LONDON (Reuters) – Allergy Therapeutics Plc announced on Monday positive results from a Phase III trial of its Pollinex Quattro ragweed vaccine, but confirmed that trials in the United States are still on hold.

The ragweed study showed that the vaccine was significantly more effective than a placebo in dealing with seasonal allergic rhino-conjunctivitis caused by ragweed pollen.

While the company cannot proceed with gaining U.S. approval because of the hold imposed by the Food and Drug Administration, it expects to have a review of the critical clinical stay of in the middle of next year, R&D Director Tom Holdich told Reuters in an interview Monday.

In the meantime, it plans to apply next year for marketing clearance for the vaccine in Canada.

“Following the (FDA) advisory committee where they agree on their general policy we would be looking to have a review of our own product following that, so it’s probably about in the middle of next year we should then have very clear and specific guidance on what we might need to do,” Holdich said.

The stay is critical to the company as it cannot complete partnering discussions until it is lifted.

In July last year, Allergy Therapeutics said the FDA had placed a hold on the final stage trial of Pollinex Quattro.

The stay has now become a review of a new accelerator that the vaccine is mixed with, known as an adjuvant.

The review of the adjuvant will need to be completed before the regulators looks at individual products, Allergy said.

The new adjuvant, which contains MPL used by a number of companies, including by GlaxoSmithKline in its Cervarix cervical cancer vaccine, has been approved in Europe but not in the Unites States.

Analyst Robin Campbell at Jefferies said that the details of the large-scale study announced today were important, and added that it was significant that the hold was still in place.

“People will be interested to dig down and find out the underlying detail of that in terms of the sub populations … the devil is in the detail,” he said. “But the overlying tone of the release is that they still have the clinical hold in place in the U.S.”

Earlier, Allergy reported sales for the full year ending June 30 up 21 percent to 31 million pounds ($56.58 million) and said its cash at year-end was 2.3 million pounds, compared with 5.7 million at the same time the previous year.