With the appointment of Scot Atlas, Trump’s new pandemic advisor, herd immunity could be back on the table. How will herd immunity work? Will one day, over 250 million people test positive for the coronavirus infection? Several weeks later, those 250 million infected will produce antibodies to SARS-CoV-2? Why 250 million? Will that protect the remaining 80 million Americas?
How many might die? The above presumes an American population of 330 million, herd immunity when 75% of the population has antibodies to the coronavirus, and a 1% COVID fatality rate. Over two million Americans would die.
Once an unknown percent of the population acquires immunity, that herd prevents future epidemics by reducing the likelihood of spread. The percent of immunity depends on the virus vaccine. Herd immunity is a concept used during vaccination to prevent outbreaks. Immunity from vaccines not only prevent disease but also reduce transmission or spread of the infection. For example, the flu vaccine requires about 90% immunity to develop herd immunity, which protects the remaining 10% of the population from getting infected or causing epidemics.
That does not mean those without immunity can’t get infected but are at a reduced risk because of herd immunity protection.
Herd immunity could also occur naturally from acquiring an infection. Scientists don’t know much about natural herd immunity. The 1918 H1N1 flu pandemic took 50 million lives worldwide and almost 700,000 Americans before it disappeared. Sweden’s approach to COVID embraced a modified herd immunity approach. With a population of 10 million, there was no lockdown and no mandatory mask requirement. The death toll was the worst in the Nordic region, and the economy still tanked.
In America, herd immunity could mean millions in unnecessary deaths. To reach herd immunity, a large percent of the population must get infected and develop antibodies. Without treatment, supplies, and reliable testing, hundreds of thousands of people will likely die or suffer complications. Additionally, not much known about the long term complications of COVID infection. Could infection with SARS-CoV-2 lead to cancer or severe disability ten years later? Infection with hepatitis C increased the risk of liver cancer.
Limited knowledge of COVID pokes holes in the effectiveness of herd immunity. Already a couple of studies suggest immunity is transient and may last months rather than years. And, other studies have shown re-infection with a different strain of the virus is possible. (2)
All this means herd immunity might not work. To go take that path means allowing COVID to spread and watching people die or end up with complications of COVID. Moreover, scientists don’t know what percentage of a population would need to get infected to acquire herd immunity. Is the risk worth the benefit?
Stay Safe: Wear A Mask.
NYT Op-ed piece by two infectious disease specialists.