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Case incidence, hospital admissions, and in-hospital mortality all increased during the second wave of COVID-19 in South Africa, when the Beta variant (B.1.351) was predominant, researchers found in a prospective cohort study.

Cases were up dramatically in the second wave compared to the first wave (240.4 per 100,000 people vs 136 per 100,000, respectively), as were hospital admissions (27.9 per 100,000 vs 16.1 per 100,000) and deaths (8.3 per 100,000 vs 3.6 per 100,000), reported Waasila Jassat, MD, from the National Institute for Communicable Diseases in Johannesburg, South Africa and colleagues.

Moreover, a multivariable analysis of the second wave showed a 31% increased risk of in-hospital death (adjusted OR 1.31, 95% CI 1.28-1.35), the authors wrote in .

"We found increased mortality in the second wave, partly explained by more admissions in older individuals and in the public sector, and by higher volumes of hospital admissions," Jassat and colleagues stated.

Higher mortality was especially prevalent in weeks when hospital capacity was stretched, she told MedPage Today separately.

The higher hospitalizations and deaths due to the Alpha variant (B.1.1.7), but little has been known about the virulence of the newer Beta variant, first identified in South Africa in September 2020. Derived from mutations, the beta variant houses a few inside its receptor binding domain, shown to exert more strength in binding to the human cell receptor, ACE2, increasing transmission risk more than other variants, the authors said.

"Hospital overcrowding at the height of a COVID-19 surge is an important cause of increased mortality," Linda-Gail Bekker, PhD, and Ntobeko AB Ntusi, MD, both from the University of Cape Town in South Africa stated in an . "Therefore, a crucial public health measure is to find ways to mitigate overcrowding through rapid expansion of hospital facilities or through a so-called curve flattening strategy."

They added that South Africa has not yet had the same vaccine coverage as most of the rest of the world, largely due to vaccine supply, global vaccine availability, and vaccine nationalism.

During March 2020 to March 2021, researchers looked at patient admission data from 644 national hospitals to compare patient characteristics between the first COVID wave in July 2020 and the second wave in January 2021, when the Beta variant dominated the country.

Primary outcome was mortality risk factors, based on adjusted variables such as province, age, comorbidities, health sector, race, sex, and mode of admission. South African patients with laboratory-confirmed COVID-19 (RT-PCR or SARS-CoV-2 antigen test) were included, if they were admitted for at least one full day in a hospital.

Of 219,265 COVID-19 patients with an in-hospital outcome, 51,037 patients died with an in-hospital case-fatality risk of 23.28%. The peak of the first wave had a significantly lower case-fatality risk (21.80%, 95% CI 21.39-22.22) than the peak of the second wave (29.34%, 95% CI 28.95-29.74).

During the first wave, the average weekly hospital admission rate increased 20%, but increased 43% during the second wave (ratio of growth rate 1.19, 95% CI 1.18-1.20).

Compared to the first wave, risk factors for hospital admission in the second wave included being ages 40 to 64 (aOR 1.22, 95% CI 1.14-1.31), age 65 or older compared with age 40 and younger (aOR 1.38, 95% CI 1.25-1.52), being of mixed race compared to being white (aOR 1.21, 95% CI 1.06-1.38), admitted in the public sector (aOR 1.65, 95% CI 1.41-1.92), and high weekly hospital admissions (more than 8,000 admissions) versus low weekly admissions (less than 3,500 admissions) (aOR 2.31, 95% CI 1.81-2.95).

Risk of in-hospital fatality per case was 17.7% during low admission weeks, but rose to 26.9% during high admission weeks (aOR 1.24, 95% CI 1.17-1.32).

Jassat and co-authors stated that their study described the demographic shift from the first to the second wave of COVID-19 in South Africa, and "quantifies the impact of overwhelmed hospital capacity on in-hospital mortality."

"We would like to scale up national genomic surveillance to better monitor the emergence of variants, and we are working with partners on case control studies to determine more conclusively the severity of the Beta variant," Jassat told MedPage Today separately. "Many countries may experience the emergence of new variants, and studies like this may assist them to determine the change in characteristics of patients and severity of disease, in waves where variants predominate."

Limitations included the use of surveillance data sequenced for results, rather than individual-level data per patient on variant lineage. This resulted in missing race and comorbidity data being "filled in" or adjusted for in sequencing.

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