This quarantine period and economic lockdown is hurting us all. Millions have already lost their jobs, fearing for their livelihoods. Many more struggle with the emotional toll of social distancing. We are all hurting, but know that the alternative would be much worse. Today’s reading recommendation lays out the two options we currently have to prevent the unchecked spread of the virus. Continuing the current measures to slow the disease’s spread is the only way to save millions of lives – at least until a potent vaccine has been developed.
There is a well-known way to stop COVID-19 from spreading unchecked: Have a large enough proportion of people develop immunity to the virus that causes it. The problem is, the only two ways to do so are to discover and widely administer a vaccine or have a whole lot of people get sick. This article explains what “herd immunity” is, how people might impart it, and how they might balance that with keeping people safe in the short term. The article will benefit anyone trying to make sense of the strategies being proposed or implemented to limit the devastation of COVID-19.
- Three approaches can stop the rapid spread of COVID-19.
- Two approaches can create a condition known as herd immunity.
- The development of herd immunity depends on how easily a virus spreads.
- Without a vaccine, herd immunity carries a hefty price.
Three approaches can stop the rapid spread of COVID-19.
With no checks on its spread, COVID-19 could infect 60% of all people by the end of 2020, killing millions in the process. One way to prevent that would be to keep people separate and test them to see if they are harboring the virus that causes the disease. A second would be to develop and administer a vaccine that imparts immunity. The third option involves letting the disease take its course, with infected people either dying or becoming naturally immune and therefore unable to spread the disease.
[Editor’s note: Coronavirus disease 2019 (COVID-19) is an infectious viral respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) also known as “novel coronavirus.” The disease was first reported in December 2019, from Wuhan, China, and has since spread globally, resulting in the 2019-20 coronavirus pandemic which impacts people and businesses worldwide.]
Two approaches can create a condition known as herd immunity.
When everyone is susceptible to a germ, it spreads exponentially. One person infects two, which infects four, which infects eight, and so on. Herd immunity is a term used to describe the situation in which a large enough proportion of a population is unable to transmit it.
“Shooting for herd immunity right away would be a disastrous strategy.”
Such a condition occurs when the immune systems of enough individuals develop antibodies against a pathogen. Antibodies develop through exposure to the disease or vaccines.
The development of herd immunity depends on how easily a virus spreads.
Every virus has a characteristic “reproduction number,” which is the number of people one infected person infects if nothing prevents the spread. The higher the reproduction number, the higher the percent of the population that needs to be immune. At a reproduction number of 2, half of the people need to develop immunity before each infected person only infects one other person.
“The current germ’s rate of spread is higher than that of the ordinary flu.”
A reproduction number of 3 means that two-thirds of the individuals in a population need to be immune for herd immunity to happen. Scientists think the reproduction number for COVID-19 is 2 to 2.5 – higher than that for the flu but much lower than that for measles, which at 12-plus is extremely contagious.
Without a vaccine, herd immunity carries a hefty price.
Some political leaders have suggested letting herd immunity to COVID-19 develop naturally – a situation similar to that which appears to have occurred with the Zika virus five years ago. The problem is, this would overwhelm hospitals’ ability to care for the sickest victims and millions would likely die – and no one knows the extent to which COVID-19 imparts immunity in people who get it. As a result, governments have turned instead to isolating sick people, reducing social contacts and closing schools.
“Suppressing transmission means that we won’t build up herd immunity.” – Azra Ghani, Imperial College London
Such a practice, however, interferes with the development of herd immunity and so requires an indefinite continuation of measures to slow the disease’s spread. The other approach to imparting herd immunity – administering a vaccine – is not yet an option. It could be a year or more before a COVID-19 vaccine is available.
About the Author
Antonio Regalado is a senior editor for biomedicine for MIT Technology Review.
Reference: What Is Herd Immunity and Can It Stop the Coronavirus? Once enough people get COVID-19, it will stop spreading on its own. But the costs will be devastating. by Antonio Regalado, MIT Technology Review