he vaccine, called ChAdOx1 nCoV-19, is being developed at unprecedented speed. Developed by University of Oxford, it appears to be safe and triggers an immune response.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged as a zoonotic virus late in 2019 and is the causative agent of COVID-19. No vaccines have been approved for prevention of COVID-19. There are currently more than 137 candidates undergoing preclinical development and 23 in early clinical development, according to WHO.
An ideal vaccine against SARS-CoV-2 would be effective after one or two vaccinations; would protect target populations such as older adults and those with comorbidities, including immunocompromised individuals; would confer protection for a minimum of 6 months; and would reduce onward transmission of the virus to contacts.
The recent trial was the first time that the vaccine had been given to humans: 543 healthy adults aged 18-55 were vaccinated with a single dose of ChAdOx1 nCoV-19. A further 534 people were given a control vaccine that gives similar minor reactions, including injection site redness and mild pain. Volunteers are having their immune response (both antibodies and T cell levels) monitored for at least 12 months, and will also be observed to see whether or not they develop COVID-19.
The preliminary data from the trial clearly demonstrates that the vaccine induces an antibody response within 28 days. This response is in a similar range to that in individuals who have recovered from COVID-19, providing encouragement that the vaccine will be able to protect the majority of people against infection.
Ten volunteers were also given a second “booster” dose of the vaccine. This increased the antibody response to even higher levels, and 100% of blood samples from this group showed neutralising activity against COVID-19 infection in a laboratory setting. The vaccine also induced T cells that specifically recognise SARS-CoV-2, the virus that causes COVID-19. Importantly, the vaccine also demonstrates an acceptable safety profile, with no vaccine-induced severe adverse events – that is, no major side-effects.