We’ve just had another summer Covid surge. Some 4½ years since the highly virulent virus Sars-CoV-2 put the world in a pandemic spin, I thought it would be useful to look at where Covid-19 is now and see where it might travel next.
What are the latest Covid variants?
The continued evolution of this coronavirus is not unexpected. We had Delta and the original Omicron variants, which were quite virulent back in 2021. Since Omicron emerged, different branches of the variant have become dominant and then fallen away as others emerged. JN1 emerged in December, 2023 – it and its sublineages F456L and R367 are now the predominant variants globally, according to the Health Protection Surveillance Centre (HPSC).
The term being used to describe a whole family of different variants – including KP.2, JN.1.7, and any other variants starting with KP or JN – is FLiRT. They appear to have independently picked up the same set of mutations. They are all descendants of the JN.1 variant that has been largely dominant this year. The particular mutations that people refer to as FLiRTs refer to specific positions in the spike protein.
Viruses such as Sars-CoV-2 mutate frequently, and when they mutate to evade recognition by antibodies, this often weakens their ability to bind to the cells they want to infect. We then see mutations appear that improve that binding ability. Even with the ongoing mutating of the virus, nothing that’s emerged in the past two years has changed the Covid landscape all that dramatically.
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According to a World Health Organisation risk evaluation, JN1 is able to evade previous immunity but “is not expected to be associated with increased infection severity”.
This is borne out by the weekly confirmed Covid-19 cases in Ireland. According to HPSC figures, the number of cases in our summer surge peaked at 1,000 cases between week 22 and week 25 before dropping slightly. The increase was especially marked in the over 65s. The surge was mirrored by an increase in hospitalisation rates, although not in intensive care admissions or deaths. This suggests there has been no associated increase in infection severity.
[ Covid-19 level hits high previously seen in 2021 surge, new data showsOpens in new window ]
Why are Covid cases rising this summer?
Well it’s not just this summer. There has been a surge in summer Covid infections – to various extents – in the five summers that Covid-19 has been around. According to a recent article in Stat magazine, there are a number of possible reasons for this – firstly the virus has evolved to be incredibly good at spreading, particularly since the emergence of the Omicron variant; and people also become susceptible to an infection again not all that long after their most recent infection or booster shot.
This is a result of two factors: the fact that immunity to Sars-CoV-2 infections naturally wanes over three to four months, and that the virus continues to evolve in ways that allow it to infect people even who have several layers of protection.
The combination of a summer surge and a winter spike in Covid-19 infections has led some experts to suggest the virus shows periodicity. In other words, it can cause a wave of cases roughly every six months or so, likely as a result of enough people becoming susceptible to infection again.
Will Covid ever become a once-a-year winter infection?
There are no signs of this occurring yet. Indeed, experts are doubtful that a winter seasonality is in the offing. According to one, the lag between the emergence of new variants and the approval of matched vaccines remains a big challenge to seasonality.
“I think people have to understand that we’re probably going to be dealing with Covid for many, many, many years to come. There will be waxing and waning of infections, summer or winter,” said Dr Aaron Glatt, a spokesperson for the Infectious Diseases Society of America.
Whither Covid? There are still too many questions and too few answers to say.