65 to 70 percent of population should have immunity to check coronavirus spread: WHO

Hyderabad: So much is being said on herd immunity subject for the last few months and WHO for the first time made a prediction on it. According to it, 65 to 70 percent of the population (all age groups, urban and rural) should have protective immunity which would put a brake on the spread of virus infection.

What percentage of the population that needs to have protective immunity is still something that is being looked into but in general the more transmissible the virus the higher the proportion of the people that needs to be immune, it said.

If you look at measles virus where one person can transmit 15 to 20 people you need 95 percent of that population to have protective immunity, through a vaccine in general, the health body pointed out.

In case of novel coronavirus, we know that one infected person could potentially transmit to two to three or it could be even more people given the setting; if it's a crowded setting it could be one person passing on the virus to more than three or four people, the WHO said.

WHO predicted 65 to 70 per cent of herd immunity can be reached safely and efficiently through a vaccine.

Private labs that have been conducting antibody tests in Hyderabad for the last few weeks have also found that the antibodies to fight coronavirus were developed in nearly 50 per cent of tests done by them. People undergoing antibody tests are not necessarily be Covid infected. People who had to go out of the house every day because of duties or business-related works, are also undergoing tests to know if coronavirus infected their bodies and also went out without their notice.

Experts say growth rate if reduced below one per cent new cases will fall considerably which is an indication of moving towards attaining herd immunity. Already growth rate in some States that reported highest cases in the country, has fallen below one percent because of which new cases have slowed down considerably.

Even in the second most-affected nation in the world--Brazil, the growth rate has come down below one per cent and it reporting less number of new cases.

Giving his view, Dr. Madala Kiran, HoD, anesthesia, and Critical Care, GMC (Nizamabad) said that if we look at the trend in States like Maharashtra, Delhi and Gujarat, cases are growing at 1% every day when the national average is above 2%. It is reflected in their sero-prevalence which is at 40% in most of the places. India is also expected to touch 1% growth rate by December end which corresponds to flattening of the curve. We will reach partial herd immunity by that time, Dr. Kiran said.