Coronavirus spreading at different rates affecting countries like US, France and UK faster than others: Study
It has been over two months since the new coronavirus made its initial appearance in Wuhan. After traveling far and wide and making its presence felt in more than 100 countries, the virus appears to be spreading at a different tempo in most of them, according to an analysis.
This tempo depends on how easily the virus spreads between people. In some countries, the virus is spreading at a faster rate than others.
For instance, in Switzerland, the virus seems to be capable of jumping from one person to up to five people. However, in Japan, the virus is less active as only two people, on average, are contracting the disease from a single infected person.
Every time a new virus attacks, epidemiologists try to figure out the degree of spread. This measure is what scientists call the Reproduction number or R naught (R0).
In other words, R0 is the number of people who can contract the virus from an infected individual. A lower number indicates that the spread is coming under control. A high one, on the other hand, could point towards a pandemic.
The World Health Organization (WHO) had earlier pegged the number to hover between 2 and 2.5, globally for COVID-19 — higher than for influenza. These variations in R0 across the globe are the result of several factors, including environment, population density and susceptibility to a disease in a population.
It also depends on the behavior of those infected. "It can be affected by several factors such as the number of susceptible individuals an infected person comes into contact with. This is why public health measures being put into effect are important and can influence the R0," Dr Krutika Kuppalli, Leader in Biosecurity Fellow at Johns Hopkins Center for Health Security and who was not involved in the study, told MEA WorldWide (MEAWW).
A few countries with high reproductions numbers include Sweden, the US, Germany, UK, Spain and France. The US has an R0 that averages between 2 and 4, meaning the virus is spreading to up to four people from an infected person.
Italy, which now ranks second after China, has an R0 between 1.7 and 1.9. As Italy inches closer to the 10,000 mark, the whole country has been placed under quarantine.
Countries on the lower spectrum include Japan, South Korea and China.
Conditions in the two worst-hit countries — China and South Korea — are improving, according to WHO. China is bringing its epidemic under control and the Republic of Korea is reporting a decline in the number of cases.
In China, the R0 stands between 0.3 and 0.5. This reflects on the number of new cases coming out of China. On March 10, the country reported only 19 new infections.
As Kuppalli pointed out, public interventions go a long way in changing the R0 and thereby the trajectory of the outbreak. A study from China found that public health measures brought down the reproductive number from 3.86 to 0.32, preventing 94.5% infections till February 18.
"The Republic of Korea has increased efforts to identify all cases and contacts, including drive-through temperature testing to widen the net and catch cases that might otherwise be missed," Dr Tedros Adhanom Ghebreyesus, Director-General of the WHO, said.
You can find the analysis here. It has not been peer-reviewed yet.