One India | 19/05/2021 12:55 PM | Click to read full article
Herd immunity may exist globally, as it does with smallpox, or in a country or region. This has happened only once on a global scale, with the eradication of smallpox in 1980. This was after a decade-long worldwide intensive vaccination campaign.
We also are also approaching global herd immunity for polio. After 33 years of immunisation campaigns, Afghanistan and Pakistan are the only countries with wild poliovirus.