The Lancet: Oxford COVID-19 vaccine is safe and protects against disease

A COVID-19 vaccine developed by the University of Oxford is up to 90% effective, a peer-reviewed paper in The Lancet has confirmed.

The vaccine protects against symptomatic disease in 70% of cases – 62% for those given two full doses and of 90% given a half then a full dose, as reported by the university last month.

The results are the first full peer-reviewed efficacy results to be published for a COVID-19 vaccine.

It was found to be safe, with only three out of 23,745 participants experiencing serious adverse events that were possibly related to a vaccine. All have recovered or are recovering and remain in the trial.

Adults in the UK, Brazil and South Africa took part, including 1,500 in Oxford. The trial was supported in the UK by National Institute for Health Research (NIHR).

The vaccine uses a chimpanzee adenovirus viral vector that cannot cause disease in humans and delivers the spike protein genetic code into vaccinated people’s cells, which then produce the protein, teaching the immune system to recognise and attack the virus.

Past trial results have found the vaccine - which can be stored in a normal refrigerator - induces antibody and T cell immune responses, and is safe in adults aged 18 years and over, including older adults.

Half the trial participants were given the COVID-19 vaccine and the other half given a meningococcal conjugate vaccine or saline.

Participants in the COVID-19 vaccine group received two standard doses.

However, a subset of 1,367 people in the UK received a half dose as their first dose, followed by a full second dose. This was because of differences in the results of quantification methods between batches of the vaccine. The low-dose/standard-dose group did not include adults over 55 years.

Study lead author Professor Andrew Pollard said: “Control of the pandemic will only be achieved if the licensing, manufacturing and distribution of these vaccines can be achieved at an unprecedented scale and vaccination is rolled out to those who are vulnerable.

“Our findings indicate that our vaccine’s efficacy exceeds the thresholds set by health authorities and may have a potential public health impact.”

Co-author Professor Sarah Gilbert University of Oxford said: “The possibility that more than one efficacious vaccine may be approved for use in the near future is encouraging.

“Here we have shown for the first time that an adenoviral vectored vaccine – a type of vaccine technology which has been in use since 2009 – is efficacious and could contribute to disease control in the COVID-19 pandemic.”

Further evidence will be required to determine duration of protection and the need for additional booster doses of vaccine.