With coronavirus cases around the world now at over 68 million, scientists have been working around the clock to develop a vaccine.
A vaccine developed at the University of Oxford was initially tipped as the front runner in the fight against Covid-19.
Yesterday, the results of the Oxford vaccine’s Phase III trial were announced, showing an overall vaccine efficacy of 70.4%.
However, the efficacy was found it increase to 90% when participants were given a low first dose, followed by a larger second dose of the vaccine.
While this suggests that giving a low first dose could be the best way to roll out the vaccine, one expert has warned that this tactic runs the risk of leaving people unprotected between doses.
Dr Julian Tang, a Clinical Virologist at the University of Leicester, explained: “A lower vaccine efficacy does run the risk of leaving a large proportion potentially unprotected despite being vaccinated.
“Those who have been vaccinated and think they are immune may behave more freely which may serve to spread the virus further if they do become infected.”
Dr Tang also warned that further data is needed to assess the vaccine efficacy in older people.
Of the 11,636 volunteers in the Phase III trial, the majority were in the 18-55 age range, with those aged 56 and older only contributing 12%.
Dr Tang said: “There is insufficient data as yet to confirm the vaccine efficacy against those over 55 years old.
“So if it is licensed by the MHRA, will it just be for the standard dose regimen but only for those aged 18-55 years?
“Or will they assume some level of efficacy (>50%) in those over 55 years also – given the current COVID-19 pandemic crisis?”
Thankfully, Dr Tang believes the more data from the trial will soon answer these questions.
He added: “More data will come from the various arms of the trial to hopefully answer some of these outstanding questions to support its licensing.”