The Elusive Seasonality of SARS-CoV-2: Why Experts Are Divided on its Transmission Pattern

The Covid-19 pandemic has not yet followed a predictable seasonal pattern, unlike other respiratory pathogens such as influenza and RSV, according to scientists tracking the virus. While many respiratory illnesses tend to peak during specific seasons, such as winter or fall, SARS-CoV-2 has not exhibited a clear pattern of seasonality. Experts have differing opinions on when the virus may settle into a seasonal pattern, with some believing it could happen soon and others unsure. The lack of seasonality has practical implications for healthcare planning, as anticipating surges and administering booster shots rely on understanding the virus’s transmission patterns. Some experts have suggested that the periodic swells of transmission could be due to waning immunity in the population. However, others argue that swells in Covid cases at different times of the year do not necessarily indicate seasonality. The emergence of new variants, like Beta, Delta, and Omicron, has also influenced the patterns of Covid transmission. The factors determining the seasonality of respiratory pathogens, such as human activities and environmental conditions, are complex and not fully understood. However, studies have shown that climate variables, such as temperature and humidity, can impact pathogen survival and transmission in the population. As the world continues to navigate the pandemic, scientists and health authorities will closely monitor the virus’s transmission patterns and adjust public health measures accordingly.