Novavax said on Wednesday that its vaccine, which targets both Covid-19 and the flu, elicited a similar immune response as its standalone vaccines against each virus, an early indication that a combination vaccine targeting both viruses could that may prove effective, although further studies are needed.
Chief Medical Officer Filip Dubovsky, speaking to reporters, said the company’s early-stage clinical trial found that up to 25 micrograms of the Covid formulation combined with up to 35 micrograms of the flu formulation showed promising levels of protective antibodies triggered.
“What we showed in this study is that we were able to get the immune responses really comparable to those of the individual vaccines before the combination,” Dubovsky said.
The participants in the phase 1 study had an average age of 59 and all had previously received Covid vaccines. Novavax is presenting the data at the World Vaccine Congress in Washington, DC on Wednesday.
Novavax plans to proceed with a Phase 2 study this year to confirm appropriate dosing levels and start a Phase 3 efficacy study at the earliest during the 2023 flu season, Dubovsky said.
Public health experts expect Covid to become a seasonal respiratory virus similar to the flu, likely requiring annual vaccination as immunity to the shots wanes over time. Vaccine makers are scrambling to develop combination shots that target both viruses to make it easier for people to protect themselves when Covid and the flu are circulating at the same time.
“Combination vaccines are an attractive public health intervention,” Dubovsky said. “You meet two life-threatening diseases in one medical contact and give a single vaccination.”
Novavax, an early competitor in the US government’s 2020 race to develop Covid vaccines, currently has no approved vaccine in the US. The company asked the Food and Drug Administration to approve its Covid vaccine in January. Dubovsky told reporters Wednesday that the FDA is still reviewing Novavax’s application.
Novavax’s Covid vaccine uses a different technology than Pfizer’s and Moderna’s vaccines, which rely on messenger RNA to turn human cells into factories that produce copies of the virus spike protein and trigger an immune response that kills Covid fought. The spike is the part of the virus that attaches to and invades human cells.
The Novavax recordings, on the other hand, synthesize the virus tip entirely outside the human body. The genetic code for the tip is put into a baculovirus that infects insect cells, which then produce copies of the tip that are purified and extracted. The spike copy, which cannot replicate or cause Covid, is injected into people to elicit an immune response against the virus.
The vaccine also uses an adjuvant containing an extract purified from the bark of a tree in South America to induce a broader immune response. The adjuvant has been used in approved vaccines against malaria and shingles. Novavax’s stand-alone Covid syringes consist of 5 micrograms of the spike copy and 50 micrograms of the adjuvant.
Novavax uses the same technology for its standalone flu vaccine candidate, which targets four strains of the virus.
While the Covid formulation is higher than the standalone vaccine at up to 25 micrograms in the combination vaccine, Dubovsky said it is well within the range of other FDA-approved Covid vaccines, which have dosages between 50 and 100 micrograms.
The 25-microgram formulation tested in the combination vaccine study is well tolerated and safe, Dubovsky said. The most common side effects were pain at the injection site, fatigue and headache, he said.