COVID, flu, RSV – how this triple threat of respiratory viruses could collide this winter

Outbreaks of seasonal diseases like influenza and respiratory syncytial virus are already putting pressure on the overburdened NHS.

As the days get shorter and the weather colder in the northern hemisphere, health officials have warned of a perfect storm of infectious respiratory diseases over the winter months.

Outbreaks of seasonal diseases like influenza and respiratory syncytial virus (RSV) are already putting pressure on the overburdened NHS. If surges of these illnesses collide with another large COVID wave, we could be facing a public health disaster.

Some have called this threat a “tripledemic”.

But how can we realistically expect the winter to play out? To try to answer this question, we can look at the recent and current trends of some of the most common winter infections in the UK.

Let’s start with the most obvious one, SARS-CoV-2 (the virus that causes COVID-19). The UK has so far been through multiple COVID waves, fuelled by a combination of behavioural changes, emerging variants and waning immunity.

In contrast to the large epidemic last winter, more recent waves have been relatively small. And despite initial concerns about a significant winter surge this year, the number of COVID cases is currently decreasing. But the pandemic isn’t over yet, and what will happen next is highly uncertain.

So far, there’s mixed evidence as to whether COVID is worse in cold weather. But during winter, people tend to stay indoors more and reduce ventilation, giving viruses more opportunity to spread.