.

Vontobel analyst Andrew Weiss said the vaccine could make peak sales of $2 billion, and estimated a 50 percent probability of success.

Shares in Novartis rose 0.4 percent by 3:40 a.m. EDT, while the European healthcare index was up 0.3 percent.

"The data is positive but the EU approval process is a key driver for Bexsero. The news will be a minor positive for Novartis shares today," Kepler analyst Tero Weckroth said in a note.

Approval of Bexsero would mean that Novartis would be able to provide vaccines to protect against all causes of meningitis, which has a high incidence rate among infants and can leave them brain-damaged, deaf or with learning difficulties.

The Vaccines & Diagnostics unit, Novartis' smallest, has three types of meningitis vaccines, including the recently launched Menveo which protects against other causes of meningitis.

Oswald said he was confident the meningitis franchise would be a blockbuster franchise for the unit.

A separate study showed the Bexsero vaccine also protected infants against MenB when given alone, or in connection with other vaccines, and that it had an acceptable tolerability profile.