The effect of coronavirus disease 2019 (COVID-19) response in China shows that quarantine, social distancing, and isolation of infected persons can contain the epidemic in other countries where COVID-19 is beginning to spread, according to a substantially-sourced commentary article published in The Lancet.
Comparing historic data from the 2002 to 2003 severe acute respiratory syndrome epidemic and the 2009 influenza A H1N1 pandemic with the current COVID-19 pandemic, researchers analyzed the early government action and social distancing measures taken by individuals. Key factors, such as the basic reproduction number, are poorly understood at present for COVID-19, which could determine the mean number of secondary cases generated by 1 primary case.
Compared with the H1N1 pandemic, during which most infected people had a short length of time to infection and a few days of peak infectiousness to others, COVID-19 has a serial interval estimated to be 4.4 to 7.5 days, making it more similar in this quality to severe acute respiratory syndrome. One of the most important unknowns for COVID-19 is the case fatality rate, which relies on data for the number of people infected. COVID-19 best estimates for case fatality rate are estimated to range between 0.3% and 1%, which is higher than the approximate 0.1% for a moderate influenza A season.
The incubation period for COVID-19 is hypothesized to be roughly 5 to 6 days, however, it is unknown whether infectiousness may start before onset of symptoms. There is further uncertainty regarding the number of asymptomatic cases of COVID-19. Compared with influenza A, the infectious period seems longer for COVID-19; studies have identified a period of ≥10 days after the incubation period. Researchers believe that the COVID-19 epidemic spreads more slowly than a new, seasonal influenza A strain, and it could have a longer duration. Furthermore, the effect of the upcoming warmer temperatures may not necessarily reduce transmission.
“What is left at present for mitigation is voluntary plus mandated quarantine, stopping mass gatherings, closure of educational institutes or places of work where infection has been identified, and isolation of households, towns, or cities,” the commentary authors concluded. They further stressed that though important leases may be gained from analyses of influenza A, there are equally important differences. Measure for response to COVID-19 may require broader-scale social distancing to allow the time essential for healthcare facilities to treat current cases and increase capacity, and, in the longer term, for vaccines and treatments to be developed. Currently underway in northern Italy is an approach targeted at the containment of the infection within certain areas; this will provide valuable data on the effectiveness of such measures.
The study authors noted there are difficult decisions ahead for governments. Moreover, individuals responses to advice on how best to prevent transmission will be as important as government actions, if not more so—early self-isolation, seeking medical advice remotely unless symptoms are severe, and social distancing are of vital importance. They concluded that, “Government communication strategies to keep the public informed of how best to avoid infection are vital, as is extra support to manage the economic downturn.”
Disclosure: One study author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Anderson RM, Heesterbeek H, Klinkenberg D, Hollingsworth TD. How will country-based mitigation measures influence the course of the COVID-19 epidemic? [published online March 9, 2020]. Lancet. doi:10.1016/S0140-6736(20)30567-5