You'd think reporters would have figured this "science" thing out by now!
Pleasantly surprised that this study was conducted by the CDC.
As expected, the reporting in the story was all screwed up (you have to read the story above to figure out how badly they got confused with the numbers - but you'll have to go to WayBack machine or something since they have rewritten the story in the last day - it said this yesterday: ""The serology test results appear to track closely with data from the Roosevelt in early April, which showed that 60 percent of the sailors who were testing positive for the virus itself - not antibodies - were in fact symptom-free." and now it says this instead (much more correct, does not confuse the 60% value) "The serology test results follow data from the Roosevelt in early April, which showed that 60 percent of the sailors who were testing positive for the virus itself - not antibodies - were in fact symptom-free."). The CDC report says
"One fifth of infected participants reported no symptoms." This is a bit lower than I would have guessed, but also not surprising since they probably did a good job on expanding the list of possible symptoms for people to respond to (these surveys can be screwed up if the full list of possible symptoms is not presented to respondents, as the WHO said yesterday).
SARS-CoV-2 Infections and Serologic Responses from a Sample ...
Median age 30
382 participants spanning people previously infected, and not. Self-selecting sample.
61.5% (235) had previously tested positive
70% (267) provided a swab for testing.
62% (238) had swab indicate current or previous infection (PCR or ELISA Antibody positive)
59% (228) of participants had ELISA Antibodies (so 96% of the infected), and 60% (135) of those ELISA-positive individuals had neutralizing antibodies.
81.5% (194) of those infected had had symptoms. (284 participants total reported symptoms, so 90 of the participants had symptoms but no sign of virus.)
1) Antibodies are promising for at least short term immunity (60% of those with positive ELISA had good neutralizing antibodies at this snapshot in time).
2) Masks and other measures help!
3) Sampling detail: "During this time, approximately 1,000 service members were determined to be infected with SARS-CoV-2, the virus that causes COVID-19. The United States Navy and CDC investigated this ongoing outbreak during April 20–24; 382 service members voluntarily completed questionnaires and provided serum specimens (a convenience sample comprising 27% of 1,417 service members staying at the base on Guam or on the ship).
The 1,417 included persons who were previously infected, currently infected, or never infected."
4) Lack of taste and smell is a very important symptom - it is very predictive if you have that symptom. Fever, not as much. "Approximately one third of participants reported fever, myalgia, and chills and had higher odds of SARS-CoV-2 infection than did persons who reported cough and shortness of breath. Participants reporting anosmia (loss of sense of smell) or ageusia (loss of sense of taste) had 10 times the odds of having infection, compared with those who did not."
5) The 62% positive by PCR/AB should not be used to determine what % of the crew has coronavirus or coronavirus antibodies, due to selection bias.
Regarding transmission in the young: "A study of adolescents and young adults with mild COVID-19 illness in China found rapid propagation of chains of transmission by asymptomatic persons (
6)"
@TheTalkingMule , perhaps you should consider this datapoint?
Huang L, Zhang X, Zhang X, et al. Rapid asymptomatic transmission of COVID-19 during the incubation period demonstrating strong infectivity in a cluster of youngsters aged 16–23 years outside Wuhan and characteristics of young patients with COVID-19: a prospective contact-tracing study. J Infect 2020;80:e1–13.
Rapid asymptomatic transmission of COVID-19 during the incubation period demonstrating strong infectivity in a cluster of youngsters aged 16-23 years outside Wuhan and characteristics of young patients with COVID-19: A prospective contact-tracing study