Since March, a total of 176455 cases of indigenous infections have been reported nationwide, affecting 29 provinces and showing a multi-point sporadic state. The epidemic in Shanghai is in a rapidly rising stage and has spilled over to other provinces and cities on many occasions. How long will this wave of COVID-19 continue? New mutant strains have emerged, how to deal with them?
Due to the long-term epidemic prevention and control measures, there has been a serious medical run in some places, and many people have begun to expect to coexist with the virus. But is this really possible? Is the virus really less toxic?
The main strain of the new crown virus that is currently circulating is Omicron, which is also the main strain of the recent domestic epidemic. Although many believe that Omiljung is only more transmissible, its toxicity is weaker and tends to be milder, resulting in a lower risk of severe illness and death. As a result, more and more people are beginning to advocate coexistence with the virus, but it is worth mentioning whether lifting the lockdown will lead to an increase in the number of COVID-19 deaths.
In a study published in JAMA Health Forum, titled "Projecting COVID-19 Mortality as States Relax Nonpharmcologic Interventions," researchers conducted a simulation study to predict how the number of COVID-19 deaths would change after restrictions were eased at different points in time. They found that in this simulation modelling study, whenever the epidemic prevention restrictions are lifted, it may lead to a significant increase in the number of COVID-19 deaths. Moreover, population immunity levels are associated with peak COVID-19 deaths.
Figure 1 Research findings (Source: JAMA Health Forum)
In the study, the researchers extended the traditional SEIR model to divide the population into susceptible, exposed, infected, recovered, and dead. Among them, people under 65 years of age are at low risk, with a 0.5% risk of death from infection without vaccination, while people over 65 years of age are at high risk and have a 3.0% risk of death from infection without vaccination. There are mainly the following vaccinations in the population: 0 doses (not yet vaccinated), 1 dose (incomplete vaccination), 2 doses (complete vaccination), after 1 dose and 2 doses of vaccination, the risk of human infection with the new crown virus is reduced by 46% and 92%, and the risk of death is reduced by 72% and 95%, respectively. The model also distinguishes between those willing to receive booster injections and those who are reluctant to receive the vaccine.
The researchers primarily predicted COVID-19 deaths in 50 U.S. states, the District of Columbia, and Puerto Rico in 2022, and they also calculated the Spearman rank correlation coefficient to measure the correlation between population immunity levels and the surge in COVID-19 deaths when restrictions are lifted. The results show that the degree of rebound in the number of COVID-19 deaths after the relaxation of epidemic prevention restrictions depends largely on the level of herd immunity in the community. For communities with high vaccination rates or a higher proportion of COVID-19 infections (indicating higher herd immunity levels), the rebound in COVID-19 deaths will not be too pronounced.
Figure 2 Model-based projections of COVID-19 deaths in 2022 after the lifting of covid-19 restrictions (Source: JAMA Health Forum)
Note: After different states in the United States relax epidemic prevention restrictions at different points in time, the number of COVID-19 deaths will rebound.
The results of this study show that due to the high spread of the current SARS-CoV-2 variant Omicron, premature deregulation of epidemic prevention and control restrictions will inevitably lead to a rebound in the number of COVID-19 deaths. And even if the time limit for the relaxation of the epidemic is delayed, it will not completely avoid the result of the rebound in the number of new crown deaths.
This study indirectly proves that there is no best way to end the new crown epidemic at present, or to adhere to active prevention and control, dynamic clearance, and hastily relax the epidemic restrictions will only cause more serious consequences.
Written by | Muzijiu
Typography | Muzijiu
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Resources:
[1] Linas BP, Xiao J, Dalgic OO, et al. Projecting COVID-19 Mortality as States Relax Nonpharmacologic Interventions. JAMA Health Forum.2022;3(4):e220760. doi:10.1001/jamahealthforum.2022.0760
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