Longer Christmas holidays would reduce number of flu cases

Date: 7 February 2018

Introduction: Researchers at UAntwerp/UHasselt call for 'social distancing' to contain flu epidemic.

The number of influenza infections registered during school holiday periods is almost 20% lower than during term time. This is because social contact patterns change during the holidays. “If the Christmas holidays were one week longer, flu epidemics would be less severe”, say researchers from the universities of Antwerp and Hasselt.

Close the schools: it’s a recommendation we often hear when the flu strikes again. If children had less contact with each other, the number of infections would also decrease. It remains to be seen whether this strategy is actually the most feasible, however. Scientists from the University of Antwerp (Centre for Health Economics Research and Modelling Infectious Diseases) and the University of Hasselt (Interuniversity Institute for Biostatistics and Statistical Bioinformatics) are now getting involved in the debate.

They applied mathematical models to data on the numbers of people who had flu-like symptoms during the 2008-09 influenza season using an extensive dataset on mobility and social contacts in Belgium. “We found that people mainly come into contact with other people in the same age group and across generations in their own families (child-parent-grandparent)”, says Prof. Niel Hens (UAntwerp/UHasselt). “Teenagers have the largest number of contacts. We compared this information to infectious disease data and found that social contacts play an important role in predicting the spread of infectious diseases like the flu.”

Holidays mitigate the epidemic

In their most recent research, Hens and his colleagues focused on the role of holiday periods and weekends. Hens: “During those days off, we behave completely differently and usually have far less social contact. We clearly see that the number of infections is systematically lower at weekends.”

“Of the four holiday periods that fall during the flu season (autumn break, Christmas holidays, spring break and Easter holidays), the Christmas holiday has by far the biggest impact on the influenza epidemic, slowing it down substantially. The school holidays that follow it also have a mitigating effect on the scale of the epidemic. Together, the four school holidays reduce the number of infections by about 2%.”

The Belgian researchers are calling for the same analyses to be carried out in other demographic contexts to conclude once and for all whether closing schools is an effective weapon in the fight against influenza. Hens: “We have already simulated the effect that a third week of Christmas holidays would have had in 2008-09 – it would have reduced the number of infections by 4%.”

Social distancing

In the fight against the flu, the scientists are now calling on the population to respect the principles of ‘social distancing’. “A significant number of people continue with their normal activities even if they have flu symptoms. During that phase, they are up to three times more contagious than people who have no symptoms, or only mild ones, and those people are therefore responsible for the vast majority of infections that occur during the flu season.”

“Using mathematical models, we have been able to prove that if these people stayed at home, we could reduce the number of flu cases by up to 75% per season. It is not always possible of course, but by ‘distancing’ ourselves from others, we can prevent many infections. Some examples of how to do this in practice include working at home, avoiding contact with colleagues, not shaking hands, washing hands thoroughly, coughing into your elbow, and so on. And asking grandparents to look after sick children is not a good idea: it is this generation that is hit hardest by the flu. Enlisting the help of other family members, wherever possible, is a better solution.”

Link: https://www.uantwerpen.be/en/research-groups/chermid/