HERD IMMUNITY: THE MYTHS and REALITIES.

Byline: NAZIR AHMED SHAIKH

For last few weeks, the concept of herd immunity is making headlines in the international media with reference to COVID- 19. Herd immunity is an epidemiological term usually reserved to describe how the population as a whole is protected from a disease depending on the levels of people vaccinated.

WHAT IT IS? Herd immunity (or community immunity) occurs when a high percentage of the community is immune to a disease (through vaccination and/or prior illness). So it is unlikely that disease will spread from person to person. The people not vaccinated (such as newborn and the immunocompromised) are offered some protection because the disease has little opportunity to spread within the community.

CONCEPT OF HERD IMMUNITY The logic of herd immunity is deceptively simple. The antibodies that our bodies need to fight off the infection are developed through two ways:

By getting the infection and allowing our body to develop antibodies naturally.

Through vaccination whenever the vaccine is developed. When a person is infected with a virus, the body produces antibodies that fight off the infection and the person recovers. After the recovery, he becomes immune to the virus which means he cannot get it again and cannot infect any other person. If 70 percent of the population of a country therefore is infected with the virus, the remaining 30 percent will have very low probability of getting infected. This is because the 70 percent who are infected and recover are not passing on the infection.

THE SWEDEN SCENARIO

Sweden has broken away from international norms and has not instituted any formal lockdowns. It has, however, strongly advised its citizens to practice social distancing and asked older citizens to stay at home while clamping restrictions on access to nursing homes. Vaccines prevent many dangerous and deadly diseases. In the United States, smallpox and polio have both been stamped out because of vaccination. However, there are certain groups of people who cannot get vaccinated and are vulnerable to disease: babies, pregnant women, and immunocompromised people, such as those receiving chemotherapy or organ transplants.

Measles was declared eliminated in 2000. Yet in 2014, there were 668 cases reported. The disease was spread when infected people traveled to the United States. These infected people then exposed unprotected people to the disease. There are a number of reasons why people are unprotected: some protection...