Another lesson for the COVID response from the TB world:
"Have we reached herd immunity?" is the wrong question.
If, by "herd immunity", we mean Rt<1, then we achieved herd immunity for TB a decade ago. And yet, 1.4 million people still die of TB every year.
"Have we reached herd immunity?" is the wrong question.
If, by "herd immunity", we mean Rt<1, then we achieved herd immunity for TB a decade ago. And yet, 1.4 million people still die of TB every year.
What's the fallacy? There are two:
1. Herd immunity isn't a magic threshold to cross. A decline in cases doesn't mean a rapid decline, nor that the current case count is acceptable. Just as for TB, millions of people could still die of COVID after "achieving" herd immunity.
1. Herd immunity isn't a magic threshold to cross. A decline in cases doesn't mean a rapid decline, nor that the current case count is acceptable. Just as for TB, millions of people could still die of COVID after "achieving" herd immunity.
2. Many factors contribute to Rt<1; immunity is only one. If we ease the TB response, deaths will rise. Saying "we've achieved herd immunity to TB" is therefore problematic. Same for COVID: when herd immunity is reached, if we stop distancing, wearing masks, etc, people will die.
Bottom line:
Herd immunity is not a magic line to cross, but part of a bigger picture.
We should not ask, "When will we achieve herd immunity for SARS-CoV-2?"
Rather, we should ask, "How do we lower the body count, and minimize the adverse impact of this pandemic on society?"
Herd immunity is not a magic line to cross, but part of a bigger picture.
We should not ask, "When will we achieve herd immunity for SARS-CoV-2?"
Rather, we should ask, "How do we lower the body count, and minimize the adverse impact of this pandemic on society?"
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