Three claims about Covid-19 infection rates and the threshold for “totally” easing restrictions
Source: Kenya’s president Uhuru Kenyatta (August 2020)
One incorrect, one misleading and one correct
In national speeches in August and September, Kenyatta said the positivity rate for Covid-19 had fallen from 13% in June. But this rate was only reached in July.
The president was closer to the mark with his estimate of an 8% positivity rate in August.
Several experts told Africa Check that reaching a 5% Covid-19 positivity rate is not the only recommendation by the WHO to guide the reopening of an economy. Other factors must be considered.
Researched by Vincent Ng’ethe
As the country waits for more guidance from the presidency, we fact-checked three claims Kenyatta made in an August 2020 national speech, variations of which he repeated in his 28 September address.
Health experts have indicated that levels of the positivity rate countrywide have fallen from a high of 13% in June …
Kenyatta said that health experts had “indicated that levels of the positivity rate countrywide have fallen from a high of 13% in June to 8% in August” and described this as “very encouraging”.
In September the president repeated a slightly different version of this claim: “Yes, the COVID positivity rate has fallen from 13% in June, 7% in August and is now at 4.4% in September.”
“If you test 1,000 people and 100 people turn [out] positive, the positivity rate is 10%,” he said. (For a deeper discussion of this rate, see here.)
The best testing data available is the national surveillance data from all approved Covid-19 testing laboratories, Dr Abdhalah Ziraba, an epidemiologist at the African Population and Health Research Center in Nairobi, told Africa Check. Kenya’s health ministry releases this information in its daily briefings.
Slower improvement than president suggested
Ziraba told Africa Check that daily, weekly or monthly positivity rates could be reported, but “often, for practical reasons, weekly averages are preferred”.
“There is less noise in the data, and they are not too infrequent, while monthly averages are prone to loss of details of how things are changing,” he said.
Africa Check compiled this data using the health ministry’s daily reports, daily press releases and its social media updates. The data shows that the highest seven-day positivity rate for June 2020 was 8%, in the last week of the month, and not 13% as the president said.
We therefore rate the president’s claim as incorrect.
Weekly Covid-19 positivity rates June-August 2020
Week Total samples tested Positive tests Positivity rate
1-7 June 18,804 805 4%
8-14 June 17,996 827 5%
15-21 June 24,676 1,144 5%
22-28 June 25,184 1,332 5%
29 June-5 July 24,067 1,816 8%
6-12 July 26,480 2,219 8%
13-19 July 28,144 3,248 12%
20-26 July 32,528 4,182 13%
27 July-2 August 39,308 4,518 11%
3-9 August 38,004 4,383 12%
10-16 August 37,689 3,684 10%
17-23 August 30,567 2,244 7%
24-30 August 28,163 1,693 6%
SOURCE: KENYA MINISTRY OF HEALTH. FOR A GRAPH OF THIS DATA CLICK HERE.
… [positivity rates have fallen] to 8% in August.
For August 2020, the weekly positivity rates were 11%, 10%, 7% and 6%, according to the ministry’s daily report of 15 September. (Note: These are calculated as seven-day moving averages by the ministry. These are considered more reliable. The table above does not have a moving average. We have also rounded up the rates.)
The average of these weekly positivity values in August came to 8.5%. We therefore rate the president’s claim here as mostly correct.
… we have a chance to reach the 5% positivity rate recommended by the World Health Organization for a total reopening of our economy and country.
In April the World Health Organization released guidelines on controlling the Covid-19 pandemic. Subsequent communications from the global health agency have advised on schools, workplaces and mass gatherings.
The WHO said decisions to introduce, adapt or lift public health or social measures should be carefully assessed. Some of the considerations should include the ability to detect a resurgence and to manage extra patients in health facilities.
Less than 5% of samples testing positive for at least two weeks was only one of the indicators that could be used to decide if the epidemic was under control.
Dr Ziraba, epidemiologist at the African Population and Health Research Center, said that a 5% positivity rate was low enough to have “minimal transmission if people are interacting and going back to their normal routines, where the risk is manageable, the healthcare system can cope with whatever infections can come up, and we are unlikely to have a flare up”.
“The positivity rate is not a magic bullet for the control of Covid-19,” Dr Amoth, of Kenya’s health ministry, told Africa Check. Before a decision was made, a number of other factors were considered, he said.
This included the number of Covid-19 patients admitted to hospitals and the number of patients in critical care.
These included mortality and the ability of the health system to manage a surge, he said.
Few tests make positivity rate less meaningful
According to the WHO, the 5% positivity rate can only be interpreted if there is thorough testing, with one thousandth of the population tested every week. Kenya’s 2019 census put the country’s population at 47.6 million, so to comply with the WHO recommendation the country would need to test at least 47,600 people a week.
Amoth conceded Kenya could be doing more tests. “If you are doing very few tests, the positivity rate will not add much value to your interventions.”
He said “challenges in the global supply chain in getting reagents” was one of the reasons for the current level of testing in the country.
Falling cases might not necessarily indicate that the pandemic was being successfully managed, Ngere said.
Depending on who was being tested, a declining positivity rate backed by good contact tracing and testing was desirable, and a sign of a slower progression of the epidemic, he said.
“However, this may not be so if the persons being tested are considered low risk. Currently, Kenya tests groups considered to be high risk: truckers, travellers, symptomatic persons referred from hospitals across the country and contacts of cases. This would therefore mean that the true population positivity could be the same or lower”.
Yes, the WHO does recommend a 5% positivity rate as a threshold for easing public health restrictions due to the pandemic. But it is not the only measure that should be used.
We therefore rate the president’s claim as misleading.