Dependence of COVID-19 Policies on End-of-Year Holiday Contacts in Mexico City
MDM Policy & Practice
Dependence of COVID-19 Policies on End-of-Year Holiday Contacts in Mexico City
El Ángel de la Independencia — Paseo de la Reforma Mexico City · Mexico
The Problem
By December 7, 2020, the Mexico City Metropolitan Area (MCMA) – home to more than 20 million people – was the epicenter of Mexico’s COVID-19 crisis, with 344,028 confirmed cases and 28,077 deaths already recorded. With the end-of-year holidays approaching, a critical question faced policymakers: could the city’s hospitals survive a surge fueled by holiday gatherings – and could schools safely reopen in early 2021?
The Approach
We built the Stanford-CIDE Coronavirus Simulation Model (SC-COSMO), an age-structured SEIR transmission model with household- and venue-specific contacts. We calibrated it to daily case and death data from February 24 to December 7, 2020, estimating 11 parameters via Bayesian methods with 1,000 posterior samples for uncertainty. We then projected outcomes through March 7, 2021 under two holiday-contact levels crossed with four policy combinations – status-quo versus intensified physical distancing, and schools closed versus open.
What We Found
If holiday contacts stayed high, hospitalizations would peak near 26,151 (95% PI 8,318–54,558) on January 25, 2021 – overwhelming the city’s 9,667 COVID-specific beds with 97% certainty. Reining in holiday contacts roughly halved the peak to 12,830 on January 31 and dropped the chance of exceeding capacity to 64%. The signal was blunt: under every scenario, MCMA needed at least 2,000 more beds.
Daily probability of hospitalization demand exceeding COVID-19 capacity in MCMA across policy scenarios (Dec 2020 – Mar 2021).
The Policy Levers
The scenarios showed how tightly the choices interacted. With high holiday contacts and only status-quo distancing, the chance of exceeding hospital capacity by early March was 50% with schools closed and 86% with schools open. Intensifying physical distancing flipped the outcome: capacity-exceedance probability fell to under 1% with schools closed and just 1.1% even with schools open. Reopening schools without tighter community distancing added roughly 376,000 cases – but reopening became feasible when distancing was sustained both in schools and across the community.
Why It Matters
MCMA had to expand hospital capacity under every scenario modeled – but the size of the crisis was a choice. Whether schools could reopen in 2021 hinged on two interlocking levers: controlling contacts during the holiday season and sustaining physical distancing afterward. Reopening, distancing, and capacity decisions could not be made in isolation – they had to be weighed together, against their joint health, economic, and social costs.
Citation
Alarid-Escudero, F., Gracia, V., Luviano, A., Roa, J., Peralta, Y., Reitsma, M.B., Claypool, A.L., Salomon, J.A., Studdert, D.M., Andrews, J.R., & Goldhaber-Fiebert, J.D. (2021). Dependence of COVID-19 Policies on End-of-Year Holiday Contacts in Mexico City: A Modeling Study. MDM Policy & Practice. DOI: 10.1177/23814683211049249
Citation
@article{f.2021,
author = {F. , Alarid-Escudero and V. , Gracia and A. , Luviano and J.
, Roa and Y. , Peralta and M.B. , Reitsma and A.L. , Claypool and
J.A. , Salomon and D.M. , Studdert and J.R. , Andrews and J.D. ,
Goldhaber-Fiebert},
title = {Dependence of {COVID-19} {Policies} on {End-of-Year}
{Holiday} {Contacts} in {Mexico} {City}},
journal = {MDM Policy \& Practice},
date = {2021-10-11},
url = {https://jorgeroac.com/publications/papers/peer-reviewed/covid19-mexico-city-holidays/},
doi = {10.1177/23814683211049249},
langid = {en}
}