The effect of large-scale anti-contagion policies on the COVID-19 pandemic

Nature (2020)

Abstract

Governments around the world are responding to the novel coronavirus (COVID-19) pandemic1 with unprecedented policies designed to slow the growth rate of infections. Many actions, such as closing schools and restricting populations to their homes, impose large and visible costs on society, but their benefits cannot be directly observed and are currently understood only through process-based simulations2–4. Here, we compile new data on 1,717 local, regional, and national non-pharmaceutical interventions deployed in the ongoing pandemic across localities in China, South Korea, Italy, Iran, France, and the United States (US). We then apply reduced-form econometric methods, commonly used to measure the effect of policies on economic growth5,6, to empirically evaluate the effect that these anti-contagion policies have had on the growth rate of infections. In the absence of policy actions, we estimate that early infections of COVID-19 exhibit exponential growth rates of roughly 38% per day. We find that anti-contagion policies have significantly and substantially slowed this growth. Some policies have different impacts on different populations, but we obtain consistent evidence that the policy packages now deployed are achieving large, beneficial, and measurable health outcomes.

We estimate that across these six countries, interventions prevented or delayed on the order of 62 million confirmed cases, corresponding to averting roughly 530 million total infections. These findings may help inform whether or when these policies should be deployed, intensified, or lifted, and they can support decision-making in the other 180+ countries where COVID-19 has been reported7.

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Estimating the effects of non-pharmaceutical interventions on COVID-19 in Europe

Nature (2020)

Abstract

Following the emergence of a novel coronavirus1 (SARS-CoV-2) and its spread outside of China, Europe has experienced large epidemics. In response, many European countries have implemented unprecedented non-pharmaceutical interventions such as closure of schools and national lockdowns. We study the impact of major interventions across 11 European countries for the period from the start of COVID-19 until the 4th of May 2020 when lockdowns started to be lifted. Our model calculates backwards from observed deaths to estimate transmission that occurred several weeks prior, allowing for the time lag between infection and death. We use partial pooling of information between countries with both individual and shared effects on the reproduction number. Pooling allows more information to be used, helps overcome data idiosyncrasies, and enables more timely estimates. Our model relies on fixed estimates of some epidemiological parameters such as the infection fatality rate, does not include importation or subnational variation and assumes that changes in the reproduction number are an immediate response to interventions rather than gradual changes in behavior. Amidst the ongoing pandemic, we rely on death data that is incomplete, with systematic biases in reporting, and subject to future consolidation. We estimate that, for all the countries we consider, current interventions have been sufficient to drive the reproduction number Rt”>𝑅𝑡Rt below 1 (probability Rt”>𝑅𝑡Rt< 1.0 is 99.9%) and achieve epidemic control. We estimate that, across all 11 countries, between 12 and 15 million individuals have been infected with SARS-CoV-2 up to 4th May, representing between 3.2% and 4.0% of the population. Our results show that major non-pharmaceutical interventions and lockdown in particular have had a large effect on reducing transmission. Continued intervention should be considered to keep transmission of SARS-CoV-2 under control.

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New Zealand Lifts Lockdown as It Declares Virus Eliminated, for Now

Saying the country had no active coronavirus cases and no new infections, officials declared that the strict clampdown on public life would end.  New York Times                                            

Commuters at a bus interchange in Christchurch, New Zealand, on Monday.

Crowds will gather again in New Zealand’s restaurants. Weddings will include as many hugs and guests as the happy couple wants — and even social distancing will not be needed.

New Zealand has no active coronavirus cases and no new cases, officials said on Monday, declaring that life could return to a form of pre-pandemic normal. Since the pandemic began, the country has reported 1,504 cases and 22 deaths nationally, and has been widely praised for its stringent approach to combating the virus.

“While the job is not done, there is no denying this is a milestone,” Prime Minister Jacinda Ardern said, adding: “Thank you, New Zealand.”

The country of five million people is one of only a few nations that appear to have eradicated the virus, at least for now. Iceland is another.