Hospitals must “see sense” on the “bizarre” plan to delay the second dose of Covid-19 vaccines that will leave many vulnerable staff members in limbo, a union has warned.

The Hospital Consultants and Specialists Association (HCSA) said the recent decision to delay the second dose of the Pfizer vaccine to many hospital workers was “ill thought out”.

As the approval of the Oxford/AstraZeneca vaccine was announced on Wednesday, a new dosing regimen was outlined, aimed at providing a speedier rollout.

Experts advising the Government, including the Joint Committee on Vaccination and Immunisation (JCVI), said that the focus should be on giving at-risk people the first dose of whichever vaccine they receive, rather than providing the required two doses in as short a time as possible.

This now means the second dose of both the Oxford/AstraZeneca and the Pfizer/BioNTech vaccines will be within 12 weeks of the first.

HCSA general secretary Dr Paul Donaldson said: “While a planned and orderly deployment of the Oxford vaccination including longer timelines makes epidemiological sense, the decision to throw a spanner in the works of the existing Pfizer rollout appears simply bizarre unless there is an unknown hitch in supply.

“We are hearing that vulnerable hospital doctors at high risk from Covid have been told not to turn up for their second dose and therefore will not receive full protection.

“They are now left in limbo by a hastily formulated policy which seems extremely ill thought out.”

Dr Donaldson added that the “chaotic” approach was “creating huge anxiety on the ground” among staff ahead of the latest wave of the virus.

Other healthcare experts have said the move to delay administering second doses will cause huge problems for thousands of partially-vaccinated elderly and vulnerable people.

Chairman of the British Medical Association’s (BMA) GP committee, Dr Richard Vautrey, said: “It is grossly and patently unfair to tens of thousands of our most at-risk patients to now try to reschedule their appointments.

“The decision to ask GPs, at such short notice, to rebook patients for three months hence, will also cause huge logistical problems for almost all vaccination sites and practices.

“For example, to make contact with even just 2,000 elderly or vulnerable patients will take a team of five staff at a practice about a week, and that’s simply untenable.”

Dr Vautrey said the BMA would support practices which honour the existing appointments for the follow-up vaccination, calling for the Government to do the same.

He added: “The Government must see that it’s only right that existing bookings for the oldest and most vulnerable members of our society are honoured, and it must also as soon as possible publish a scientifically-validated justification for its new approach.”

An NHS spokesperson said: “The MHRA, JCVI and UK Chief Medical Officers have updated the second dose timing guidance which the NHS has to follow, so as to increase the number of vulnerable people protected against Covid over the next three months, potentially saving thousands of lives.

“The NHS immediately informed GPs on the day the revised instruction was given, with extra financial and logistical support now being provided to help ensure thousands more receive the vaccine quickly.”