People aged 40-49 will be prioritised next for a Covid-19 vaccine, with scientific advisers saying the move will “provide the greatest benefit in the shortest time”.

The Joint Committee on Vaccination and Immunisation (JCVI) had considered whether groups such as teachers and police officers should be vaccinated next, but concluded the most effective way to prevent death and hospital admission is to carry on prioritising people by age.

It said modelling studies for phase 2 of the vaccination programme also indicate that the speed of vaccine deployment is the most important factor in helping prevent severe illness and death.

This means that in phase 2, priority will be given in the following order:

– All those aged 40-49

– All those aged 30-39

– All those aged 18-29

These groups will be vaccinated once all those in phase 1 (the over-50s and most vulnerable) have received a jab, with the Government having a set of target for them of mid-April.

Professor Wei Shen Lim, Covid-19 chair for the JCVI, told a briefing that age “remains a dominant factor – it is still one of the most important causes of severe disease, even in those aged 50 years and below”.

He said that even within different occupational groups, it is older people who are more at risk than those who are younger.

In a statement, he added: “Vaccinations stop people from dying and the current strategy is to prioritise those who are more likely to have severe outcomes and die from Covid-19.

“The evidence is clear that the risk of hospitalisation and death increases with age.

“The vaccination programme is a huge success and continuing the age-based rollout will provide the greatest benefit in the shortest time, including to those in occupations at a higher risk of exposure.”

A UK Government spokeswoman said the JCVI advice reflected the fact age remains “the strongest factor” linked to death and hospital admission and “the speed of delivery (of vaccines) is crucial.”

She added: “All four parts of the UK will follow the recommended approach, subject to the final advice given by the independent expert committee.

“The UK Government remains on course to meet its target to offer a vaccine to all those in the phase 1 priority groups by mid-April, and all adults by the end of July.”

The JCVI said that targeting occupational groups (such as teachers) would have been more complex to deliver and may slow down the vaccine programme, leaving some vulnerable people at higher risk for longer.

It also said that, operationally, simple and easy-to-deliver programmes are “critical for rapid deployment and high vaccine uptake”.

Dr Mary Ramsay, head of immunisations at Public Health England (PHE), said: “Delivering a vaccination programme on this scale is incredibly complex and the JCVI’s advice will help us continue protecting individuals from the risk of hospitalisation at pace.

“The age-based approach will ensure more people are protected more quickly.

“It is crucial that those at higher risk – including men and BAME (black, Asian and minority ethnic communities) communities – are encouraged to take the vaccine, and that local health systems are fully engaged and reaching out to under-served communities to ensure they can access the vaccine.”

On Thursday evening, Metropolitan Police Federation chairman Ken Marsh criticised the Government over the move, saying: “It’s absolutely disgusting – they don’t give a damn about us.

“Prime Minister Boris Johnson and Home Secretary Priti Patel should hang their heads in shame.”

In other developments:

– The Queen has urged those hesitant about the coronavirus jab to be vaccinated and encouraged them to “think about other people rather than themselves”.

– Positive attitudes towards the coronavirus vaccine have increased, with 94% of adults saying they have either received the jab or would be likely to have it if offered, Office for National Statistics (ONS) figures show.

– New research from the British Red Cross has indicated eight in 10 people from black, Asian and minority ethnic communities trust information about vaccines from family members more than from the Government and the media.

– Justice Secretary Robert Buckland has said employers such as care homes must have a “clear rationale” if they want to require new staff to have the coronavirus vaccination as a condition of employment.

Meanwhile, a top scientific adviser has said keeping windows open and improving ventilation in schools is much more effective at reducing coronavirus transmission than asking young children to wear face masks.

Professor Calum Semple, a member of the Scientific Advisory Group for Emergencies (Sage), told BBC Radio 4’s Today programme that he is “not a fan” of asking young children to wear masks, and there are better strategies for managing the virus.

Some schools, including Selsdon Primary School in Croydon, south London, have said pupils must wear face coverings at all times, except during sports lessons or when eating or drinking.

But the Department for Education has said primary school children should not be asked to wear masks.