- The outbreak containment strategies in China based on non-pharmaceutical interventions (NPIs) appear to be effective.
- But quantitative research is still needed to assess the efficacy of NPIs and their timings.
- Using epidemiological and anonymised human movement data, a modelling framework has been formulated.
- The lessons drawn from China provide robust evidence and provide a preparation window and fighting chance against COVID-19.
On March 11, 2020, the World Health Organization declared COVID-19 a pandemic. An article in Nature has published a modelling framework that uses daily travel networks to simulate different outbreak and intervention scenarios across China.
The research group estimated that there were a total of 114,325 COVID-19 cases (interquartile range 76,776 – 164,576) in mainland China as of February 29, 2020. Without NPIs, the COVID-19 cases would likely have shown a 67-fold increase (interquartile range 44 – 94) by February 29, 2020, with the effectiveness of different interventions varying.
The early detection and isolation of cases was estimated to have prevented more infections than travel restrictions and contact reductions, but combined NPIs achieved the strongest and most rapid effect.
The lifting of travel restrictions since February 17, 2020 does not appear to lead to an increase in cases across China if the social distancing interventions can be maintained, even at a limited level of 25% reduction on average through late April.
The research findings contribute to an improved understanding of NPIs on COVID-19 and to inform response efforts across the World.
Nonpharmaceutical interventions (NPIs)
As of March 30, 2020 the COVID-19 outbreak has resulted in 693,282 confirmed cases and 33,106 deaths across the World. As an emerging disease, effective pharmaceutical interventions are not expected to be available for months, and healthcare resources will be limited for treating all cases.
These include isolating ill persons, contact tracing, quarantine of exposed persons, travel restrictions, school and workplace closures, cancellation of mass gatherings, and hand washing, among others.
These measures aim to reduce transmission, thereby delaying the timing and reducing the size of the epidemic peak, buying time for preparations in the healthcare system, and enabling the potential for vaccines and drugs to be used later on.
Three major groups of NPIs have been implemented to contain the spread and reduce the outbreak size of COVID-19 across China.
- First, inter-city travel restrictions were used to prevent further seeding of the virus during the Chinese new year (CNY) holiday.
A cordon sanitaire of Wuhan and surrounding cities in Hubei Province was put in place two days before CNY’s day on January 25, 2020. Since CNY’s day, travel restrictions in other provinces were also put in place across the country.
- Early identification and isolation of cases comprised the second group of NPIs, including improving the screening, identification, diagnosis, isolation, reporting, and contact tracing of suspected ill persons and confirmed cases.
Along these lines, local governments across China encouraged and supported routine screening and quarantine of travellers from Hubei Province in an attempt to detect COVID-19 infections as early as possible.
Highlighting how these efforts improved detection and diagnosis, the average interval from symptom onset to laboratory confirmation dropped from 12 days in the early stages of the outbreak to 3 days in early February.
- Third, contact restrictions and social distancing measures, together with personal preventive actions, such as hand washing, were implemented to reduce the community-level exposure risk.
As part of these social distancing policies, the Chinese government encouraged people to stay at home as much as possible, cancelled or postponed large public events and mass gatherings, and closed libraries, museums, and workplaces.
Additionally, school holidays were also extended, with the CNY holiday end date changed from January 30 to March 10 for Hubei province, and February 9 for many other provinces.
The implementation of these NPIs coincided with a rapid decline in the number of new cases across China, albeit at high economic and social costs. The research findings show that combined NPIs substantially reduced COVID-19 transmission across China.
Earlier implementation of NPIs could have significantly reduced the magnitude and geographical range of the outbreak, but equally, a delayed response would have lead to a larger outbreak.
Three key points
- First, they support and validate the idea that population movement and close contact has a major role in the spread of COVID-19 within and beyond China.
As the lockdown of Wuhan happened at the latter stages of the pre-CNY movement, travel restrictions did not halt the seeding of the virus from Wuhan, but did prevent cases being exported from Wuhan to a wider area.
- Secondly, the importance and effects of the three types of NPIs differed. Compared to travel restrictions, improved detection and isolation of cases as well as the social distancing likely had a greater impact on the containment of outbreak.
The social distancing intervention reduced contact with people who travelled from the epicentre of the outbreak. This is likely to have been especially helpful in curbing the spread of an emerging pathogen to the wider community, and reduced the spread risk from asymptomatic or mild infections.
- Third, given travel and work resuming in China, the country should consider at least the partial continuation of NPIs to ensure that the COVID-19 outbreak is sustainably controlled for the first wave of this outbreak.
For example, early case identification and isolation should be maintained, which may also help to prevent and delay the arrival of a second wave, considering the increasing numbers of cases imported from other countries and the presence of asymptomatic or subclinical infections found in China.
Mitigating COVID-19 effects
China’s aggressive, multifaceted response is likely to have prevented a far worse situation, which would have accelerated spread globally.
The lessons drawn from China provide robust evidence and provide a preparation window and fighting chance for containing the spread and mitigating the effects of COVID-19 in other regions around the World.
Did you subscribe to our daily newsletter?
It’s Free! Click here to Subscribe!
Source: Nature
