COVID-19 Vaccine: Chadox1 by Oxford University shows some positive results in monkeys, human trails still underway

HealtScientists all over the world are racing to launch a vaccine for the new coronavirus. As per the World Health Organization , eight vaccine candidates in the world are already in the human trial phase and 110 more are right now in preclinical stages.

The Oxford University’s Chadox1 entered human trials late April. The vaccine is an adenovirus vector that reportedly develops a strong immune response with only one shot. Now, a preprint research article released by the university says that the vaccine is effective in rhesus monkeys who received a shot of the vaccine before the human trials began.

The study is not peer-reviewed yet but has been shared online to help public health experts learn more about COVID-19.

The study

For the study, Dr Sarah Gilbert, one of the lead scientists in the Chadox1 team, and her colleagues injected their adenovirus vaccine in six rhesus macaques, a non-human primate that is often used in biomedical research. The dose of the vaccine was half that of what is being used for humans right now.

Three other monkeys were kept as controls and were given Chadox GFPs - a control vaccine which does not create an immune response but has a green fluorescent protein to study it - in the same dose as is being given to humans right now.

The team found that a single dose of the vaccine stimulated both the arms - cell-mediated and humoral - of the adaptive immunity (the one you develop after being infected with a microbe). Antibodies against the targetted spike protein of the virus were found in all the 6 monkeys within 14 days of immunisation, whereas no antibodies against the COVID-19 causing virus were found in the control group.

Upon being injected with the virus, all the monkeys showed a significant reduction in viral load (amount of virus present) in their respiratory tract and did not develop signs of pneumonia.

Also, none of the infected animals showed signs of severe or worse disease on being injected with the virus.

Chadox1

Chadox1 is an adenovirus vector-based vaccine being developed at the Jenner Institute under the Oxford University.

Adenovirus vectors are the most common type of vectors used for vaccine development. Vector vaccines involve the use of other live or dead microbes to pass on the DNA/RNA (nucleic acid) of the target microbe into the body of a person. When you get the vaccine, your immune system reacts to it in the same way it would if you were exposed to the target microbe in a natural setting and produce antibodies against the said microbe. Hence, without ever getting sick you will be protected from the disease.

The vaccine uses the DNA sequence for the spike protein from SARS-CoV-2, the causative agent of COVID-19. The adenovirus vector in Chadox1 will not replicate inside the human body, which is why it is being considered safe for the elderly and children too.

For more information, read our article on Why is it taking so long to develop a vaccine for COVID-19?

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