https://www.cnbc.com/2021/08/12/her...with-the-covid-delta-variant-experts-say.html
Here’s why herd immunity from Covid is ‘mythical’ with the delta variant
LONDON — Achieving herd immunity with Covid vaccines when the highly infectious delta variant is spreading is “not a possibility,” a leading epidemiologist said.
Experts agree on several reasons why such a goal — where overall immunity in a population is reached and the spread of the virus is stopped — is not likely.
Sir Andrew Pollard, head of the Oxford Vaccine Group, told British lawmakers Tuesday that as Covid vaccines did not stop the spread of the virus entirely — with vaccinated people still able to be infected and transmit the virus — the idea of achieving herd immunity was “mythical.”
“I think we are in a situation here with this current variant where herd immunity is not a possibility because it still infects vaccinated individuals,” said Pollard, one of the lead researchers in the creation of the AstraZeneca-University of Oxford vaccine.
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Pollard noted on Tuesday that Covid, and the current virulent delta variant, are different. “The problem with this virus is [it is] not measles. If 95% of people were vaccinated against measles, the virus cannot transmit in the population,” he told the U.K.’s All-Party Parliamentary Group on the coronavirus.
Pollard said that while Covid vaccines might slow the spread of the virus — because fully vaccinated but infected people appeared, in studies, to shed less virus, giving the virus less opportunity to spread — new variants were likely to emerge that would also spread.
“I suspect that what the virus will throw up next is a variant which is perhaps even better at transmitting among vaccinated populations and so that’s even more of a reason not to be making a vaccine program around herd immunity.”
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“The delta variant is highly transmissible meaning that the proportion of people needing to be fully vaccinated for herd immunity is probably not achievable,” he said. “The vaccines provide very effective protection against severe disease/hospitalisation/death but are less effective in preventing infection, mild disease and transmission, especially for the delta variant.”
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