US drug developer, Novavax Inc, said on Monday that it is starting a mid-stage study of its experimental Covid-19 vaccine in South Africa, as the country experiences a surge in coronavirus cases.

The Phase 2b trial study of NVX-CoV2373 will be conducted on about 2,665 healthy adults and will evaluate the safety and immunogenicity in about 240 medically stable, HIV-positive adults, the company said in a statement.

“Because South Africa is experiencing a winter surge of Covid-19 disease, this important Phase 2b clinical trial has the potential to provide an early indication of efficacy, along with additional safety and immunogenicity data for NVX-CoV2373,” said Novavax research chief Gregory Glenn.

South Africa is fifth worst affected country with 583,653 coronavirus cases and 11,677 deaths, according to a Reuters tally.

The Bill & Melinda Gates Foundation is providing a $15 million grant towards the clinical trial, the company said.

Novavax said it intends to initiate the Phase 2 portion of this trial in the United States and Australia in the near future and that it would include about 1,500 candidates.

Earlier this month, Glenn told Reuters the company would start much larger late-stage clinical trials soon and could potentially glean enough data to obtain regulatory approvals as early as December.

The US government in July had awarded Novavax $1.6 billion to cover testing and manufacturing of a potential vaccine for the novel coronavirus in the United States with the aim of delivering a 100 million doses by January.

Last month, AstraZeneca said late-stage trials of its experimental drug AZD1222, which is developed by AstraZeneca and Oxford University, are under way in Brazil and South Africa and due to start in the United States, where prevalence is higher.

Recently, Novavax, Inc, announced collaborating with SK bioscience, a vaccine business subsidiary of SK Group, for the antigen component of NVX-CoV2373, Novavax’ COVID-19 vaccine candidate, for supply to global markets including the COVAX Facility. In addition, the companies have signed a letter of intent with the Republic of Korea’s Ministry of Health and Welfare to work toward broad and equitable access to NVX-CoV2373 for the global market as well as to make the vaccine available in South Korea.

Under the terms of the agreement, SK bioscience will manufacture the vaccine antigen component for use in the final drug product globally during the pandemic period.

NVX-CoV2373 was developed using Novavax' recombinant nanoparticle technology to generate a stable, prefusion antigen derived from the coronavirus spike (S) protein. It contains Novavax' patented saponin-based Matrix-M adjuvant to enhance the immune response and stimulate high levels of neutralizing antibodies. Phase 1 data from the Company’s Phase 1/2 randomized, observer-blinded, placebo-controlled trial shows that NVX-CoV2373 was generally well-tolerated and elicited robust antibody responses numerically superior to that seen in human convalescent sera.

SK bioscience, using its cell culture and recombinant protein capability, will initiate the production of the NVX-CoV2373 antigen at its vaccine facility in Andong L-house, South Korea beginning in August 2020.

This contract development and manufacturing organization agreement leverages the capacity reservation agreement between SK bioscience and the Coalition for Epidemic Preparedness Innovations (CEPI). Novavax' NVX-CoV2373 will be manufactured using a part of the reserved capacity at SK Bioscience’s “L-House” facility.

This agreement further boosts the potential global supply of the NVX-CoV2373 vaccine and is an important component of Novavax’ collaboration with CEPI. Through that partnership with CEPI, Novavax has committed to develop and manufacture significant amounts of NVX-CoV2373, including vaccine derived from antigen coming from SK bioscience, if proved safe and effective, to be procured and distributed by the COVAX Facility through a globally fair allocation framework.

"We are proud to partner with SK bioscience to fulfill our commitment to ensure global supply of NVX-CoV2373 in alignment with our partnership with CEPI,” said Stanley C. Erck, President and CEO of Novavax. “SK bioscience shares our sense of urgency to ensure broad and equitable access for our COVID-19 vaccine candidate around the world.”

Jaeyong Ahn, CEO of SK bioscience said, "SK's accumulated vaccine R&D and production capability has been spotlighted by the world's most advanced global pharmaceutical companies as well as the global initiatives for the COVID-19 vaccine manufacturing and supply such as CEPI." He added, "We will cooperate with the government supporting its two-track strategy, developing vaccine in Korea and securing COVID-19 vaccine from a global manufacturer in a short period of time."