Researchers compare the percent excess mortalities due to the zero-COVID-19 policy or the living-with-COVID policy

In a recent study posted to the medRxiv* preprint server, researchers compared the percent excess mortalities due to the zero-coronavirus disease 2019 (COVID-19) (ZC) policy or the living-with-COVID (LWC) policy.

Background

Since the emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant in 2021, several countries have applied the LWC instead of the ZC policy to facilitate the normalcy of pre-COVID life. However, the high infectivity and transmissibility of Omicron have raised concerns regarding the mortality burden associated with the LWC policy.

About the study

In the present study, researchers estimated the excess mortalities to compare the efficacy of the LWC and ZC policies in protecting human lives within the same country during the COVID-19 pandemic.

The team collected all-cause mortality from governmental sources for four countries, including Australia, New Zealand, South Korea, and Singapore, and one region, including Hong Kong. The information collected included weekly or monthly data related to mortalities observed between January 2020 and March 2022 in Singapore, April 2022 in South Korea, March 2022 in Australia, June 2022 in New Zealand, and April 2022 in Hong Kong. Furthermore, data related to confirmed COVID-19 cases as well as COVID-19-associated mortalities were collected for the four countries and one region from Google’s COVID map.     

Expected mortality estimated in the study was defined as deaths noted in a period assuming the absence of the pandemic. It is calculated according to past trends of all-cause mortality. The team employed the linear regression method to calculate expected mortality. Furthermore, excess mortality was estimated as the difference between observed and expected mortality, while percent COVID-excess mortality (PCEM) was calculated as the percentage of deaths associated with COVID-19 divided by expected mortality. The team then compared PCEM with percent excess mortality (PEM) to assess the contribution of COVID-19-related deaths to overall excess mortality.

Results

The Singaporean government's monthly mortality statistics generated a PEM curve from January 2020 to March 2022. Before August 2021, PEM in Singapore under the ZC policy ranged between 0 and 10%. In August 2021, Singapore adopted the LWC policy and then had the Delta epidemic. Peak PEM reached a value of 31.53%, while the average value from September to December 2021—the time of the Delta outbreak—was 24.23%. Under the LWC program, the mortality burden—measured as the discrepancy between observed mortality and predicted mortality—rose sharply. Overall, Singapore's LWC strategy throughout the studied period could not effectively reduce the death burden.

In South Korea, PEM dropped to less than 0% in January 2022. According to the most recent data, PEM significantly rose following the policy change. Additionally, during the Omicron outbreak, the PECM curve was much lower than the PEM curve, indicating that COVID indirectly caused a high number of deaths under the LWC policy when coming into contact with the Omicron variety. It could be attributable to overburdened medical resources or an underestimation of mortality linked to COVID. Overall, the LWC policy in South Korea did not successfully reduce the mortality burden throughout the studied period, particularly in response to the Omicron variation. 

According to the most recent data, PEM significantly rose following the regulation change. Additionally, the PCEM curve was much lower than the PEM curve, indicating that a sizable portion of deaths under the LWC policy was driven by COVID-19 indirectly. It could be attributable to overburdened medical resources or an underestimation of mortality linked to COVID. The mortality burden under the LWC policy also increased significantly, as shown by the discrepancy between observed mortality and predicted mortality. Before April 2022, Australia's LWC program as a whole did not effectively reduce the mortality burden.

In accordance with the LWC strategy, New Zealand was the only country to reach an average PEM of around 10%. This might be due to the country's extremely high vaccination rate, particularly among the elderly. The lack of a significant disparity between the PCEM and the PEM curves suggests that the mortality burden associated with COVID-19 was accurately reflected in the data on COVID-related deaths.

Furthermore, even during the period of the policy shift, the mortality burden, as shown by the discrepancy between observed mortality and projected mortality, remained virtually unchanged. Overall, the LWC strategy in New Zealand throughout the studied period had a satisfactory success rate in reducing the mortality burden.

Conclusion

The study findings showed that PEM was considerably higher when the LWC policy was applied than during the ZC policy application. The researchers believe that the precondition associated with the transition of each policy should be thoroughly examined, while the current LWC policy needs appropriate revision to attain a lower PEM.

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Written by

Bhavana Kunkalikar

Bhavana Kunkalikar is a medical writer based in Goa, India. Her academic background is in Pharmaceutical sciences and she holds a Bachelor's degree in Pharmacy. Her educational background allowed her to foster an interest in anatomical and physiological sciences. Her college project work based on ‘The manifestations and causes of sickle cell anemia’ formed the stepping stone to a life-long fascination with human pathophysiology.