How Lagos backlogs led to highest daily COVID-19 cases

Nigeria hit a record-shattering daily count of 4,035 cases of COVID-19 on December 22, 2021, an 847 percent increase that many by error attributed to the rise of the fast-spreading omicron variant.

The rare surge was fuelled by backlogs aggregated largely from Lagos in previous days and others from Akwa-Ibom, the National Centre for Disease Control (NCDC) has said.

Adetifa Ifedayo, NCDC director-general, in an exclusive interview with BusinessDay, said over 2,000 of those cases accrued from unreported cases in Lagos between December 13 and 19. Complementing it were backlogs from Akwa-Ibom between December 20 and 21.

The centre collates COVID-19 cases based on reports from states across the country daily, and cases reported daily are often an aggregate of positive results of PCR and rapid diagnostic tests done the previous day.

But sometimes and maybe slightly more frequently, some states report backlogs of cases that failed to come in before NCDC’s typical reporting.

“Lagos contributed most of those backlogs. As you know, Lagos literally had the most cases and they had a bit of struggle to keep up with the numbers and recording,” Ifedayo said, saying, “We don’t have 100 percent of states reporting every day. When that happens, the backlog can get added to whatever we finally report.”

Daily case counts and their waves have been one of the most observed indicators during the outbreak and have been a reliable early warning sign of severe disease and death in previous coronavirus waves.

The record-shattering surge of December 22 shifted worries over undercounting of COVID-19 cases to the question of whether the NCDC data now reflect the true scale of coronavirus incidence.

Although reported cases are basically laboratory results of some tests and not an encompassing count of the cases in the country, it still leaves a view of the state of things.

For instance, BusinessDay analysis shows that despite the rise and fall of infections, there are no wide margins in the rate of testing in months that recorded the lowest confirmed cases and months when waves peaked.

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Between March 29 and May 2 last year, nearly 188,000 tests were done and 5,160 cases were confirmed. This was one of the periods of a steep decline in infections.

Out of 236,709 tests done last November, just 2,131 cases were confirmed.

During the peak of infection last December, there were 19,981 cases confirmed from 136,456 tests, based on the epidemiology reports released for three weeks.

The data indicate that while Nigeria’s testing lags rates in some African countries, the positivity rate is still largely driven by COVID-19 variants and their capacity to spread.

“The way we test has been fairly consistent and the patterns can be assumed to be reliable. They have been reliable enough for us to pick up when cases start to go up and when cases start to go down. Do they reflect the entire universe of cases we have? No. Even in places that test more, considering that a lot of COVID-19 cases are asymptomatic, they have far more cases than any country is able to actually report,” the director-general said.

Omicron began to dominate cases in the country from mid-November, overtaking Delta as the most common variant identified from genetic sequences, according to the NCDC.

By December, Nigeria had triggered a full-blown fourth wave of COVID-19 wave, which saw the NCDC pushing a campaign for responsible yuletide celebration.

Interestingly, the wave is declining as quickly as it surged with less than 700 cases recorded daily since the start of 2022.

There are now indications that case counts might begin to lose their relevance as experts observing the disease say more attention should shift to the rate of hospital admissions than the rate of infections, which might leave little or no symptoms.

Last month, 12,547 COVID-19 patients were hospitalized as some states reopened their isolation centres on the rising fourth wave.

It was similar in 2020 with 12,126 active cases being monitored.

Instead, Wafaa El-Sadr, director of ICAP, a global health centre at Columbia University, said at this stage of the pandemic, the focus should be “shifting on preventing illness, disability and death, and therefore counting those,” in a report.

With tests still largely privatised and profit-oriented, Nigeria might keep working with a partial view of the disease, which in any case has not been as brutal as seen in the US, for instance.