This is supported by a new study from the University of Oxford: people with large amounts of the virus in their bodies did not transmit it like the unvaccinated. Measuring viral load overestimates how infectious fully vaccinated people are
One of the major concerns with respect to coexistence with the Delta variant (now prevalent) is that and vaccinated, if infected, have the same ability to transmit the virus of the unvaccinated.
Even with the same viral load they are less infectious
a hypothesis that had been made by measuring the viral charges of individuals infected with Delta, which were found to be very high. This dynamic has often been used as argument of the no vax in the debates, but had been disproved over time by the numbers on the cases. Relative scientific studies, however, were still few.
Now a pre-print of an important study on this subject has come out from the University of Oxford. The research, dated September 29 and not yet revised, says that vaccinated people are less infectious even with Delta and even if the CT cycle count (which measures viral load) the same. Furthermore, it shows that children appear to be less infectious and less susceptible, even with Delta, just as they did with the other variants.
And give
Data was derived from a retrospective observational cohort study of SARS-CoV-2 contacts infected from index cases (the first infected of an outbreak) using swab data from England between 02 Jan 2021 and 02 Aug 2021 The second infections occurred mainly by contact within families (70%), but also after home visits (10%), events or activities (10%) and at work or school (10%). The results showed that two doses of Pfizer or AstraZeneca in Alpha variant index cases reduced PCR positivity in contacts. Even with the Delta variant, the vaccines attenuated the associated infections: two doses of Pfizer reduced transmission more than with AstraZeneca. Protection from infections decreased over time after the second vaccination, Delta returned to similar levels to unvaccinated within 12 weeks with the AstraZeneca vaccine, and Pfizer saw a substantial decrease in protection after that time, but not as drastic.
Viral load does not measure infectivity
Delta variant infections had higher alpha viral loads in both symptomatic and asymptomatic infections, regardless of vaccination status. The viral load of vaccinated and unvaccinated was similar. This did not lead to the same likelihood of infecting: most of the protective effect of the vaccines remained, that is, the study showed that other factors are important in reducing vaccine-associated transmission. For example, the authors of the article write, it is possible that vaccination facilitates a more rapid elimination of viable infectious virions, leaving behind ineffective and damaged virions that still contain RNA detectable by PCR (molecular buffer. Measuring viral load, therefore, overestimates how infectious vaccinated people are. It suggests more than anything else a greater infectivity of the virus itself, not only as a factor in the dynamics of the viral load: vaccinated people are not as contagious as unvaccinated people infected with Delta, even with the same viral load.
October 2, 2021 (change October 2, 2021 | 13:29)
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