LONDON

The head of the UK Vaccine Taskforce wrote in an article published on Wednesday that the first coronavirus vaccines were likely to be “imperfect” and “might not work for everyone.”

Kate Bingham, writing in the medical journal The Lancet, said that “vaccination is widely regarded as the only true exit strategy from the pandemic that is currently spreading globally,” and as such never before has a vaccine “been as eagerly anticipated.”

She sought to lower expectations, however.

“We do not know that we will ever have a vaccine at all,” she wrote. “It is important to guard against complacency and over-optimism.

“The first generation of vaccines is likely to be imperfect, and we should be prepared that they might not prevent infection but rather reduce symptoms, and, even then, might not work for everyone or for long.”

Bingham described the UK’s vaccine strategy as being “to build a diverse portfolio across different formats to give the UK the greatest chance of providing a safe and effective vaccine, recognising that many, and possibly all, of these vaccines could fail.”

The world’s leading vaccine candidate is that under development by Oxford University and AstraZeneca, with its phase 3 trials still ongoing.

A vaccine by Pfizer and German company BioNTech is also progressing well, with Pfizer’s chief executive saying it was in the “last mile” but also asking for “patience”.

Johnson & Johnson’s vaccine candidate is also in phase 3 trials, which will resume shortly after being paused briefly due to a participant’s unexplained illness.