Schools opening and Covid-19 diffusion: Evidence from geolocalized microdata

Automated local lockdowns for SARS-CoV-2 epidemic control-assessment of effect by controlled interrupted time series analysis

Objectives

During the COVID-19 pandemic, broad non-pharmaceutical interventions such as national lockdowns were effective but had significant drawbacks, prompting targeted approaches, such as Denmark's localized lockdowns, based on specific epidemiological criteria. This study evaluates the effect of Denmark's automated local lockdown strategy on epidemic control to inform future response.

Methods

This was a register-based controlled interrupted time series analysis, examining SARS-CoV-2 infection rates in Danish parishes from March to September 2021. The matching of control parishes was based on location, time, and pre-lockdown infection trends, with the lockdown's start defined as the day after a parish exceeded the lockdown criteria. Follow-up included 3-week pre-lockdown and 2-week post-lockdown.

Results

A total of 30 parishes were mandated to lockdown, approximately 3.5% of the population of Denmark. A total of 94 control parishes were used as 109 controls. The decrease in the incidence during the 2-week follow-up period after the initiation of the lockdown was 13% points higher in case parishes: in case parishes, the incidence was reduced by 78% compared with 65% in control parishes.

Conclusions

Our findings demonstrate that local lockdowns did have a positive effect in mitigating the spread of the SARS-CoV-2 virus, making them valuable in the fight against the COVID-19 pandemic and an important alternative to national lockdowns.

Schools and the transmission of Sars-Cov-2: Evidence from Italy

This paper studies the effect on the spread of Sars-Cov-2 in Italy of schools' re-openings and closures. Exploiting different re-opening dates across regions after the summer break of 2020, I show that early-opening regions experienced more cases in the 40 days following school re-openings compared with late-opening ones. However, there is great uncertainty around the estimates, and this suggests a wide dispersion in the effects of school re-openings on Sars-Cov-2 transmission. I also study the effect of school closures in Campania, one of the biggest regions in Southern Italy. Using a synthetic control approach, I show that school closures are associated with lower numbers of cases relative to the counterfactual group, particularly in younger age groups. In contrast, I find no significant effects on older age groups, which are more likely to require hospitalization. Finally, by exploiting survey data, I provide descriptive evidence on the increased incidence rate among teachers and students relative to the general population, following school re-openings.

Will the last be the first? School closures and educational outcomes

Governments have implemented school closures and online learning as one of the main tools to reduce the spread of Covid-19. Despite the potential benefits in terms of containment of virus diffusion, the educational costs of these policies may be dramatic. This work identifies these costs, expressed as decrease in test scores, for the whole universe of Italian students attending the 5th, 8th and 13th grade of the school cycle during the 2021/22 school year. The analysis is based on a difference-in-difference model in relative time, where the control group is the closest generation before the Covid-19 pandemic. Results suggest a national average loss between 1.8-4.0% in Mathematics and Italian test scores. After collecting the precise number of school closure days for the universe of students in Sicily, this work also estimates that the average days of closure decrease the test score by 2.4%. In this context, parents appear to have a partial compensatory effect, but only when holding higher levels of education and when their children are attending low and middle schools. This is likely explained by the lower relevance of parental inputs and higher reliance on other inputs, such as peers, for the higher grades. Finally, the effects are also heterogeneous across class size, parents' country of birth and job conditions, pointing towards potential growing inequalities driven by the lack of frontal teaching.

School-age vaccination, school openings and Covid-19 diffusion

This article investigates the relationship between school openings and Covid-19 diffusion when school-age vaccination becomes available. The analysis relies on a unique geo-referenced high frequency database on age of vaccination, Covid-19 cases and hospitalization indicators from the Italian region of Sicily. The study focuses on the change of Covid-19 diffusion after school opening in a homogeneous geographical territory (i.e., with the same control measures and surveillance systems, centrally coordinated by the Regional Government). The identification of causal effects derives from a comparison of the change in cases before and after school opening in the school year 2020/21, when vaccination was not available, and in 2021/22, when the vaccination campaign targeted individuals of age 12-19 and above 19. Results indicate that, while school opening determined an increase in the growth rate of Covid-19 cases in 2020/2021, this effect has been substantially reduced by school-age vaccination in 2021/2022. In particular, we find that an increase of approximately 10% in the vaccination rate of school-age population reduces the growth rate of Covid-19 cases after school opening by approximately 1%.

Back to school or … back to lockdown? The effects of opening schools on the diffusion of COVID-19 in Italian regions

The opening of schools that coincided with the beginning of fall 2020 and the arrival of the second wave of COVID-19 in continental Europe has fostered significant debate in several countries. Some contributions have suggested that youngsters play a minor role in the spread of the virus, given the specific characteristics of this infection; other scholars have raised concerns about the necessary movement that involves keeping schools open, and the consequent potential spread of the virus. In this study, we focus on the Italian case, an interesting setting in which to test the impact of opening schools on the spread of COVID-19, because of the different dates at which schools have opened in the various Italian provinces, and because of the different rates at which the virus has spread across Italy. Our results suggest that open schools have a positive impact on COVID-19 cases, whose spread occurs between 10 and 14 days after opening. While closing schools or using distance learning have other social and economic consequences, making it necessary for policymakers to adopt a holistic evaluation, it should be taken into account that open schools have an impact on the spread of the pandemic.

Voting, contagion and the trade-off between public health and political rights: Quasi-experimental evidence from the Italian 2020 polls

Natural disasters raise challenging trade-offs between public health safety and inalienable rights like the active involvement in political choices through voting. We exploit a quasi-experimental setting provided by multiple ballots across regions and municipalities during the Italian 2020 elections to estimate the effect of voters' turnout on the spread of COVID-19. By employing an event-study design with a two-stage Control Function strategy, we find that post-poll new COVID infections increased by an average of 1.1% for each additional percentage point of turnout. Based on these estimates and real political events, we also show through a simulation that in-person voting during a high-infection regime may have a large impact on public health outcomes, more than doubling new infections, deaths and hospitalizations. These findings suggest that policy-makers' responses to natural disasters should be flexible and contingent to the emergency severity, in order to minimize social costs for citizens.

Schools under mandatory testing can mitigate the spread of SARS-CoV-2

We use event study models based on staggered summer vacations in Germany to estimate the effect of school reopenings after the summer of 2021 on the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Estimations are based on daily counts of confirmed coronavirus infections across all 401 German counties. A central antipandemic measure in German schools included mandatory rapid testing multiple times per week. Our results are consistent with mandatory testing contributing to the containment of the viral spread. We find a short-term increase in infection rates right after summer breaks, indicating the uncovering of otherwise undetected (asymptomatic) cases through the testing. After a period of about 2 wk after school reopenings, the growth of case numbers is smaller in states that reopened schools compared with the control group of states still in summer break. The results show a similar pattern for older age groups as well, arguably as a result of detected clusters through the school testing. This means that under certain conditions, open schools can play a role in containing the spread of the virus. Our results suggest that closing schools as a means to reduce infections may have unintended consequences by giving up surveillance and should be considered only as a last resort.

News shocks at the local level: Evidence from a conditional Covid-19 containment measure

To reduce the spread of Covid-19 whilst limiting the economic costs of containment policies, governments have introduced geographically-flexible conditional restrictions - measures targeting sub-national areas whose severity depends on the virus's local incidence rate. I analyze whether conditional measures impact transmission rates via a news-shock effect - that is, by incentivizing indirect actions in anticipation of the policies being carried out. Exploiting a natural experiment from Romania in a regression-discontinuity framework, I provide early empirical evidence in this sense: I find that the Covid-19 incidence rate fell significantly in targeted constituencies following the announcement of a conditional containment measure, but prior to the policy being implemented. My results add to a broader literature on news-driven fluctuations, wherein expectations of future policies can impact immediate behaviors. I conclude by discussing an important avenue for future research.

Association of COVID-19 Incidence and Mortality Rates With School Reopening in Brazil During the COVID-19 Pandemic

Question

Is the reopening of schools during the COVID-19 pandemic associated with increased COVID-19 incidence and mortality?

Findings

In this cross-sectional study of 643 Brazilian municipalities including 18 761 schools, on average, there was no systematic association between school reopening and COVID-19 incidence or mortality in São Paulo State up to 12 weeks after reopening, which was also the case for schools in the most vulnerable conditions. Aggregate mobility was already high before the school reopening and did not significantly increase afterwards.

Meaning

The results of this study suggest that reopening schools under appropriate protocols in low- and middle-income countries during the pandemic is unlikely to be associated with higher aggregate COVID-19 cases or deaths when counterfactual mobility is already high.

Importance

School closures because of COVID-19 have left 1.6 billion students around the world without in-person classes for a prolonged period. To our knowledge, no study has documented whether reopening schools in low- and middle-income countries during the pandemic was associated with increased aggregate COVID-19 incidence and mortality with appropriate counterfactuals.

Objective

To test whether reopening schools under appropriate protocols during the COVID-19 pandemic was associated with increased municipal-level COVID-19 cases and deaths in São Paulo State, Brazil.

Design, Setting, and Participants

This observational study of municipalities in São Paulo State, Brazil, uses a difference-in-differences analysis to examine the association between municipal decisions to reopen schools during the COVID-19 pandemic and municipal-level COVID-19 case and death rates between October and December 2020. The study compared 129 municipalities that reopened schools in 2020 with 514 that did not and excluded data for 2 municipalities that reopened schools and closed then again.

Main Outcomes and Measures

New COVID-19 cases and deaths per 10 000 inhabitants up to 12 weeks after school reopenings and municipal-level aggregate mobility for a subset of municipalities.

Results

There were 8764 schools in the 129 municipalities that reopened schools compared with 9997 in the control group of 514 municipalities that did not reopen schools. The municipalities that reopened schools had a cumulative COVID-19 incidence of 20 cases per 1000 inhabitants and mortality of 0.5 deaths per 1000 inhabitants in September 2020 (the baseline period) compared with an incidence of 18 cases per 1000 inhabitants and mortality of 0.45 deaths per 1000 inhabitants during the baseline period in the comparison group. The findings indicated that there were no statistically significant differences between municipalities that authorized schools to reopen and those that did not for (1) weekly new cases (difference-in-differences, –0.03; 95% CI, –0.09 to 0.03) and (2) weekly new deaths (difference-in-differences, –0.003; 95% CI, –0.011 to 0.004) before and after October 2020. Reopening schools was not associated with higher disease activity, even in relatively vulnerable municipalities, nor aggregate mobility.

Conclusions and Relevance

The findings from this study suggest that keeping schools open during the COVID-19 pandemic did not contribute to the aggregate disease activity.