R₀ (Pronounced R naught)

Virus transmission term ‘R₀’(Pronounced R naught) : Covid-19

Context: While people around the world are currently living under a lockdown due to the COVID- 19, researchers are still in the process of understanding the nature of its transmission.

About R₀(Reproduction Rate)

• It is the rate at which a virus is transmitted.
• It is also called the basic reproduction number, it indicates the average number of people who will contract the virus from a person who has already been infected, in a population that does not have immunity for the said disease.

Its Mathematical Representation

• R₀ is the division of the number of new infections by the number of existing infections, or the average number of new infections over an infectious period
• R₀= new infections/existing infections

Infectious Period

• It depends on the virus, which can be a few weeks, months, or even decades.
• The virus is assumed to be introduced to a population that does not have herd immunity or vaccination against it.

Range of R0 for Eradicating a Disease

• The ideal scenario is when the R₀ is below 1.
• This means the infection is transmitted to fewer people. When such a rate is maintained over a considerable period of time, the disease is eradicated.

About World Study

• While many studies have differed in their conclusions, the World Health Organization (WHO) has estimated the R₀ for coronavirus at 1.4 to 2.5.
• In China’s Wuhan, where the disease originated, lockdown measures brought the Rt (effective rate) down to 0.3, thus significantly slowing the number of new infections.
• Governments around the world which have enforced such measures are hoping to follow the same path, although experts fear a second wave of infections once lockdowns are lifted.