Abstract
Thanks to the high vaccination rates posted in Israel and the United Arab Emirates since mid-December 2020, by end of March 2021 a significant portion of the population has been vaccinated. This adds to the percentage of those who have been infected and have recovered, protected to a different extent depending on the time of infection. The manuscript tries to understand the effect of vaccinated and previously infected on the number of new cases, based on the available data for the number of cases, tests, vaccines’ doses, and fatalities. The positive effect of vaccinations on the new cases has been masked so far by confounding factors, as it is not evidenced by the proposed data.
Highlights
According to their latest statement [1], the World Health Organization (WHO) supports herd immunity for Covid-19 through vaccination
This paper aims to provide a first answer to the following questions: For how long will infected and recovered individuals belong to the removed category? How many of those vaccinated belong to the removed category and for how long? How protective are vaccines and prior infections toward new strains? We will try to answer these questions based on the available data for the number of cases, tests, fatalities, and vaccine doses
The percentage of the population that has been vaccinated (February 5, 2021) starts to become significant, and the number is growing fast. This permits a first assessment of the hypothesis of herd immunity by vaccination or infection
Summary
According to their latest statement [1], the World Health Organization (WHO) supports herd immunity for Covid-19 through vaccination. How protective are vaccinations or prior infections and for how long is an open question [6,7,8,9]. Using Kermack and McKendrick’s [10] simple SIR model (S susceptible, I infected, R removed), vaccination would lower the number of “susceptible” individuals—moving them to the “removed” category, thereby limiting further spread of the virus. A substantial percentage of the population needs to be vaccinated. The percentage of people that must be vaccinated against Covid-19 for herd immunity is not known [1]. People who have been infected and have recovered are moved from the “susceptible” to the “removed” category. The removal is only temporary, protection against subsequent waves with possibly different strains is unlikely
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