What a virologist says about controlling a pandemic

image of virus under microscope

This electron micrograph of the SARS-CoV-2 virus particles was captured and color-enhanced at the NIAID Integrated Research Facility (IRF) in Fort Detrick, Maryland. How did New Zealand effectively control a pandemic without using a vaccine? The country eliminated community transmission of the virus, showing on a large scale how effective intervention methods can be.

The novel coronavirus that causes COVID-19 reached New Zealand Feb. 28, 2020. By early May, the country had mostly returned to normal activity. A pandemic was controlled and stopped in its tracks without antiviral medication or a vaccine. Another surprise was that flu infections virtually stopped during the peak times for infections in the Southern Hemisphere.

As a flu researcher who conducts ongoing investigations in my homeland, I was curious on two fronts:

  1. First, how would these COVID-19 interventions affect flu and other serious viral respiratory infections?
  2. What can we learn about transmission of viruses and what New Zealand implemented to tackle a future pandemic?

COVID-19 lockdown and flu season

Shortly before COVID-19 reached New Zealand, the country implemented the first in a series of increasingly restrictive measures to prepare for the virus. This included public health measures such as testing, contact tracing, quarantining and physical distancing. Once community transmission of the virus was discovered, a month-long nationwide lockdown began. This included border closures, stay-at-home orders, public education and similar measures. That occurred March 25, a few weeks before the usual start of the nation’s flu season.

Through our surveillance of flu activity there, we found evidence that the measures implemented to successfully eliminate COVID-19 probably contributed to no confirmed outbreaks of the flu during New Zealand’s 2020 flu season. So far, flu activity here in the U.S. is very low. While flu activity can continue through March, it looks like the U.S. flu season will follow the trend set by New Zealand and the Southern Hemisphere.

This raises a few interesting questions about flu in the future.

What can happen to flu?

We know we have four different, major strains of flu circulating. Within each of those major strains, there are a lot of different subvariants, particularly in recent years. As the virus mutates and changes each year, our global investigations inform vaccine composition and what we predict will be the predominant strains infecting humans. From a public health perspective, it’s good to have no flu. But from a virology perspective, we need to look at the impact shutting down a flu season has had on the evolution of viruses. Because of the low infection rates, there is a good chance of many of those subvariants disappearing maybe making vaccine selection less complicated.

Lessons for future pandemics

With public cooperation and support, New Zealand’s strategy eliminated community transmission of the virus that causes COVID-19 by early May. Borders still remain closed to non-citizens, but otherwise, life in New Zealand has mostly returned to normal. We saw on a large scale how effective intervention methods can be. A pandemic was controlled by a population controlling their behavior for a short period of time.

It’s encouraging news as to how effective the pandemic intervention measures really were – these are things we can all do without having to develop anything. New Zealand’s efforts highlight how successful they can be. It suggests that when we have another pandemic, which we’re almost certainly going to have, there are lessons to be learned from New Zealand’s response: Early and strict interventions can absolutely stop these pandemics in their tracks.

About the Author

Richard Webby

Richard Webby, PhD, is a faculty member and director of the World Health Organization Collaborating Center for Studies on the Ecology of Influenza in Animals and Birds at St. Jude Children’s Research Hospital. View full bio.