I decided last night it would be sensible to see what facts I can find out about this coronavirus that is spreading around the world. There are rumours of a relaxing of the lockdown and so finally I should learn what I can about the disease. Trying to find reliable sources might be tricky but I’ll spend around an hour and see what I can get.
Data from published epidemiology and virologic studies provide evidence that COVID-19 is primarily transmitted from symptomatic people to others who are in close contact through respiratory droplets, by direct contact with infected persons, or by contact with contaminated objects and surfaces.
It would appear that from first contact with the virus it takes a median of 5.1 days for symptoms to show. This means 50% of people will have symptoms before or by five days after infection and the other 50% after 5.1 days. Most people will show symptoms within the first 11 days of transmission. By most I mean around 97%.
During the incubation period, also known as the “presymptomatic” period, some infected persons can be contagious. Therefore, transmission from a pre-symptomatic case can occur before symptom onset. It is possible that people infected with COVID-19 could transmit the virus before significant symptoms develop. It is important to recognise that pre-symptomatic transmission still requires the virus to be spread via infectious droplets or through touching contaminated surfaces.
A Harvard document has “reports” of people being infectious two days before symptoms start. This is not good and a reason for social distancing. LINK.
An asymptomatic laboratory-confirmed case is a person infected with COVID-19 who does not develop symptoms. Asymptomatic transmission refers to transmission of the virus from a person, who does not develop symptoms. There are few reports of laboratory confirmed cases who are truly asymptomatic, and to date, there has been no documented asymptomatic transmission. This does not exclude the possibility that it may occur. Asymptomatic cases have been reported as part of contact tracing efforts in some countries.
My current understanding is that testing for Covid-19 requires there to be virus in saliva and or snot. This means that you are likely to be showing symptoms as the virus has replicated enough in your body to affect your mucus membranes. So, if you get a test and it is negative there are some issues. Firstly, false negatives are possible and so the test might say NO but actually you have the disease. Also, you might not have enough of the virus yet so still have the disease but test negative. A positive test is more likely correct although there will be a false positive rate, this is likely much lower than the false-negative rate.
This is quite interesting because one of my standard lessons to Year 11 and also the sixth form is about this exact thing. Is a medical test good enough for use with the public looking at type 1 and type 2 errors.
Source Of Information
All of this information came from World Health Organisation reports from their excellent pages covering this disease.
I feel a little happier now that I have a good source for these facts and feel more confident that I know what I’m talking about. For me one of the saddest aspects of this is the fact that the WHO have to have a page dedicated to myths that are circulating the internet and discussions because largely people can be stupid. It doesn’t help that the US President is a fucking lying racist sexist moron and other leaders around the world are also stupid [Brazil and UK, also many more].
When this is over I hope there’s a bonfire of those leaders who did nothing for the two or three weeks when it was clear that Italy was fucked. It seemed obvious to me at that moment that we needed to shut the country down to save lives. It was ridiculous that I was expected to work in an environment of around 1500 people many of whom had returned from skiing holidays or similar. I just don’t think the leaders of many countries understand the following:
- Exponential growth
- Six degrees of separation
- Vectors of disease transmission
- How to be nice and do the best you can for humanity