Studies find that herd immunity is an impractical strategy – YubaNet

According to a new model developed by scientists at the University of Georgia, September 23, 2020 – Achieving herd immunity to COVID-19 is an unrealistic public health strategy. The study was recently published in the minutes of the National Academy of Sciences.

The management of COVID-19 poses a challenge to public health policy makers.

How to prevent overwhelming healthcare infrastructure while avoiding major social turmoil? The discussion revolved around two proposed strategies. One idea is aimed at “control” and eliminates infections in the community through drastic social distancing measures, while the other strategy is “mitigation”, which is sufficient for the population without exceeding healthcare. Capacity aimed at achieving herd immunity by allowing a large proportion of infections.

“Because it marks the end of the COVID-19 threat, the concept of herd immunity is appetizing,” said Toby Brett, a postdoctoral fellow and lead author of the study at the Odum School of Ecology. “But this approach aims to avoid eradicating the disease, so lockdown measures are taken to ensure that a sufficient number (but not too many) of people are infected at a given time. With these challenges, the swarm’s immune strategy is actually like trying to walk a barely visible tightrope. “

This study was conducted by Brett and Peyman Rohani of the University of Georgia. Infectious Disease Ecology CenterIs investigating suppression and mitigation approaches to control the spread of SARS-CoV-2, the virus that causes COVID-19.

Recent studies have investigated the effects of both suppression and mitigation strategies in some countries, but Brett and Rohani ask whether countries can achieve herd immunity without overburdening the healthcare system. He said he tried to decide and how to do it and define the control efforts needed to implement it.

They have developed an age-based disease infection model that simulates SARS-CoV-2 infection in the United Kingdom and controlled the spread of the infection by self-isolation of symptomatic individuals and various levels of social distance.

According to their simulations, the UK would have died as many as 410,000 without COVID-19-related controls, of which 350,000 were from individuals over the age of 60.

They found that using a suppression strategy resulted in a much lower expected number of deaths: 62,000 for individuals over the age of 60 and 43,000 for individuals under the age of 60.

With high involvement in self-isolation (defined as a reduction of at least 70% of infection), suppression can be achieved in two months regardless of social isolation measures, the closer the school, workplace, and social gathering are, the faster. There is a possibility.

When considering strategies to build herd immunity through mitigation, their model significantly increases hospital capacity so that the healthcare system is not overwhelmed if social distance is maintained at a certain level. I found it necessary. Instead, in order to achieve herd immunity in view of the hospital resources currently available, the United Kingdom is to ensure that the number of sick individuals is equal to, but not exceeding, the capacity of the hospital. You need to adjust the level of social distance in real time. If the virus spreads too quickly, the hospital will be overwhelmed, but if it spreads too slowly, the infectious disease will be suppressed without acquiring immunity to the herd.

Brett and Rohani further noted that much is unclear about the nature, duration, and efficacy of COVID-19 immunity, and that their model assumes complete long-term immunity. They warned that widespread exposure is unlikely to achieve herd immunity if immunity is not perfect and there is great potential for reinfection.

“We recognize that there is still much to learn about COVID-19 transmission and immunity, but we believe that such modeling is invaluable in so-called’situational logic’,” Rohani said. He said. “The model allows stakeholders to consider the outcome of alternative behavioral policies.”

Pejman Rohani is a professor of ecology and infectious diseases at the Regents and UGA athletic meet and is a member of the Odum Ecology School and the Department of Infectious Diseases of the Faculty of Veterinary Medicine. Tobias Brett is a postdoctoral fellow at the Rohani Institute. The research reported in this news release was supported by the National Institute of Medical Sciences, National Institute of Health Sciences, through a grant from the MIDAS (Model of Infectious Disease Pathogen Research) program under Award No. 5R01GM123007.

Transmission dynamics by Tobias S. Brett and Pejman Rohani reveal the impracticality of the COVID-19 herd immune strategy. PNAS September 22, 2020 First Edition doi.org/10.1073/pnas.2008087117