Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

New study shows the effectiveness of lockdown measures on preventing COVID-19 spread

Emergency health measures such as social distancing, shelter-in-place and travel restrictions had a significant impact on stopping the spread of COVID-19, new research shows.

A New Zealand economist joined an international team of researchers to produce the first peer-reviewed analysis of local, regional and national policies implemented in six countries in efforts to stem the spread of COVID-19.

Manaaki Whenua – Landcare Research economist Dr Kendon Bell says the study, which appeared this week in the journal Nature, showed non-pharmaceutical interventions, such as travel restrictions, business and school closures, and lockdown orders, averted roughly 530 million COVID-19 infections across the six countries in the study, China, South Korea, Italy, Iran, France and the United States, for the period ending April 6. Of these infections, 62 million would likely have been “confirmed cases,” given limited testing in each country.

The study evaluated 1,717 policies implemented in those countries in the period extending from the emergence of the virus in January to April 6, 2020.

The analysis was carried out by Bell and an international, multi-disciplinary team at the Global Policy Laboratory, led by Prof. Solomon Hsiang and based at UC Berkeley, California, all themselves working under lockdown restrictions.

Dr Bell says that among the huge volume of research currently underway into the virus, this is the first study to use statistical methods of economics to analyse how the virus spreads and how different policies affect that spread.

He says the aim of the research is to try to understand how past attempts to control the virus have been successful, so that information can be used to underpin future decision-making. “Seeing whether policies have been effective at slowing this virus is really important, as you can learn from them. It’s important for future research to try to understand what the best approach is for controlling the pandemic. It’s not over yet.”

Although New Zealand is in a different position from any of the six countries studied, Bell says the analysis suggests that the policy approach New Zealand took was very effective at slowing the spread of COVID-19.

“The modelling looks back and shows how effective different policies were. If you adopt a business-as usual approach with an absence of policy responses, the number of cases doubles about every couple of days. So, it wouldn’t be long before the virus spreads through the population to a meaningful extent. It wouldn’t take long for infection numbers to spin out of control. In New Zealand, everyone would have lost someone they know.”

“We all knew the spread of the virus was exponential, but we just didn’t know how fast. I think it was surprising to everyone to see infection numbers doubling every two days.”

How emergency health measures slowed the COVID-19 pandemic

Cumulative confirmed cases in each locality analysed by the study (area of circle is number of cases)

Left map: actual cases observed at the end of the study period.
Right map: projected cases that would have occurred by the same date if no policy actions had been taken
Source: Global Policy Laboratory | UC Berkley


South Korea