A new study from the UK has shown that the Delta variant of the COVID-19 virus can transmit easily from vaccinated people to their household contacts.
Research from the Imperial College of London highlights how the variant can spread even in a vaccinated population.
However, it also showed that contacts were less likely to get infected if they were vaccinated themselves, and stressed that it did not weaken the argument for vaccination as the best way of reducing serious illness from the virus.
They added that booster shots were also a necessity.
Dr Anika Singanayagam, co-lead author of the study, explained: "By carrying out repeated and frequent sampling from contacts of Covid-19 cases, we found that vaccinated people can contract and pass on infection within households, including to vaccinated household members."
"Our findings provide important insights into... why the Delta variant is continuing to cause high Covid-19 case numbers around the world, even in countries with high vaccination rates."
The study, which enrolled 621 participants, found that of 205 household contacts of people with Delta Covid-19 infection, 38 per cent of household contacts who were unvaccinated went on to test positive.
This is in comparison to just 25 per cent of vaccinated contacts.
Imperial epidemiologist Neil Ferguson added that the study also highlights that, in the context of the UK, the event of herd immunity would be "unlikely" for the foreseeable future.
Previously, Chief Medical Officer Dr Tony Holohan said that Ireland’s high vaccination rate has prevented many hospital admissions, as well as hundreds of ICU admissions and deaths.
However, he added that vaccines in Ireland "are probably not performing as well as we might have hoped in terms of preventing transmission."
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