Jet Automatic Hypodermic Injection Apparatus – Vaccine Gun (2021) | Hacker News Reader

Jet Automatic Hypodermic Injection Apparatus – Vaccine Gun (2021)

americanhistory.si.edu

39 pointsareoform19 comments

I learned today that these are real-life hyposprays. In fact, the Star Trek hyposprays are named after the brand name for one of these. Here's a photo of what these look like in action,

https://pbs.twimg.com/media/Fjooo0jXEAEri7D?format=jpg&name=...

They work with pressure to deliver a dose of the vaccine subcutaneously without needles. (I had always thought that they were some kind of needle-based injector instead)

I just think it's so cool that we already have hyposprays and it's a thing that we can improve! And deploy everywhere, including dense jungles. These worked on literal pedal power. And were painless.

    > Hingson's device used a piston to propel the vaccine at a rapid speed into and under the skin—the vaccine moved so quickly and under such pressure that no needles were needed. Public health practitioners gleefully noted that this method of vaccination was so painless that it could be used on a sleeping baby. But best of all, the jet injector could hold 500 or more doses of vaccine, meaning that hundreds of doses could be delivered within an hour.

Alas, they were phased out due to backwash and contamination from the injection process. But that's a fixable problem. I think.

I only received one injection with this device, but I can tell you it wasn't painless. In fact, it was by far the most painful injection I've ever had.

In my limited experience, high pressure pneumatic wounds are accute blunt force trauma and the pain is intense and long lasting.

It doesn't surprise me that this would hurt a lot.

I'm sorry that you experienced that! Would you happen to know what kind of injection you had? Was it subcutaneous, intradermal, or intramuscular? And what kind of vaccine was it?

I found a study addressing the pain and the authors theorized that the depth of the injection determined the pain experienced by the patients, https://www.pnas.org/doi/full/10.1073/pnas.0700182104

    > Motivated by the limitations of injections, needle-free liquid jet injectors were invented more than 50 years ago (4) and have been used for delivering several vaccines and protein drugs. More recently, a number of other technologies have also been proposed to deliver proteins across the skin without using needles (5–13). These technologies are at varying degrees of development. As of today, however, liquid jet injectors comprise the only needle-free tool in the hands of clinicians for delivery of proteins and other macromolecules. Commercially available liquid jet injectors use compressed gas or a spring to create high-pressure jets of drug solutions that deliver drugs in the s.c. or i.m. region (14, 15). Despite their long history, needle-free liquid jet injectors have been met with disappointing acceptance as a result of frequent bruising and pain (4), which immediately offset their advantages against needles. We hypothesized that pain and bruising originate from deep penetration of jets into skin leading to their interactions with nerves and blood capillaries. This issue could potentially be addressed by minimizing the penetration depth of jets into the skin; however, attempts to reduce the penetration depth have led to a concurrent loss of delivery efficiency (16). Decoupling penetration depth and delivery efficiency has been difficult as a result of the very design of conventional jet injectors. We overcame this issue by adopting a new strategy of jet injection, pulsed microjets. We propose the use of high-velocity microjets (v >100 m/s) to ensure skin penetration but small jet diameters (50–100 μm) and extremely small volumes (a few nanoliters) to limit the penetration depth. We describe a microjet device that meets these criteria and demonstrate its capabilities by using insulin as a model drug.

> Alas, they were phased out due to backwash and contamination from the injection process.

That's how the army gave my aunt Hep C. Numerous attempts have been made to solve this "backwash" issue, but fluid dynamics is a harsh mistress. When you shoot a droplet at a fluid interface, the interface shoots back.

> phased out due to backwash and contamination from the injection process. But that's a fixable problem. I think.

I'm kinda glad that they don't keep trying to fix it in production when a good enough alternative exists.

(Backwash = spreading disease from one patient to the next, and nasty stuff too like Hepatitis)

Side note, high pressure injection was and still is a common workplace accident[1].

It happens when you work with highly pressurized fluids, like with a grease gun, and there is a leak. The high pressure jet can penetrate your body without too much visible damage, but you just injected yourself with nasty chemicals, and the consequence can be serious, or even fatal.

The jet injector idea was that if high pressure jets can inject people with poison, why not use the same principle to inject medicine.

[1] https://en.wikipedia.org/wiki/High_pressure_injection_injury

Also a hazard when operating a waterjet cutter. Mine came with cards that advise the doc to treat the wound like a gunshot wound.

Yeah human tissue is very fragile and "tangible" physics is not well taught. Doesn't need much pressure to go through your meat.

An even cooler approach is microneedle polymer array patches, currently under R&D last time I checked (it’s been a while though). It consists of an elastomeric array of microscopic needles (<1/4 mm I think) that are coated with vaccine, making it truly biocompatible and painless, since the pain nerves are located deeper under the skin, while the blood capillaries are closer.

There are variants of this approach where, rather than having the needles be coated, they're made of a dissolvable sugar with the vaccine incorporated into them (so they are the vaccine in some sense). You'd apply them like a bandaid, wait a bit for it to dissolve, then take them off, and the whole process could be done at home with no supervision at all.

Yep, that too. Do you know if they’ve been marketed already? Or still in the R&D phase? I last looked at it ~8 years ago when I was working with someone who started a company around that.

They keep saying it's painless but I've heard more than once that's it's very painful.

Yeah I can't find any reputable source that suggests that are painless and I can't understand how they could be.

I got 5-6 shots with these entering the military. All but one felt like a normal shot if anything. The last one felt like I was jabbed with an knife and bled severely.

Afterwards, I was told if the gun is flush + perpendicular to the muscle, it's fine but if it's at an angle or not held still it cuts as it moves.

does this produce the polio vaccine scar we most commonly see on people born 1950-70

No... https://www.healthline.com/health/smallpox-vaccine-scar

Looks like gear that vets and farmers still use.

Super ominous ending

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