Race to Develop Omicron-proof Boosters Before Northern Winter

Vaccine manufacturers are in a race to develop or tweak COVID-19 vaccines to address the Omicron variants that are sweeping through the globe – and get them ready for use as boosters when the weather cools in the northern hemisphere.

More infectious Omicron strains BA.4 and BA.5 have become dominant in many parts of the world and while they appear less virulent, they have mutated to be more capable of evading neutralizing antibodies generated by vaccinated people.

BA.4/5 showed 4.2-fold more resistance to sera from vaccinated and boosted people according to research from Qian Wang, David Ho and colleagues published in a recent preprint article.

Pfizer and Moderna dominate 

Nine candidate vaccines are in the pipeline that offer “multi-variant vaccines, booster vaccines, or vaccines targeting Omicron”, according to UNICEF’s COVID-19 Vaccine Market Dashboard.

But market leaders Pfizer-BioNTech and Moderna have the upper hand and are racing ahead with tweaks to their vaccines to ensure Omicron-ready boosters can be manufactured and ready within months.

In late June, Pfizer-BioNTech announced preliminary results for their vaccine tweaked to combat Omicron BA.1 that “elicited a 13.5 and 19.6-fold increase in neutralizing geometric titers against Omicron BA.1” – and was also effective in neutralising BA.4/BA.5 – but “with titers approximately three-fold lower than BA.1”. 

Moderna booster targets Omicron BA.4 and BA.5 

This week, Moderna announced preliminary results from trials of its Omicron candidate booster vaccine – mRNA-1273.214  – which showed a 6.3-fold rise in neutralizing antibodies against BA.4 and BA.5 strains in comparison to a 3.5-fold increase elicited by the original vaccine.

“One month after booster, BA.4/5 neutralizing titers were 776 for mRNA-1273.214 and 458 for the currently authorized booster,” according to Moderna, which is also working on a second booster called mRNA 1273.222, that specifically targets BA.4/ 5.

“This superior breadth and durability of immune response following a bivalent booster has now been shown in multiple Phase 2/3 studies involving thousands of participants,” said Moderna CEO Stephane Bancel. “We are working with regulators to advance two bivalent vaccine candidates, mRNA-1273.214 and mRNA-1273.222, based on different market preferences for Omicron subvariants, clinical data requirements, and urgency of starting fall booster campaigns for vulnerable populations.”

The race to develop Omicron-specific boosters accelerated after the US Food and Drug Administration (FDA) recommended the inclusion of an Omicron component in COVID-19 booster vaccines after a meeting of its Vaccines and Related Biological Products Advisory Committee on 28 June.

“As we move into the fall and winter, it is critical that we have safe and effective vaccine boosters that can provide protection against circulating and emerging variants to prevent the most severe consequences of COVID-19,” said the FDA.

The “overwhelming majority” of independent experts on the FDA advisory committee had voted in favour of boosters including an Omicron component to be ready for use in the US in fall 2022, it added.

“We have advised manufacturers seeking to update their COVID-19 vaccines that they should develop modified vaccines that add an omicron BA.4/5 spike protein component to the current vaccine composition to create a two-component (bivalent) booster vaccine, so that the modified vaccines can potentially be used starting in early to mid-fall 2022,” added the FDA.

However, it has not advised manufacturers to modify vaccines for primary vaccination.

India and South Korea approve local vaccines 

A COVID-19 vaccine developed by SK bioscience in South Korea, in partnership with GlaxoSmithKline and the University of Washington, was been approved in South Korea.

Among the candidate vaccines targeting Omicron are two Chinese vaccines, one from the Beijing Institute of Biologic Production, and the other from Sinocell.

Meanwhile, three new vaccines have been approved in various parts of the world. On Wednesday, the US finally approved Novavax which was approved in the European Union late last year. Novavax is also in the process of testing a booster to deal with Omicron.

Meanwhile, India approved the first mRNA vaccine developed by an Indian company, Gennova, in late June. 

At the same time, South Korea approved a recombinant protein-based vaccine, SKYCovione, developed by local company SK bioscience in partnership with GlaxoSmithKline (GSK) and the University of Washington’s School of Medicine.

SK bioscience has already signed an advance purchase agreement with the Korea Centers for Disease Control and Prevention for 10 million doses of the two-dose SKYCovione.

SK bioscience announced on Wednesday that its candidate booster had proven to be effective against Omicron in a small Phase I/ II trial involving 81 adults who received the booster seven months after completing primary vaccination.

“Neutralizing antibody titres against the Omicron variant BA.1 were 25 times the titres right after the second dose, and 72 times the titres seven months after the second dose,” according to the company.

Meanwhile, SK bioscience was recently approved to manufacture Novavax for European Union markets.

Image Credits: Pixabay.

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