The term herd immunity means that enough of a population has gained immunity to stifle a pathogen’s spread. You can think of herd immunity as being similar to fire starting in a field: If the field is dry and filled with weeds, the fire will catch and spread quickly. However, if the field is well-maintained with watering and trimming, the fire will fizzle out. Future embers that might land there will be far less likely to ignite.
The embers are much like SARS-CoV-2, the coronavirus that causes COVID-19.
Herd immunity can theoretically be achieved either through infection and recovery or by vaccination. The danger of trying to achieve herd immunity through infection is that many people will die or be forced to live with post-recovery disabilities. Moreover, research has shown that the immune response resulting from infection does not always provide strong enough long-term protection against COVID-19 and its evolving strains. Thus, public health experts still recommend vaccination against the coronavirus to achieve the strongest and most reliable protection.
When the COVID-19 pandemic erupted, scientists quickly began to develop vaccines so that populations could develop immunity to slow the firelike spread of the coronavirus. In the meantime, nearly all countries mandated or encouraged social distancing, masking and other public health measures.
