Agencies:

Oxford University researchers said their vaccine candidate had triggered a dual immune response in humans against the coronavirus that causes Covid-19.

A preliminary report on early-stage human trial data of the vaccine candidate � which is being developed jointly with the British pharma giant AstraZeneca � had shown an �accepted safety profile�, the researchers said.

The Oxford-AstraZeneca vaccine candidate is made from a weakened version of a common cold adenovirus that causes infections in chimpanzees. The team of researchers led by Dr Sarah Gilbert of The Jenner Institute at Oxford genetically changed the adenovirus by adding the genetic material of the spike glycoprotein(s) that are found on the surface of the SARS-CoV-2 virus (which causes Covid-19).

The Oxford AstraZeneca ChAdOx1 nCoV-19 vaccine candidate is currently undergoing large (Phase III) human trials in the United Kingdom and Brazil.

During human clinical trials, vaccine candidates are assessed on three parameters, viz., reactogenicity (ability to produce common, adverse reactions), immunogenicity (ability to provoke an immune response), and safety.

In Phase I and II, Oxford trial 1,077 participants were enrolled to receive either ChAdOx1 nCoV-19 (543) or MenACWY (534), the vaccine against sepsis, which was used as an active control.

Study

The study revealed two important outcomes:
First, that there were �no serious adverse events related� to the vaccine candidate
Second, that while neutralizing antibodies, which specifically kill the virus, increased in a two dose regimen, the vaccine candidate also showed a �marked increase� in the response generated by cellular immunity.
�ChAdOx1 nCoV-19 was safe, tolerated, and immunogenic, while reactogenicity was reduced with paracetamol. A single dose elicited both humoral and cellular responses against SARS-CoV-2, with a booster immunisation augmenting neutralising antibody titres,� the study by the Oxford COVID Vaccine Trial Group reported.