What is R0 and why is it important?

R0 is a mathematical term that represents the number of new infections that could stem from a single case

The R0 value indicates how contagious an infectious disease is and hence it is an important marker to study the progression of a disease

As an infection is transmitted to new people, it reproduces itself. Therefore, R0 is also referred to as the reproduction number

R0 indicates the average number of people who contract a contagious disease from an infected person

It specifically applies when everyone in the population is completely vulnerable to the disease

That is, people in a population where no one has been vaccinated, no one has had the disease before and when there’s no way to check the spread of the disease

Using the R0 value, the transmission rate of a disease or its decline can be calculated

If R0 is less than 1, each existing infection causes less than one new infection. In this case, the disease will decline and eventually die out

If R0 equals 1, each existing infection causes one new infection. The disease will stay alive and stable, but there won’t be an outbreak or an epidemic

If R0 is more than 1, each existing infection causes more than one new infection. The disease will be transmitted between people, and there may be an outbreak or epidemic

R0 of a disease is calculated on the basis of its infectious period, mode of transmission, and contact rate

If the disease has a longer infectious period, then it is more likely that an infected person can transmit it to other people

So the R0 value will be higher if it has a longer infectious period

The disease will be transmitted quickly, if an infected person comes in contact with people who aren’t infected or vaccinated. Therefore, high contact rate will result in a higher R0 value

The mode of transmission also contributes to the R0 value

For example, airborne illnesses are transmitted the fastest and easiest. Therefore, they tend to have a higher R0 value than those spread through direct contact

Countries have been trying to find out the R0 value of COVID-19 as a metric to find out the transmission rate of the virus

But the R0 value is not a constant number

The estimates can vary by location, depending on factors such as how often people come into contact with each other and the efforts taken to reduce viral spread

Preliminary studies estimated a global R0 value for COVID-19 to be between 2 and 3.This means each infected person has spread the virus to an average of 2 to 3 people

But some recent studies suggest COVID-19 has an even higher R0 value

According to Institute of Mathematical Sciences, Chennai, between April 13 and May 10, the R0 value of COVID-19 in India remained steady at 1.29

At the beginning of lockdown, it was 1.83

An R0 of 1 and above tends towards exponential growth whereas an R0 of below 1 tends towards the end of the outbreak

Therefore, it is important to is keep the R0 value below 1

Видео What is R0 and why is it important? канала The Hindu