Scientists are warning of the risk of lifting lockdown too soon. Well indeed. Many of them have been staking their reputations on the inevitable spread of the virus if that old R number doesn't start coming down faster, but the whiff of freedom is too strong now, and won't be denied. And many are beginning to suspect that the modeling which led to the whole panicked response, starting with Neil Ferguson's hugely influential doomsday scenario, may not have been that reliable after all.
Matthew Parris in the Times today:
You can scare people out of their wits, which is what the government has done, or announce “Panic Over – Back to Normality”, which is how people are reading the signs now: but the terrain between bomb-shelter and the all-clear will prove almost impossible to navigate.
So my guess is that as June approaches “the” science is holding its breath. From the coldly academic point of view, the science should be nervously hoping for a massive “second wave”. It’s what their modelling and clinical assumptions have predicted. Be under no illusion: university faculties, doctors, epidemiologists and modellers have a great deal of reputational capital riding on this. If lockdowns are lifted across the world and the sky does not fall in, they will quite simply have been proved wrong.
They will protest, of course, that all they did was report the results of their modelling, and it was for politicians to decide how to respond; but if you tell a prime minister that up to half a million people may die and that our health service will collapse unless he takes a sledgehammer to our economy, he will reach for the sledgehammer. He did.
They will protest that “herd immunity” is far more complex than reported, that localised outbreaks, hotspots, regional variations, differences between the infectiousness of “superspreaders” and others, and maybe even differences between the susceptibility of the uninfected all complicate the picture. Well, yes, no doubt. It would have been helpful to hear this at the beginning rather than the end.
Science is about prediction or it is nothing. I suspect “the” science got it wrong, and herd immunity never was 60 per cent.
What's going on, then? Are we approaching herd immunity, even though the results from antibody testing seem to show disappointingly low levels of immunity to Covid-19 in tested populations?
It may be, according to some recent studies, that immunity is more widespread than generally believed because immunity can be conferred by exposure to other coronaviruses. Ross Clark in the Spectator:
Two weeks ago I wrote here about a study by the La Jolla Institute for Immunology in California, which found that between 40 and 60 per cent of people who had never been exposed to SARS-CoV-2 – the virus which causes Covid 19 – nevertheless seemed to develop an immune response to the disease in their T Cells. They appeared to have a cross-reactive immunity which had been gained through exposure to other coronaviruses – those which cause the common cold.
Now comes another study providing more evidence of the same phenomenon from a team at the Emerging Infectious Diseases Program from Duke-NUS Medical School in Singapore. Nine of 18 patients they studied showed an immune reaction in their T cells to a protein in SARS-CoV-2, in spite of never having been exposed to the virus.
The team also found that survivors of SARS – the novel coronavirus disease which had an outbreak in 2002/03 and then largely disappeared – possess a ‘robust’ cross-reactive immune response to SARS-CoV-2. [...]
Real-world evidence has already questioned the assumption that most of us would become infected were the disease allowed to run its course. In the accidental experiment of the Diamond Princess – a close community where the infection was allowed to spread unchecked for a fortnight in January, and everyone was eventually tested – only 17 per cent of passengers and crew became infected.
Even if cross-reaction from other coronaviruses does not provide full immunity, it might explain why many people suffer only mild symptoms or no symptoms at all. According to an ONS study of 19,000 people published last week, 79 per cent of people who tested positive for SARS-CoV-2 showed no symptoms up until the day they were tested.
There's more on similar lines at the Times of Israel:
Could exposure to the coronaviruses that cause the common cold help protect against COVID-19? Is herd immunity closer than previously thought?
As nations lift lockdowns and experts worry about a potential second peak in cases, our ability to ward off infection is one of the hottest topics of scientific debate.
Ever since it became apparent that children were less vulnerable to COVID-19 early in the pandemic, scientists have speculated that the regular spread of benign viruses in places like schools could have bolstered their immune response to the latest coronavirus.
Now the idea of “cross immunity” among the broader population is gaining some ground.
In a recent post on Twitter, Francois Balloux of University College London noted an “intriguing” lack of an immediate resurgence in COVID-19 cases following the easing of lockdowns in several countries.
Among the possible explanations, he noted, were seasonality and enduring social distancing practices.
But he posited a “wilder” hypothesis as well — that a “proportion of the population might have pre-existing immunity to #SARSCoV2, potentially due to prior exposure to ‘common cold’ coronaviruses.”
Balloux said that might explain issues like cases where there is no transmission between spouses.
Earlier this month, an American study in the journal Cell suggested between 40 and 60 percent of the population could be immunized against COVID-19 without ever being exposed to it.
Researchers put this down to the action of protective cells, known as T lymphocytes, that had been activated by other coronaviruses responsible for colds.....
Interesting. It would explain a lot, including perhaps, as suggested in a comment here, why Japan has escaped so lightly.