In order to fight a pandemic, travel restrictions are mostuseful in its early and late phases, a new study suggests.
Analysis of human mobility and epidemiological data by aglobal consortium of researchers, led by the University of Oxford in the UK andNortheastern University in the US, shows that human mobility was predictive ofthe spread of the epidemic in China.
“Our findings show that early in the coronavirus outbreaktravel restrictions were effective in preventing the import of infections froma known source,” said study researcher Moritz Kraemer from the Universityof Oxford.
Restrictions of travel from Wuhan province in China,unfortunately, came too late.
The research, published in the journal Science, showed thatthe impact of travel restrictions declines as the epidemic grows. Provincesoutside Hubei that acted early to test, track and contain imported coronaviruscases fared the best in preventing or containing local outbreaks, the studysaid.
Mobile geolocation data from China-based search engine giantBaidu Inc, combined with a rich epidemiological dataset from the Open COVID-19Data Working Group, showed that local person-to-person transmission happenedextensively early on in the coronavirus outbreak and was mitigated by drasticcontrol measures.
However, with an average incubation period of five days, andup to 14 days in some cases, these mobility restrictions did not begin topositively impact the data on new cases for over a week — with thingsappearing to get worse in the 5-7 days immediately after the lockdown as localtransmission was well under way.
According to the researchers, among the cases reportedoutside Hubei, 515 had a known travel history to Wuhan and a symptom onset datebefore January 31, 2020, compared with only 39 after this date, illustratingthe effect of travel restrictions in decreasing the spread to other Chineseprovinces.
“This is where a full package of measures, includinglocal mobility restrictions, testing, tracing and isolation need to worktogether to mitigate the epidemic,” Kraemer added.
Chinese provinces and other countries that have successfullyhalted internal transmission of COVID-19 need to consider carefully how theywill manage to reinstate travel and mobility to avoid the reintroduction andspread of the disease in their populations, the researchers said.
“Travel and mobility restrictions are the most usefulright at the start, when local transmission has not yet become a factor,”said Samuel V Scarpino, Professor at Northeastern University.
“After transmission is established, physical distancingand the quarantine of sick individuals will work, but it takes time,”Scarpino added.