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Two More players test positive


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1 hour ago, Harry Stottle said:

How it is picked up is one thing,  but I can tell you exactly how it can be transmitted during a RL game, but I don't need to spell it out do I Tommy.

I for example go for a pint a couple of times a week and there would be 10 of us under normal circumstances sat around a single table, that has been shelved for now and we sit 4 at a table under the guidelines, now if we were on a rugby field any guidelines remotely like the general public has to adhere to has been bypassed e.g. we could wrestle with each other, perform gang bear hugs, breath cough and splutter well within the social distancing measures, most probably fall onto or put our hands into someone else's spittle on the ground and a host of other things that would help us to get contaminated.

Very careful consideration should be made as to whether to abandon the season, but I fear if reports are coming out each week of infections at different clubs and subsequently matches keep being cancelled it could very well sway in that direction.

Yes. 

I read that the Green MP Lucas was at a grand demonstration today, all not distancing and because she had a cough,  she borrowed / shared a drink of water from a plastic (!) bottle.  Brilliant.

I do hope these events encourage players etc to keep up and stay with it.

 

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18 minutes ago, Tommygilf said:

Because no Salford players tested positive after the Hull game, or Wire after the Wakefield one, or Wakefield after the Catalans game.

Fair assumption.

So far.

"We'll sell you a seat .... but you'll only need the edge of it!"

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4 hours ago, Tommygilf said:

Because no Salford players tested positive after the Hull game, or Wire after the Wakefield one, or Wakefield after the Catalans game.

How do we know that Wakefield didn’t contract after the Catalans game? It can take a while to show up 

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21 minutes ago, DoubleD said:

It might help reduce the extent of the spread but it won’t prevent players catching the virus in the first instance or the resulting impact 

It will help identify if an infectious player has played a game or not. From what we've seen infections appear to have occurred between matches and the Tuesday testing, but because we don't test straight after the match we have opposition players who've tested negative forced to isolate.

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On 02/09/2020 at 16:55, Les Tonks Sidestep said:

They are using a pretty reputable company who are using PHE approved PCR (antigen) tests. Those tests can, and do, give false negatives (I've seen figures suggesting a negative is only 75-80% reliable) whereas a positive is pretty nailed on to be correct (>99%). No test is 100% accurate (+ve and/or -ve) and the claims made are often based on fairly small subsets within smallish evaluation samples - Radio 4's More or Less did a couple of features on Covid tests a few months ago, well worth a listen if you can find them on iPlayer.

Indeed. The problem with false positives is, it it is highly dependent on the prevalence of the disease. 

The problem with the 99%+ accuracy is that it relates to the probability that, if you have the virus, you will test positive. 

What we actually want to know is the converse, if you test positive, what is the probability that you actually have the virus. This takes into account false positives. 

Time for Bayes' theorem 

https://www.mathsisfun.com/data/bayes-theorem.html

Using the figures on here, (99.9% accuracy of positives & to be generous 95% accuracy on negatives with prevalence of 0.05% - using an example population of 60 million:

There are 4 possible outcomes. 

True positive  (test positive and have the virus)

False positive  (test positive but don't have the virus)

True negative (negative, no virus)

False negative (negative, but have virus)

With a prevalence at a given time of 0.05% it means 30k people would currently have the virus.

True positives would be 99.9% of 30k = 29,970

False negatives would be 0.01% of 30k = 30 people.

All good so far. 

True negatives would be 95% of 59,970,00 = 56,971,500

Our interest is in the false positives 5% of 59,970,000 = 2,998,500

So, the probability given a positive test result that you actually have the virus is 29,970 ÷ (29,970+2,998,500) = 0.99%

So, if the whole country was tested tomorrow, a random person getting a positive test result is less than 1% likely to actually have the virus. 

99.9% of a small number is much less than 5% of a really big number. 

As far as RL goes, the sample is way to small to be significant and what other way is there? We can only err on the side of caution. 

Does anyone know if we've had players with positive tests followed by negative? Is anyone who has previously tested positive tested for antibodies? Has any player who tested positive (or a confirmed contact of such a player) had Covid symptoms?

Which is why it's pointless testing everyone and they generally only test those with symptoms where the prevalence is going to be much higher. It's needle in a haystack stuff. 

P.S.

Please feel free to check my arithmetic. 

P.P.S.

"More or less" is also available as a podcast with all back episodes on BBC sounds et al. 

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