It's no secret that coronavirus vaccines are hot-selling medicines for which there's a massive market. Pfizer is expected to make $36 billion in 2021 alone from sales of its coronavirus shot, Comirnaty, and it's hard to see demand falling while the pandemic rages.

Nonetheless, the shots that are currently approved for sale aren't perfect. If a competitor were to develop a new product that doesn't fall victim to the same pitfalls, Pfizer's dominance might come to an end. In my view, intranasal vaccines might well precipitate that outcome. Here's why.

A nurse holds up a vial of an intranasal coronavirus vaccine while clad in protective gear.

Image source: Getty Images.

Jabs just don't cut it

The trouble with the jabs made by Pfizer, Johnson & Johnson, and Moderna is that they don't seem to effectively prevent infection or stop infected people from transmitting the virus as they are at preventing severe disease and death. That's because the current crop of vaccines on the market doesn't induce a strong antibody response where the body is most likely to first encounter the virus in the nose and mouth. 

Though the shots do confer some protection from infection and help people resolve their infections a bit faster, thereby reducing their period of infectiousness, the omicron variant's high infectivity poses an additional challenge. 

And that's where there's room to disrupt the existing market for coronavirus vaccines and steal some of Pfizer's $36 billion market share. In contrast to jabs, intranasal vaccine sprays appear to be excellent at inducing immunity in the nose and mouth in animal studies.

So, in theory, they should be much better at preventing infection and perhaps also transmission from infected people. And that could make the sprays into a massive cash cow, assuming that national healthcare systems will be willing to buy them on an ongoing basis like they've been with the jabs.

Engineering issues abound

The new vaccine format isn't necessarily a slam-dunk, though. There are a pair of essential catches that might derail efforts. 

The first catch is that it might be hard to adapt certain vaccine technologies to the aerosolized spray format. The small biotech Altimmune was an early mover into the intranasal coronavirus inoculation space, but its phase 1 clinical trial foundered when its candidate failed to generate immunity compared to the jabs on the market. It's entirely possible that other competitors will wipe out when it comes to adapting existing vaccines to the intranasal format, so the concept is still risky. 

The second catch is that it's unclear whether generating robust immunity in the nose and mouth will also confer protection against severe disease, which typically involves infection of the lungs, but some preliminary evidence suggests that it does.

In any event, there are likely workarounds for both of these issues, and a few companies are already moving forward. 

This company might make a fortune on vaccine sprays

AstraZeneca (AZN 0.20%) already has a coronavirus jab on the market, and it's working on using that product as a jumping-off point with its intranasal candidate. In the third quarter of 2021, AstraZeneca sold $1.05 billion worth of its jab. That's peanuts compared to Pfizer's Comirnaty sales totaling $13 billion in the same quarter. But AstraZeneca's nasal spray might just end up giving Pfizer a run for its money.

AstraZeneca previously made an intranasal flu vaccine, though its use was eventually discontinued in the U.S. With luck, it'll be able to use its prior experience in the field to successfully adapt its coronavirus shot to the aerosolized spray format. 

So far, researchers have confirmed that its vaccine is effective at generating immunity in animal models when it's administered as a spray, but replicating those results in people could be a challenge. A phase 1 trial in a group of 54 healthy adults is being conducted in conjunction with the University of Oxford, and it could be completed by the end of March.

After that, the spray would still need to clear the remainder of its trials, so it's a bit too early for investors to hop into the stock based on the state of the development process. Still, if its vaccine performs better as a spray than a shot when it comes to curbing infection, AstraZeneca will have a lifesaving product that will shake up the entire market.

Stay tuned -- if the early clinical trial results look favorable, it might spark another vaccine development race for intranasals that sends the participating pharma stocks and vaccine stocks into the stratosphere once again.