Adults who have been fully vaccinated against SARS-CoV-2 can carry the same viral load of the delta variant as those who are unvaccinated, a preliminary analysis of UK data suggests.
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The latest results from the UK’s national covid-19 infection survey show that having two vaccine doses remains the most effective way to ensure protection against delta. But, although people who are fully vaccinated have a lower risk of becoming infected, those infected with the delta variant can carry similar virus levels as unvaccinated people, the data show. The authors said the implications for transmission were not yet clear but suggested that the potential for fully vaccinated individuals to transmit the virus to others would make achieving herd immunity more of a challenge.
Sarah Walker, professor of medical statistics and epidemiology at the University of Oxford and chief investigator of the survey, said, “We don’t yet know how much transmission can happen from people who get covid-19 after being vaccinated—for example, they may have high levels of virus for shorter periods of time.
“But the fact that they can have high levels of virus suggests that people who aren’t yet vaccinated may not be as protected from the delta variant as we hoped. This means it is essential for as many people as possible to get vaccinated—both in the UK and worldwide.” /