Novavax’s COVID-19 Vaccine is Safe and Immunogenic in Early Trial
On August 4th, nearly two months since the inception of vaccine testing, Novavax announced preliminary data from its Phase 1 trial. The vaccine produced a promising immune response in the participants but with a high rate of mild side effects.
By Ruchi Jhonsa, Ph.D.
With COVID-19 cases skyrocketing around the world, the need for a safe and efficacious vaccine is pressing. To try and meet the rising demands, a number of companies are advancing various types of vaccines with the funding received from the government and other agencies. Novavax is one such that received immense funding in the last few months from various government bodies, including CEPI, the US government (Operation Warp Speed), and the Department of Defense to develop and manufacture its COVID-19 vaccine.
NVX-CoV2372 Elicits Robust Humoral Response
NVX-CoV2373 is a recombinant nanoparticle vaccine with full-length prefusion stabilized SARS-CoV-2 spike glycoprotein that is mixed with Matrix-M adjuvant to create a strong immune response. In the Phase 1 trial conducted at two sites in Australia, 131 participants were enrolled and divided into five groups. Each group received a dose of 5ug or 25ug of the vaccine with or without adjuvant on Day 0 and a booster dose of the same on Day 21.
The antibody response in each of the participants was measured on Day 21 and Day 35. While the 25ug dose of the vaccine didn’t produce a great immune response, combining it with adjuvant showed a dramatic effect. Within 21 days of the first dose of the 5ug and 25ug vaccine with the adjuvant, participants started showing a humoral immune response. A single dose of the vaccine produced antibody titers in the range of 1000s, which was much lesser than the response seen in patients infected with the virus.
However, vaccine generated response escalated rapidly following a booster of the vaccine on Day 21 and showed a titer value of approximately 63,000 on Day 35, which is 8-fold higher than that of patients recovered from COVID-19 infection. When compared to the top contenders, Novavax’s vaccine is as good as Moderna’s mRNA-1273 and Pfizer and BioNTech’s BNT162b1 in generating a strong antibody response.
“You can see there was no difference between the responses in 5 and 25 mcg. In other words, this is a dose sparing regimen,” Gregory Glenn said on a conference call on Tuesday.
However, more important than getting a high antibody response is getting a strong neutralizing antibody response. The neutralizing antibodies hold power to kill the virus in the vicinity while blocking their interaction with the human cells. Thus, they provide the best evidence that protective immunity has been established. Like mRNA-1273 and BNT162b1, NVX-CoV2372 was able to generate a very robust neutralizing antibody response, almost 4-fold higher than that of convalescent plasma in 100% of participants after a round of booster dose.
Dr. Gregory Glenn, Novavax’s R&D chief, said during a conference call “There is a strong correlation between the severity of the disease and the antibody titer. So, this is a very good anchor for understanding our data. Our immune response sera measured at Day 35 is quite high and is certainly in line with what one might expect to be protective.” However, the data is still preliminary and whether it will protect people from COVID-19 infection is unclear.
NVX-CoV2372 Generates Pro-inflammatory Cellular Response
T cell response data, meanwhile, was measured in a subset of participants, and NVX-CoV2373 induced antigen-specific polyfunctional CD4+ T cell responses with a strong bias toward Th1 cytokines. It is an indication of good cellular response, as Th1-type cytokines tend to produce the pro-inflammatory responses including interferon-gamma, IL-2, TNF-alpha, and others, which are responsible for killing the virus. NVX-CoV2373 elicited a strong cellular response with both doses of the vaccine only when an adjuvant accompanied it. Induction of cellular immunity was also seen with Moderna, AstraZeneca, and Pfizer-BioNTech’s vaccine. However, it remains to determine to what extent these vaccines generate this response and how effective it will be to kill the virus.
The safety profile of the vaccine was comparable to other top contenders. About 80% of volunteers had side effects at the site of injection, including pain and tenderness. More than 60% had other side effects, which include muscle pain, headaches, and fatigue. The majority of reported symptoms were mild or moderate, but eight patients had side effects that were graded severe. However, all the reactions resolved after two days and none required hospitalization.
“The Phase 1 data demonstrate that NVX-CoV2373 with our Matrix-M adjuvant is a well-tolerated COVID-19 vaccine with a robust immunogenicity profile,” said Gregory M. Glenn, M.D., President, Research and Development at Novavax. “Using a stringent wild-type virus assay performed by investigators at the University of Maryland School of Medicine, NVX-CoV2373 elicited neutralizing antibody titers greater than those observed in a pool of COVID-19 patients with clinically significant disease.”
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