Critical steps to eliminate covid19

KENWYN NICHOLLS

ON OCTOBER 24, the Prime Minister eased lockdown restrictions allowing gyms to be reopened at 50 per cent capacity and beaches and pools from 6 am to 6 pm; churches and other places of worship to restart services but not to exceed one hour; public servants to return to their respective offices full-time. Bars and restaurants were to remain open but only for take-away services.

According to the TT coronavirus dashboard, a daily media update by the Ministry of Health, the ensuing three weeks ending November 14 showed gratifying improvements in several monitored categories: active cases fell from 1,380 on October 24 to 592 on November 14.

When a cluster which came to light at the maximum security prison in Golden Grove in the first two weeks of November is omitted, newly confirmed cases which had averaged 32 a day for the week ending October 24 fell to 27, 22 and 24 for the three weeks that followed, and average weekly inpatient caseloads decreased from 76 to 61, 49 and 34 for the identical period.

Most importantly, deaths per week attributed to the virus fell from nine for the week ending October 24 to three, three and zero for the ensuing three weeks ending November 14.

Despite the obvious improvements, the ministry’s chief epidemiologist continued to express weariness with the slow downward movement of the statistical data which he termed as “plateauing.” His concern is well placed given the pronouncement by Finance Minister Colm Imbert that success with the radical initiatives outlined in his national budget rested squarely on the country’s ability to eliminate the covid19 bug.

Elimination (of infectious disease) is defined as “reduction to zero of the incidence of a specified disease in a defined geographical area as a result of deliberative efforts; continued measures to prevent re-establishment of transmission are required.” In epidemiological terms it means bringing active cases down to zero or near zero in a geographical location, and continued vigilance via testing. For interested readers, a study of the New Zealand experience in eliminating the virus is highly recommended.

It is my opinion that plateauing will persist and TT will not attain the desired goal of zero active cases in the absence of radical changes in the country’s test, trace and isolate programme. Testing for covid19 is the initial step for identifying and isolating infected individuals to reduce spread. Equally important is contact tracing to identify exposed people, ie, people who may have had direct or primary contact with the index case as well as secondary and possibly tertiary contacts, ie, people who may have had contact with the primary contact. The TT dashboard reveals little action re contact tracing: the positivity rates are simply too high.

Positivity rates answer the question: what percentage of tests conducted are positive for covid19? For the week following easing of restraints, October 25-31, the number of tests performed was 901 or 128 a day; November 1-7: 842 or 120 a day; and November 8-14: 776 or 111 a day. Since, as stated above for this period, newly confirmed cases averaged 27, 22 and 24 a day, the calculated positivity rates for this period are 21 per cent, 18 per cent and 22 per cent, a virtual quadrupling of the internationally accepted benchmark of five per cent.

According to experts on global health and infectious diseases at the Johns Hopkins University in the US, such persistently elevated positivity rates suggest that a community may be testing the sickest patients and possibly missing the milder or asymptomatic patients, a dangerous development. Multiple global studies have shown that for any outbreak 20-45 per cent of infected people may be asymptomatic and thus escape isolation, and, more critically, become super-spreaders in an unsuspecting population.

The ministry at this point should have completed training of people and deployed rapid antigen test kits. In terms of fighting the pandemic, the kits should now be the frontline tool in controlling and ultimately eliminating the wily virus.

According to the US Centers for Disease Control and Prevention, people should be tested “if they have been in close contact, such as within six feet, of a person with documented SARS-CoV-2 infection for at least 15 minutes, even if they do not have symptoms.” It should be noted that exposure begins 24-48 hours before symptoms become manifest.

Test results are available in 15 minutes, ie, before people tested are allowed to leave the facility, a fact that makes contact tracing and isolating more efficient and effective, and minimises the leakage of asymptomatic but contagious people into the community.

Any question about sensitivity of the Standard Q and Standard F test kits (purchased by the ministry through WHO) can be resolved by simply repeating the test in five-seven days on people who tested negative but are clinically suspected of harbouring the virus. Needless to say such people should be isolated until retested. These kits are available on the open market at around US$5 each, and is a worthwhile investment given the stakes involved as discussed above.