To achieve this would cause an impermissible death rate

The argument

This argument against a herd-immunity strategy holds that, however the epidemiology is framed, reaching herd immunity through natural infection would require so many deaths that the human cost is simply impermissible — disqualifying the approach on moral grounds alone. The arithmetic is unforgiving. Herd immunity by infection requires a large majority of the population — estimates for covid commonly ran from roughly 60% to 70% or more — to have caught the virus. In a country of tens of millions, that is tens of millions of infections, and even a modest infection-fatality rate, applied to numbers that large, yields a death toll in the hundreds of thousands. Those deaths are not abstract: they fall heavily on the elderly, the chronically ill and the disabled, and the strategy's premise of 'shielding the vulnerable' while the virus runs through everyone else was, critics argued, impossible to deliver, since the vulnerable are not a separable group but live among, are cared for by, and cannot be sealed off from the infected majority. A surge of cases on that scale also overwhelms hospitals, so that people die who could otherwise have been saved, compounding the toll. The moral point is decisive. A government's first duty is to protect its citizens' lives, and a policy that knowingly accepts mass death as the route to its goal treats those deaths as an acceptable price — a calculation the argument holds no state is entitled to make when alternatives exist. Other countries showed that suppression, testing and, ultimately, vaccination could reach safety without paying in hundreds of thousands of lives. From this standpoint, a strategy whose mechanism is mass fatality is ruled out before any debate about its efficiency. Because achieving herd immunity by infection would cause an impermissible death rate, this argument holds, herd immunity will not work.

Premises

Counter-arguments

The argument makes a moral case but is filed under a claim about efficacy. That a strategy's human cost is impermissible is a reason not to adopt it; it is not a demonstration that the mechanism fails. A policy can be effective and still forbidden, and the position asserts that herd immunity will not work — which mortality figures, however large, do not establish. The moral case is also comparative, and so requires the alternatives to be both available and less costly. Before vaccines existed, the choice lay between suppression of unknown duration and other paths, each carrying mortality of its own from delayed diagnosis and treatment and from the effects of prolonged closure, so the calculation the argument says no state may make is one that every policy in that period involved. Defenders of the position have a stronger route available that the argument does not take: immunity from infection proved to wane, and new variants produced widespread reinfection, so the threshold could not be held even if it were reached. That is an efficacy failure of the kind the position needs, and its availability shows that the argument as posed argues for a different conclusion — that the strategy was impermissible — rather than for the one under which it sits. Population immunity was in the end substantially achieved, but by vaccination, which supports the reading that the concept works and the route was wrong.

Rejecting the premises

[Rejecting P1] Even granting the arithmetic, a projected death toll is a moral cost rather than a demonstration that the mechanism fails; the position asserts inefficacy, which mortality figures alone do not establish. [Rejecting P2] That the vulnerable cannot be sealed off is a criticism of shielding specifically, and hospital overload depends on the pace of infection rather than on whether population immunity is reachable at all. [Rejecting P3] The comparison requires alternatives that are available and less costly, but before vaccines every option carried mortality of its own, so a rule forbidding states to weigh such costs would rule out the alternatives too.