I see after doing a search experts knew... months ago... about the possiblity of superspreaders and clusters.
To his credit this guy in Germany knew or suspected super spreaders or super spread clusters... he explains that targeted testing is what is needed.
Q: Should all countries be testing everybody?
A: I’m not sure. Even in Germany, with our huge testing capacity, and most of it directed to people reporting symptoms, we have not had a positivity rate above 8%. So I think targeted testing might be best, for people who are really vulnerable – staff in hospitals and care homes, for example. This is not fully in place even in Germany, though we’re moving towards it. The other target should be patients in the first week of symptoms, especially elderly patients who tend to come to hospital too late at the moment – when their lips are already blue and they need intubation. And we need some kind of sentinel surveillance system, to sample the population regularly and follow the development of the reproduction number.
here is some more...
https://www.theguardian.com/world/2...-drosten-germany-coronavirus-expert-interview
Christian Drosten, who directs the Institute of Virology at the Charité Hospital in Berlin, was one of those who identified the Sars virus in 2003. As the head of the German public health institute’s reference lab on coronaviruses, he has become the government’s go-to expert on the related virus causing the current pandemic.
In an exclusive interview, Drosten admits he fears a second deadly wave of the virus. He explains why Angela Merkel has an advantage over other world leaders – and why the “prevention paradox” keeps him awake at night.
Q: Germany will start to lift its lockdown gradually from Monday. What happens next?
A: At the moment, we are seeing half-empty ICUs in Germany. This is because we started diagnostics early and on a broad scale, and we stopped the epidemic – that is, we brought the reproduction number [
a key measure of the spread of the virus] below 1. Now, what I call the “prevention paradox” has set in. People are claiming we over-reacted, there is political and economic pressure to return to normal. The federal plan is to lift lockdown slightly, but because the German states, or Länder, set their own rules, I fear we’re going to see a lot of creativity in the interpretation of that plan. I worry that the reproduction number will start to climb again, and we will have a second wave.
Q: If the lockdown were kept in place longer, could the disease be eradicated?
A: There is a group of modellers in
Germany who suggest that by prolonging lockdown here for another few weeks, we could really suppress virus circulation to a considerable degree – bringing the reproduction number below 0.2. I tend to support them but I haven’t completely made up my mind. The reproduction number is just an average, an indication. It doesn’t tell you about pockets of high prevalence such as senior citizens’ homes, where it will take longer to eradicate the disease, and from where we could see a rapid resurgence even if lockdown were extended.
Q: If there were such a resurgence, could it be contained?
A: Yes, but it can’t happen based on human contact-tracing alone. We now have evidence that almost half of infection events happen before the person passing on the infection develops symptoms – and people are infectious starting two days prior to that. That means that human contact-tracers working with patients to identify those they’ve been exposed to are in a race against time. They need help to catch all those potentially exposed as quickly as possible – and that will require electronic contact-tracing.
Q: How close we are to achieving herd immunity?
A: To achieve herd immunity we need 60-70% of the population to carry antibodies to the virus. The results of antibody tests suggest that in
Europe and the US, in general, we are in the low single digits, but the tests are not reliable – all of them have problems with false positives – and herd immunity is also not the whole story. It assumes complete mixing of the population, but there are reasons – in part to do with the social networks people form – why the whole population may not be available for infection at any given time. Networks shift, and new people are exposed to the virus. Such effects can drive waves of infection. Another factor that could impact herd immunity is whether other coronaviruses – those that cause the common cold, for example – offer protection to this one. We don’t know, but it’s possible.
