Contrary to the belief that repeat infections should become milder, recent cases have often involved a harsh week of coughing, headaches, or fever, along with lingering exhaustion.

Although symptoms have always varied, with some barely noticing the infection, experts in immunology are cautioning that current infections may be severe and prolonged.

The course of a COVID infection is determined by the initial interaction between the virus and our immune defenses. However, decreased immunity and the evolving virus are affecting this balance.

Professor Eleanor Riley from the University of Edinburgh experienced a particularly severe infection herself, noting that antibody levels against COVID are currently lower than they have been since vaccines were introduced. These antibodies act as microscopic defense missiles; their decreased presence means the virus can cause more significant illness.

Vaccination intervals and the waning of infection-induced immunity have led to this decline in antibodies. Despite the transformative effect of vaccines previously, notably less are being offered now, restricted mainly to the over-65s and at-risk groups.

Professor Peter Openshaw of Imperial College London anticipates many will face considerable illness, significantly impacting even the young and healthy, with some developing 'long COVID.'

Vaccination strategies focus on those at highest risk, aiming to reduce NHS strain, while the virus's evolution complicates antibody effectiveness.

Even though our T-cells can combat severe illness by destroying infected cells, their activation can also cause the unpleasant symptoms associated with COVID.

While there's hope for COVID to become a milder infection over time, as with other human coronaviruses, we're not at that point yet. Repeat infections should eventually lead to natural immunity, but for now, a difficult winter may be ahead for some.