WASHINGTON, June 14 (Reuters) - Novavax on Monday (Jun 14) reported late-stage data from its United States-based clinical trial showing that its vaccine is more than 90 per cent effective against COVID-19 across a variety of variants of the virus.

The study of nearly 30,000 volunteers in the United States and Mexico puts Novavax on track to file for emergency authorisation in the US and elsewhere in the third quarter of 2021, the company said.

Novavax's protein-based COVID-19 vaccine candidate was more than 93 per cent effective against the predominant variants of COVID-19 that have been of concern among scientists and public health officials, Novavax said.

Protein-based vaccines are a conventional approach that use purified pieces of the virus to spur an immune response. Vaccines against whooping cough and shingles employ this approach.

During the trial, the B117 variant first discovered in the United Kingdom became the most common variant in the United States, it said.

Novavax also detected variants of COVID-19 first found in Brazil, South Africa and India among its trial participants, Novavax's head of research and development, Dr Gregory Glenn, told Reuters.

The vaccine was 91 per cent effective among volunteers at high risk of severe infection and 100 per cent effective in preventing moderate and severe cases of COVID-19. It was roughly 70 per cent effective against COVID-19 variants that Novavax was unable to identify, Glenn said.

"Practically speaking, it's very important that the vaccine can protect against a virus that is wildly swinging around" in terms of new variants, Glenn said.

Novavax said that the vaccine was generally well-tolerated among participants. Side effects included headache, fatigue and muscle pain and were generally mild. A small number of participants experienced side effects described as severe.

Novavax remains on track to produce 100 million doses per month by the end of the third quarter of 2021 and 150 million doses per month in the fourth quarter of 2021, the company said.

The Maryland-based company has repeatedly pushed back production forecasts and has struggled to access raw materials and equipment needed to make its vaccine.

However, in a May investor call, chief executive Stanley Erck said that major manufacturing hurdles had been cleared and that all of its facilities could now produce COVID-19 vaccines at commercial scale.

Erck said that Novavax had begun its regulatory filing in India in partnership with the Serum Institute of India (SII), which is contracted to make Novavax shots.

Erck said that his understanding was that SII was no longer constrained by raw materials shortages.

SII had said in March that US restrictions on exports of supplies used for vaccines were limiting its ability to scale up production.