SINGAPORE - A new Covid-19 vaccine could be available in Singapore, with American firm Novavax having applied for interim authorisation by the Health Sciences Authority (HSA).

Confirming this, the authority told The Straits Times that Novavax had submitted data in its application via the Pandemic Special Access Route on Nov 22.

"HSA has commenced a careful and thorough rolling review of the data to ensure that the vaccine meets requirements for quality, safety and efficacy for interim authorisation before it is approved for use in Singapore," said its spokesman.

She added that the time taken for the review could range from several weeks to months, depending on the completeness of the data submitted and the time taken by the company to respond to HSA's queries that may surface during regulatory evaluation.

According to the US biotechnology company, clinical trial data compiled from two phase three trials shows that the non-mRNA vaccine has an efficacy rate of around 90 per cent across a variety of viral variants.

The vaccine is given in two 0.5ml doses, and 21 days apart.

Trials among 30,000 participants for the vaccine in the United States and Mexico demonstrated 100 per cent protection against moderate and severe disease, and a 90.4 per cent efficacy rate.

Similarly, a trial of 15,000 participants in Britain demonstrated an efficacy rate of 96.4 per cent against the original virus strain, 86.3 per cent against the Alpha (B.1.1.7) variant and 89.7 per cent efficacy overall, said the company.

Novavax said in response to queries from ST that it is ready to begin delivery of its vaccine doses as soon as it receives "regulatory authorisation and completion of any release requirements by the authorities".

Singapore had signed an advance purchase agreement with the company in January this year to secure supplies of its vaccine.

Health Minister Ong Ye Kung had said in June that the Ministry of Health had been looking for good quality vaccines that are safe and effective, to be part of the national vaccination programme.

As Novavax is a protein-based vaccine, it uses a laboratory-made version of the Sars-CoV-2 spike protein to stimulate an immune response. Sars-CoV-2 is the virus that causes Covid-19.

The supply of the Novavax vaccine would make it the fifth vaccine available here - alongside Pfizer-BioNTech/Comirnaty, Moderna, Sinovac and Sinopharm. Sinopharm has not been included in the national vaccination programme as the manufacturer has not applied for interim approval for use, as at Oct 23.

Asked about the potential use of the vaccine as a booster, a Novavax spokesman said that the company's filings to date have been for the vaccine to be used in a primary two-dose regime.

"We expect to apply for additional authorisations following the completion of our booster studies," added the spokesman.

She also said that analysis of blood samples from the company's primary vaccine series has shown cross-reactive antibodies to the Alpha, Beta and Delta variants, and these increased six to tenfold with a booster dose.

Data from its recent phase two booster study, in which the booster dose was given six months after the two-dose primary series, has shown a 4.6-fold increase in functional antibody levels.

"This reinforces our confidence in the potential for a booster dose of the Novavax Covid-19 vaccine to help protect against Covid-19," the spokesman added.

Novavax and the Serum Institute of India recently received emergency use authorisation for the vaccine to be used in Indonesia and the Philippines.

The companies have also filed for the vaccine to be under the World Health Organisation's Emergency Use Listing.

This article was first published in The Straits Times. Permission required for reproduction.