Three NHS sites will offer smaller doses of the smallpox vaccine to people at high risk of contracting monkeypox, in a bid to stretch limited supply.
The NHS will also stop offering post-exposure jabs to anyone who is not considered to be in a clinical risk group.
The Government, which expects to deliver its last remaining doses of the vaccine to the NHS this week, said ‘fractional dosing’ has been commonly used in other worldwide outbreaks when vaccine supplies are constrained.
A 0.1ml dose of the smallpox Jynneos vaccine, instead of the 0.5ml dose that is typically administered, will begin to be offered to eligible patients in one Manchester vaccine clinic from today, and two London clinics ‘shortly’.
The Government said the measure has the potential to enable a five-fold increase in the number of people that can be offered vaccination, pointing to clinical studies suggesting a ‘near-identical immune response’ in patients.
Fractional dosing is already approved in Europe and the US, with UKHSA and JCVI now working together to ‘test the feasibility of the approach’ via this pilot.
At the same time, also in light of dwindling vaccine stocks, UKHSA has decided reduce eligibility for post-exposure vaccination to close contacts who are at highest risk of severe illness.
The change, supported by the JCVI, means post-exposure vaccines will be prioritised for people with immunosuppression, children under the age of 5 years and pregnant women, who will continue to receive the 0.5ml dose until more clinical data is available regarding fractional dosing for these groups.
The UK purchased an additional 150,000 doses of the smallpox vaccine at the start of the current monkeypox outbreak, however only 50,000 doses could be delivered immediately, with the remaining 100,000 needing to made to order.
UKHSA head of immunisation Dr Mary Ramsay said: ‘Global supplies of the smallpox vaccine used to combat monkeypox are limited but we acted early to ensure the UK obtained the maximum number of doses available.
‘Adopting this tried and tested technique will help to maximise the reach of our remaining stock, including the 100,000 doses due to arrive in the country next month, potentially enabling us to offer protection for many more thousands of people.
‘We will continue to remain agile in our response to the monkeypox outbreak and will adapt our approach as new science and advice becomes available.’
JCVI chair Professor Sir Andrew Pollard said: ‘The use of fractional dosing will allow more people to be vaccinated sooner by optimising use of the constrained vaccine supply, and this approach is expected to reduce the spread of monkeypox.
‘Dosing in this way has been successfully used in outbreaks of other viral diseases around the world and existing data we have reviewed indicates this should not compromise protection.’
The latest UK monkeypox case numbers show overall decline, UKHSA said on Friday.
As of 15 August, there were 3,195 confirmed and highly probable cases of monkeypox in the UK, with London showing the fast rate of decline.
Over 33,000 doses of vaccine have been administered, mainly to gay, bisexual, or other men who have sex with men.
‘There is no robust evidence of sustained transmission outside these networks,’ the update said.
