by Oliver Steele, April 25, 2022 Revised April 28, 12:10 AM Shanghai Time
<iframe width="776" height="371" seamless frameborder="0" scrolling="no" src="<https://docs.google.com/spreadsheets/d/e/2PACX-1vT35m7QXRmF4XFc3rbCh1WP9PMXJd0yKeXkEpKXpVy_h_ufIq78pF5Fccp_9WHyHlX4nYeS5kFo5SKz/pubchart?oid=384688515&format=interactive>"></iframe>
As of April 25, I’ve been in the Shanghai lockdown for more than a month.
On March 22, I started tracking Shanghai’s COVID-19 statistics, as reported in the English-language papers. I did this as a way of keeping touch with what’s going on in the city outside this apartment. It was also because I wanted to see a different view of the data than what was being summarized in the papers.
The latest numbers and charts are in this spreadsheet. This accompanying document describes the values and graphs in the spreadsheet, the sources and methods used to collect the data, and some choices about how to present it.
I am particularly interested in what’s happening outside of the quarantine centers. I also wanted to see how many total transmissions were occurring, regardless of whether the newly-infected individual ended up with a symptomatic or “asymptomatic” case.
The major difference between the data that is summarized in the spreadsheet, and articles in the press, is that the spreadsheet summaries combine symptomatic and asymptomatic cases, while distinguishing cases detected in quarantine centers from cases detected during residential screening. My rationale for grouping the data this way is further discussed in the Presentation Choices section below.
I was interested in this way of slicing the data: because both asymptomatic and symptomatic individuals are contagious; because both symptomatic and asymptomatic cases detected in the community will trigger or extend a period of residential lockdown; and because Long Covid appears to affect many people who had relatively mild symptoms, and would be reported as asymptomatic in China.
Note: As of April 26, Shanghai Times started including a graph of “New infections found in screening of high-risk people”. (By “high-risk”, they mean “outside of quarantine”.) This goes halfway towards what I wanted. The missing piece is combining all infections, regardless of whether they are symptomatic.
Note that I do not have training as a virologist, epidemiologist, statistician, or infection disease expert; nor have any of these reviewed this document.
Sections
These definitions used to describe the data. Note that these definitions are specific to Shanghai in Spring 2022. For example, in other countries (and, I believe, during other times in China), a person could be considered a case if they tested positive on an antigen test. During the current outbreak, antigen results are not considered conclusive.
Some or all of these definitions may be familiar to anyone living in Shanghai.
Symptomatic cases, in the Shanghai reports, are cases that are confirmed positive on a nucleic acid test, and that also have symptoms. I believe that during the reporting period, a case is considered symptomatic only if if there are respiratory symptoms confirmed by a CT scan.
Asymptomatic cases are cases that are confirmed positive on a nucleic acid test, but do not have symptoms, using the criterion above. (The term does not indicate that there are no symptoms at all. For example, a patient could have a fever, intestinal discomfort, or other non-respiratory symptoms; or, be coughing or sneezing, but not show a lung abnormality on an X-Ray.) In some reporting, this category is referred to as asymptomatic infections, not “cases”.
A close contact is an individual who was in close and extended proximity to a symptomatic or asymptomatic case. The exact meaning of “close” in this definition has changed over time; these data simply pass through the numbers that are reported under this category. The definition has always, by my understanding, included a roommate or family member with the same address; it has never, to my knowledge, included other residents of the same building, even if they share a ventilation system.
The media reports distinguish between close contacts of symptomatic cases (who are taken into quarantine), and close contacts of asymptomatic cases (who are “placed under observation”). I am unclear as to whether people in this latter category are removed from their homes.