Zimbabwe’s daily Covid-19 infection rate falls

By weekend the average daily infection rate for Covid-19 had fallen to around half the level of the start of the year and had dropped to actual numbers not seen since the middle of December.

On January 1 the seven-day running average had reached 172, with 217 new cases on that day as the accelerating second wave started its grip. The running average rose to a peak of 956 on 14 January and then started falling, reaching 88 by Saturday with that day’s actual total being 59, the fourth consecutive daily total in double figures.

The Saturday average was just nine percent of the peak average.

The seven-day running average gives the trend, since the actual daily figures, with their spikes and dips, are affected by many factors that make trends difficult to see, such as results for two or three days of testing in one centre being released simultaneously, or the test results of major cluster coming into the statistics, or a day when few people came forward for testing.

The raising of the national lockdown from level two to level four soon after New Year’s Day, followed by a two-week extension at the end of last month, appears to have been critical in taming and then beating back the second wave.

The swift Government action as the second wave became apparent was coupled with far greater compliance of personal precautions, such as masking and social distancing, by most Zimbabweans did tame the second wave fairly quickly.

As the accompanying graph shows, when the running average is taken there was a sharp rise in the average number of daily new infections in the first two weeks of January from 217 on New Year’s Day, with the running average at 172, to an average of 956 as families, colleagues and friends of those infected near the beginning of the second wave were infected in turn.

Then there was a steady decline, now slowing a bit but with the average still falling, for the next four and a bit weeks. The rate of decline was the principle factor in the Government’s decision to extend the original 30-day level four lockdown for another two weeks as at the end of the fourth week the infection rate, while down significantly, was still higher than it had been at the start of the year.

The recovery rate and number of active cases roughly follow the pattern of the infection rate. As the number of daily new infections falls, the number of active cases started falling a day or two later.

Active cases diminish as more people get better each day than fall sick each day. The number of active cases on Saturday 3 617, higher than the 2 368 on New Year’s Day, but this is due to the fact that it can take up to two weeks for a sick person to be declared free of infection.  But it was still far below the peak of 10 326 on 16 January.

Most importantly, of the just over 21 000 people who tested positive in the first 44 days of the year, just over 80 percent were better and fully recovered by Saturday with the active case total still reflecting the people infected during the last couple of weeks of the waning wave.  The recovery rate tells us two things.

First, moving in the opposite direction from the changes in active cases the recovery rate falls when more people fall sick each day than get better and rises when more people get better each day than fall sick.  But it also gives an indication of just how bad the second wave was.

The very steep fall, to 56,3 percent on 13 January, meant that 43,7 percent of all Zimbabweans who had been infected since the first case in March were still sick, and so the second wave was very bad. If the number of people infected each day had remained the same throughout the first nine and a bit months of the pandemic in Zimbabwe we would expect the recovery rate to steadily climb into the high 90s as a percentage and be varying by tiny fractions of a percent each week. That huge dip meant a serious wave.

The strong climb of the rate out of the big dip, to 85,7 percent by Saturday simply reflects what the raw data has already told us, that around 80 percent of those who fell sick so far in the second wave are now better, with the last 5 percent recording the recovery of everyone who fell sick before the second wave. Again that comparison tells us a lot of just how bad the second wave actually was.

The death rate tends to lag about 10 days behind the infection rate, simply because people take some time, on average, to reach the most severe stage of symptoms if they are in the group who are hit by severe complications.

So the death rate, again using seven-day running averages, hit its peak on 25 January with an average of 43 daily deaths over the previous week, before mirroring the steady fall already seen in infection rates 10-days earlier.

It had fallen to an average of 12 deaths by Saturday, although that day, reflecting the continual decline, was just 5 deaths, the first time we had seen single figures since 4 January.

Again there are spikes and dips in the daily total graph from the bunching of test results and other factors, but the running seven-day average evens these out and gives the trend.

The second wave showed how easy it was for infection rates to suddenly zoom when many Zimbabweans dropped their guard, as became common in the last few weeks of last year.

This was stressed by President Mnangagwa on Thursday when he made it crystal clear that until the large majority of Zimbabweans were vaccinated, so creating the necessary pool of immune people and the required fire breaks, we all had to maintain the maximum personal precautions. The dramatic fall in infection rates was not a sign that the pandemic was over, just that control measures were working.

While the case for reducing the level of the lockdown now exists, the fact that life cannot return to normal means that the lockdown has to remain even if at a lower level. That means that personal precautions, such as masking, high levels of personal hygiene and social distancing have to be followed and, where necessary, enforced.

In countries where high levels of control have minimised the impact of Covid-19, Governments have tended to use any leeway in infection rates to open the economy while clamping down hard on social activities that produce crowds on the basis that it is more important for people to earn a living rather than go to parties or watch soccer. Bulawayo24

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