To eradicate the covid-19, how many people must receive the coronavirus vaccine?

For a while now it has become evident that in the United States at least, vaccination is the only path out of the coronavirus pandemic. Coronavirus vaccinations are being used aggressively, but how many people must be immunized to prevent this pandemic?

At the University of Connecticut, computational biologists use data and computer models to answer biological questions. They have been monitoring the COVID-19 epidemic in the United States using a computer model to anticipate the frequency of hospitalizations at John Dempsey Hospital in the University of Connecticut.

Such type of computer model, as well as the underlying theory, can also be used to determine the vaccination rates required to break the coronavirus transmission chain. To prevent the pandemic, approximately 70% of the population in the United States must be immunized. But there is a degree of uncertainty about the way individuals act in various parts of the country and unanswered questions about whether the vaccine completely prevents the virus or only protects people becoming infected.

The coronavirus will be unable to transmit from individual to individual if enough people are immunized.

Knocking off the spread

Clinical studies have demonstrated that a person will not get infected with COVID-19 after being vaccinated for coronavirus. Even if a person does not become infected can get a coronavirus infection. However, let us also presume that a person vaccinated may not transmit the virus to others, even though researchers do not yet know whether that is true.

The virus has difficulty in finding new persons to infect when enough of the population is vaccinated and the pandemic begins to die. And not all must be vaccinated, only enough people to prevent the transmission of infection. The number of individuals to be vaccinated is known as the critical level of vaccination. Once that number has reached a population, you acquire immunity from herd immunity. Herd immunity occurs when infected individuals cannot identify anybody who could get infected by so many vaccinated individuals that the virus can not spread to anybody else. To safeguard persons who are unable to receive vaccination, this is necessary.

The critical level of vaccination is determined by the infectiousness of the virus and the efficacy of the vaccine. Infectiousness is calculated using the basic reproduction number – R0 – which is the average number of people an infected person would infect if no preventive measures were in place.

The greater the infectiousness of a disease, the greater the number of persons who must be vaccinated to achieve herd immunity. The more efficient the vaccine, the fewer people who need to be immunized.

R0 levels fluctuate due to differences in social behavior in different locations.

Not everywhere is a similar situation

R0 levels vary by region due to differences in population behavior, for example in rural and urban areas social interactions are not the same or in warm climates compared to cold ones.

Using statistics on positive cases, hospitalizations, and fatalities, the above model calculates that Connecticut now has an R0 of 2.88, which means that every infected person on average would infect 2.88 other individuals if no precautions were in place. County estimates vary from 1.44 in remote Alpine, California to 4.31 in city Hudson, New Jersey.

The fact that the R0 value has affected different locations at different periods is especially difficult for the whole of the U.S. because of its diversity of climate (activity has been far from consistent). Estimates vary from 2.47 to 8.2, while most scientists put R0 in 3 for the whole U.S.

The efficacy of vaccines is uniform and widely established, while the R0 fluctuates by location and across studies. The COVID-19 vaccines from Pfizer-BioNTech and Moderna are 95 percent and 94.5 percent effective, accordingly.

We can determine the critical level of vaccination with R0 and vaccine efficacy values. 69% of the population in Connecticut must be immunized at R0 of 2.88. This would be 70% for the US as a whole, with an R0 of 3. This would be 80 percent in New York with an estimated R0 of 4.26

There is a great deal of uncertainty

Whereas the math is rather easy, it becomes difficult to take major challenges into account that epidemiologists still do not have answers to.

First, the formula for the critical level of vaccination implies that people interact at random. In reality, however, people engage in highly disciplined networks based on job, travel, and social relationships. When these contact behaviors are taken into account, some researchers discovered that the critical level of vaccination is significantly lower than if random contacts were expected.

Other unknowns could, unfortunately, have a counter-effect.

Vaccination trials reveal that those who have been vaccinated do not become infected with COVID-19. However, it is yet unclear if the immunizations prevent people from contracting minor illnesses that they can then pass on to others. If vaccinated persons can still become infected and spread the virus, vaccination will not give herd immunity — while it will still prevent major diseases and significantly cut mortality.

One final point which still has to be answered is how much time a person has been immunized against coronavirus. If immunity declines within few months, everyone will need to be vaccinated repeatedly.

The number of people who need to be vaccinated to terminate that epidemic is difficult to determine with accuracy. Yet the coming of vaccines of COVID-19 in 2020 was the most exciting news. In 2021, when a big number of people in the U.S. will receive the vaccine, the government will move to the level of critical vaccination, regardless of that level, to return life to normal.

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About the author


Hi. I'm Shoaib Humayun, a passionate blogger with an interest in everything. This blog guides people about their ideas.

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