'Oxford COVID-19 vaccine safe for people with weak immunity'

New Delhi, July 1 Volunteers have begun participating in Brazil's first clinical trial of Oxford COVID-19 vaccine. The ChAdOx1 vaccine technology is based on an adenovirus, and it is considered very safe, even in people with a weak immune system.

The vaccine being used in the Brazilian trial, on 5,000 volunteers, is similar to the one used in the UK and South Africa. The ChAdOx1 vaccine technology is based on an adenovirus, another virus, which causes mild upper respiratory tract infections. "We have removed some of the adenovirus genes, so that when we use it as a vaccine, the adenovirus can't spread through the body. That makes it very safe, even in people with a weak immune system. But because it is still a live virus, it is good at inducing a strong immune response after vaccination", said Professor Sarah Gilbert, Nuffield Department of Medicine, Oxford University. Gilbert gave a short talk while participating in an informal discussion with ambassadors of the UN member states.

According to the Oxford University, many strains of adenoviruses infect humans; therefore people have developed antibodies against it. "We started with an adenovirus, which was isolated from a chimpanzee and doesn't circulate in human populations, so there is no prior immunity to it. Then we add a gene to encode one of the proteins from the pathogen that we want to vaccinate against for SARS-CoV-2 we use the spike protein, which covers the surface of the coronavirus," added Gilbert.

The ChAdOx1 vaccine technology has been used to produce candidate vaccines against a number of pathogens including flu, chikungunya, Zika and another coronavirus, Middle East Respiratory Syndrome

( With inputs from IANS )