The majority of the ship did not get infected at all, they were all tested.
Your hopeful theory about massive numbers of hidden infections is almost certainly FALSE.
I agree. There is no data to support the massive hidden infection claim. There are undoubtedly some infections with only very mild or no noticeable symptoms that don't get tested or reported in the total infection statistic, but it's far lower than Turveyd is suggesting. There was some rather wild early speculation coming out of Italy that's not reliable. However in the town of Vo' in Northern Italy there was a study done were the entire town of 3300 was tested repeatedly. That study was mentioned in the Financial Times (
https://www.ft.com/content/0dba7ea8-6713-11ea-800d-da70cff6e4d3) but I don't recall specific data on what were called submerged infections. If that study has been published yet, I think it would contain very accurate data that could answer the question of what fraction of Covid infections present no symptoms at all and are therefore likely to remain uncounted. I'll try to track it down. In any case it is no where near the numbers TheFarmer and Turveyd are throwing out. CDC is estimating ~ 1 submerged in 4 infections for the U.S. but on what data I have no idea, since we, by and large, only test quite symptomatic folks in the U.S. (Likely the CDC estimate is inferred from some of the studies in other countries.) The number of undetected would be very small in say a place like Germany where they tested nearly everyone who could have been exposed. They are still doing something like over 300K tests a day there! It's a rate that would allow them to test every man women and child in <9 months! Germany has a 1.3% death rate which I regard as a highly reliable number for a country with excellent public health system and very aggressive CoVid mitigation, plus their average age for covid infected is 49, which is over a decade younger then Italy's. So I think Germany's good results are easily explained. The U.S. rate will be greater than double that, allowing for more "submerged" infections in the U.S. and worse health care outcomes..
edit. I just found this in the Guardian, but this is not a peer reviewed paper and it is a little unclear as to the large number "submerged" infections found -- had they previously been sick and recovered, or did they never get sick? -- and exactly what fraction of them cold transmit the virus -- I would guess this later number could correspond to those, if they were asymptomatic, still in the incubation period. If we want to understand this paper we need the scientific report. But this is interesting nevertheless.
In one Italian town, we showed mass testing could eradicate the coronavirus
By identifying and isolating clusters of infected people, we wiped out Covid-19 in Vò
Andrea Crisanti and
Antonio Cassone
Fri 20 Mar 2020 03.00 EDT Last modified on Thu 26 Mar 2020 11.10 EDT
It’s now about one month since Covid-19 began to
sweep across Italy. With more than
total cases topping 40,000 as of 19 March, it is now the worst-affected country outside of China.
But in the last two weeks, a promising pilot study here has produced results that may be instructive for other countries trying to control coronavirus. Beginning on 6 March ,along with researchers at the University of Padua and the Red Cross,
we tested all residents of Vò, a town of 3,000 inhabitants near Venice – including those who did not have symptoms. This allowed us to quarantine people before they showed signs of infection and stop the further spread of coronavirus. In this way, we eradicated coronavirus in under 14 days.
Scientists say mass tests in Italian town have halted Covid-19 there
Read more
While we believe it is too late to enact this approach in a
city such as Milan, where infections are out of control, there could still be time to do this in the UK before the crisis gets even worse
: the government could identify and isolate clusters
, quarantine everyone affected, trace their recent contacts, and quarantine and isolate them, too – whether they had symptoms or not.
Our experiment came to be by chance. The Italian authorities had a strong emotional reaction to news of
the country’s first death – which was in Vò. The whole town was put into quarantine and every inhabitant was tested. The tests were processed by us at the University of Padua. It became clear that this was a unique epidemiological setting – and an application was put in to keep the town in lockdown and run a second round of tests after nine days.
Advertisement
In the first round of testing, 89 people tested positive. In the second round, the number had dropped to six, who remained in isolation. In this way, we managed to eradicate coronavirus from Vò, achieving a 100% recovery rate for those previously infected while recording no further cases of transmission.
We made an interesting finding: at the time the first symptomatic case was diagnosed, a significant proportion of the population, about 3%, had already been infected – yet most of them were completely asymptomatic. Our study established a valuable principle: testing of all citizens, whether or not they have symptoms, provides a way to control this pandemic.
The nature of this crisis means that establishing a structured response like this is key, while
widespread testing is crucial in telling an accurate story of how many people are affected, and what the mortality rate of the virus actually is. In Italy, we have struggled with a rampant rise of mortality (the number of casualties divided by the number of infected people), which has reached an apparent value of 8% – far higher than the mortality rate in China and grimly close to that during the 2002-2003
Sars outbreak.
Coronavirus: the week explained - sign up for our email newsletter
Read more
This high rate is misleading, though. After the first few days of the initial outbreak, cases were classed as all of those found to be infected by the virus. Yet since then, only the obviously symptomatic subjects – those needing medical care – have been tested for the virus and thus counted as cases.
The decision to only test those who presented for treatment with symptoms of the virus was taken by major Italian public health experts, apparently in line with World Health Organization (WHO) suggestions. The consequence has been that people who haven’t asked for medical attention have only been tested very occasionally in
Italy. Nonetheless, asymptomatic or quasi-symptomatic subjects represent a good 70% of all virus-infected people and, still worse, an unknown, yet impossible to ignore portion of them can transmit the virus to others. Full testing would give us a clearer picture of how many people actually have the virus, and how many pass it on.
If the fact that only those presenting with the virus were being tested was accounted for, the mortality percentage would fall to more “normal” levels. This is shown by the mortality in the Veneto region, which is steadily around 2.5-3%, still high but threefold less than the ones in
Lombardy and Emilia-Romagna.
Why this marked difference? Veneto is comparable to the other two northern regions for education, general lifestyle, personal income and age of the population – all factors, particularly the last one, believed to influence Covid-19 mortality. Although a non-homogeneous data collection and other variables could explain the difference, there is one main factor that is likely playing a role. In Veneto, the virus was more actively sought out through testing, a programme that included part of the asymptomatic population. Official numbers speak of roughly eight in every 100 people tested in Veneto, against about half and one-third of that proportion in Lombardy and Emila-Romagna, respectively.
Italy will be Europe's canary in the coalmine for the post-Covid economy
Marchel Alexandrovich
Read more
Advertisement
Unfortunately, it would be near impossible to repeat this model in a large city, due to the number of people who would need to be tested. However, our findings warrant careful consideration by health policymakers in Italy and around the world. They invite researchers to eradicate the virus through extensive testing of both symptomatic individuals and all of their social contacts – including relatives, friends and neighbours. In this way, we catch out the disease before it has the chance to spread – and, most importantly, before the carrier has the chance to unwittingly pass it on to other people.
In the absence of specific therapies or a vaccine, quarantine, distancing and identification of asymptomatic carriers remain the only real measures to controlthis epidemic. In the UK, authorities could still identify and isolate clusters, and test everyone who has come into contact with those infected. Wisely, though probably belatedly, WHO has just this week recommended what we have found in our research to be the best line of defence:
testing, testing, testing.
• Andrea Crisanti is professor of microbiology at the University of Padua; Antonio Cassone is a former director of the department of infectious diseases at the Italian institute of health