“One touch of nature makes the whole world kin.” (Shakespeare)
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Herd immunity occurs when a large part of the population becomes immune to a virus, through vaccination or infection. If enough people are resistant to the cause of a disease, such as a virus or bacteria, it has nowhere to go. The infection rates drop and the disease peters out.
The key to herd immunity is that, even if a person becomes infected, there are too few susceptible hosts around to maintain transmission - those who have been vaccinated or have already had the infection cannot contract and spread the virus.
This is what stopped the Zika virus outbreak in Brazil; two years after the outbreak began, 63% of the population had exposure to the virus, reaching the right level for herd immunity. Herd immunity is also what stopped polio in the United States and many other countries.
The way ahead is to reach planetary herd immunity by vaccinating at least 65% of the world population. To do so we need, within the next few weeks, 9 billion doses (2 doses to 4.5 billion people), spread evenly across all countries.
If some countries like Israel today have vaccinated 85% of their population while Tanzania almost none, and this pattern of unevenness continues for the 194 states of the world, no planetary herd immunity will be reached. If vaccine roll-out is uneven the world would become divided into the have been and have not been (vaccinated) like the old haves and have nots relating to wealth. Foyers of Corona will still exist; inevitable movements of people and material will then continue to spread the disease.
So what to do in practice?
An immediate first step is for the UN and its specialized agency WHO to set up a top level committee to coordinate action for attaining world herd immunity. And a Vaccine Minister as national focal point in each country.
The Biden action of the US to vaccinate all its population is by itself excellent but unless Central and South America as well as Asia and Europe follow, general/herd immunity WILL NOT BE GARANTEED. Similarly, for the EU; it was very late in ordering sufficient number of doses; it was not able/willing to manufacture vaccines in numerous sites and even tried to restrain/prevent the export of vaccines to Africa and other countries. Such counterproductive measures do not contribute to attain this planetary immunity which the world needs so desperately.
Concerted world action is needed based on scientifically advanced countries (UK, USA, India, Belgium, Russia, China, Germany, France, Japan, Canada, Australia, South Korea, South Africa to mention but a few) to boost their vaccine production rate and /or immediately set up new vaccine production units. Also setting up a practical regional vaccine distribution network, for example vaccines manufactured in South Africa for Africa, Australia for the Pacific, USA for Central America, China and India for the rest of Asia, island states and Africa, and so on.
In the absence of data about the duration of coverage of the presently available vaccines, it is necessary to plan for the production of booster doses, by the end of 2021 or whenever they will be needed. Covid-19 can and will be eradicated, as we have achieved for small pox and polio in human populations and rinderpest in cattle.
Dr Michael ATCHIA
(President, Mauritius Academy of Science and Technology)
(Past Programme Director, United Nations)
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