TY - JOUR
T1 - Will an imperfect vaccine curtail the COVID-19 pandemic in the U.S.?
AU - Iboi, Enahoro A.
AU - Ngonghala, Calistus N.
AU - Gumel, Abba B.
N1 - Funding Information:
There are currently no approved vaccines and effective therapies for use against COVID-19. Hence, control efforts against COVID-19 are focused on using basic non-pharmaceutical interventions (NPIs), such as social distancing, quarantine of people suspected of being exposed to COVID-19, isolation of confirmed cases, use of face masks in public and contact-tracing (Ngonghala et al., 2020; Ferguson et al., 2020; Eikenberry et al., 2020). There is now a concerted global effort to develop a safe and effective anti-COVID-19 vaccine to help combat the COVID-19 pandemic. Although the development of new vaccines generally take years, a number of pharmaceutical companies, with support from numerous government agencies and regulatory authorities, are doing everything possible to fast-track the availability of a safe and effective vaccine against COVID-19. Over a dozen organizations have announced plans to start efficacy testing for their candidate vaccines (Knvul and Katie, 2020; Callaway, 2020; Kirkpatrick, 2020). In fact, scientists at the Jenner Institute at the Oxford University have developed a new coronavirus vaccine that is undergoing early-phase trials, and they expect the first few million doses of their vaccine to be widely available as early as September 2020 (Callaway, 2020; Kirkpatrick, 2020). A Maryland-based biotechnology company Novavax has begun human clinical trials for its candidate vaccine in Australia (Knvul and Katie, 2020). Similarly, Mesoblast, a company supported by the National Institutes of Health (NIH), started a 240-patient clinical trial aimed at testing whether cells derived from bone marrow could help patients who developed a deadly immune reaction to the coronavirus (Knvul and Katie, 2020). Thus, there is an urgent need to develop and use mathematical models to assess the population-level impact of a future hypothetical vaccine against COVID-19. This forms the objective of the current study.One of the authors (ABG) acknowledge the support, in part, of the Simons Foundation (Award #585022) and the National Science Foundation (Award #1917512). CNN acknowledges the support of the Simons Foundation (Award #627346). The authors are grateful to the two anonymous reviewers and the Handling Editor for the constructive comments. The authors are grateful to Dr. Elamin H. Elbasha (Merck Inc.) for the careful reading of the manuscript and for the valuable comments on the computation of the vaccine-derived herd immunity threshold.
Funding Information:
One of the authors ( ABG ) acknowledge the support, in part, of the Simons Foundation (Award 585022 ) and the National Science Foundation (Award 1917512 ). CNN acknowledges the support of the Simons Foundation (Award # 627346 ). The authors are grateful to the two anonymous reviewers and the Handling Editor for the constructive comments. The authors are grateful to Dr. Elamin H. Elbasha (Merck Inc.) for the careful reading of the manuscript and for the valuable comments on the computation of the vaccine-derived herd immunity threshold.
Publisher Copyright:
© 2020 The Authors
PY - 2020
Y1 - 2020
N2 - The novel coronavirus (COVID-19) that emerged from Wuhan city of China in late December 2019 continue to pose devastating public health and economic challenges across the world. Although the community-wide implementation of basic non-pharmaceutical intervention measures, such as social distancing, quarantine of suspected COVID-19 cases, isolation of confirmed cases, use of face masks in public, contact tracing and testing, have been quite effective in curtailing and mitigating the burden of the pandemic, it is universally believed that the use of a vaccine may be necessary to effectively curtail and eliminating COVID-19 in human populations. This study is based on the use of a mathematical model for assessing the impact of a hypothetical imperfect anti-COVID-19 vaccine on the control of COVID-19 in the United States. An analytical expression for the minimum percentage of unvaccinated susceptible individuals needed to be vaccinated in order to achieve vaccine-induced community herd immunity is derived. The epidemiological consequence of the herd immunity threshold is that the disease can be effectively controlled or eliminated if the minimum herd immunity threshold is achieved in the community. Simulations of the model, using baseline parameter values obtained from fitting the model with COVID-19 mortality data for the U.S., show that, for an anti-COVID-19 vaccine with an assumed protective efficacy of 80%, at least 82% of the susceptible US population need to be vaccinated to achieve the herd immunity threshold. The prospect of COVID-19 elimination in the US, using the hypothetical vaccine, is greatly enhanced if the vaccination program is combined with other interventions, such as face mask usage and/or social distancing. Such combination of strategies significantly reduces the level of the vaccine-induced herd immunity threshold needed to eliminate the pandemic in the US. For instance, the herd immunity threshold decreases to 72% if half of the US population regularly wears face masks in public (the threshold decreases to 46% if everyone wears a face mask).
AB - The novel coronavirus (COVID-19) that emerged from Wuhan city of China in late December 2019 continue to pose devastating public health and economic challenges across the world. Although the community-wide implementation of basic non-pharmaceutical intervention measures, such as social distancing, quarantine of suspected COVID-19 cases, isolation of confirmed cases, use of face masks in public, contact tracing and testing, have been quite effective in curtailing and mitigating the burden of the pandemic, it is universally believed that the use of a vaccine may be necessary to effectively curtail and eliminating COVID-19 in human populations. This study is based on the use of a mathematical model for assessing the impact of a hypothetical imperfect anti-COVID-19 vaccine on the control of COVID-19 in the United States. An analytical expression for the minimum percentage of unvaccinated susceptible individuals needed to be vaccinated in order to achieve vaccine-induced community herd immunity is derived. The epidemiological consequence of the herd immunity threshold is that the disease can be effectively controlled or eliminated if the minimum herd immunity threshold is achieved in the community. Simulations of the model, using baseline parameter values obtained from fitting the model with COVID-19 mortality data for the U.S., show that, for an anti-COVID-19 vaccine with an assumed protective efficacy of 80%, at least 82% of the susceptible US population need to be vaccinated to achieve the herd immunity threshold. The prospect of COVID-19 elimination in the US, using the hypothetical vaccine, is greatly enhanced if the vaccination program is combined with other interventions, such as face mask usage and/or social distancing. Such combination of strategies significantly reduces the level of the vaccine-induced herd immunity threshold needed to eliminate the pandemic in the US. For instance, the herd immunity threshold decreases to 72% if half of the US population regularly wears face masks in public (the threshold decreases to 46% if everyone wears a face mask).
KW - COVID-19
KW - Non-pharmaceutical intervention
KW - SARS-CoV-2
KW - Social distancing
KW - Vaccination
UR - http://www.scopus.com/inward/record.url?scp=85089599846&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85089599846&partnerID=8YFLogxK
U2 - 10.1016/j.idm.2020.07.006
DO - 10.1016/j.idm.2020.07.006
M3 - Article
AN - SCOPUS:85089599846
SN - 2468-0427
VL - 5
SP - 510
EP - 524
JO - Infectious Disease Modelling
JF - Infectious Disease Modelling
ER -