Serum’s heat-stable rotavirus vaccine shines in phase 3

Serum Institute of India’s rotavirus vaccine candidate showed better efficacy than Merck’s and GlaxoSmithKline’s approved vaccines in a late-stage trial, as well as tolerating much higher temperatures during storage, putting it in a strong position to notch an approval from the World Health Organization.

In a phase 3 trial carried out in Niger, the newly developed live, oral rotavirus pentavalent vaccine showed nearly 67% efficacy in preventing severe rotavirus gastroenteritis—which causes diarrhea—among infants.

Dubbed BRV-PV, the vaccine posted efficacy figures slightly higher than the 61% posted by GlaxoSmithKline’s Rotarix and much better than the 39% demonstrated by Merck’s RotaTeq, both in previous trials. The new results were published in the New England Journal of Medicine.

However, what's more exciting to the medical community is the vaccine's stability at high temperatures. Serum's vaccine is stable for two years at 37°C (99°F) and for six months at 40°C (104°F).

Both RotaTeq and Rotarix need to be kept at 2°C to 8°C (36°F to 46°F) during storage and transportation. Rotavac, another oral rotavirus vaccine produced by Indian company Bharat Biotech and launched in the country in 2015, has to be kept frozen at -20°C (-4°F). 

BRV-PV vaccines were not refrigerated throughout the period of the trial, Rajeev Dhere, executive director at the Serum Institute in charge of the rotavirus project, told FiercePharma. "Vaccine efficacy figures with point estimates may not be the factor of proving superiority, but keeping the vaccine out of the cold storage is surely the first of it’s kind move and that’s why it stands out," he said.

Rotavirus remains one of the deadliest threats to children and infants, especially in impoverished regions of the world. WHO estimates the disease kills about 215,000 children under 5 each year.

Of the 1,780 infants who received three doses of the Serum Institute vaccine, investigators found 31 severe rotavirus gastroenteritis cases. The 1,728-person placebo arm reported 87 cases.

"This provides hope in environments where there wasn’t any," Rebecca F. Grais, who directed the trial for Doctors Without Borders, told The New York Times. "Our level of enthusiasm is very high."

Serum will charge $6 for three doses of its shot, with bargaining room for large orders, the NYT reports. According to procurement agreement prices posted by the United Nations Children’s Fund (UNICEF), GSK is providing Rotarix at €3.76 (about $4) for two doses, while Rotateq costs the agency $10.50 for a three-dose regimen.

The Indian company has submitted an application to the WHO for a prequalification approval for the vaccine, to be marketed as Rotasiil, with an initial production of about 60 million doses per year, about 80% of which will be supplied to United Nations agencies, said Dhere.

Working on a potential competitor to Serum's heat-stable shot is Hilleman Labs, a Merck co-owned lab in phase 1/2 testing with its candidate. Hilleman is currently looking for partners to manufacture and market its vaccine.