Delta Tears Apart the Herd Immunity Narrative

As the Delta variant continues to spread, health experts are questioning whether the long-held goal of achieving herd immunity from Covid-19 through vaccination is still viable. 

Herd immunity is achieved when a certain threshold of the global population has either been inoculated against a pathogen or has recovered from infection.

I agree with Stuart Ray, MD (right), professor of medicine at the Johns Hopkins University School of Medicine that herd immunity is a dangerous strategy for tackling Covid-19. 

He is of the view that rushing toward herd immunity by ignoring risky behavior in the hope that infected people will survive, become resistant and reduce the susceptible population is an approach that will increase deaths and disability, and should be avoided. 

And even if there are those who still opt for this strategy, I'm maintaining a stance that herd immunity is not achievable. With the regular emergence of more infectious strains, it would appear that I am right. 

Just consider the Malaysian situation. It's really bad and some may even say, it's getting out of hand. Already, 60 percent of Malaysia's adult population have been fully vaccinated but Covid cases remain stubbornly high. In fact, the country has been steadily climbing higher and higher, and now ranks at #23 among countries with the most number of infections todate!

“If the question is ‘will vaccination alone allow us to dampen and control the pandemic?’ the answer is: No”, epidemiologist Mircea Sofonea (left) told AFP. 

He said herd immunity hinged on two basic factors. “That’s the intrinsic infectiousness of the virus and the efficacy of vaccines to protect against infection. And at the moment, that efficacy isn’t there”. 

Delta has shown to be roughly 60 percent more transmissible than the Alpha variant of the SARS-CoV-2 virus, and up to twice as infectious as the original strain that emerged in late 2019. The more effective the virus becomes at infecting people, the higher the herd immunity threshold becomes. 

“Theoretically, it’s a very simple calculation to make”, said eminent French epidemiologist Antoine Flahault (right). For the original virus, which had a reproduction rate between zero and three – meaning each infected person infects up to three others – herd immunity could have been achieved with around 66 percent of people immunized, Flahault told AFP. 

“But if the reproduction rate is eight, as with Delta, that puts us closer to 90 percent”, he said. 

Were vaccines 100 percent effective at stopping Delta infections, that 90 percent could conceivably be possible. Unfortunately, they aren’t. 

Notwithstanding the above, Flahault said “what scientists are recommending is to get the maximum number of people protected” through vaccination. 

Eventually, of course, all pandemics end. 

Sofonea said it’s likely that Covid would become another endemic disease over time, “just not with vaccines alone”. 

As I have said all along, it’s really time to accept the fact that we have to co-exist with Covid. The world doesn’t really have a choice.