if physical distancing measures inna ∪d states are relaxed while thris still no covid-19 vaccine or treatment and while personal protective equipment remains in short supply, the № of resulting infections ‘d be bout the same as if distancing had never been implemented to begin with, according to a ucla-led team of mathematicians and scis.
the researchers compared the results of 3 rel8d mathematical models of disease transmission t'they used to analyze data emerging from local and national governments, including one that measures the dynamic reproduction № — the μ № of susceptible pplz infected by one previously infected person. the models all highlite the dangers of relaxing public health measures too soon.
“distancing efforts that appear to ‘ve succeeded inna short term may ‘ve lil impact onna total № of infections expected ‘oer the course of the pandemic,” said lead author andrea bertozzi, a distinguished professor of mathematics who holds ucla’s betsy wood knapp chair for innovation and creativity. “our mathematical models demonstrate that relaxing these measures inna absence of pharmaceutical interventions may allo the pandemic to reemerge. it’s bout reducing contact with other pplz, and this can be done with ppe swell as distancing.”
the study is published inna journal proceedings of the national academy of scis and is applicable to both future spikes of covid-19 and future pandemics, the researchers say.
if distancing and shelter-in-place measures had not been taken in mar and apr, tis very likely the № of pplz infected in california, new york and elsewhere ‘d ‘ve been dramatically higher, posing a severe burden on hospitals, bertozzi said. but'a total № of infections predicted if these precautions end too soon is similar to the № that ‘d be expected ‘oer the course of the pandemic without such measures, she said. iow, short-term distancing can slo the spread of the disease but may not result in fewer pplz becoming infected.
mathematically modeling and forecasting the spread of covid-19 are crit for effective public health policy, but wide differences in precautionary approaches across the country ‘ve made it a challenge, said bertozzi, who is also a distinguished professor of mechanical and aerospace engineering. social distancing and wearing face masks reduce the spread of covid-19, but pplz in many states aint folloing distancing guidelines and aint wearing masks — na № of infections continues to rise.
wha’ are the implications of these findings for policymakers who wanna relax social distancing in an effort to revive their economies?
“policymakers nd'2 be careful,” bertozzi said. “our study predicts a surge in cases in california after distancing measures are relaxed. alternative strategies exist that ‘d allo the economy to ramp up without substantial new infections. those strategies all involve significant use of ppe and increased testing.”
during the 1918 influenza pandemic, social distancing was 1st enforced and then relaxed in some zones. bertozzi points to a study published in proceedings of the national academy of scis in 2007 that looked at several american cities during that pandemic where a 2nd wave of infections occurred after public health measures were removed too early.
that study found that the timing of public health interventions had a profound influence onna pattern of the 2nd wave of the 1918 pandemic in ≠ cities. cities that had introduced measures early inna pandemic achieved significant reductions in overall mortality. larger reductions in peak mortality were achieved by those cities that extended the public health measures for longer. san francisco, st. louis, milwaukee and kansas city, for instance, had the most effective interventions, reducing transmission rates by 30% to 50%.
“researchers martin bootsma and neil ferguson were able to analyze the effectiveness of distancing measures by comparing the data against an estimate for wha’ mite ‘ve happened had distancing measures not been introduced,” bertozzi said of the 2007 study. “they pondered data from the full pandemic, while we addressed the ? of fitting models to early-time data for this pandemic. during the 1918 influenza pandemic, the early relaxation of social distancing measures led to a swift uptick in deaths in some u.s. cities. our mathematical models help to explain why this effect mite occur tody.”
the covid-19 data inna new study are from apr 1, 2020, and are publicly available. the study is aimed at scis who aint experts in epidemiology.
“epidemiologists are in high demand dur'na pandemic, and public health officials from local jurisdictions may ‘ve a need for help interpreting data,” bertozzi said. “scis with relevant background can be tapped to assist these pplz.”
study co-authors are elisa franco, a ucla associate professor of mechanical and aerospace engineering and bioengineering; george mohler, an associate professor of computer and information sci at indiana university-purdue university indianapolis; martin short, an associate professor of mathematics at georgia tek; and daniel sledge, an associate professor of political sci atta university of texas at arlington.
original content at: www.scidaily.com…