Will chicken eggs change the Covid-19 vaccine landscape?
Author: Andrea Taylor
A promising new vaccine candidate is getting a flurry of attention this week, even in a very crowded landscape that includes 11 vaccines on the market and 50+ more in Phase 2 or 3 trials. The newcomer NDV-HXP-S vaccine, developed through collaborations between researchers at University of Texas at Austin, PATH, and Mount Sinai, among others, is a mouthful to say but the name captures the two reasons people are excited about it.
NDV refers to the Newcastle Disease Virus, a disease that effects birds but does not harm people. Using NDV as a viral vector for vaccines means the vaccine can be developed in chicken eggs, as is commonly done for the flu vaccine. NDV has also been used as a vector for vaccines against SARS 1, RSV, and Ebola.
HXP stands for HexaPro, a spike protein developed by researchers in the US that is stronger than the protein used by the vaccines currently on the market. This means it can work well in difficult climates. Several of our current Covid-19 vaccines (we’re looking at you, mRNA) are divas – extremely difficult to manufacture and difficult to transport. The HexaPro protein was designed to be rugged and easy to make without falling apart, intentionally created with lower-income markets in mind.
The NDV-HXP-S vaccine candidate is being eyed as a potential gamechanger for several reasons:
- Manufacturing: Many low- and middle-income countries (LMICs) already have expertise in making flu vaccines using chicken eggs and could apply this to making Covid-19 vaccine. And manufacturers in 80 LMICs can use HexaPro without paying royalties, thanks to a licensing agreement with University of Texas. This means countries such as Brazil and Thailand could own the manufacturing of this vaccine from start to finish.
- Cost: Experts estimate that it could be produced for as little as $0.50 to $1 per dose, which would make it the cheapest Covid-19 vaccine by far.
- Scale: Production can be scaled up very quickly, using existing infrastructure. The vaccine is so potent, that each egg can provide enough for 5 to 10 doses (typically flu vaccine gets 1 to 2 doses per egg).
This is not going to be a quick fix, however. The vaccine candidate is just beginning Phase 1/2 clinical trials in Brazil, Thailand, Vietnam, and Mexico (all of which also have the capacity to make it). If all goes well, it could potentially enter Phase 3 trials by late summer and, if effective and safe, start production by end of 2021 at earliest.
But most of the world will still be waiting for vaccines at the end of this year so this may still come in time to supply LMICs. It could also put us a much better position for global equity if boosters are needed.
To serve LMICs, a vaccine needs to be effective, affordable, available, and easy to transport. This vaccine looks like it can tick three of those boxes so far. We will have to wait on clinical trial results to see if it can tick all four.