ImmunityBio is set to commence two trials in South Africa to evaluate its hAd5 T-cell-based Covid-19 vaccine candidate’s potential to offer prolonged protection in previously Covid-19 infected or vaccinated individuals.

Targeting both spike (S) and nucleocapsid (N) proteins of SARS-CoV-2, the second-generation hAd5 viral-vector vaccine candidate can potentially induce B and T cell memory to these antigens and offer long-term viral immunity.

One of the new trials will analyse the use of the vaccine candidate as a ‘universal boost’ in health workers who have received a spike-only antibody-based vaccine that is already available.

The second trial will assess the vaccine candidate’s safety and efficiency when administered intranasally in previously infected participants.

The South African Health Products Regulatory Authority (SAHPRA) has granted approval for this intranasal administration study.

If these trials are successful, the optimal administration route will be identified, and a Phase III universal boost study will be conducted in 9,670 participants.

South African Medical Research Council president and CEO Glenda Gray said: “Providing people with long-term immunity is vital as it is making it easier for people to become vaccinated in circumstances where jabs are difficult to administer.”

The subcutaneous plus intranasal (SC plus IN) administration of the vaccine as a dual prime without a boost was observed to be effective in inducing humoral and T-cell responses in preclinical studies. This effectiveness was similar to the SC plus IN prime with a boost, the company noted.

Last month, ImmunityBio reported initial data from a Phase I clinical trial of its hAd5 Covid-19 vaccine candidate, which stimulated the generation of T cell reactive to vaccine-delivered S and N protein antigens in healthy subjects.

In another development, Elixirgen Therapeutics dosed the first and second subjects in a Phase I/II clinical trial of its Covid-19 vaccine, EXG-5003, in Japan.

EXG-5003 is a self-replicating ribonucleic acid vaccine that expresses the receptor-binding domain of the spike protein of SARS-CoV-2. It can be administered intradermally and is temperature controllable.

This trial will analyse the safety and immunogenicity of the vaccine in 60 adults aged 20 to 55.