Lag time

By August 9, 2021Media, Science

Some idiots have demonstrated their ignorance about the Covid-19 pandemic in stating that because there are fewer deaths in the current outbreaks, then the Delta variant has a lower mortality rate. The only time you can determine the death rate is after the event, or if you look at the number of deaths today and compare that with the number of cases in the past. That is because there is a lag time between infection of a person and their possible death from the virus. Also, to cope with the vagaries of testing and detection, which make the daily numbers of new infections jump around considerably, I tend to stick to the seven-day moving average (SDMA) of cases. This is where the average for today is the total number of cases detected today and in the previous 6 days, divided by 7. It makes for a much smoother curve and will give a peak infection rate which is clear. Relatively, Australia has had so few cases of Covid-19 that even the SDMA does not smooth the data sufficiently to give accurate estimates of peaks. Here are a few examples.

Example 1: The UK had its third wave of Covid-19 beginning in early December 2020 and it peaked at 59,417 cases per day (SDMA) on January 9th. Many people died during this wave, with the maximum number of deaths of 1251 (SDMA) being reached on January 23rd. That is a lag time of 14 days.

Example 2: The US had its second wave of Covid-19 beginning in the middle of June, 2020, and it peaked at 70,608 new cases per day (SDMA) on July 19th. The peak in deaths was on August 4th with an SDMA of 1,185 per day. That is a lag time of 16 days.

Example 3: France had its second wave of Covid-19 beginning in October 2020, and it peaked at 52,907 new cases per day (SDMA) on November 7th. Deaths peaked at an SDMA of 667 per day on November 19th. That is a lag time of 12 days.

So the lag time between the peak in cases and the peak in deaths is about two weeks. There is another interesting feature of the lag time. It seems to be a feature of everything that occurs during this pandemic. The UK’s fourth wave really started to kick off in May 2021, and it peaked on July 21st at an SDMA of 47,101 new cases per day, two days after Boris Johnson’s ‘Freedom Day’ on July 19th1,4. It then started to decline and that was looked upon by some as vindication of the decision to relax many of the Covid-19 restrictions. While it is true that the number of new cases per day has continued to decline, down to 25,760 (SDMA) on August 3rd, 15 days after the peak. Now, however, that decline has stopped and has reversed. Daily new cases have now climbed to 26,615 (August 7th). Since Johnson’s ‘Freedom Day’, when daily deaths were at 42 per day, they have climbed to 90 per day (August 7th)1. The turnaround in the infection rate does not augur well, especially when you consider that a place like Iceland, which has 75% of its entire population fully vaccinated (the UK is 57%)5, is now having a wave of Delta variant infection, which is higher than the rate of infection in their first two waves in March 2020 and October 20206.




  • Russell says:

    According to the above general lag time we await a rise in the number of deaths from Delta in NSW within two weeks. this is a tragedy, one that might well have been avoided had the danger of even one person carrying the virus been very clear to Gladys “the golden girl”. She wasn’t keen on a lockdown in the Dan Andrews mode, being of different ideological bent. And so critical days were lost; over a week passed blithely until it became clear to all that a new surge was now moving at a great rate around Sydney’s south western LGAs.
    Was she dumb, was she playing politics or what? For mine, Berejiklian should be made to pay a high price at the next state election, because her inaction has made likely that over 100 people will eventually pay the ultimate price – life. Lest we forget this unforgiveable error by the NSW Liberal-Nationals !

    • admin says:

      As I said in another rant, the Liberals find it almost impossible to admit that anyone even vaguely associated with another political party could be correct about something. To learn from Dan Andrews would have been unconscionable. The only problem for the Liberals is that Dan was right in going hard and fast and, now that the vacuous Morrison has realised it, he is busily pedalling his tricycle away from Gladys, and saying it is her problem and is nothing to do with him.

      • Jon says:

        > Morrison …. is busily pedalling his tricycle away from Gladys, and saying it is her problem and is nothing to do with him.

        Now where have we see that behaviour from Captain Buckpasser before I wonder? The fires? Bridget McKenzie’s sports rorts handouts? The massive fail on Auspost Watchgate? The sexual mistreatment of women and Parliament House standards under his stewardship? Or Tudge’s car parks rorts maybe?

        Let’s face it, Morrison is constantly pedalling away from anyone linked to anything vaguely controversial. Along with total denial of responsibility for anything dodgy or unsuccessful, it’s one of his many go-to ploys. Oddly enough (maybe not) he still hasn’t been taken to task for this spineless “leadership” style by the compliant (pathetic) Press Gallery .

        Morrison’s standards are so low that not only will he not take responsibility for what his Ministers do, he won’t make them accountable for their actions under the much vaunted but little observed “Westminister system of Ministerial accountability”. Robodebt and ~678 Aged Care deaths are just two of the more egregious examples off the top of my head. His latest embarrassing attempt to deflect blame shows his cavalier attitude to both corruption and accountability and shines a stark light on his Pentecostal hypocrisy. “Not my fault. Nothing to see here. Blah blah blah.” If Labor can’t do something with that they don’t deserve to be in power and their strategists need to be shown the door quick smart.

        Loved this one liner from a CT letter to the Ed: “Pentecostal PM blasts ‘crazy’ virus conspiracies.” Some much said in so few words.

        • admin says:

          Yep. It is in his makeup. If you never accept responsibility, you can expect no blame. It is the only way such a vacant, narcissistic incompetent can convince himself that he is competent. I think the media are starting to catch on and I fully expect him to be given the arse before the election, as some of the Liberal head wankers are pushing Frydenberg.

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