Oxford vaccine passes first human trials
— 3 minute read — By Sam Portillo
On 20th July, the Oxford University vaccine group announced the results of the first human trials in their project to create an immunising jab for the novel coronavirus. The trial involved 1,077 healthy volunteers between the ages of 18 and 55, all of whom produced coronavirus antibodies after one or two doses of the vaccine.
If successful, the UK government will order 100 million doses of the vaccine to be made available to the public, starting with those at greatest risk from COVID-19, including NHS staff and elderly people.
Traditionally, vaccines contain a deactivated sample of the virus it seeks to protect against, so that the immune system learns the threat and produces the necessary antibodies in case of future infection. The Oxford vaccine, known as ChadOx1 nCoV-19, does not contain SARS-CoV-2 however. Instead, it uses an adenovirus responsible for the common cold in chimpanzees, fitted with spike proteins which form the “crown” around the novel coronavirus. It is these spike proteins on the virus’s exterior which the immune system identifies and responds to.
The adenovirus is engineered in a way which means it cannot replicate, and therefore, cannot cause infection. 70 percent of trial participants did however experience fever or headache after taking the vaccine, which are usual side-effects of an immune response. In this case, doctors would recommend over-the-counter painkillers like paracetamol.
The vast majority of volunteers developed an immune response after one dose. After two doses, every trial participant tested positive for COVID-19 antibodies. The researchers were happy to find that the vaccine not only induced the creation of antibodies, but also T-cells – a type of white blood cell which can alert the immune system to threats and annihilate infected cells themselves. Antibody levels peaked 28 days after vaccination and remained detectable for the full duration of trials. The number of T-cells peaked after just 14 days, but recent studies suggest they may be key to long-term coronavirus immunity, remaining in the body for a much longer time than antibodies.
Vaccine projects like the one at Oxford University offer the best escape from the pandemic. With everyone in the population immunised, the virus would be unable to find new hosts, leaving the epidemic to wither of its own accord – without the need for mitigation measures like social distancing or travel bans.
ChAdOx1 makes for a promising prospect: but promises can be broken. The first stage of the trial only included 1,077 volunteers, all between the ages of 18 and 55. Before the vaccine can be deemed effective, it must prove that it protects people from real infection. For this reason, researchers have recruited 30,000 volunteers in the U.S., 5,000 in Brazil, and 2,000 in South Africa, where the virus is much more prevalent than in the UK.
Researchers must also recruit “vulnerable” volunteers, like children and people over the age of 55, in order to check the vaccine is reliably safe. Many scientists believe the world will need an assortment of vaccines to overcome this pandemic, some which may work best in young people, and some in people with weaker immune systems, for example. Careful not to place all its eggs in one basket, the UK has signed preliminary deals for three other prototypes: one from British GSK and French Sanofi, one from American Pfizer and German BioNTech, and one from French Valneva. It may well be an 11th-century, English university, however, that wins the race.