Very interesting article on the changing face of Covid….
“We’d expected strong seasonal wintertime patterns where you don’t see a lot outside those winter months,” said Kissler (Harvard Epidemiologist). This was because, with limited information to go on at the time, respiratory viruses have a natural advantage in the winter when people are cooped up indoors and when our immune systems are potentially less effective. And for many viruses, once a winter wave has passed, people remain immune for long enough to suppress infection until the following year.
Two years on, Kissler’s view has changed. “We’re in a different landscape now,” he said. “The fact we’re having such a rapid succession of variants – we seem to be racking them up at alarming speed – is the most surprising thing and that’s changed the way the waves look.”
“I would’ve thought it would have reached a steady state by now,” he said. “It seems the opposite is the case.”
Others have also been taken by surprise by this pattern. “It does look as if the successive waves are getting closer together,” Prof Peter Openshaw, an immunologist at Imperial College London, said. “They are actually becoming more frequent, with one piling in on top of the other.”
The change, Openshaw said, is that in the first year of the pandemic, new waves were driven by the emergence of more transmissible variants, such as Alpha and Delta, which spread infection more easily. Now, successive variants, including the latest BA.2.75 variant, nicknamed Centaurus, are being driven primarily by “immune escape” – the ability to infect people who have been vaccinated and infected, even fairly recently.