Comparative Epidemiologic Analysis of COVID-19 Patients in the First and Second Waves, Uganda, 2020–2021
Background: The first COVID-19 wave in Uganda occurred during late 2020, caused by Alpha and Eta variants of SARS-CoV-2. In March 2021, the country began offering Astra-Zeneca COVID-19 vaccine, and in late April 2021, Uganda entered a second wave caused by the SARS-CoV-2 Delta variant. Social media rumours at the time were widespread about Delta variant causing hospitalization in younger persons and deaths among fully vaccinated persons. To investigate, we compared epidemiologic characteristics of hospitalized (HP) and non-hospitalized (NHP) COVID-19 patients in the 2 major COVID-19 waves in Uganda.
Methods: We defined ‘wave 1’ as November–December 2020, and ‘wave 2’ as April–June 2021. At each of the 2 major hospitals in Kampala, we randomly selected 100 HP in wave 1 and 100 in wave 2. We retrieved contact information for randomly-selected, PCR-confirmed NHP (200 for each wave) from laboratory records and interviewed them by phone. Demographic, clinical, and self-reported vaccination data were collected from patients, medical records, and/or next-of-kin.
Results: A higher proportion of HP in wave 2 than wave 1 were female (46% vs. 27%, p=0.0001). More wave 2 than wave 1 had severe disease or died (65% vs. 31%, p<0.0001). HP were non-significantly older in wave 2 than wave 1 (47 years vs. 42 years, p=0.31), and the median age of HP was significantly older than NHP in wave 2 (47 years vs. 27 years, p<0.0001) but not wave 1 (42 years vs. 35 years, p=0.15). No wave 2 patients were fully vaccinated.
Conclusions: Demographic and epidemiologic characteristics of COVID-19 patients differed between COVID-19 waves in Uganda. However, hospitalized patients were not younger in wave 2 than wave 1, and no patients were fully vaccinated. Results were immediately communicated to the public through the Ministry of Health. Different variants of COVID-19 should be studied independently and results used for public risk communication.