09/27/2026
I might get shut down by Meta for saying this. Oh well.
A lot is being said in some circles about the new Nobivac NXT self-amplifying mRNA shots. They've been available in Canada for 2 years but are even newer in th USA.
To my knowledge, at the time of this post (9/2026) the NXT shots are not currently on the US market.
Since RV shots are legally required in the USA, you should know: You can request a killed virus Rabies shot specifically. That's the standard RV that's been used for decades.
Downsides of the conventional shot include adjuvants, frequent booster shots, with possibly shorter duration of immunity (Rabies Challenge Fund studies suggested a 7 year duration of immunity but that's not widely accepted).
An interesting fact: in the linked study, the level of neutralizing antibodies is defined. When this subject comes up, about doing a titer for Rabies as a replacement for blind boostering, the argument is always, we don't know what level is protective.
Yet, apparently, when Big Pharma needs a defined number for protective, neutralizing antibodies, we have it. Interesting.
I mean this ain't new. If I want to bring my pet to a Rabies-free country, I have to prove this level of neutralizing serum antibody. It's a number that has been around for decades.
Okay so moving along.
Self amplifying RNA Rabies vaccines for dogs and cats were USDA approved in 2023 and are anticipated to reach the US market soon. To gain approval, Merck performed a 3 part study.
Part one was a graded dose study. The aim of this part was to determine what dose of saRNA was needed to reliably produce neutralizing antibodies in cats or dogs. For each species (cat/dog) there were 10 pets given one of 3 doses of NXT and 5 animals given the standard RV shot (35 animals in each group).
One year later, 34/35 cats had neutralizing antibodies - in fact, robust levels that far exceed what's deemed protective. That one cat had received the standard RV.
The dogs, who were followed only for 90 days, showed a much less robust response to conventional and to RNA shots, but the RNA-V dogs all had neutralizing levels of antibodies at 90 days.
Next was a 3 year duration of immunity study where 12 week old treated and control dogs or cats were housed together for 3 years. One shot was given to treated kittens and puppies. Serial blood tests measured circulating antibodies. After 3 years, all animals were challenged with live Rabies virus.
None of the untreated cats or dogs were reported to seroconvert: they did not develop measurable antibodies to RV.
2/30 mRNA V'd cats were removed from the study for problems deemed to be unrelated to the shot, while 1/15 untreated cats was removed. Meanwhile 2/29 treated dogs and 0/13 untreated dogs were removed from the study.
All 28 RNA-V treated cats survived a Rabies challenge at 3 years, while none of the 14 untreated cats survived. All developed signs of Rabies infection and were euthanized.
The RNA-V treated dogs all survived the challenge at 3 years, while 11/13 untreated dogs developed Rabies and were euthanized.
A Field Safety Study was done with 665 cats aged 12 weeks to 21 years. They were followed daily for 2 weeks after the shot to screen for adverse events.
There were 662 dogs in the Field Safety Study aged 12 weeks to 16 years. They were followed daily for 2 weeks after the shot to screen for adverse events.
Since the only adverse events reported in those 14 days were mild and transient, the shots were deemed safe.
Links to papers in comments.
