Are you looking at the immune effects of a coronavirus herd, or is it dangerous to suggest?

“Hard immunity” was a term that is rarely used beyond epidemiology and vaccine science.

But now it is one of the most controversial concepts of the coronavirus pandemic.

It’s a simple concept. When one population is exposed to the virus, people become immune and can no longer spread the bug to others.

Once a certain threshold is reached, no one who is susceptible enough to be infected by the virus will leave, it is the herd’s immunity.

As a general rule of thumb, about 70-80% of the population must be immune to stop the spread of viruses like SARS-CoV-2 (very highly contagious, like measles). For viruses, the number can be even higher (about 95%).

But what if we reach herd immunity at a much lower level in the real world?

Back in March, theoretical epidemiologist Sunetra Gupta published his analysis. Presumably, herd immunity to COVID-19 could be as high as 20% if many of us appear to be resistant to the infection, probably due to previous exposure to the coronavirus involved. Suggests.

Her paper has been widely criticized by other epidemiologists, especially those who advise the government.

It was based on mathematical analysis, not actual observations.

Moreover, by the time it was released, the virus was beginning to spread rapidly among residents of nursing homes.

Herd immunity-based policies, that is, policies that enable vulnerable populations to be protected while at the same time building natural resistance among low-risk populations, are disaster-based disasters Became clear.

But what if she and other disease modelers are right? And what does the future outbreak management mean?

In countries such as Brazil and Sweden, and parts of the United States that did not pursue aggressive lockdown strategies, there is evidence that their outbreaks are now at some natural peak and events are beginning to diminish. There is.

However, tests on the population suggest that 20%-at most-have antibodies to the virus.

Everything was hit hard, killing an estimated 1 in 500 in Manaus, Brazil, but the collective immunity appears to have fallen well below 70%.

With the greater ability to test the virus and the need to be prepared to protect vulnerabilities, is it time to revisit the idea of ​​herd immunity?

Gupta said: “We can’t just consider the reaction along a single axis of how we control coronaviruses.

“The strategy the welfare state should take at the moment is to protect vulnerabilities and allow the virus to spread among people at no risk of death.

“We have to think about who is paying this price.

“We have introduced a system that does not protect vulnerabilities, and now we are asking financially vulnerable people to pay for it.”

Her view split the scientific community, but few people agree with the theory, but they’re not sure enough about us, so they’re back immunity to see if development really works. can not.

Dr. Souimya Swaminathan, Principal Scientist at the World Health Organization (WHO), said:

“We should discuss herd immunity in the context of vaccines.”

Moreover, it is not clear what the “immunity” to SARS-CoV-2 looks like.

There is strong evidence that antibodies to the virus decrease over time.

Currently, the number of cases of multiple infections is increasing.

This is good evidence that a persistent herd’s immunity never develops, and some argue that it may even challenge the development of a vaccine.

Other experts claim that other coronaviruses cause repeated infections, but it is a mild illness, and this new coronavirus will behave in the same way as many of us are exposed to it. Let’s

For now, it’s still mostly academic discussion.

But that is a debate that we will hear more about, as the real cost of an aggressive blockade is beginning to affect not only the economy but also the long-term health of people.