Would collective immunity stop the spread of the coronavirus? | Coronavirus epidemic

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Like the Covid-19 virus itself, the idea of ​​collective immunity has returned to public life after being suppressed for months. It was originally touted as a way to contain the pandemic – by allowing a sufficient number of infections to occur and thereby reduce the number of potential hosts not immune to the virus. The disease would then stop spreading, it was argued.

The notion quickly fell out of favor when researchers highlighted the high number of deaths expected to occur in the UK before herd immunity was achieved. Nonetheless, the idea resurfaced and made headlines once again.

According to the signatories of the Great Barrington statement which was released last week, now is the time to remove lockdown restrictions for most of society and allow people to live their lives while protecting the vulnerable. and elderly. The immunity of the herds would strengthen and soon the scourge of Covid-19 would disappear.

It’s a tempting argument. But is collective immunity really a panacea whose time has come? Can he lift the curse of Covid from the world? Many British scientists recommend caution.

As they point out, only around 8% of the UK population has been infected with the Covid-19 virus. “To get herd immunity, we would need it to reach around 70%,” said Sir Robert Lechler, president of the Academy of Medical Sciences. “Not only are we far from it, but we now know that immunity to Covid-19 wanes over time and people can be re-infected with the virus. “

For this reason, scientists say it is highly unlikely that herd immunity can be maintained without a vaccine or regular reinfection. Specifically, if attempts were made to gain herd immunity by lifting lockdown restrictions, there would be a sharp increase in excessive deaths, mainly among the elderly and the most vulnerable. NHS services are said to be overwhelmed as a high number of ‘long Covid’ cases would have long-term consequences even for those who only suffer from mild initial symptoms.

Scientists also cite the example of Manaus in Brazil. The city has suffered a devastating wave of Covid-19 cases that killed more than 3,000 people earlier this year. Then the virus levels went down and claims were made that the city had achieved herd immunity. However, cases have started to rise again in Manaus, suggesting that the city has failed to obtain collective immunity despite its high death toll.

In fact, the concept of herd immunity is simply not acceptable, added Michael Head, senior researcher in global health at the University of Southampton. He describes Great Barrington’s statement as nothing more than an online petition and points to groups of experts – from Independent Sage to the Academy of Medical Sciences – who have spoken out against the idea.

“In the UK there was a full national lockdown for about three months,” he added. “Meanwhile, despite very little life in the UK as ‘normal’, thousands of vulnerable people – who globally represent a quarter of the population – have died from the pandemic coronavirus and yet we still only have 8% of the population with some level of immunity. “

Raising that level to 60 to 70 percent in order to gain collective immunity would therefore have devastating consequences, Head concluded.

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