Herd immunity through infection vs vaccination
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Sydney — The coronavirus pandemic has brought “herd immunity” to the public consciousness, kindling hope the phenomenon can help slow or even end the outbreak.
Herd immunity refers to a large portion of a community developing a degree of immunity to a virus, thereby reducing person-to-person spread. As a result, the whole community gains protection, not just those who are immune.
Natural infection vs vaccination
There are two pathways to herd immunity: natural infection or vaccination.
Natural infection refers to when a large number of people have had a disease and recovered. However, the extent of protection via natural infection is unknown with the new coronavirus. Moreover, more people would die while waiting for herd immunity than if a vaccine was produced.
“The risk is not acceptable,” said Catherine Bennett, epidemiology chair in the faculty of health at Melbourne’s Deakin University. “We can’t afford to have people infected to reach herd immunity when we know so little about the longer-term effects.”
Vaccination can provide widespread immunity faster and more reliably.
There is no vaccine for Covid-19 — the disease caused by the coronavirus — though trials at different stages are underway around the world. It usually takes several years for a vaccine to be identified, tested, produced and distributed for public use. Vaccine makers hope to dramatically compress that timeline for Covid-19 through faster trials and by manufacturing at scale even before products have proved successful.
Experts believe if no other measures are taken, herd immunity could kick in when 50% to 70% of a population gains immunity through vaccination. The precise level depends on the vaccine’s efficacy rate, which experts say will be 70% at best.
Balancing vaccine distribution
How a vaccine is distributed has implications for effectiveness. If shared unevenly — for example, if the wealthy have greater access than those in poorer locations — that would create safe clusters but leave large areas of susceptible people.
In the early stages of distribution, higher priority may be given to healthcare workers and others on front lines, or those considered most vulnerable — a process known as targeted vaccination. That risks missing people who might be considered “super-spreaders”, such as public transport workers.
“We need to be sure that we spread the vaccine equitably through the population,” said Joel Miller, a senior lecturer in applied mathematics at La Trobe University in Melbourne, who uses mathematical models to help governments ...
Herd immunity refers to a large portion of a community developing a degree of immunity to a virus, thereby reducing person-to-person spread. As a result, the whole community gains protection, not just those who are immune.
Natural infection vs vaccination
There are two pathways to herd immunity: natural infection or vaccination.
Natural infection refers to when a large number of people have had a disease and recovered. However, the extent of protection via natural infection is unknown with the new coronavirus. Moreover, more people would die while waiting for herd immunity than if a vaccine was produced.
“The risk is not acceptable,” said Catherine Bennett, epidemiology chair in the faculty of health at Melbourne’s Deakin University. “We can’t afford to have people infected to reach herd immunity when we know so little about the longer-term effects.”
Vaccination can provide widespread immunity faster and more reliably.
There is no vaccine for Covid-19 — the disease caused by the coronavirus — though trials at different stages are underway around the world. It usually takes several years for a vaccine to be identified, tested, produced and distributed for public use. Vaccine makers hope to dramatically compress that timeline for Covid-19 through faster trials and by manufacturing at scale even before products have proved successful.
Experts believe if no other measures are taken, herd immunity could kick in when 50% to 70% of a population gains immunity through vaccination. The precise level depends on the vaccine’s efficacy rate, which experts say will be 70% at best.
Balancing vaccine distribution
How a vaccine is distributed has implications for effectiveness. If shared unevenly — for example, if the wealthy have greater access than those in poorer locations — that would create safe clusters but leave large areas of susceptible people.
In the early stages of distribution, higher priority may be given to healthcare workers and others on front lines, or those considered most vulnerable — a process known as targeted vaccination. That risks missing people who might be considered “super-spreaders”, such as public transport workers.
“We need to be sure that we spread the vaccine equitably through the population,” said Joel Miller, a senior lecturer in applied mathematics at La Trobe University in Melbourne, who uses mathematical models to help governments ...
