{"id":97238,"date":"2020-03-20T15:54:08","date_gmt":"2020-03-20T19:54:08","guid":{"rendered":"https:\/\/valorguardians.com\/blog\/?p=97238"},"modified":"2020-03-20T16:11:19","modified_gmt":"2020-03-20T20:11:19","slug":"cruise-ship-diamond-princess","status":"publish","type":"post","link":"https:\/\/www.azuse.cloud\/?p=97238","title":{"rendered":"Cruise Ship Diamond Princess"},"content":{"rendered":"

\"\"
\nDiamond Princess<\/em><\/p>\n

The last group of about 130 crew members got off the Diamond Princess last Sunday, vacating the contaminated cruise ship and ending Japan\u2019s criticized quarantine that left about one fifth of the ship\u2019s original population infected with the new virus.<\/p>\n

The British-flagged, U.S.-operated cruise ship carried an infected passenger part way before returning to its home port in Yokohama, near Tokyo, on Feb. 3. Of the 3,711 passengers and crew members on board, 705 were infected on the ship, triggering international criticism of the quarantine and Japan\u2019s disease control capability.<\/p>\n

Warning, some math ahead. I checked so you don’t have to. Poetrooper sends:<\/p>\n

Diamond Princess Mysteries<\/h3>\n

Willis Eschenbach<\/strong><\/p>\n

OK, here are my questions. We had a perfect petri-dish coronavirus disease (COVID-19) experiment with the cruise ship \u201cDiamond Princess\u201d. That\u2019s the cruise ship that ended up in quarantine for a number of weeks after a number of people tested positive for the coronavirus. I got to wondering what the outcome of the experiment was.<\/p>\n

So I dug around and found an analysis of the situation, with the catchy title of Estimating the infection and case fatality ratio for COVID-19 using age-adjusted data from the outbreak on the Diamond Princess cruise ship (PDF), so I could see what the outcomes were.<\/p>\n

As you might imagine, before they knew it was a problem, the epidemic raged on the ship, with infected crew members cooking and cleaning for the guests, people all eating together, close living quarters, lots of social interaction, and a generally older population. Seems like a perfect situation for an overwhelming majority of the passengers to become infected.<\/p>\n

And despite that, some 83% (82.7% \u2013 83.9%) of the passengers never got the disease at all \u2026 why?<\/p>\n

Let me start by looking at the age distribution of the Diamond Princess, along with the equivalent age distribution for the entire US.<\/p><\/blockquote>\n

\"\"
\nFigure 1. Number of passengers by age group on the Diamond Princess (solid) and expected number of passengers given current US population percentages (hatched).<\/em><\/p>\n

When as a young man I lived in a port town with cruise ships calling, we used to describe the passengers as \u201cnewlyweds and nearlydeads\u201d. Hmmm \u2026 through some improbable series of misunderstandings and coincidences, I\u2019m in the orange zone now \u2026 but I digress \u2026<\/p>\n

In any case, Figure 1 shows the preponderance of \u2026 mmm \u2026 I\u2019ll call them \u201cfolks of a certain distinguished age\u201d on the Diamond Princess. Folks you\u2019d expect to be hit by diseases.<\/p>\n

Next, here\u2019s the breakdown of how many people didn\u2019t get the virus, by age group:<\/p><\/blockquote>\n

\"\"
\nFigure 2. Percentage of unaffected passengers on the Diamond Princess. \u201cWhiskers\u201d on the plot show the uncertainty of each percentage.<\/em><\/p>\n

In addition to the low rate of disease incidence (83% didn\u2019t get it), the curious part of Figure 2 for me is that there\u2019s not a whole lot of difference between young and old passengers in terms of how many didn\u2019t get coronavirus. For example, sixty to sixty-nine-year-old passengers stayed healthier than teenagers. And three-quarters of the oldest group, those over eighty, didn\u2019t get the virus. Go figure. Buncha virus resistant old geezers, I guess \u2026<\/p>\n

Next, slightly less than half the passengers (48.6% \u00b1 2.0%) who got the disease showed NO symptoms. If this disease is so dangerous, how come half the people who got it showed no symptoms at all? Here\u2019s the breakdown by age:<\/p><\/blockquote>\n

\"\"
\nFigure 3. Percentage of Diamond Princess passengers who had coronavirus but were symptom-free. There was only one illness among the youngest group, and they were symptom-free. As in Figure 2, the \u201cwhiskers\u201d on each bar of the graph show the uncertainty.<\/em><\/p>\n

Again, a curious distribution. Young and old were more likely to be symptom-free, while people in their 20s, 30s, and 40s were more likely to show symptoms. Who knew?<\/p>\n

There were a total of 7 deaths among those on board. All of them were in people over seventy. So even though the generally young were more likely to show symptoms if they had it, it hits old people the hardest.<\/p>\n

Finally, according to the study, the age-adjusted infection fatality rate was 1.2% (0.38%\u20132.7%). Note the wide uncertainty range, due to the small number of deaths.<\/p>\n

For me, this is all good news. 83% of the people on the ship didn\u2019t get it, despite perfect conditions for transmission. If you get it, you have about a 50\/50 chance of showing no symptoms at all. And the fatality rate is lower than the earlier estimates of 2% or above.<\/p>\n

It is particularly valuable to know that about half the cases are asymptomatic. It lets us adjust a mortality rate calculated from observations, since half of the cases are symptom-free and likely unobserved. It also gives a better idea of how many cases there are in a given population.<\/p>\n

To close out, I took a look at the current state of play of total coronavirus deaths in a few selected countries. Figure 4 shows that result.<\/p><\/blockquote>\n

\"\"
\nFigure 4. Deaths from coronavirus in four countries. Note that the scale is logarithmic, so an exponential growth rate plots as a straight line. Blue scale on right shows the deaths as a percentage of the total population.<\/em><\/p>\n

At this point at least, it doesn\u2019t appear that we are following the Italian trajectory. However \u2026 it\u2019s still early days.<\/p>\n

Finally, a plea for proportion. US coronavirus deaths are currently at 67, we\u2019ll likely see ten times that number, 670 or so, might be a thousand or three \u2026 meanwhile, 3,100 people die in US traffic accidents \u2026 and that\u2019s not 3,100 once in a decade, or 3,100 per year.<\/p>\n

That\u2019s 3,100 dead from auto accidents EACH AND EVERY MONTH \u2026 proportion \u2026<\/p>\n

My best to all on a day with both sun and rain here, what\u2019s not to like?<\/p>\n

w.<\/p><\/blockquote>\n

Methods, data and comments can be found here: WUWT<\/a>
\nThanks, Poe<\/p>\n","protected":false},"excerpt":{"rendered":"

Diamond Princess The last group of about 130 crew members got off the Diamond Princess last … Cruise Ship Diamond Princess<\/span>Read more<\/a><\/p>\n","protected":false},"author":657,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[296,406,88,387],"tags":[],"class_list":["post-97238","post","type-post","status-publish","format-standard","hentry","category-china","category-guest-link","category-health-care-debate","category-international-affairs"],"_links":{"self":[{"href":"https:\/\/www.azuse.cloud\/index.php?rest_route=\/wp\/v2\/posts\/97238","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.azuse.cloud\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.azuse.cloud\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.azuse.cloud\/index.php?rest_route=\/wp\/v2\/users\/657"}],"replies":[{"embeddable":true,"href":"https:\/\/www.azuse.cloud\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=97238"}],"version-history":[{"count":1,"href":"https:\/\/www.azuse.cloud\/index.php?rest_route=\/wp\/v2\/posts\/97238\/revisions"}],"predecessor-version":[{"id":97245,"href":"https:\/\/www.azuse.cloud\/index.php?rest_route=\/wp\/v2\/posts\/97238\/revisions\/97245"}],"wp:attachment":[{"href":"https:\/\/www.azuse.cloud\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=97238"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.azuse.cloud\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=97238"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.azuse.cloud\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=97238"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}