Asymptomatic SARS-CoV-2 Infection in Havana, Cuba, March-June 2020: Epidemiological Implications

Area of Science:

• Epidemiology
• Infectious Diseases
• Public Health

Background:

• Asymptomatic COVID-19 cases represent a significant portion globally (18-50%) and in Cuba (53%), particularly Havana (58%) in 2020.
• Understanding the transmission dynamics of asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections is crucial for effective disease control.

Purpose of the Study:

• To investigate the epidemiological implications of asymptomatic SARS-CoV-2 infection during Havana's 2020 COVID-19 epidemic.
• To analyze transmission patterns associated with asymptomatic versus symptomatic cases.

Main Methods:

• A cross-sectional study analyzed 1287 confirmed COVID-19 cases in Havana from March to June 2020.
• Data included demographics, case type, and source of infection, with cases categorized as asymptomatic or symptomatic.
• Transmission was assessed using a contact matrix and analysis of secondary case generation.

Main Results:

• Asymptomatic cases constituted 57.7% of infections, more prevalent in younger age groups and autochthonous transmissions.
• Symptomatic cases were more common in older adults and imported/introduced infections.
• While most primary cases (78.5%) didn't generate secondary cases, symptomatic individuals were more likely to transmit the virus (63.2%) compared to asymptomatic ones (14.4%), excluding superspreader events.

Conclusions:

• Asymptomatic SARS-CoV-2 infection was prevalent in Havana but had a lower transmission capacity than symptomatic infections.
• Superspreader events, though infrequent, were critical drivers of epidemic spread under specific circumstances.