Percentages of Vaccination Coverage Required to Establish Herd Immunity against SARS-CoV-2

Abstract

The pandemic associated with SARS-CoV-2 is a worldwide public health challenge. The WHO has proposed to achieve 70% COVID-19 vaccination coverage in all countries by mid-2022. Nevertheless, the prevention strategy based on COVID-19 vaccination and other applied prevention measures has not been sufficient to prevent SARS-CoV-2 epidemic waves. This study assessed the vaccination coverage that would be required to establish herd immunity against SARS-CoV-2, taking into account virus transmissibility (Ro values from 1.1 to 10) and COVID-19 vaccination effectiveness. The study found that high percentages of vaccination coverage and high levels of vaccination effectiveness are necessary to block the transmission of Omicron and other SARS-CoV-2 variants with greater infectious capacity. COVID-19 vaccination programs could establish herd immunity against SARS-CoV-2, with Ro values ranging from 3 to 10 and levels of COVID-19 vaccination effectiveness of 70–100%. Factors reducing COVID-19 vaccination effectiveness (emergent variants, infections among vaccinated individuals, high risk individuals) and factors increasing SARS-CoV-2 transmissibility (close settings) increased the percentages of vaccination coverage that would be required to establish herd immunity. Two measures should be implemented to establish herd immunity against SARS-CoV-2: (1) achieve ≥90% COVID-19 vaccination coverage in all countries worldwide, and (2) increase the effectiveness of COVID-19 vaccines in preventing Omicron infection to at least 88%.

Estimating the Global Spread of Epidemic Human Monkeypox with Bayesian Directed Acyclic Graphic Model

“…The additional assumptions our deterministic SIR model also follows are (1) a fixed infectious period and that (2) the duration of these compartments are exponentially distributed. The minimal vaccine coverage considering the effectiveness against monkeypox is often derived by Vc = Ic/E = [1 − (1/Ro)]/E [ 15 ]), where Ic denoted the herd immunity threshold and E denoted the level of vaccine effectiveness. Following this rationale, we estimated the herd immunity threshold (Vc) using our maximum estimated R 0 /R e to allow for the cross-protection afforded by smallpox vaccination.…”

Indirect Dispersion of SARS-CoV-2 Live-Attenuated Vaccine and Its Contribution to Herd Immunity

“…A population has reached herd immunity when it has a proportion of immune individuals against a particular pathogen equal to or above the HIT [ 62 , 63 ]. To calculate the proportion of the immune population required to reach the HIT, one must consider the pathogen dispersion capacity, which is given by the reproduction number R 0 , which indicates the average number of non-immune individuals whom a sick individual infects [ 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 ]. The fraction of the population required to reach HI in populations with a homogeneous immune response elicited by highly effective vaccines is calculated by the formula 1 − 1/R 0 .…”

“…Nevertheless, the HIT can be calculated more precisely by considering several population factors and vaccine effectiveness [ 52 , 60 , 64 ]. It is generally considered that 70% percent of immune individuals against a particular pathogen in a population confers HI [ 52 , 58 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 ]. A similar percentage has been considered necessary for the SARS-CoV-2 case considering an R 0 = 3 and a HIT = 67 [ 58 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 ].…”

“…It is generally considered that 70% percent of immune individuals against a particular pathogen in a population confers HI [ 52 , 58 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 ]. A similar percentage has been considered necessary for the SARS-CoV-2 case considering an R 0 = 3 and a HIT = 67 [ 58 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 ]. This percentage might vary between countries or regions [ 67 , 74 , 75 ].…”

The Effect of COVID-19 Vaccine Acceptance, Intention, and/or Hesitancy and Its Association with Our Health and/or Important Areas of Functioning

“…COVID-19 vaccination was, therefore, seen as one of the possible methods of returning to a state of normalcy. Earlier researchers suggested at least a 70% vaccination record to achieve herd immunity [ 25 ]. However, until now, there have been challenges with the vaccination drive.…”