AKS-452 is a CoV-2 protein subunit vaccine based on the Ambifect™ Fc-fusion protein platform. Akston and Strides Group have signed a licensing, manufacturing, and commercialization agreement to launch AKS-452 worldwide as AmbiVax-C™.

The vaccine is designed to induce a Th1/Th2 mixed immune response in patients against the Receptor Binding Domain (RBD) of the novel coronavirus spike protein. Being the primary locus for infection, the RBD is highly conserved among mutated forms of the virus.

Unlike other vaccines that must be kept refrigerated or even deep-frozen for transport and storage, AKS-452 has been shown to be shelf-stable for at least six months at 25° Celsius (77° Fahrenheit) and maintains its potency for one month at 37° Celsius (99° Fahrenheit). This can greatly simplify distribution and is critically important for vaccinating the billions of people not served by sophisticated and costly cold-chain transportation.

The vaccine has been engineered to use standard, low-cost, antibody manufacturing techniques, such that a single production line could produce over one billion doses per year.


  • Full Receptor Binding Domain (RBD) presented to immune system
  • Glycosylated Fc activates immune system response
  • Clinical studies show robust, neutralizing antibody production
  • Designed to induce and/or augment antibody titers in patients
  • Production uses established, high-volume methods
  • Effective at microgram doses

Development status and plans

Akston’s AKS-452 COVID-19 vaccine could provide a practical solution to the problem of vaccinating and boosting the immunity of people all over the world against the SARS-CoV-2 virus.

Akston’s team realized early on that its Ambifect™ Fc-fusion protein platform could be used to design a vaccine that could be safe and effective, transportable at ambient temperatures, produced at very low cost, and suitable for repeated dosing as immunity wanes.

The vaccine is designed to meet the specific needs of developing countries — low cost production and little or no refrigeration needed for transport and use.

A Phase I trial in the Netherlands showed AKS-452 to be safe and well-tolerated. Most importantly, it produced a 100% seroconversion rate in a 90 ug single-dose regimen, as well as in a 45 ug two dose regimen. A Phase II study there showed a robust overall 98% seroconversion response after either two 45 μg doses (100%), or a single 90 μg dose (96%) in healthy adults at 56 days. These also resulted in robust antibody neutralization of variants, including Delta and Omicron.

A Phase II/III clinical study in India included 1,600 healthy volunteers – 100 in an open-label bridging study and 1,500 in a double-blind, placebo-controlled trial. The results showed no significant safety issues and a 91% seroconversion rate at Day 56. Volunteers in the bridging study had antibody titers that persisted at statistically-significant high levels through six months, with serum taken from them showing protection against variants of concern.

The results have been submitted for Emergency Use Authorization (EUA) in India as a prime vaccine. Other clinical studies are designed to support its approval for use as a booster shot to itself and other approved vaccines.