Summary of Positivity Trajectory, Testing, and Updated Weekly Cases for COVID-19 in Liberia

Up to Week ending: August 21, 2021

Jallah Kennedy, PhD, MPHConsultant Epidemiologist (Volunteer)

Epi-surveillance Pillar for the COVID-19 Response at the Ministry of Health/National Public Health Institute of Liberia

World Health Organization

Weekly Summary Key Messages for COVID-19 in Liberia (up to August 21, 2021)• First COVID-19 case reported on March 16, 2020. Timeline in response – 524 days; 75 weeks; and 17 months.• Total number of cases: 5,530. About 60% of all cases occurred from May-July 2021 with about 60% of cases concentrated

among travelers. Outgoing travelers constitute about 55% of all cases from May 1-August 21, 2021.• Total Deaths 225

• Crude Case Fatality Rate(Community and TU) – 4.1%

• Total Laboratory samples tested 120,748*• Weekly samples tested (Aug 15-21) 1,703• Weekly new cases (Aug 15-21) 26 (17 PCR and 9 RDT)• There was a decrease in the percentage change of cases by 7% for the week of August 15-21, 2021, compared with the

pervious week (Aug 8-14) from 28 to 26 new cases. • The weekly positivity based on PCR cases is 1.0%, a decrease of 69% from 24 to 17 cases. • It is recommended to consider measuring the concordance between RDT and PCR. This will provide additional information about

the sensitivity of the RDT to confirmatory PCR tests.• Testing rates had decreased by 258% over five(5) weeks from the peak of the cases in the third wave from 4,440 during the week

of June 27-July 3, 2021, to 1,241 for the current week of Aug 1-7, 2021. There was an increase (improvement) in testing from 1,241 to the 1,887 for the week of Aug 8-14. However, there was a reduction in testing during the week of Aug 15-21 to 1,703

• Cases (based on dates of sample collection) have decreased in the last 6-7 weeks from 859 (peak) during the week of June 20-26, 2021, to 26 during the current week (Aug 15-21)

• Based on the 14- and 28-day moving averages (see slides #5-6), it is probable that the 'third wave' of the COVID-19 infection isbeing controlled. Keeping these averages as good markers for the progress with values below 5% will signal sustained progresstoward bending of the epidemic curve in Liberia. It is, therefore, recommended that to reduce variability of relativity, the 14- and 28-day moving averages be considered as among the key indicators. Additionally, there should be sustained adherence to public health recommendations (wearing masks, hand washing, social distancing….), vaccination, testing, timely reporting of test results, cases investigation, contact tracing, and treatment

*The number is from the daily Situation Reports and may be different from those in the lab line list

Key Messages (Mar 10, 2020 – Aug 21, 2021) – Testing Rates per Population

Total Samples Tested in Liberia • Samples Tested 120,748 • % of the Population Tested 2.71%• Samples Tested per 10,000 Population 271• Samples Tested per 100,000 Population 2,707

• Only about 3% of the citizens/residents in Liberia have been tested for COVID-19 using PCR.

• About 60% of testing in the last 3-4 months are among travelers. There are even lower testing rates in other

counties except Montserrado County. Montserrado County accounts for about 80% of all testing.

• The proportion of voluntary testing thus far in August 2021 is increasing.

• The low testing rates in counties outside of Montserrado will make it difficult to determine the true

community transmissions. It is likely that those being tested in those counties outside of Montserrado may be

those that are high risk or have contacts with cases, thereby, leading to the high positivity rates.

Moving Averages - Key Messages for up to the Week of August 15-21, 2021

• Moving Averages (Cases)

7- Day = 2.4(Previous 7-Day was 3.4)

14-Day = 2.9(Previous week ending Aug 14 = 2.7)

28-Day = 2.4(Previous week ending Aug 14 = 3.3)

• Positivity Rates (%)- Moving Averages

7- Day = 1.0% (Previous 7-Day was 1.3%)

14-Day = 1.1% (Previous week ending Aug 14 = 1.3%)

28-Day = 1.1% (Previous week ending Aug 14 = 1.4%)

Contact Tracing

Expected contact tracing (assuming there is at

least 5 contacts to each COVID-19 infected case)

of all contacts of new cases is being done at

limited rates with an average in the last two

weeks (August 8-21, 2021) of about 24.7%

(Range = 15.6% – 46.7%) at an average ratio of

1.2 contacts to each case (range = 0.8-2.3)

Range = 0.8-2.3Average = 1.2SD= 0.5

PCR Laboratory Testing

[COVID-19 Cases, n= 3,378] Turnaround Time in Days from Sample Collection to Testing in Liberia. May 1- August 21, 2021Range: 0-41Median: 1SD: 3

Daily Situation Reports