london covid19 may be a seasonal infection linked to low temperatures and humidity much like seasonal influenza according to new robust evidence found by researchersthe study recently published in the journal nature computational science also supports the considerable contribution of airborne sarscov2 transmission and the need to shift to measures that promote air hygienea research team led by the barcelona institute for global health isglobal spain noted that a key question regarding sarscov2 is whether it is behaving or will behave as a seasonal virus like influenza or whether it will be equally transmitted during any time of the yeara first theoretical modelling study suggested that climate was not a driver in covid19 transmission given the high number of susceptible individuals with no immunity to the virushowever some observations suggested that the initial propagation of covid19 in china occurred in a latitude between 30 and 50 degrees n with low humidity levels and low temperatures between 5 degrees and 11 degrees celsiusthe question of whether covid19 is a genuine seasonal disease becomes increasingly central with implications for determining effective intervention measures said xavier rodo director of the climate and health programme at isglobal and coordinator of the studythe researchers first analysed the association of temperature and humidity in the initial phase of sarscov2 spread in 162 countries across five continents before changes in human behaviour and public health policies were put into placethe results show a negative relationship between the transmission rate r0 and both temperature and humidity at the global scale the researchers saidhigher transmission rates were associated with lower temperatures and humidity they saidthe researchers then analysed how this association between climate and disease evolved over time and whether it was consistent at different geographical scalesthey used a statistical method that was specifically developed to identify similar patterns of variation at different windows of timethe team found a strong negative association for short time windows between the number of cases and temperature and humiditythe patterns were consistent during the first second and third waves of the pandemic at different spatial scales worldwide countries down to individual regions within highly affected countries and even to the city levelthe first epidemic waves waned as temperature and humidity rose and the second wave rose as temperatures and humidity fell according to the researchershowever this pattern was broken during summertime in all continents they saidthis could be explained by several factors including mass gatherings of young people tourism and air conditioning among others said alejandro fontal researcher at isglobal and first author of the studywhen adapting the model to analyse transient correlations at all scales in countries in the southern hemisphere where the virus arrived later the same negative correlation was observedthe climate effects were most evident at temperatures between 12 degrees and 18 degrees celsius and humidity levels between 4 and 12 grammes per cubic metre gm3however the study authors warned that these ranges are still indicative given the short records availableusing an epidemiological model the researcher showed that incorporating temperature