Importation Risk Index calculation
The specific methodology to derive importation risk index for a for a
given destination was demonstrated by many researchers (Haider et al.,
2020; Massad & Wilder‐Smith, 2009). Based on these studies we used the
similar methodology to derive the importation risk index using the
following equation.
\(Importation\ risk\ index=\sum_{i=1}^{n}{a\frac{P}{T}\frac{I}{N}}\)
where, a is the transmission rate, which is assumed to be 2.5
(recommended by WHO), P is the total number of India bound seats
from the international airports in the origin country, and T is
the total number of seats in all the airlines originating from the
selected airports or origin country. I is the total number of
2019-nCoV infected patient in the origin country and N is the
population of the origin country. The Importation Risk Index is a
weighted risk number and is proportional to the risk possessed by a
country to import 2019-nCoV cases into India.
The estimation was carried out for 24 airports selected across ten
countries, and a Pearson Correlation coefficient test between the
estimated risk index and the total number of imported 2019-nCoV cases in
India from these countries up to 24th March, as
reported by the government, was performed. The detailed results are
presented below.