COVID-19 Vaccination Mandates and Vaccine Uptake (preprint)

We evaluate the impact of government-mandated proof of vaccination requirements for access to public venues and non-essential businesses on COVID-19 vaccine uptake. We find that the announcement of a mandate is associated with a rapid and significant surge in new vaccinations (more than 60% increase in weekly first doses), using the variation in the timing of these measures across Canadian provinces in a difference-in-differences approach. Time-series analysis for each province and for France, Italy and Germany corroborates this finding. Counterfactual simulations using our estimates suggest the following cumulative gains in the vaccination rate among the eligible population (age 12 and over) as of October 31, 2021: up to 5 percentage points (p.p.) (90% CI 3.9-5.8) for Canadian provinces, adding up to 979,000 (425,000-1,266,000) first doses in total for Canada (5 to 13 weeks after the provincial mandate announcements), 8 p.p. (4.3-11) for France (16 weeks post-announcement), 12 p.p. (5-15) for Italy (14 weeks post-announcement) and 4.7 p.p. (4.1-5.1) for Germany (11 weeks post-announcement).

COVID-19 Vaccination Mandates and Vaccine Uptake (preprint)

We estimate the impact of government-mandated proof of vaccination requirements for access to public venues and non-essential businesses on COVID-19 vaccine uptake. We use event-study and difference-in-differences approaches exploiting the variation in the timing of these measures across Canadian provinces. We find that the \emph{announcement} of a vaccination mandate is associated with large increase in new first-dose vaccinations in the first week (more than 50\% on average) and the second week (more than 100\%) immediately following the announcement. The estimated effect starts waning about six weeks past the announcement. Counterfactual simulations using our estimates suggest that these mandates have led to about 289,000 additional first-dose vaccinations in Canada as of September 30, 2021, which is 1 to 8 weeks after the policy announcements across the different provinces. Time-series analysis corroborates our results for Canada, and we further estimate that national vaccine mandates in three European countries also led to large gains in first-dose vaccinations (7+ mln in France, 4+ mln in Italy and 1+ mln in Germany, 7 to 12 weeks after the policy announcements).

COVID-19 Vaccination Mandates and Vaccine Uptake (preprint)

We estimate the impact of government-mandated proof of vaccination requirements for access to public venues and non-essential businesses on COVID-19 vaccine uptake. We use event-study and difference-in-differences approaches exploiting the variation in the timing of these measures across Canadian provinces. We find that the announcement of a vaccination mandate is associated with large increase in new first-dose vaccinations in the first week (more than 50% on average) and the second week (more than 100%) immediately following the announcement. The estimated effect starts waning about six weeks past the announcement. Counterfactual simulations using our estimates suggest that these mandates have led to about 289,000 additional first-dose vaccinations in Canada as of September 30, 2021, which is 1 to 8 weeks after the policy announcements across the different provinces. Time-series analysis corroborates our results for Canada, and we further estimate that national vaccine mandates in three European countries also led to large gains in first-dose vaccinations (7+ mln in France, 4+ mln in Italy and 1+ mln in Germany, 7 to 12 weeks after the policy announcements). NOTE: The reported numbers may change with more data. Please see updated version when available.

Face Masks, Public Policies and Slowing the Spread of COVID-19: Evidence from Canada (preprint)

We estimate the impact of indoor face mask mandates and other non-pharmaceutical interventions (NPI) on COVID-19 case growth in Canada. Mask mandate introduction was staggered over two months in the 34 public health regions in Ontario, Canada. Using this variation, we find that mask mandates are associated with a 25 percent or larger weekly reduction in new COVID-19 cases in July and August, relative to the trend in absence of mandate. Province-level data provide corroborating evidence. We control for factors such as mobility (using Google geo-location data) and past cases. Our analysis of additional survey data shows that mask mandates led to an increase of about 30 percentage points in self-reported mask wearing in public. Counterfactual policy simulations suggest that mandating indoor masks nationwide in early July could have reduced new COVID-19 cases in Canada by 25 to 40 percent in mid-August (700 to 1,100 fewer cases per week).

Face Masks, Public Policies and Slowing the Spread of COVID-19: Evidence from Canada (preprint)

We estimate the impact of indoor face mask mandates and other non-pharmaceutical interventions (NPI) on COVID-19 case growth in Canada. Mask mandate introduction was staggered from mid-June to mid-August 2020 in the 34 public health regions in Ontario, Canada's largest province by population. Using this variation, we find that mask mandates are associated with a 22 percent weekly reduction in new COVID-19 cases, relative to the trend in absence of mandate. Province-level data provide corroborating evidence. We control for mobility behaviour using Google geo-location data and for lagged case totals and case growth as information variables. Our analysis of additional survey data shows that mask mandates led to an increase of about 27 percentage points in self-reported mask wearing in public. Counterfactual policy simulations suggest that adopting a nationwide mask mandate in June could have reduced the total number of diagnosed COVID-19 cases in Canada by over 50,000 over the period July--November 2020. Jointly, our results indicate that mandating mask wearing in indoor public places can be a powerful policy tool to slow the spread of COVID-19.

Face Masks, Public Policies and Slowing the Spread of COVID-19: Evidence from Canada (preprint)

We estimate the impact of mask mandates and other non-pharmaceutical interventions (NPI) on COVID-19 case growth in Canada, including regulations on businesses and gatherings, school closures, travel and self-isolation, and long-term care homes. We partially account for behavioral responses using Google mobility data. Our identification approach exploits variation in the timing of indoor face mask mandates staggered over two months in the 34 public health regions in Ontario, Canada's most populous province. We find that, in the first few weeks after implementation, mask mandates are associated with a reduction of 25 percent in the weekly number of new COVID-19 cases. Additional analysis with province-level data provides corroborating evidence. Counterfactual policy simulations suggest that mandating indoor masks nationwide in early July could have reduced the weekly number of new cases in Canada by 25 to 40 percent in mid-August, which translates into 700 to 1,100 fewer cases per week.

A Social Network Model of COVID-19 (preprint)

I construct a dynamic social-network based model of the COVID-19 epidemic which embeds the SIR epidemiological model onto a graph of person-to-person interactions. The standard SIR framework assumes uniform mixing of infectious persons in the population. This abstracts from important elements of realism and locality: (i) people are more likely to interact with members of their social networks and (ii) health and economic policies can affect differentially the rate of viral transmission via a person's social network vs. the population as a whole. The proposed network-augmented (NSIR) model allows the evaluation, via simulations, of (i) health and economic policies and outcomes for all or subset of the population: herd immunity, testing, contact tracing, lockdown/distancing; (ii) behavioral responses and/or imposing or lifting policies at a specific time or conditional on observed states. As the NSIR model keeps track of individual states, an economic cost-benefit module and agent heterogeneity (e.g., in savings, employment status; ability to pay bills) is easily incorporated. I find that viral transmission over a network-connected population can proceed slower and reach lower peak than transmission via uniform contacts. The resulting longer epidemic duration may imply larger overall economic costs, e.g., if accompanied by prolonged lockdown policies. If lifted early, distancing policies mostly shift the infection peak into the future with associated economic costs. Delayed or intermittent (on-off-on) interventions or endogenous behavioral responses can lead to a twin-peaked infection rate, a form of 'curve flattening', but may have costlier economic consequences by prolonging the epidemic duration.