NHS Highland has moved to reassure elderly residents amid concern vulnerable over 80s in some areas are facing delays for Covid boosters.

Health boards and GP practices are now in the process of vaccinating adults aged 70 years, care home residents, NHS staff and those over 16 who were previously shielding. 

The Joint Committee on Vaccination and Immunisation (JCVI) has said boosters and flu vaccinations should be administered together "where appropriate" and at least six months after second Covid shots.

Elderly people living in some parts of the Highlands including Lochaber have been receiving flu vaccines separately, without boosters.

A spokesman for NHS Highland said it was not possible to deliver both vaccines together in every area due to logistical and geographical challenges.

He said those who had received only flu vaccinations would be communicated with "shortly".

READ MORE: Masks and vaccine passports hailed for Scotland's 'consistently declining' Covid rates 

NHS Greater Glasgow and Clyde, Lanarkshire, Grampian, Fife, Forth Valley, Lothian, Borders and Ayrshire and Arran, said boosters and flu vaccinations were being administered together while Western Isles said patients were being given the option of having the jags together or separately.

NHS Tayside said people over 70 and those who were previously shielding were currently being invited for their flu vaccination at their own GP practices.

The board said lettered invitations for boosters for this group would follow and will take place at community vaccination centres. Details on NHS Orkney's website state that it is initially prioritising flu vaccinations.

Concerns over waning vaccine immunity were strengthened after a major survey in England found evidence of “breakthrough infections” more than three months after full vaccination.

Researchers at Imperial College London analysed more than 100,000 swabs and found that Covid infection rates were three to four times higher among unvaccinated people than those who had received two shots.

READ MORE: Scotland records 2762 new Covid cases and 32 deaths 

But while full vaccination drove infection rates down substantially, from 1.76% in the unvaccinated to 0.35% in the three months after the second dose, infection rates rose again to 0.55% three to six months after the second shot.

The finding suggests that protection against infection, with or without symptoms, starts to wane several months after full vaccination, though other studies show that vaccine protection against hospitalisation and death is far more robust.

A spokesman for NHS Highland said: "We are using different methods to deliver the expanded flu and COVID-19 vaccination programmes to cover the diverse geography across our board area. 

"Where it is possible and practical, the vaccines are being co-administered. This is not always possible as the delivery of the vaccines varies in different areas."

Dr Andrew Buist, Chair of BMA Scotland GP Committee said:“Under arrangements agreed with the Scottish Government it is up to health boards to organise both Covid booster and flu vaccinations in the best ways to suit their local areas, taking into account factors like demographics and rurality.

"Of course GPs – not withstanding the huge pressures we are under – will play a role, based on how boards design their programme, and this will clearly vary from board to board.

"This is obviously complex but it is vital that boards put in place effective plans to ensure their local populations and in particular vulnerable and elderly people have easy access to these vital jabs as we head into what will be a tough winter.”

The Scottish Government has said other eligible groups - including all those aged 16 to 49 years and adults over 50 - will be able to book an appointment online from October.

READ MORE: Thousands possibly given wrong PCR test result as investigation launched 

AN NHS Inform official said it was waiting for updated guidance and said the system was not yet accepting bookings.

People on the highest risk list who were severely immuno-suppressed at the time of their last Covid vaccination are being offered a third primary dose instead of a booster.

The JCVI he committee based its advice on preliminary data from the Octave trial, which showed that almost everyone who was immunosuppressed did mount an immune response after two doses, as indicated by either antibodies or T cells—but in around 40% of people the levels of antibodies were low.

It is not yet clear how much this may affect their protection against Covid-19.