Covid-19 second wave in Nigeria: What does the data say?

On November 20, 2020, Chikwe Ihekweazu, director-general, Nigeria Centre for Disease Control (NCDC), met with senior journalists in Lagos to brief them about the progress of the work the agency had done since the emergence of Covid-19 in Nigeria.

Though unmentioned, there was a sense of congratulations in the room. Everyone was delighted that the doomsday predictions about death and hospitalisations had not happened in Nigeria.

When asked why Nigeria’s experience was different from that witnessed in Europe and the Americas, the NCDC DG answered that he did not know, but added that the measures put in place in the early phases of the pandemic in Nigeria helped.

However, a few weeks after the meeting, the pattern and the scale of the infections changed dramatically. After recording the lowest number of confirmed infections on October 23, 2020, the numbers are rising. In November 2020, the daily average confirmed cases was 156, but just a few weeks later in the middle of December, it was 796.

This time is different

There is no mistaking that Nigeria is currently experiencing the second wave of the Covid-19 pandemic. While the reason for the second wave remains unclear, what can be observed is a rising number of sick individuals, mounting towards a defined peak in infections, and then a decline. The peak of the first wave was reached on July 1, 2020, with 790 confirmed cases and the lowest was on October 23, with 37. This resulted in a span between the trough on February 27, when the first case was recorded, and the peak on October 23, when the country recorded the lowest number of cases in 2020, before another rise.

October 24, 2020, could then be considered the starting point of the second wave. On that day the number of confirmed cases was 48. Though we’re still in the early stages of a second increase in the number of cases, both the data on infections and its consequences suggest a frustratingly long second wave. It is already clear that compared to the first wave, the rate of confirmed infections is faster and higher.

In the first wave, the 4,323 confirmed infections that occurred in week 14 (15th June-22nd June) was highest. The 2020 peak has been doubled in the first week of 2021 with 9,898 confirmed cases just a few weeks into what is considered the start of the second wave.

The growth pattern of infections in the first wave was unparalleled (the last pandemic of such scale was over 100 years ago). If the first wave numbers NCDC announced at what became a nightly national ritual moved at an oscillating rate, which means the second wave moved at an unsuspecting pace. Its steps were slow and steady as against sharp consistent increase with few declines before the first wave peaked. This fed into an illusion by the time the second wave arrived.

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For instance, on March 18, 2020, the daily confirmed cases grew by 400%, the first major increase and three-digit rate of growth since the first confirmed case. Whereas, the second wave maintained a two-digit growth rate at the start with the exception of a 74% decline on November 7. The first three-digit growth rate of 408% increase did not arrive until November 8, 2020. The second wave was revealed after the 277% spike in the daily confirmed cases on December 15, when 758 cases were confirmed.

Is the second wave predictable?

Can we predict the pattern of the second wave, given what we know about the first wave? The simple answer is no. In terms of the daily pattern of the first and second wave, so far, the growth patterns are different. What we know about the first wave are: the index case was recorded on February 27; a triple-digit was recorded 21 days later on March 18. The numbers swung from 97 recorded cases on March 28, nearly doubling to 174 cases on April 1, before it peaked at 174 cases on July 1, with 790 confirmed cases.

If we are to follow the 11% average trend of the first wave, it means that Nigeria will record an average of 4,704 daily cases till February 8, 2021, to reach the peak, with total confirmed cases totalling close to 244,000. Since the daily growth rate followed in the second wave is already different from that of the first wave, let us employ another method – the moving averages.

Seven-day Moving averages

The seven-day moving average helps smoothen out daily ups-and-downs to show a clearer picture of what is happening in case trends. It is especially important in the Nigerian case because the case reporting can go down over weekends, which can give a false sense of decline before the numbers seem to jump on Monday and Tuesday, as staff catch up on entering results that may have come in over the weekend. First, we plot the seven-day moving averages for the first wave (see: graph 2).

Smoothening the seasonal trend

In the first wave, the moving average followed an inverted U-shape pattern that rose slowly to the peak with a continuous decline until it ended. However, the seven-day moving average in the second wave follows a zig-zag pattern as the number of cases in the last month of 2020 increased faster, specifically from December 13, 2002, to January 1, 2021.

A seasonal trend forecast of COVID-19 cases confirmed daily in Nigeria predicts a value based on existing ones. The forecast spans from January 10 to July 28, 2021. It relies on the existing historical data of the daily confirmed cases and the number of deaths in Nigeria from the first case in February 2020 till January 8, 2021. This method of forecasting is adopted in order to help with overall smoothing, trend smoothing and the seasonal smoothing.

Our forecast reveals that the peak of the second wave is at least six months away. Though we expect fluctuation in the daily confirmed number of cases, the data is clearly trending upwards, both from the evidence of the seven-day moving average and the seasonal forecast.

The expectation is that by the end of January 2021, the total confirmed cases will hit 134,982, with a total casualty of 1,459. Specifically, we expect that the total number of deaths in January should be around 172 and it is expected to rise to 185 in February. By the end of July, the total confirmed cases of COVID-19 in Nigeria are expected to rise to 482,669 with 2,553 casualties in total should this trend continue.

What are the options before the government?

There are at least two important considerations. The first is the understanding of the source of the new infections. Chikwe Ihekweazu recently said the spike in infections was due to a convergence of circumstances, including increases in local and international travels, and business and religious congregations with minimal compliance with Covid-19 safety protocols. The second is the vaccine game plan of the government.

Both considerations will also be based on the fact that Lagos remains the epicentre of the infections, accounting for 35% of all infections. The data show confirmed cases are more prevalent among men, with 6 out of 10 of all infections, and the consequence of travels since they were eased in July 2020. Whereas, the lowest daily confirmed cases among international arrivals was in the second week of October (12-18, 2020), it increased to 270 on December 14, 2020.

Though the second wave appears more threatening, it is not yet out of control. And the government is wary of the kind of response that led to the most devastating impact on the economy in the second and third quarters of 2020, when it recorded a decline in GDP of 6.1% and 3.6%, respectively.

During the first wave, the government implemented three different phases of reopening after the lockdown started March 30, 2020. The first phase of reopening from May 4 to May 30 allowed markets and banks to open three times a week, so people could restock food and essential supplies, but imposed curfews between 8pm and 6am.

The second phase of reopening from June 1 to June 30 allowed banks and government offices to open for longer periods and imposed a narrow curfew between 10pm to 4am, while the ban on interstate remained except for agriculture produce, petroleum products, manufactured goods and essential services.

All airports also remained closed to domestic and international flights. The third phase allowed schools to reopen for graduating students and interstate movements were also opened, while flights, initially between Lagos and Abuja, opened July 8.

Two things motivated the Federal Government to phase the reopening. The first was the acknowledgement that the lockdown hurts the economy, especially sectors classified as non-essential that depend on a daily income for survival. The second was that early data on infections showed that only between 5 and 15% of cases required intensive care, according to the commissioner for health in Lagos State, when he spoke during BusinessDay’s National Conversation in June 2020.

These are the underlying data we believe will determine the government’s approach this time. The intensity of warnings about the dangers of Covid-19 by both the NCDC and Babajide Sanwo-Olu, the governor of Lagos State, has increased since the start of the year.

The expectation is that they will continue to monitor if those that require intensive care rise beyond the 5 to 15% observed in the first wave before another lockdown. Notwithstanding this data on Covid-19 infections in Nigeria, the actual cases of infections are not known, nor the actual death rates, especially given the secrecy and attitude of many Nigerians to the virus testing and contact tracing management, and uncoordinated hospitalisations.

Working on these measures will improve considerably Nigeria’s response to the recent spike, as a complete lockdown and total restriction of movement are out of consideration.