Lift­ing lock­down: it's com­plex

Grocott's Mail - - Covid-19 -

Epi­demi­ol­o­gist Tom Moul­trie talks to Steven Lang about lock­down reg­u­la­tions and sta­tis­tics.

Pro­fes­sor of De­mog­ra­phy at the Univer­sity of Cape Town, Tom Moul­trie, be­lieves it is not ir­ra­tional to re­lax lock­down reg­u­la­tions just as the coun­try ex­pe­ri­ences a sharp in­crease in the num­ber of Covid-19 in­fec­tions and deaths.

He ex­plains that the main pur­pose of the lock­down was to buy time for the coun­try and not to re­strict the spread of the virus. There was never any re­al­is­tic prospect of sti­fling the pan­demic in South Africa as has been done in some small is­land states; how­ever, it al­lowed the na­tional and pro­vin­cial de­part­ments of health to set in place mech­a­nisms, pro­cure equip­ment and to ready them­selves for what is go­ing to come next.

Moul­trie ar­gues that the gov­ern­ment has done its best to limit the neg­a­tive con­se­quences of the pan­demic. The ini­tial im­ple­men­ta­tion of the lock­down was largely suc­cess­ful.

“The tra­jec­tory of the curve has been shifted, but that’s the point – de­lay the ef­fects of the out­break, rather than hugely at­ten­u­at­ing it,” Moul­trie said.

The rate of in­fec­tion has un­folded in dif­fer­ent ways in our nine prov­inces just it has var­ied in other coun­tries. The West­ern Cape was the first prov­ince where the virus spread rapidly, but now it ap­pears that the East­ern Cape and Gaut­eng are on sim­i­lar cour­ses.

There is still a lot of un­cer­tainty about whether the West­ern Cape is go­ing to peak any­time soon or what the na­ture of the peak is go­ing to be.

One ar­gu­ment sug­gests that in­stead of it be­com­ing a peak it will grow and then plateau out so that it be­comes quasi en­demic for some time.

Moul­trie said we bought time at a huge cost to the econ­omy, not­ing that the un­em­ploy­ment fig­ures re­leased this week are the high­est ever. How­ever, if we had al­lowed the pan­demic to run its course, our econ­omy could have been in a far worse sit­u­a­tion than we are now.

Cur­rent epi­demi­o­log­i­cal mod­els pre­dict that 42 000 peo­ple will die of Coro­n­avirus in South

Africa, and since the cur­rent num­ber of deaths is just over 2 200, it means that the worst is still to come. This fig­ure is from a model based on over­seas ex­pe­ri­ences where 700 peo­ple per mil­lion die. It should be men­tioned that in some states in Amer­ica, the death rate has al­ready ex­ceeded this fig­ure.

Com­ment­ing on the ac­cu­racy and use­ful­ness of data on the pan­demic pub­lished by gov­ern­ment, Moul­trie said the fig­ures be­ing re­leased to the public only re­flect cases that have been re­ported on a par­tic­u­lar day. In some cases, peo­ple could have died sev­eral days pre­vi­ously but the death was only re­ported in the past 24 hours.

When peo­ple die in med­i­cal fa­cil­i­ties they are re­ported to the pro­vin­cial au­thor­i­ties, but in many cases peo­ple suc­cumb to the virus at home with­out ever hav­ing been prop­erly di­ag­nosed as a vic­tim of Covid-19.

Other fac­tors, such as last

week’s public hol­i­day can also af­fect the “lumpi­ness to the data”. Over­all, though, the sta­tis­tics rep­re­sent a rea­son­ably ac­cu­rate pic­ture of the sit­u­a­tion.

The sta­tis­tics are a func­tion of the test­ing strat­egy em­ployed. Health­care pro­fes­sion­als want test­ing to be car­ried out in such a way as to find those in­fected as soon as pos­si­ble – hence the screen­ing process widely used in the coun­try. The sooner in­fected pa­tients are iden­ti­fied, the sooner they can be treated.

Epi­demi­ol­o­gists, on the other hand, look to em­ploy a strat­egy that would be sta­tis­ti­cally rep­re­sen­ta­tive of the en­tire pop­u­la­tion to en­sure the ac­cu­racy of their mod­els. Moul­trie em­pha­sised how dif­fi­cult it is to build ac­cu­rate mod­els, “The story here is one of com­plex­ity. That we are deal­ing with a ma­jor health emer­gency, and a health emer­gency left unchecked would any­way have cre­ated an eco­nomic emer­gency.”

He stressed the words of Pres­i­dent Cyril Ramaphosa who said that “This is now in our hands. It’s up to us.” We should be vig­i­lant in avoid­ing in­fec­tions.

The re­lax­ation of reg­u­la­tions does not mean that you have to do what­ever is al­lowed. Moul­trie ad­vises be­ing pru­dent as you choose where to go and what to do.

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