A group of researchers at Stanford published a peer-reviewed study earlier this month assessing the impact of lockdowns and stay-at-home orders — what they refer to as non-pharmaceutical interventions (NPIs) in early 2020. The study did not find evidence to support that NPIs were effective in preventing the spread.
“In summary, we fail to find strong evidence supporting a role for more restrictive NPIs in the control of COVID in early 2020,” the study concludes. “We do not question the role of all public health interventions, or of coordinated communications about the epidemic, but we fail to find an additional benefit of stay-at-home orders and business closures. The data cannot fully exclude the possibility of some benefits. However, even if they exist, these benefits may not match the numerous harms of these aggressive measures. More targeted public health interventions that more effectively reduce transmissions may be important for future epidemic control without the harms of highly restrictive measures.”
The study was co-authored by Dr. Eran Bendavid, Professor John P.A. Ioannidis, Christopher Oh, and Jay Bhattacharya. The lead author, Dr. Bendavid, is an associate professor in the Department of Medicine at Stanford. The other authors collectively work in departments including the Department of Epidemiology and the Department of Biomedical Data Science. According to the Spectator, the study was published in the European Journal of Clinical Observation.
The group studied the effects of NPIs in 10 countries: England, France, Germany, Iran, Italy, Netherlands, Spain and the United States, which had more restrictive measures, were compared to Sweden and South Korea, where measures were less restrictive. After they accounted for the less restrictive NPIs in South Korea and Sweden, they found “no clear, significant beneficial effect of more restrictive NPIs on case growth in any country.”
“In the framework of this analysis, there is no evidence that more restrictive non-pharmaceutical interventions (“lockdowns”) contributed substantially to bending the curve of new cases in England, France, Germany, Iran, Italy, the Netherlands, Spain, or the United States in early 2020,” they write. “By comparing the effectiveness of NPIs on case growth rates in countries that implemented more restrictive measures with those that implemented less restrictive measures, the evidence points away from indicating that more restrictive NPIs provided additional meaningful benefit above and beyond less restrictive NPIs. While modest decreases in daily growth (under 30%) cannot be excluded in a few countries, the possibility of large decreases in daily growth due to more restrictive NPIs is incompatible with the accumulated data.”
“The direction of the effect size in most scenarios point towards an increase in the case growth rate, though these estimates are only distinguishable from zero in Spain (consistent with non-beneficial effect of lockdowns),” the study continues. “Only in Iran do the estimates consistently point in the direction of additional reduction in the growth rate, yet those effects are statistically indistinguishable from zero. While it is hard to draw firm conclusions from these estimates, they are consistent with a recent analysis that identified increase transmission and cases in Hunan, China during the period of stay-at-home orders from increased intra-household density and transmission.In other words, it is possible that stay-at-home orders may facilitate transmission if they increase person-to-person contact where transmission is efficient such as closed spaces.”
If you want to read the whole study for yourself, you can do so here.