Delaying Herd Immunity Is Costing Lives
Delaying Herd Immunity Is Costing Lives by Martin Kulldorff for American Institute for Economic Research
Climate scientists are frustrated by people who do not believe in climate change. In epidemiology, our frustration is with anti-vaxxers. Most anti-vaxxers are highly educated but still argue against vaccination. We now face a similar situation with ‘anti-herders’, who view herd immunity as a misguided optional strategy rather than a scientifically proven phenomenon that can prevent unnecessary deaths.
Because of its virulence, wide spread and the many asymptomatic cases it causes, Covid-19cannot be contained in the long run, and so all countries will eventually reach herd immunity. To think otherwise is naive and dangerous. General lockdown strategies can reduce transmission and death counts in the short term. But this strategy cannot be considered successful until lockdowns are removed without the disease resurging.
The choice we face is stark. One option is to maintain a general lockdown for an unknown amount of time until herd immunity is reached through a future vaccine or until there is a safe and effective treatment. This must be weighed against the detrimental effects that lockdowns have on other health outcomes. The second option is to minimise the number of deaths until herd immunity is achieved through natural infection. Most places are neither preparing for the former nor considering the latter.
The question is not whether to aim for herd immunity as a strategy, because we will all eventually get there. The question is how to minimise casualties until we get there. Since Covid-19 mortality varies greatly by age, this can only be accomplished through age-specific countermeasures. We need to shield older people and other high-risk groups until they are protected by herd immunity.
Among the individuals exposed to Covid-19, people aged in their 70s have roughly twice the mortality of those in their 60s, 10 times the mortality of those in their 50s, 40 times that of those in their 40s, 100 times that of those in their 30s, and 300 times that of those in their 20s. The over-70s have a mortality that is more than 3,000 times higher than children have. For young people, the risk of death is so low that any reduced levels of mortality during the lockdown might not be due to fewer Covid-19 deaths, but due to fewer traffic accidents.
Considering these numbers, people above 60 must be better protected, while restrictions should be loosened on those below 50. Older people who are vulnerable should stay at home. Food should be delivered and they should receive no visitors. Nursing homes should be isolated together with some of the staff until other staff who have acquired immunity can take over. Younger people should go back to work and school without older coworkers and teachers at their sides.
While the appropriate magnitude of countermeasures depends on time and place as it is necessary to avoid hospital overload, the measures should still be age-dependent. This is how we can minimise the number of deaths by the time this terrible pandemic is over.