A major study of NHS staff and care home residents and workers will reveal for the first time whether Covid-19 vaccines curb transmission in the community as well as reduce serious disease in an individual.
Clinical trials of the two vaccines currently in use in the UK – Pfizer/BioNTech and Oxford/AstraZeneca – were unable to provide sufficient evidence that they stopped the virus being passed on to others from vaccinated individuals.
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Identifying vaccines that can curb transmission is crucial as it would be a step towards genuine herd immunity – which happens when enough people are vaccinated so that the wider population benefits indirectly.
Implications for lockdown
A document by Public Health England suggests that results showing reduced transmission could lead to the lockdown being lifted sooner.
Public Health England and a number of academic institutions are working together on the surveillance study, which will follow tens of thousands of vaccinated healthcare workers, care home residents and staff over the coming weeks and months.
As these groups are already tested regularly for coronavirus, even without symptoms, the study could start to produce results within weeks.
The current vaccines in use have been proven to provide up to 90 per cent protection against serious illness from Covid-19, meaning those most at risk of severe disease or death have been prioritised for jabs.
Vaccine regime could change
But if any of the vaccines being monitored are shown to reduce transmission between individuals, this could mean the priority regime being flipped towards groups which fuel circulation of the virus, such as secondary school pupils and office workers.
The PHE vaccination surveillance strategy published this week says: “This [study] will inform policy decisions around whether to prioritise vaccination of those with worse outcomes or those who transmit more.”
Because the UK is among the leading countries to start its vaccination programme, the study could be the first in the world to identify whether Covid vaccines stop transmission.
Some 40,000 NHS staff are already tested every two weeks and have blood samples taken every four weeks as part of the SIREN (Sarscov2 Immunity & REinfection EvaluatioN) study, and the new research will use this data. Experts will also use the Vivaldi study by University College London and PHE that monitors infection rates in care homes.
The PHE strategy document says: “Healthcare workers are one of the earliest groups to be offered the vaccine therefore this study is likely to provide one of the earliest estimates of vaccine effectiveness against infection.”
The new study will also monitor the safety and efficacy of the vaccines.
Suggesting that the study could have an impact on the timing of the lockdown restrictions being lifted, the paper adds: “The outcomes of this surveillance will be reported as soon as they become available to the JCVI [Joint Committee on Vaccination and Immunisation], to support vaccine policy recommendations, and to SPI-M [Sage’s epidemiological modelling group] to support dynamic modelling to understand the impact of the vaccination programme on the need for nonpharmaceutical interventions.”
— to inews.co.uk