Double vaccinated people have been warned to be on the look out for five symptoms that might indicate a Covid infection.
The latest research has shown that the anyone who catches the Delta variant despite having had two jabs is far more likely to develop symptoms compared to previous strains.
In light of the findings, experts are warning people not to assume they are immune from infection.
Vaccinated people have been told the virus may cause different symptoms from those most closely associated with the disease.
The ZOE Covid app, which is tracking the outbreak, has found the most common symptoms being reported by those who have caught Covid recently are a runny nose, headache, loss of smell, sneezing, and a sore throat.
The NHS is still only listing three symptoms of Covid – a high temperature, a new continuous cough and loss of taste or smell – and there are calls for this list to be expanded to encourage more people to be tested.
Yesterday, findings from a University of Oxford study of 700,000 fully vaccinated people showed around half of those who became infected reported experiencing symptoms.
This compared to less than 10% of people who became infected with the Alpha variant, which spread across the country over the winter.
Professor Tim Spector, the lead researcher for ZOE has also warned that the data shows vaccines may be getting less effective as time goes on.
It means that older and more vulnerable people who likely got their jabs at the start of the year may now be more likely to get ill.
The latest update from the app showed there are currently 13,604 new daily symptomatic cases in fully vaccinated people in the UK, a slight increase on last week after a few weeks of decreases.
The rest of countries around the world have similar results too
Prof Spector said: ‘Daily cases of Covid remain stubbornly high but it’s reassuring to see that unlike in previous waves, these rates aren’t yet translating into high numbers of hospitalisations and deaths.
‘However, seeing what is happening with increasing deaths in Israel we need to be vigilant.
‘Whilst vaccines have helped to reduce the severity of the disease, this stalling in cases suggests that we’re starting to see the protection provided by vaccines waning, meaning more fully vaccinated people could be infected in the future.’