The effects of school closures and of public transportation shut-downs on transmission rates in a virus pandemic
The global SARS-CoV-2 pandemic has brought to our attention the vulnerability of our globalized societies to viruses. The damages caused by viruses are not a new phenomenon. During the twentieth century, smallpox alone killed about 300 million people (Koplow, 2003) and influenza killed about 100 million people (Taubenberger and Morens, 2006). However, the scale of the economic consequences of the coronavirus pandemic may be unprecedented. Most countries have implemented drastic policy measures in order to contain the outbreak by reducing social interactions to a minimum. These measures include the closing of schools and universities, shut-downs of public transportation, and general curfews. While it is often unclear how effective these measures actually are, it has become apparent that the economic cost may be enormous. Fortunately, there is scientific evidence on previous virus pandemics that may also provide insights on which could be the most effective measures for the containment of the current global pandemic.
Adda (2016) analyzes the role of social interaction and economic activity in the spread of viruses. For this purpose, he exploits detailed data describing the incidence of three major viral diseases (influenza, gastroenteritis, and chickenpox) over a period of up to a quarter of a century in France. The data on the spatial and temporal evolution of the three diseases are complemented by quasi-experimental evidence on school closures, on shut-downs of public transportation, and on expansions of the railway. The availability of quasi-experimental variation allows estimating the causal impact of related policy measures on disease propagation. The role of transportation infrastructures is estimated by exploiting information on both general and more local transportation strikes and by exploiting the expansion of the high-speed train network throughout France. The role of schools in the propagation of viruses is evaluated by using information on school closures due to holidays that vary within the year and across the country.
The analysis shows that school closures have a pronounced significant effect on the incidence of flu-like illnesses. The estimates indicate a reduction in the rate of transmission to children by 0.14 individuals infected. School holidays also decrease the transmission rate of flu-like illnesses for adults by about 0.1 people infected. For the elderly, there is a small but insignificant decrease for flu-like illnesses, but a significant increase in the propagation rate for acute diarrhea. In principle, the effect of school closures could go in either direction for the elderly. On the one hand, school closures may decrease the general incidence of a disease leading to an indirect effect also on the elderly. On the other hand, school holidays are a period when children are more likely to interact with their grandparents leading to a direct effect of more transmissions to the elderly. The overall effect is therefore ambiguous and is estimated to be even detrimental in the case of acute diarrhea.
With respect to public transportation, the analysis provides evidence that shut-downs can effectively reduce the propagation rate of diseases. In more detail, the estimates suggest that public strikes decrease the propagation rate within a region for adults and the elderly in the case of flu-like illnesses and decrease the rate across regions for all age groups in the case of both flu-like illnesses and acute diarrhea. Furthermore, opening up a new high-speed rail line strikingly increases the transmission rates for both flu-like illnesses and acute diarrhea and for all age groups. The effect is larger for flu-like illnesses than for acute diarrhea.
For the coronavirus pandemic, these results suggest that school closures can help reducing the transmission rate, but are only a suitable measure for protecting the elderly if the school children do not increase their interactions with their grand-parents as a consequence. Shut-downs of public transportation may be a crucial cornerstone in the containment of the disease. In particular, reducing public transportation across regions is an effective means for curbing transmission rates.