Big Data research points out Omicron outbreak had lower mortality rates compared to previous strains of Covid-19
Brazilian study analyzed data from over 40,000 patients admitted to ICUs in the country
Peer-Reviewed PublicationDuring the peak of the Covid-19 pandemic, a constant public fear was the rise of a new variant of the disease. Among the countless possibilities of a SARS-CoV-2 viral mutation, some were really alarming, such as Omicron, Delta, and Gamma. The strains with greater virulence and ability to invade the immune system are defined as variants of concern (VOCs), since they also have the potential to overwhelm the health system, increasing the number of admissions to intensive care units (UTIs). Recently published in the Intensive Care Medicine journal, a new study led by the D'Or Institute for Research and Education (IDOR) used Big Data analysis techniques to compare the profile of patients admitted to Brazilian ICUs during the dominance of different VOCs.
As a research object, the authors evaluated a multicenter cohort of patients with Covid-19 confirmed by RT-PCR diagnosis. These patients were admitted to one of the 231 Brazilian ICUs evaluated in the study, totalizing 47,465 admissions between February 27th, 2020, and March 29th, 2022. The admission data were all provided by Rede D'Or, the largest private hospital network in Latin America.
The scientists divided the information into three time periods: epoch 1 (when there was no dominant VOC; total: 21,996 admissions), epoch 2 (Gamma/Delta dominance; total: 21,183 admissions), and epoch 3 (Omicron dominance; total: 4,286 admissions). After that, they studied the hospital mortality within 60 days after admission, also considering the need for mechanical ventilation (intubation) in the three periods. These complex calculations were executed by a biostatistics software, which employed mathematical models that considered the multiple variables able to interfere with the patient's chance of mortality, such as age, sex, comorbidities, among others, resulting in what the authors described as the adjusted mortality rate.
The researchers noted that during epoch 3 (Omicron dominance), patients were older, averaging 68 years old, whereas this number was 52 years old at epoch 2 and 55 years old at epoch 1. Omicron patients also had a larger number of dysfunctional strokes caused by Covid-19 and required less mechanical ventilation. In the same group, adjusted mortality was lower compared to the previous two epochs. However, for patients who required mechanical ventilation, mortality rates were very similar between all VOCs dominances.
“Patients who need mechanical ventilation at Ômicron are the most fragile, such as the elderly and immunosuppressed patients, and they are at greater risk of developing severe forms of the disease. One of the things our study reveals is that, for these patients, there is still a need to be cautious about the risk of hospitalization and death. Even in epoch 3, the most recent in the study, when there was already vaccination coverage, it wasn't noticed a relevant downturn in mortality rates for patients with Covid-19 who needed mechanical ventilation”, informs the first author and researcher at IDOR, Dr. Pedro Kurtz.
The researcher points out that, according to vaccination data for the Brazilian population, by the end of 2021 more than 60% of adults received the first dose of vaccination, 30% a second dose, and more than 90% of those aged over 60 years old had a full vaccination. Vaccination coverage, therefore, must have contributed to the lower mortality observed in the Omicron period. However, the authors show that even with complete vaccination, the dissemination of variants with high infectivity puts vulnerable patients at risk, especially those who are older, with comorbidities, and who may need hospitalization in more severe cases.
JOURNAL
Intensive Care Medicine
ARTICLE TITLE
Variants of concern and clinical outcomes in critically ill COVID-19 patients
ARTICLE PUBLICATION DATE
24-Apr-2023
Characterizing the contaminated couriers of omicron SARS-CoV-2 variants
HIGHLIGHTS
- SARS-CoV-2 may spread through contaminated shipping containers
- How long Omicron variants persist on shipping materials may be influenced by temperature, humidity and material
- Researchers measured the viability of BA.1 and BA.5 Omicron variants on 4 shipping materials
- The virus was most stable, and most likely to spread, at the lowest temperature.
Washington, DC – The virus that causes COVID-19 spreads through droplets and small particles, but contaminated surfaces of shipping materials may also contribute to outbreaks. Environmental persistence was thoroughly studied at first, but less research has been focused on how long newer, highly transmissible variants remain viable on surfaces.
This week in Microbiology Spectrum, an open-access journal of the American Society for Microbiology, a team of researchers in China reported their findings on how environmental factors affect the persistence of 2 different, highly transmissible Omicron variants on shipping materials. They found that viability depends on the type of surface, the temperature and the original viral concentration.
The study could provide guidance for safety practices in the shipping industry. “Our findings provide initial information to determine the likelihood of objects serving as sources of transmission,” said study leader Bei Wang, Ph.D., from the Institute of Pathogen Biology at the Chinese Academy of Medical Sciences, in Beijing. “For instance, viruses may survive for extended periods at lower temperatures, making it essential to reinforce personal protection and disinfection procedures to control viral transmission during transportation.”
During the pandemic, as information emerged about routes of transmission and sources of outbreaks, researchers began to investigate whether materials used in transportation might pose a risk. “It was necessary to confirm the stability of viruses on those surfaces to improve a safe delivery process,” said Wang.
Concern and new question arose as the virus mutated and infectious variants emerged. Many, like Omicron, are highly transmissible, in part because they can evade a person’s immune response. Omicron subvariants can even infect people who have been infected before by other variants. Previous studies of SARS-CoV-2 variants have also shown that not every variant remains viable for the same duration on shipping materials, suggesting a link between genetic mutations and viral stability. “We wanted to consider exploring the mechanisms of the stability of mutations under different environmental factors.”
In the new work, the researchers tested sterilized samples of 4 different materials to measure how long Omicron variants BA.1 and BA.5 would survive at different temperatures. The materials included paper cartons, polyethylene packing film, iron and nonwoven fabric, which is used in shipping for breathable bags, insulated pads for meat packaging trays, fruit liners and other containers. For seven days, 180 samples of each material, treated with viral titers for the two sub variants, were kept at 4 degrees Celsius (39 degrees Fahrenheit), 25 Celsius (77 Fahrenheit), or 37 degrees (99 Fahrenheit).
At the end of the week, the researchers found that temperature had the most impact on survival, and the virus was most stable, and thus was most likely to persist on the packing material, at the lowest temperature. At the highest temperature, only four BA.1 samples and five BA.5 samples still tested positive. In general, the BA.5 subvariant persisted on more samples and temperatures than the BA.1 subvariant, suggesting that BA.5 might be more environmentally stable. They also found that the persistence varied by material. On the paper carton, for example, neither subvariant survived for more than 1 day at any temperature. Nonwoven fabric inoculated with BA.5 were most likely to test positive at all temperatures.
The study outlines protocols for safely shipping goods without starting an outbreak. “The survival time is not as long as we expected at room temperature, so it is generally safe to transport materials at room temperature,” said Wang. In the future, he said, his group hopes to publish similar protocols. “We plan to extend this methodology to include additional organic materials and a range of temperatures.”
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JOURNAL
Microbiology Spectrum
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