08/19/2021 16:07
Clarín.com
Society
Updated 08/19/2021 4:08 PM
A study carried out by the University of Oxford revealed a fact that could undermine the long-awaited
herd immunity
: vaccinated adults who are infected with the Delta variant of the coronavirus
can reach the same levels of virus as those not vaccinated
.
This result is derived from an extensive analysis of data that both the university, the Office for National Statistics (ONS) and the Department of Health and Social Care (DHSC) of the United Kingdom collected among
almost 3.5 million swabs
carried out in that country. between December 2020 and August of this year.
The study further shows that there is abundant evidence that the Covid vaccines used in the UK (AstraZeneca, Pfizer and Moderna)
continue to offer significant protection against hospitalizations and death
.
But in this new analysis it was shown that although being fully vaccinated means that the risk of becoming infected is lower, with the Delta variant a person
can have virus levels similar
to those of unvaccinated people.
The implications of this for transmission remain unclear, the researchers cautioned.
"We still
don't know how much transmission can occur
from people who get Covid-19 after being vaccinated; for example, they may have high levels of the virus for shorter periods of time," said Sarah Walker, professor of medical statistics and epidemiology at the Oxford University.
"But the fact that they may have high levels of the virus suggests that
people who are not yet vaccinated may not be as protected
from the Delta variant as we expected," he added.
In this way, the idea of achieving herd immunization to protect unvaccinated people could be dropped, if the transmissibility is also high, because the virus would continue to circulate in the same way.
"I suspect that, in part, the higher levels of virus that we're seeing in these Delta infections in vaccinated people are consistent with the fact that
unvaccinated people are just going to be at higher risk,
" Walker said.
The powerful Delta variant caused positive cases, hospitalizations and deaths related to Covid to increase in the United Kingdom in recent days.
In the week ending August 18, 211,238 people were infected,
an increase of 7.6%
compared to the previous seven days.
During the same period, 655 people died there within 28 days of a positive test, a 7.9% increase compared to the previous seven days.
Hospitalizations also rose, with 5,623 admitted for coronavirus between August 8, 2021 and August 14, 2021, an increase of 4.3% compared to the previous week.
Vaccines with protection
Although the study showed a negative face with respect to the viral load that the infected still vaccinated can carry, it also made it clear that
the vaccines have a high protection of serious diseases and death
against the Delta variant.
"The low incidence of hospitalization seen to date suggests that, in this sense, at least vaccines are protecting people from developing severe Covid," said Penny Ward, visiting professor of pharmaceutical medicine at King's College London. The Guardian.
This study, which has not yet been peer-reviewed, noted that "two doses of either vaccine still provided at least the same level of protection as having had Covid-19 before."
Other conclusions highlighted by the researchers is that "one dose of the
Moderna
vaccine
has a similar or greater efficacy against the Delta variant than the single doses of the other vaccines."
At the same time "two doses of
Pfizer-BioNTech
have a greater initial effectiveness against new Covid-19 infections, but this
decreases faster
compared to two doses of
Oxford-AstraZeneca
."
The results suggest that after four to five months the effectiveness of these two vaccines would be similar;
however, the researchers say the long-term effects need to be studied.
They also found that "the time between doses does not affect the efficacy in preventing new infections", while "younger people have even more protection against vaccination than older people."
"Although vaccines reduce the chance of contracting Covid-19, they
do not eliminate it
. More importantly, our data shows the potential for vaccinated people to still transmit Covid-19 to other people, and the importance of testing and self-isolation for reduce the risk of transmission, "said Koen Pouwels, principal investigator at the University of Oxford's Nuffield Population Health Department.
With information from Télam
DD
Look also
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Studies done in Argentina confirm that Covid vaccine combinations are safe