Vaccine breakthrough in fight against Covid

Study reports ‘strong immune response’ in the first phase of clinical trials

A POTENTIAL Covid vaccine being developed in the UK is safe and triggered “strong immune responses” in the first phase of human clinical trials.

Initial results, reported in the Lancet, show that the vaccine led participants to generate both antibodies and T cells in two to four weeks.

Antibodies are proteins which can detect and attack virus particles in the bloodstream and lymphatic systems, while T cells destroy cells infected with virus.

It is unclear how long the response lasts for, however, as the study – which followed 1,077 healthy adults aged 18 to 55 years with no known history of Covid-19 – only covered the first 56 days of the trial.

Studies of people known to have been infected with Covid show that their antibodies can disappear within three months, though they may still have cellular immunity. Ideally, a vaccine should confer protection for at least six months.

The trial, led by Oxford University, is ongoing and participants will be monitored for at least one year. Further testing will also be needed to confirm whether the vaccine protects against infection by exposing participants to the Sars-cov-2 virus.

Professor Sarah Gilbert, co-author of the study, said the early results “hold promise”, but further work is needed.

She said: “As well as continuing to test our vaccine in phase three trials, we need to learn more about the virus. For example, we still do not know how strong an immune response we need to provoke to effectively protect against Sarscov-2 infection. If our vaccine is effective, it is a promising option as these types of vaccine can be manufactured at large scale.”

None of the participants reported any serious reactions to the vaccine. The most commonly reported side effects were fatigue and headache, pain at the injection site, muscle ache, chills, fever, and high temperature, but these were reduced with paracetamol.

It is one of around 250 candidate vaccines in development worldwide. The Lancet also reported yesterday on a separate vaccine trial in China, where 97 per cent of participants developed binding antibodies and 88% a T cell response, at a low dose.

The results were even stronger at a high dose, but the study only followed participants up to day 28 so it is still unclear how long the response lasts.