The Spread of COVID-19:How Humidity, Latitude, and Temperature Affect the Spread

One of the most challenging aspects of the coronavirus pandemic is the lack of answers about the disease’s spread and seasonality. The questions continue to mount as researchers, scientists, and medical professionals beg questions like, “is severe acute respiratory syndrome coronavirus 2 associated with seasonality?” and “can the spread of this disease be estimated?”

Answering these questions is vital. Coronavirus disease 2019 (COVID-19) has become a global crisis with nearly 13 million confirmed cases and close to 500,000 total deaths globally. Understanding and investigating the potential associations of factors like climate and seasonality.

This study, published in the JAMA Network in 2020, addresses those questions by answering a cohort study of 50 cities with and without the coronavirus disease 2019, areas with substantial community transmissions of COVID-19, and specific areas with similar weather patterns with mean temperatures between 5-11 degrees C.

With hopes to examine the association of climate, seasonality, and spread, this study examined whether or not a particular type of climate or seasonality could slow the spread of the coronavirus disease 2019.

The Study: What Happened

The study investigated 50 different cities to view their climate data—it looked at cities both with and without substantial community spread of COVID-19. In essence, 8 cities—Wuhan, China; Tokyo, Japan; Qom, Iran; Paris, France; Daegu, South Korea; Seattle, US; and Madrid, Spain—were compared in relation to 42 other cities that had not been affected or did not show signs of substantial community spread.

Data were collected from early January to early March 2020. Communities were defined as having substantial community transmission when a country had at least 10 reported deaths at the time of March 2020.

The 8 cities with substantial community spread (as reported as of March 10, 2020) were located roughly on the 30 – 50 degrees north corridor. They all had similar weather patterns with average temps ranging from 5-11 degrees Celsius. They all had low specific and low absolute humidity. They all had similar weather patterns, too.

There was a substantial lack of community establishment in expected locations based on proximity, though. For example, Wuhan China reported 3,136 deaths and 80757 (at 30.8 degrees N), Moscow, Russia had 0 deaths and 10 cases (at 56.0 degrees N), and Hanoi, Vietnam had 0 deaths and 31 cases (at 21.2 degrees N).

The Results: What the Study Shows 

Generally speaking, the study showed that the distribution of substantial community outbreaks of COVID-19 along restricted latitude, temperature, and humidity measurements was consistent with the behavior of a seasonal respiratory virus.

The study shows that it could be possible—though it is not conclusive—to estimate the regions that will be at a higher risk of substantial community spread of COVID-19 in the upcoming weeks through weather modeling. This effort could help to focus on the concentration of public health efforts on containment.