‘Immunity debt’ is a misguided and harmful idea

The author is a science commentator

Respiratory syncytial virus is a little-known and hard-to-spell seasonal scourge that, like flu, most severely impacts kids and older folks. It often triggers coughs and colds however may cause critical respiratory difficulties in a small minority of infants.

RSV is so frequent that greater than 80 per cent of UK kids are contaminated by their second birthday — however case numbers plummeted in the course of the Covid-19 pandemic. Measures reminiscent of masking, plus faculty and nursery closures, supposed to gradual the unfold of Covid, additionally put the brakes on an infection charges. Now the virus is resurgent, notably within the US, with the wave hitting sooner than anticipated.

That has fuelled hypothesis that pandemic mitigations, together with lockdowns, created a dangerous “immunity debt”, with kids left weak by an absence of publicity to the standard lower and thrust of viral infections. However scientists have dismissed the idea, as utilized to particular person immunity, as misguided.

The dialogue swirling round immunity debt exhibits how simple it’s for a plausible-sounding idea to flow into as misinformation. On this case, misinformation dangers selling the unfounded assertion that infections are clinically helpful to kids, in addition to feeding the revisionist narrative that Covid measures did extra hurt than good.

Professor Peter Openshaw, a respiratory physician and immunologist who research RSV and flu at Imperial Faculty London, says the present “excessive and unseasonal” RSV wave is assumed to be a results of lockdowns inflicting ranges of immunity to wane in kids, dad and mom and carers, paving the way in which for a better variety of infections.

However to border this as an immunity debt, Openshaw warns, mistakenly suggests “that immunity is one thing we have to spend money on, and that by defending ourselves from an infection we’re build up a deficit that has finally to be repaid. This may not be a great message for public well being: we might nonetheless have open sewers and be consuming from water contaminated with cholera if this concept have been adopted to its logical conclusion.” Delaying RSV an infection may very well be helpful, he provides, because the virus is deadliest to infants youthful than six months. Globally amongst under-fives, one in 50 deaths is attributable to RSV.

Deborah Dunn-Walters, professor of immunology on the College of Surrey, says it’s important to differentiate between particular person and inhabitants immunity (herd immunity) when scrutinising how pandemic measures could have altered the unfold of non-Covid illnesses. A smaller pool of individuals being contaminated in the course of the pandemic can lead, after the lifting of measures, to an even bigger pool of vulnerable folks. That fall in inhabitants immunity can gasoline a surge just because there are extra folks obtainable to be contaminated (different elements, together with the climate and virus severity, may have an effect on transmission).

However there isn’t a proof that a person is worse off for having prevented earlier an infection. “Immunity debt as a person idea is just not recognised in immunology,” Dunn-Walters says. “The immune system is just not considered as a muscle that needs to be used on a regular basis to be saved in form and, if something, the other is the case.” The fixed onslaught of frequent pathogens reminiscent of cytomegalovirus, she provides, means the immune system begins to malfunction and slacken with age. She rejects the concept that an infection is someway good for well being, saying vaccination is a far safer means of constructing inhabitants immunity.

Stephen Griffin, a virologist at Leeds College who believes paediatric pandemic vaccines have been underused, argues we’re nonetheless too complacent about childhood respiratory illnesses. Whereas there isn’t a vaccine for RSV, Griffin acknowledges, “we can vaccinate in opposition to each flu and Covid — and but we don’t.” Altering that norm, he says, might assist to neuter the worst results of a predicted “tripledemic” this winter. The UK Well being Safety Company advises that eligible kids ought to obtain the flu vaccine.

The immunity debt idea holds broad attraction as a result of it may be employed in so some ways. It appears to intuitively clarify the present wave of respiratory sickness. It’s engaging to those that would downplay illness in kids, and those that advocate for an infection over vaccination. It supplies a post-hoc justification for opposing measures reminiscent of masking, regardless that proof means that such measures curbed Covid and nearly banished flu.

Immunity debt additionally performs to the concept that the ebb and circulate of childhood sicknesses are finest left to nature — till one remembers that all the childhood vaccination schedule is about maintaining the worst of nature at bay.