The writer is a science commentatorRespiratory syncytial virus is a little-known and hard-to-spell seasonal scourge that, like flu, most seriously affects children and older people. It usually triggers coughs and colds but can cause serious breathing difficulties in a small minority of infants.
RSV is so common that more than 80 per cent of UK children are infected by their second birthday — but case numbers plummeted during the Covid-19 pandemic. Measures such as masking, plus school and nursery closures, intended to slow the spread of Covid, also put the brakes on infection rates. Now the virus is resurgent, particularly in the US, with the wave hitting earlier than expected.
That has fuelled speculation that pandemic mitigations, including lockdowns, created a harmful “immunity debt”, with children left vulnerable through a lack of exposure to the usual cut and thrust of viral infections. But scientists have dismissed the concept, as applied to individual immunity, as misguided.