Genetic study reveals value of lockdowns, travel restrictions in curbing COVID-19

Stringent nonpharmaceutical interventions (NPI), like travel restrictions and lockdowns, have helped ease morbidity and mortality amid the novel coronavirus disease (COVID-19) pandemic, reveals a recent study.

Drawing from over 29,000 publicly available whole genome sequences of SARS-CoV-2 from 57 different locations, the researchers estimated the time the epidemic began in these places. This timing was evaluated in relation to the date the most stringent interventions were instituted, as well as to the cumulative deaths.

A series of regression models showed that the number of days from the central epidemic seeding time (CEST) to the first institution of the maximum NPI was significantly predictive of the number of deaths 1 month later, both according to the Deming regression (p=0.0031) and univariate linear (p=0.011) analyses.

In particular, delaying maximum NPI implementation by an additional 14 days led to a 2.91-fold increase in deaths 1 month after (95 percent confidence interval [CI], 1.35–6.27), according to the Deming model. Univariate regression found a 2.0-fold increase (95 percent CI, 1.19–3.32).

Similarly, the gap from CEST to maximum NPI correlated significantly with the viral effective population size at the time of maximum NPI (p<0.0001 for both Deming and univariate regressions). According to the researchers, viral effective population size could be used as a proxy measure for epidemic prevalence under the appropriate conditions.

Moreover, allowing the virus 14 more days of transmission before maximum NPI correlated with a 2.18-fold (95 percent CI, 1.52–3.13) and 2.08-fold (95 percent CI, 1.54–2.83) increase in effective population size according to Deming and univariate regression analyses, respectively.