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Despite high mobility due to informal labour: reduced spread with tighter contact restrictions
Researchers from Charité – Universitätsmedizin Berlin and the German Center for Infection Research (DZIF), together with Ecuadorian colleagues, have gained new insights into the spread of coronavirus at the beginning of the pandemic in Ecuador. In this section, study lead Prof. Dr. Jan Felix Drexler answers questions about the research findings.
What was the research question or scientific inquiry behind your study?
Latin America accounted for one-fifth of the world's reported COVID-19 cases and one-third of the deaths in 2020, despite having only 8 percent of the world's population. Ecuador was among the first hotspots with high COVID-19 mortality, although measures were put in place early on to limit human contact and movement. The country has a high proportion of informal labor, which entails high mobility of people. We wanted to know if the measures nevertheless had an impact on the spread of SARS-CoV-2 in Ecuador.
How did you approach the topic?
We analyzed 2 percent (nearly 2,000) of the respiratory samples sent to the Ecuadorian Reference Laboratory for nationwide COVID-19 surveillance between March 2020 and February 2021 by PCR for SARS-CoV-2 and 12 common respiratory viruses. We also decoded the genome of about 630 SARS-CoV-2 samples to reconstruct the "relationships" of the viruses and thus their distribution. We compared the results using mathematical and bioinformatics methods with information on the strictness and duration of contact restrictions.
What did you discover?
The more severe the contact restrictions, the fewer respiratory samples were positive for SARS-CoV-2 or other viruses and the fewer different SARS-CoV-2 lineages circulated. In early 2020, when no contact restrictions were in place, SARS-CoV-2 was introduced into Ecuador about 100 times almost simultaneously. Throughout the year, we found different patterns of spread, with more short-distance transmissions possibly associated with recreational activities during less stringent restrictions. During strict measures, SARS-CoV-2 was less likely to be introduced from one area to another than during lax or suspended contact restrictions.
Was there anything that surprised you?
We were surprised at how well the different experimental approaches - i.e., PCR and genetic comparisons - agreed in their conclusions about the impact of the measures on the spread of SARS-CoV-2. We also found it interesting that these data from a poor country confirm similar studies from rich countries like Switzerland.
What’s your takeaway?
Our virological analyses suggest that contact restrictions in Ecuador attenuated the spread of SARS-CoV-2 to some degree during the first year of the pandemic, despite high labor mobility. This finding may be considered in future pandemics of similarly transmitted pathogens when weighing the pros and cons of contact restrictions. Because, of course, not only does the spread of pathogens involve societal costs, but so do containment measures.
Moreira-Soto A et al. Virological evidence of the impact of non-pharmaceutical interventions against COVID-19 in Ecuador, a resource-limited setting. Emerg Microbes Infect 2023 12(2):2259001. doi: 10.1080/22221751.2023.2259001