The vaccines from Pfizer and AstraZeneca offer significant protection against the delta variant of COVID-19, according to the results of two studies conducted in the United Kingdom and published this Monday.
The findings have generated optimism among health authorities globally, as this highly communicable variant that was first detected in India in February has appeared in dozens of countries, raising
fears that the strain will cause a wave of infection that will force a reversal reopening plans
, overwhelm health systems and even undermine vaccination programs.
Two separate studies by researchers in England and Scotland found that while the delta vaccines have slightly less protection compared to previous variants, two doses did offer considerable protection against severe disease and hospitalization.
[Novavax's COVID-19 vaccine is 90% effective, according to the company]
The first of these, conducted by England's public health agency, studied more than 14,000 people infected with the variant, also known as B.1,617.2.
In the case of Pfizer's vaccine, two doses reduced the risk of hospitalization by 96%.
And two doses of the AstraZeneca vaccine reduced this risk by 92%.
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The other study, conducted by academics and public health officials in Scotland, and the results of which were published in the Lancet medical journal, found lower effectiveness of vaccines against the delta variant, compared to earlier strains.
However, the levels of protection against severe disease were similar.
The study, which looked at 19,543 cases, found that two doses of Pfizer's vaccine reduced the risk of infection by 79%, compared with a 92% reduction for the Alpha variant, first detected last year in England and also known as B.1.1 .7.
For the AstraZeneca vaccine, the figures were 60% and 73%, respectively.
Both vaccines reduced the risk of hospitalization by about 70% after two doses.
The delta variant worries health officials around the world, including in the United States.
It currently
represents more than 6% of the virus samples sequenced in the country
, according to data from the Centers for Disease Control and Prevention (CDC).
While it may seem like a relatively small proportion, the speed with which it is moving is worrying.
A month ago, the strain accounted for just over 1% of sequenced virus samples, according to the CDC.
There is evidence that existing COVID-19 vaccines are working against the delta variant.
Experts believe the variant sparked the huge wave of infections seen in India over the past two months.
Now it is causing concern in the UK, where it accounts for 91% of new cases, according to Health Secretary Matt Hancock.
UK delays reopening due to delta threat
Concerned about this more infectious variant, the United Kingdom delayed the lifting of restrictions due to the coronavirus pandemic for another month.
[People currently hospitalized for COVID-19 have one thing in common: they had not been vaccinated]
The Prime Minister, Boris Johnson, had planned, according to the plan raised in February, to lift all restrictions on June 21, but this Monday he
announced that he will extend them until July 19
, so restaurants, nightclubs and other public spaces they won't be able to open fully yet.
"I think the sensible thing to do is wait a little longer," Johnson said.
"I trust that it will not be more than these four weeks," added the prime minister, who hopes at this time to further expand the vaccination, which is advancing at great pace there.
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The World Health Organization (WHO) designated the delta variant as "variant of interest" on May 10.
That classification means that a variant may be more transmissible or cause more serious disease, not respond to treatment, evade the immune response, or be undiagnosed by regular testing.
The variant has been identified in 74 countries, on every continent except Antarctica, the WHO said in its latest weekly epidemiological update published on Tuesday.
It is spreading very fast: a month ago the WHO said it was present in just over 40 countries.
The delta variant was the fourth to be declared "worrisome" by the WHO.
The other three are B.1,1.7, which was first identified in the UK and is now known as the
Alpha
variant
; B.1,351, or
Beta
, first detected in South Africa; and P.1, which was first found in Brazil and is now identified as
Gamma.