Coronavirus Disease COVID-19 Archives

Posted on 24 August 2022 by admin

Severe COVID-19 increases risk of future cardiovascular events

Study: COVID-19 severity and risk of subsequent cardiovascular events. Image Credit: Yurchanka Siarhei / Shutterstock.com

To date, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is the virus responsible for the coronavirus disease 2019 (COVID-19), has infected over 603 million individuals and claimed more than 6.4 million lives worldwide.

About 30% of COVID-19 survivors continue to experience a wide range of persistent symptoms for several weeks since their initial diagnosis. This condition is commonly referred to as post-acute sequelae of SARS-CoV-2 infection (PASC) or “long COVID.”

Study: COVID-19 severity and risk of subsequent cardiovascular events. Image Credit: Yurchanka Siarhei / Shutterstock.com

Study: COVID-19 severity and risk of subsequent cardiovascular events. Image Credit: Yurchanka Siarhei / Shutterstock.com

Background

Even though multisystem inflammatory syndrome is the most common PASC syndrome in adults and children, a wide range of other symptoms, including sleep difficulties, persistent fatigue, type 1 diabetes, and neurological disorders, have been reported. The incidence of these symptoms varies from one person to another based on their demographic and clinical characteristics.

Several studies have indicated the manifestation of multiple cardiovascular complications, such as arrhythmia, hypertension, acute myocardial infarction, thromboembolism, and cerebrovascular accidents, in individuals who have recovered from COVID-19. However, a limited number of studies have confirmed that severe COVID-19 leads to a high risk of cardiovascular diseases.

A recent Clinical Infectious Diseases journal study determines the relationship between COVID-19 severity and risk of subsequent cardiovascular events (CVEs) in a large cohort.

Study findings

A retrospective cohort study was performed using nationwide health insurance claims data of adults from the United States Health Verity Real-Time Insights and Evidence database. Increased COVID-19 severity was found to enhance the risk of developing subsequent CVEs among individuals without a cardiac history in previous years.

As compared to COVID-19 patients who required outpatient care, those who required hospital admission were more likely to experience CVEs. Among COVID-19 hospitalized patients, those admitted to the intensive care unit (ICU) were almost 80% more likely to develop CVEs than non-ICU hospitalized patients.

In fact, non-ICU hospitalized patients exhibited only a 28% possibility of experiencing CVEs thirty days after initial COVID-19 symptoms. Additionally, as compared to COVID-19 outpatients, hospitalized patients were more likely to be admitted for a CVE after recovering from COVID-19.

In younger adults, the incidence of cardiovascular sequelae was lower as compared to older adults. Aside from CVEs, other severe outcomes, such as thrombotic events and cerebrovascular accidents, were observed in patients who recovered from severe COVID-19. However, such observations were less likely in COVID-19 patients who required only outpatient care.

The study findings emphasize the importance of vaccination, as demonstrated by its ability to reduce severe disease. Similarly, prompt antiviral treatment of acute COVID-19 has been recommended, which would help reduce the possibility of transition to severe illness.

Both COVID-19 vaccination and timely therapeutic interventions would alleviate the risk of severe COVID-19 and subsequently decrease the possibility of experiencing CVEs.

The findings of the present study are consistent with previous research that has reported a higher incidence of myocarditis and pericarditis in patients who recovered from severe SARS-CoV-2 infection. Nevertheless, it was observed that elevated cardiovascular risk after acute infection may not be exclusive to COVID-19.

In fact, some other diseases that have been associated with an increased risk of long-term CVEs are influenza and pneumonia bacteremia. Additionally, 22-65% of sepsis survivors are at an increased risk of CVEs.

The underlying mechanism responsible for the increased risk of CVEs following SARS-CoV-2 infection has not been determined. SARS-CoV-2 infects cardiac myocytes through their interaction with the angiotensin-converting enzyme 2 (ACE-2) receptor, which might remain persistent; therefore, this interaction induces chronic inflammatory responses and subsequent tissue damage or fibrosis.

Another mechanism related to the development of CVEs following recovery from COVID-19 is an autoimmune response to cardiac antigens that causes delayed damage to cardiac tissues. Anti-heart antibodies also correlated with cardiovascular manifestation and COVID-19.

Viral toxicity is another possible mechanism that might cause long-term cardiac damage or thrombosis in vasculitis. However, in the future, more research is needed to confirm the mechanisms related to cardiac damage after SARS-CoV-2 infection.

Conclusions

Due to the lack of a COVID-19-negative control group, the authors failed to quantify the elevated risk of CVEs in COVID-19 patients. The unwanted inclusion of patients with a history of CVEs could have overestimated the result as well. The impact of vaccination status on the incidence of CVE was not studied.

Despite these limitations, the present study strongly emphasized that patients who recovered from severe COVID-19 were at a greater risk of developing CVEs. As compared to COVID-19 patients who required outpatient care, those who were admitted to the ICU were at a higher risk of experiencing CVEs.

The importance of COVID-19 vaccination in preventing severe infection was strongly emphasized in this study.

Journal reference:

Wiemken, L. T., McGrath, L. J., Andersen, K. M., et al. (2022). COVID-19 severity and risk of subsequent cardiovascular events. Clinical Infectious Diseases. doi:10.1093/cid/ciac661.

Posted on 5 July 2022 by admin

Modeling the influence of COVID superspreading events

In a recent study posted to the medRxiv* preprint server, University of Kansas researchers assessed the effect of superspreading events (SSEs) on the United States (US) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak dynamics.

Study: Exploring the Role of Superspreading Events in SARS-CoV-2 Outbreaks. Image Credit: StockTom / Shutterstock

Background

SARS-CoV-2, the novel coronavirus that emerged in late December 2019, has quickly swept over the globe, resulting in over 546 million illnesses and more than 6.3 million fatalities thus far. Coronavirus disease 2019 (COVID-19) has strained the US healthcare network, with several hospitals exceeding or nearing capacity and few limiting services.

Governments at the state and national levels have responded by issuing guidelines and regulations for decreasing SARS-CoV-2 transmission, including social-distancing directives, mask mandates, stay-at-home instructions, and restrictions on big gatherings. However, insufficient adherence and compliance by the population have affected the efficiency of these laws and regulations, encouraging SSEs, which have assisted the SARS-CoV-2 transmission.

About the study

In the present study, the researchers developed a continuous-time Markov chain (CTMC) model to examine the impact of SSEs on the dynamics of the SARS-CoV-2 outbreak in the US. The authors defined SSEs as social or public events that lead to numerous SARS-CoV-2 infections over a short period.

The current research sought to determine the effect of SSEs compared to non-SSEs on COVID-19 outbreak dynamics, the efficacy of hospitalization and quarantine as containment methods for SSE relative to non-SSE-dominated outbreaks, and the impact of quarantine violation on the efficacy of quarantine for SSE compared to non-SSE-dominated outbreaks.

The investigators simulated a CTMC model for SARS-CoV-2 spread utilizing Gillespie’s direct algorithm under three distinct scenarios: 1) neither hospitalization nor quarantine; 2) quarantine, hospitalization, premature hospital discharge, and quarantine violation; and 3) hospitalization and quarantine but not premature hospital discharge or quarantine violation. They also alter the rate of quarantine violations under realistic hospitalization and quarantine (RHQ) scenarios.

Results

The study results demonstrated that the SARS-CoV-2 outbreaks with SSE dominance were often more variable yet less severe and more prone to extinction than outbreaks without SSE dominance. The authors observed this after eliminating hospitalization and quarantine conditions or upon the inclusion of hospitalization, quarantine, early hospital discharge, and quarantine breach.

However, the severity of the most catastrophic SSE-dominated outbreaks was higher than the most severe outbreaks without SSE dominance, despite most SSE-dominated outbreaks being less severe. Upon the inclusion of quarantine and hospitalization, while excluding quarantine breach and premature hospital discharge, SARS-CoV-2 outbreaks dominated by SSE were more susceptible to extinction than outbreaks without SSE dominance but were more severe and less variable.

Upon the inclusion of quarantine, hospitalization, premature hospital discharge, and halved quarantine breach, outbreaks dominated by SSE were comparable to when quarantine and hospitalization were included, but quarantine breach and premature hospital discharge were excluded. Besides, when quarantine breach was doubled outbreaks were similar to when quarantine and hospitalization were excluded.

Quarantine and hospitalization were more potent at regulating outbreaks dominated by SSE than those without SSE dominance in all scenarios. Similarly, quarantine breaches and premature hospital discharge were significant for outbreaks dominated by SSE.

SSE-dominated outbreaks were extremely improbable to become extinct when quarantine and hospitalization were excluded. They were moderately unlikely to become extinct when quarantine, hospitalization, premature hospital discharge, and quarantine violation were included. Furthermore, they were highly plausible to become extinct when hospitalization and quarantine were included, but quarantine breach and premature hospital discharge were excluded.

Moreover, SSE-dominated outbreaks were more likely to become extinct when quarantine violations were halved. However, outbreaks dominated by SSE were less likely to become extinct when quarantine breaches were doubled.

Conclusions

Altogether, the study findings showed that COVID-19 outbreaks dominated by SSE differ noticeably from non-SSE-dominated outbreaks in their severity, variability, and chances of extinction. They also vary, albeit more low-key, from outbreaks dominated by superspreading individuals (SI). The possibility of hospitalization or quarantine and the likelihood of premature hospital discharge or violation of quarantine significantly impact the dynamics of SSE-dominated outbreaks.

Hospitalization and quarantine were substantially effective preventative interventions for COVID-19 outbreaks dominated by SSE. Nevertheless, premature hospital discharge and breach of the quarantine drastically diminished their efficacy. Besides, the team assessed control techniques using the probability of extinction.

The present findings have significant public health consequences, necessitating SARS-CoV-2 modelers must: 1) assess the contribution of SSEs or SIs to COVID-19 spread; and 2) differentiate between SSEs, SIs, and non-SIs/non-SSEs in their models. More research into the combined and individual effects of SSEs and SIs on SARS-CoV-2 outbreak dynamics and the efficacy of control strategies for various kinds of outbreaks were required to guide eradication and containment initiatives.

*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.

Posted on 2 June 2022 by admin

COVID-19 superspreader events typically originate from few carriers

A recent research paper published in the journal Physics of Fluids analyzed the overdispersion in the coronavirus disease 2019 (COVID-19) airborne transmission.

Study: Analysis of overdispersion in airborne transmission of COVID-19. Image Credit: oxinoxi / Shutterstock

Background

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has been characterized by overdispersion and superspreading events comparable to SARS and other respiratory virus outbreaks. Any incident that results in more than the typical number of secondary transmissions is referred to as superspreading.

Overdispersion is a non-random trend of grouping in the context of contagious diseases, which frequently involves a large proportion of zero cases and a limited percentage of large outbreaks.

Nevertheless, the specific functions and influences of established physical and viral factors correlated to transmission processes on overdispersion are still unknown. Moreover, the characteristics and nature of superspreading episodes are instrumental in explaining the spread of SARS-CoV-2. To date, mechanistic simulations depicting airborne transmission have not been combined with real-world occupancy and distribution data to better explain large-scale characteristics of disease dynamics, such as transmissibility overdispersion.

About the study

In the present study, the authors used real-world occupancy information from over 100,000 social contact contexts in 10 United States (US) metropolises to undertake mechanistic modeling of COVID-19 point-source transmission via infectious aerosols. The primary purpose of this study was to use the molecular basis of airborne disease transmission to investigate event-level SARS-CoV-2 spread overdispersion utilizing real-world data from a significant number of social engagements.

The team tried to establish an algorithm centered on aerosol dispersion with randomized data and obtainable occupancy information to derive the distribution of the number of secondary infections for every infectious case. They investigated whether observed trends of overdispersion in secondary transmissions could be replicated through simulations utilizing the above algorithm.

Further, the scientists aimed to develop an analytical function (rather than a fit) that may explain the probability density function of the number of secondary infections arising from the dynamics of the problem. Furthermore, they attempted to determine the dominant factors that cause overdispersion and the consequences for mitigation strategies.

To achieve this, the scientists used 100,000 random social-contact conditions to solve an aerosol dispersal model by combining real-world area and occupancy data with practical ventilation and viral load rate to attain the probability distributions for the number of secondary infections for each infectious case in those situations.

Results and discussions

According to the simulated results, the aerosol transmission pathway was compatible with overdispersed individual COVID-19 infectivity. In addition, with exposure time, ventilation rate, and speaking time, SARS-CoV-2 load fluctuation was the most substantial factor controlling secondary attack rates. According to the authors, they, for the first time, generated analytical equations that precisely characterized the modeled probability density functions of secondary attack and infection rates. Besides, the generated analytical expressions revealed how the quantitative link among personal-level viral load variance and event-level occupancy governs overdispersion simultaneously.

These findings reveal that even in the case of airborne transmission, about 4% of index cases in indoor contexts were responsible for 80% of secondary cases, underlining the need for identifying and concentrating mitigation efforts on superspreading event causes. The results emphasize the significance of interventions, including isolation through rapid testing to identify intense viral shedding periods, for reducing exposures during stages of heightened viral shedding, improved ventilation, and the higher likelihood of outbreaks with SARS-CoV-2 variants of concern (VOCs) correlated with superior viral loads. Ultimately, considering viral burden and occupancy over indoor environments, the present analytical function may predict the spatially specified likelihood of outbreaks and outbreak magnitude via point-source transmission events.

Conclusions

Overall, the study findings demonstrated that around 4% of COVID-19 index cases possibly caused 80% of secondary SARS-CoV-2 infections, resulting in an extended tail probability distribution function of secondary infections per infectious event. Overdispersion appears to be notably driven by personal-level heterogeneity in SARS-CoV-2 load, with occupancy coming in second. The team then developed an analytical function that mimics the modeled SARS-CoV-2 overdispersion. Further, they illustrated the efficacy of potential COVID-19 mitigation techniques using this analytical function.

The present analysis adds a relevant dimension to the growing body of proof regarding SARS-CoV-2 airborne transmission by linking the mechanistic insights of COVID-19 aerosol spread with reported large-scale epidemiological features of outbreaks and thus unfolds as a potent tool for evaluating the likelihood of epidemics and the possible effects of mitigation actions on extensive disease dynamics. The simulation in this article covers overdispersion in the number of secondary cases rendered by each infectious case over an hour in such 100000 instances, assuming one index case at each site. The team mentioned that when combined with appropriate data, the current analytical expressions created and confirmed using simulations could explain overdispersion through drastically broader timeframes and contact vicinities.

Journal reference:

Swetaprovo Chaudhuri, Prasad Kasibhatla, Arnab Mukherjee, William Pan, Glenn Morrison, Sharmistha Mishra, and Vijaya Kumar Murty , “Analysis of overdispersion in airborne transmission of COVID-19”, Physics of Fluids 34, 051914 (2022), DOI: https://doi.org/10.1063/5.0089347, https://aip.scitation.org/doi/10.1063/5.0089347

Posted on 15 March 2022 by admin

Resurging COVID-19 events related to cold-chain food or packaging contamination

Study: Time course and epidemiological features of COVID-19 resurgence due to cold-chain food or packaging contamination. Image Credit: Sorn340 Studio Images/Shutterstock

In a recent study published in the latest issue of the Biomedical Journal, researchers reviewed coronavirus disease 2019 (COVID-19) resurgence events in China related to frozen food and packaging contaminated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

They identified one of the weak links of the SARS-CoV-2 epidemic where patient zero often remained hidden and was hard to detect, such that the infectious disease outbreak was apparent only after a while and by that time had spread uncontrollably. The current review findings could help devise more effective COVID-19 mitigation and intervention strategies for the future.

Background

After the first COVID-19 outbreak of late 2019 in Wuhan, China, several incidences of COVID-19 resurgence events related to frozen food or packaging contamination have been reported as China imports frozen food from countries where the COVID-19 epidemic is ongoing.

Most of these events reported since July 2020 traced back to frozen shrimp imported from Ecuador. Later, in September 2020, the live SARS-CoV-2 virus was isolated from the outer packaging of imported frozen cod carried by the two stevedores found to be SARS-CoV-2-positive during a routine nucleic acid amplification test (NAAT) testing of the personnel in Qingdao Port, China. According to the authors, this event is the first known case where live SARS-CoV-2 was detected on cold-chain food in the world, confirming that it can survive on cold-chain food packaging and spread through cross-border transportation.

Perhaps SARS-CoV-2 itself is not responsible for the material surface contamination. In lieu, the enclosed and highly humid environment of food packaging and processing facilities and transportation favors the material-to-human SARS-CoV-2 spread. To date, epidemiological features of such COVID-19 outbreaks and the risk of this transmission route remain unclear.

In the present study, researchers conducted a literature search on the official website of the Centers for Disease Control of China and local authorities to identify COVID-19 resurgence events related to cold-chain food or packaging contamination. Additionally, they gathered the relevant epidemiological events and laboratory evidence to support their work.

Incidences of COVID-19 resurgence in China

On August 6th, 2020, in Yingkou, Liaoning Province, China, three packaged food samples were SARS-CoV-2-positive, whereas all 43 employees and 306 personnel of the enterprise tested SARS-CoV-2-negative in the NAAT and antibody tests. This finding led researchers to one of the most intriguing findings of this literature review that SARS-CoV-2 does not transmit via eating or buying cold-chain food products. Thus, it is evident that only the port staff, especially the stevedores, were at high risk of contracting SARS-CoV-2 as they came in direct contact with virus-contaminated materials and needed COVID-19 vaccination on priority.

Further, this finding led to the understanding that successful COVID-19 transmission to humans occurs through the material surface only when – i) a human (host) comes in direct contact with the SARS-CoV-2-contaminated material surface, including food packaging and ii) the human carrier sheds the virus to the surface.

Interestingly, SARS-CoV-2 stays viable (live) and stable on material surfaces, such as cardboard and plastic, for days, particularly under refrigerated (4°C) and frozen (-10 to -80°C) conditions; however, when it finds another human body through direct contact, it rapidly disseminates via human-to-human transmission.

Incidences of COVID-19 resurge in other countries

A rather popular COVID-19 resurgence event occurred in Auckland, New Zealand in August 2020. After 102 consecutive days of zero local cases of COVID-19 in Auckland, authorities reported four lab-confirmed COVID-19 cases in one Auckland household with no overseas travel history. Notably, one of the SARS-CoV-2-positive individuals in this household worked with a cold-chain company.

Within two days, three more employees tested SARS-CoV-2-positive, and seven family members of these cold-chain workers also tested positive. By October 2020, there were 179 origin-unknown cases with a C.12 lineage of SARS-CoV-2, designated as the outbreak of Auckland August Cluster.

Likewise, similar outbreaks have occurred in several other countries, including Australia, Japan, Germany, and the United States, among workers of food processing facilities.

Additionally, there have been multiple cruise ship outbreaks of norovirus in the United States between July and October 2019. The present food provisioning review traced this infection to imported frozen raspberries from China, which then had to be recalled. Workplace conditions, such as prolonged close contact with coworkers, shared workspace and transportation, and congregate housing, also add to the risk for SARS-CoV-2 infection.

According to the data released by the Centers for Disease Control and Prevention (CDC), United States, between March 1^st and May 31^st, 2020, there were 28,364 reported cases and 132 deaths among workers in 382 meat and poultry processing facilities in several US states. Often these workplaces were crowded and highly humid, overall, conducive for human-to-human, human-to-material, and material-to-human transmissions.

Conclusions

To conclude, the study highlights the significance of surveying materials and the entire territory where imported products arrive as frequent human testing alone does not suffice. Additionally, the study data suggest that regular sampling and proper disinfection of imported products are effective ways to detect SARS-CoV-2 and prevent its spread on material surfaces.

In 2021, the Joint Prevention and Control Mechanism of the State Council of the People’s Republic of China issued a series of technical guidance for the prevention of COVID-19 transmission related to cold-chain food and controlled occurrence of several community-level outbreaks with the potential to turn into an epidemic.

Posted on 28 February 2022 by admin

Health events amongst pregnant females after COVID-19 vaccination

Study: Safety of COVID-19 vaccines in pregnancy: a Canadian National Vaccine Safety (CANVAS) Network study. Image Credit: Huseyin Eren Obuz/Shutterstock

In a recent study posted to the medRxiv* preprint server, researchers evidenced that messenger ribonucleic acid (mRNA)-based coronavirus disease 2019 (COVID-19) vaccines are safe in pregnancy, with lower rates of significant adverse event following immunization (AEFIs) in pregnant women than non-pregnant females.

Background

Multiple research works have published positive recommendations for mRNA-based COVID-19 vaccines in pregnancy, based on the evidence of high efficacy in pre-authorization clinical trials. However, in the absence of a contemporaneous control group to enable comparison with background rates of AEFIs and comparisons based solely on historical rates of AEFIs, apprehensions surrounding the safety of mRNA vaccines during pregnancy are still lurking around.

The Canadian National Vaccine Safety (CANVAS) Network, established during the 2009 influenza pandemic, has been monitoring COVID-19 vaccine safety in Canada since the vaccine rollout in December 2020 to provide rapid, real-time safety data.

The CANVAS actively follow-up individuals with significant health events and actively enrolls control group(s) to enable comparisons with unvaccinated individuals in a similar time frame.

About the study

In the present study, researchers recruited pregnant and non-pregnant females aged 15-49 years, as of 4 November 2021, under the ‘vaccinated’ and ‘control’ cohorts in Canada to evaluate the safety profile of mRNA-based COVID-19 vaccines.

The females in the vaccinated cohort had received the first dose of a vaccine within seven days before enrolling for the study. They had an active email address and telephone number and could communicate in English or French. They reported the occurrence of AEFIs over an email after seven days following each dose of the COVID-19 vaccine and at seven months after their first vaccine dose. The control group participants were unvaccinated and reported significant health events that occurred seven days, 28 days, and six months after enrolling in the study.

All the participants had to report injection site reactions; however, only those who indicated having a significant health event had to provide further details.

The researchers analyzed two types of exposures for the study analysis:

vaccination status among pregnant people;

pregnancy status among vaccinated people.

Two endpoints were analyzed, including ‘significant’ and ‘serious’ health events, including common and uncommon symptoms following the first and second doses of COVID-19 vaccines. The former is defined as a new or worsening of a health event sufficient to cause work/school absenteeism or medical consultation in the previous seven days, and the latter describes any event resulting in hospitalization.

Likewise, they analyzed three vaccine groups:

BNT162b2,

mRNA-1273, and

any mRNA vaccine.

They also examined associations between the outcomes and the exposures, using two sets of univariate/multivariate (MV) logistic regression models. When fitting MV models, they adjusted known or expected covariates such as age group, prior COVID-19 infection, and trimester of pregnancy, as appropriate.

Lastly, they conducted two sensitivity analyses to evaluate the robustness of the findings.

Study findings

Significant health events were lower in pregnant people than in age-matched non-pregnant vaccine recipients. Among pregnant females, AEFI was higher in those who received the second dose of the mRNA-1273 vaccine. However, there was no difference in AEFIs after either dose of the BNT162b2 vaccine.

Initial clinical trials of the mRNA-1273 and BNT162b2 vaccines have reported relatively high rates of AEFIs compared with most routinely used vaccines, including higher rates for dose two than dose one.

The current study analysis revealed similar patterns among pregnant females. Although the analysis specifically quantified the significant and serious AEFI rates in this population for each of the mRNA vaccines, the lower rate of significant AEFIs among pregnant people, compared with vaccinated non-pregnant females, revealed interesting insights.

During pregnancy, dynamic immunologic adaptations occur, for instance, a skewed response towards a T helper cell 2 (Th2)-dominant state. Since mRNA vaccines have specifically elicited a Th1-biased immune response, the Th2-bias during pregnancy may be partially responsible for this lower rate of significant AEFIs.

Conclusions

Considering the high rate of complications related to COVID-19 in pregnancy, it is crucial to maximize vaccine coverage in this at-high risk population for the protection of both the pregnant female and her young infant. Immunized mothers pass on antigen-specific immunoglobulin G (IgG) antibodies against SARS-CoV-2 via placenta or breast milk.

Overall, the study data appropriately informed about the reactogenicity of COVID-19 vaccines during pregnancy. This information should be considered alongside effectiveness and immunogenicity data to make appropriate recommendations about the best use of COVID-19 vaccines in pregnancy. The long-term data from this cohort following a six-month follow-up, when available, could also prove quite useful. Similar data from countries where the ChAdOx-S vaccines are used could provide a complete overview of the safety of COVID-19 vaccines in pregnancy.

In the future, research studies should identify whether the observed reduced reactogenicity of non-COVID-19 mRNA vaccines in pregnant people in this study is a feature of the vaccine platform or these specific vaccines.

*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.

Posted on 8 February 2022 by admin

Impact of SARS-CoV-2 Omicron and Delta variants on serious hospital events

Study: Serious hospital events following symptomatic infection with Sars-CoV-2 Omicron and Delta variants: an exposed-unexposed cohort study in December 2021 from the COVID-19 surveillance databases in France. Image Credit: PHOTOCREO Michal Bednarek/Shutterstock

In a recent study posted to the medRxiv* pre-print server, a team of researchers assessed the differences in risk of hospitalization in adults after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron and Delta variants of concern (VOCs).

The emergence of the SARS-CoV-2 VOCs, Delta, and Omicron necessitated extensive research about the manifestations of the variants. The varied effects of the VOCs on adult patients, including the severity of disease and COVID-19-related hospitalizations, have been comprehensively studied. However, several studies suggest significant differences in the impact of the different variants on the occurrence of serious hospital events.

About the study

The present retrospective cohort study investigated the differences and the various factors involved in COVID-19-related hospital events occurring in adults infected with SARS-CoV-2 Omicron and Delta VOCs.

COVID-19 cases in France between 6 December 2021 and 7 Jan 2022 were recorded and grouped into two arms – Delta and Omicron arms. The cases eligible for the study were of patients over 18 years of age, who had symptomatic manifestations of COVID-19 and were reverse transcription-polymerase chain reaction (RT-PCR) positive for SARS-CoV-2. Among the eligible cases, patients suspected to be infected with the Omicron VOC and the Delta VOC were known as exposed and non-exposed individuals, respectively.

The two groups were compared based on known risk factors like age, gender, the status of vaccination, and comorbidities. The study considered intensive care unit (ICU) admission of the COVID-19 patient, requiring critical care, or, death of the patient in the hospital as a serious hospital event.

A multiplex quantitative RT-PCR (RT-qPCR) was used to characterize the variant present in the SARS-CoV-2-positive samples. The results of the mutation screening were evaluated based on the presence of spike proteins, characteristic to either Delta or Omicron VOC. The primary outcome of the study was the number of COVID-19-related serious hospital events among symptomatic patients who had tested positive for the SARS-CoV-2 Omicron or Delta VOC.

Results

The study results showed that a total of 149,064 patients were included in the research. A total of 36% of patients in the SARS-CoV-2 Delta VOC cohort were unvaccinated as compared to the 17% of patients in the Omicron VOC arm. A slightly higher number of comorbidities was observed in the Delta arm than in the Omicron arm.

During the follow-up period of the study, 497 serious hospital events were observed, of which the Delta arm accounted for 447 cases while the Omicron arm had 50 cases. ICU admission was the most common serious hospital event.

Within the Delta VOC arm, 92% and 97% of the serious hospital events were observed within 14 and 21 days of SARS-CoV-2 detection while in the Omicron cohort, 84% and 100% of the serious events were observed within 14 and 21 days of the positive COVID-19 test, respectively. Notably, patients who were vaccinated with the booster dose had a higher number of serious hospital events as compared to the patients vaccinated with the primary dose.

Patients belonging to the age group of 18 to 79 years were at 7.7 times lower risk of serious hospital events in the case of Omicron symptomatic patients as compared to the Delta symptomatic patients. In patients 80 years and older, Omicron-infected patients had a 3.3-fold lower risk of serious events than patients infected with Delta. It was also noted that the odds of occurrence of a serious event increased with the increasing age of the patient. Also, male patients were at a significantly higher risk of serious events than women; this risk was lesser in vaccinated individuals.

The risk of serious hospital events was lowered by 6.7 times in vaccinated patients of ages between 18 and 79 years, irrespective of whether they received the booster vaccine or not, while the same risk was lowered by 2.2 times in patients of ages over 80 years who had received the primary vaccine dose; the risk was further reduced by 4.3 times when the patients received the booster dose.

Conclusion

The study findings showed that the SARS-CoV-2 Omicron VOC has lower disease severity and a lower incidence of serious hospital events as compared to the Delta VOC. Despite the lower vaccine efficacy reported against the Omicron VOC as compared to the Delta VOC, no significant difference was observed in the protection provided by the vaccines against severe hospital events in this study.

According to the authors, the higher risk of occurrence of serious events in the elderly can be lowered with vaccination and booster dose administration.