Britannic Herd Immunity and Coronavirus

Epidemiologist William Hanage was more than perplexed by the plan, reflecting in The Guardian:

When I heard about Britain's 'herd immunity' coronavirus plan, I thought it was satire.

Much public policy, foolishly considered and expertly bungled, tends to succumb to satire; having Prime Minister Boris Johnson leading the show provides an even better chance of that happening.

Herd immunity, as a policy, would involve easing off risk and preventive measures, allowing what would effectively be a mass infection, and focusing on recovery from younger members of the populace. Doing so would provide the assurance of immunity to prevent the calamity of another wave come winter. The result is a true peculiarity in health policy: a reluctance to ban mass gatherings, close spaces of public contact and deploy mass quarantine measures.

This, suggests Hanage, is erroneous; it presumes the same rationale used in mass vaccination whereas:

This is an actual pandemic that will make a very large number of people sick, and some of them will actually die. Even though the mortality rate is quite likely quite low, a small fraction of a very large number is still a large number.

On March 12, Johnson's press statement had a certain dressing of alarm. All that seemed to evaporate before a sense of fatalism. Loved ones would be lost. Major public events, he had been told by his experts, would not be banned, because doing so "will have little effect on the spread." To close down schools would cause more harm than good. As for those suffering symptoms that might be coronavirus-related, avoid seeking testing and disturbing the health system. Surf the internet, instead.

Sir Patrick Vallance, Britain's chief scientific adviser, seemed to more than hint that herd immunity as an idea had taken an infectious hold. On Radio Four's Today programme on Friday, he stated that:

Our aim is to try and reduce the peak, broaden the peak, not suppress it completely; also, because the vast majority of people get mild illness, to build up some kind of herd immunity so more people are immune to this disease and we reduce the transmission.

This might have struck those with susceptibility and an assortment of vulnerable conditions as terrifying, though Sir Patrick was insisting that they, too, be protected. Even with a mortality rate of 1%, the death rate would be impressively contained.

That was certainly a scenario entertained by the UK chief medical officer Chris Whitty. A percent of deaths would equate to a loss of 500,000 people in circumstances where 80% of the country would contract the virus. For herd immunity to be achieved, calculated Vallance, "probably about 60%" of people needed infection.

Fuelling this particular approach was a worry shared by Johnson and his advisors that behavioural fatigue might set in. An early imposition of strict restrictions would see a lack of cooperation and caution. Besides, containing the virus initially might work with harsh measures, but not make it go away before the cold spell.