A Nice Day for an Infection? Weather Conditions and Social Contact Patterns Relevant to Influenza Transmission

Abstract

Although there is no doubt that significant morbidity and mortality occur during annual influenza epidemics, the role of contextual circumstances, which catalyze seasonal influenza transmission, remains unclear. Weather conditions are believed to affect virus survival, efficiency of transmission and host immunity, but seasonality may also be driven by a tendency of people to congregate indoors during periods of bad weather. To test this hypothesis, we combined data from a social contact survey in Belgium with local weather data. In the absence of a previous in-depth weather impact analysis of social contact patterns, we explored the possibilities and identified pitfalls. We found general dominance of day-type (weekend, holiday, working day) over weather conditions, but nonetheless observed an increase in long duration contacts (1 hour) on regular workdays with low temperatures, almost no precipitation and low absolute humidity of the air. Interestingly, these conditions are often assumed to be beneficial for virus survival and transmission. Further research is needed to establish the impact of the weather on social contacts. We recommend that future studies sample over a broad spectrum of weather conditions and day types and include a sufficiently large proportion of holiday periods and weekends.

Changing social contact patterns under tropical weather conditions relevant for the spread of infectious diseases

“…We first used the methods of Willem et al [10] to estimate the model-free estimates of relative change in R 0 and the number of contacts between weekdays and weekends. The relative change in the number of contacts also takes into consideration the number of contacts and the diary weight for each participant.…”

“…These factors affect influenza transmission because they may prolong the virus's survival, impede the human immune system, or enhance contact intensity among people [8][9][10]. These factors affect influenza transmission because they may prolong the virus's survival, impede the human immune system, or enhance contact intensity among people [8][9][10].…”

“…A study conducted in Belgium [10], found that the number of contacts lasting longer than 1 h increased during weekdays, and when the temperature, precipitation, or absolute humidity of the air was low during the winter time. A study conducted in Belgium [10], found that the number of contacts lasting longer than 1 h increased during weekdays, and when the temperature, precipitation, or absolute humidity of the air was low during the winter time.…”

Humidity: A review and primer on atmospheric moisture and human health

“…For the United States, absolute humidity was identified as a critical determinant of 24 observed influenza mortality (Barreca and Shimshack, 2012) and anomalously low humidity levels were found to precede the onset of increased wintertime influenza-related mortality in the United States by several weeks (Davis et al, 2012;Shaman et al, 2010). The respiratory impact of low atmospheric humidity was evident in other studies in Belgium (Lander et al, 2012), China (Xiao et al, 2013), Japan (Harata et al, 2004), Israel (Yaari et al, 2010), the Netherlands and Portugal (van Noort et al, 2012), and was inferred in forensic studies of major historical influenza outbreaks in England and Wales (He et al, 2013). Yet in studies that utilized relative humidity, Zhang et al (2013) found a negative association between RSV and Rodriguez-Martinez (2015) uncovered no relationship.…”

Spatial and Temporal Spread of Acute Viral Respiratory Infections in Young Children Living in High-altitude Rural Communities

“…In certain high altitude regions, inclement weather may drive people indoors for longer periods of time 11 , increasing the length of the time individuals are exposed to indoor pollution 9 and/or social contacts with patients with ARI 12,13 . We have previously reported that in rural highland communities of the Peruvian Andes, social contacts that could facilitate the transmission of infections were very frequent and physical contacts appeared to be higher than in some other developing counties 14 .…”