Tag: 25/3/22

Categories : COVIDTags :

20% of South Africans Still Lack Immunity as Fifth Wave Approaches

On By ModernMedia
South African flag with COVID theme
Image by Quicknews

In an interview with 702, CSIR senior researcher Dr Ridhwaan Suliman warned that 20% of South Africans still do not have any immunity to COVID, either from vaccination or prior infection. Since the start of the pandemic in South Africa, he has been tweeting his graphs of infections and explaining the science to the public.

Explaining the figure, he said: “It’s an extrapolation of recent research studies that show sero-prevalence levels across the country, up to about 80% currently. That means levels of immunity of people having previous infections, so natural immunity, plus acquired immunity through vaccination. So based on the 80% sero-prevalence levels, it means there’s still 20% that are susceptible… and 20% of South Africa’s population leaves 12 million people who don’t have levels of immunity or sero-prevalence currently.”

This number is however greatly increased from a previous survey conducted in January 2021, which reported a 19.1% rate.

https://twitter.com/rid1tweets/status/1506576605556219906

He pointed out that this leave South Africa with a large number of people who are immune-naïve to COVID, who are therefore at risk of more severe consequences such as hospitalisation and death. However, the high levels of immunity means that, as seen in the Omicron wave, outcomes are reduced in severity.

Interviewer Bruce Whitfield asked Dr Suliman his opinion of prospective waves, as evidenced by increasing infections in countries like the US and China, and indeed, his own observations of queues starting to build up outside mobile COVID testing stations.

Dr Suliman replied that although the infections have been driven by the highly transmissible Omicron B.A.2 variant which is also dominant in South Africa, it “hasn’t resulted in a further uptick or resurgence following our fourth wave of the original Omicron strain, and so we’re currently in an ‘inter-wave’ period with low levels of transmission.”

He says that the situation is encouraging, with hospitalisations at their lowest levels seen since before the first wave in May 2020, but that this is still an inter-wave period.

Regarding when the fifth wave would be, Dr Suliman pointed out that each of the previous four waves “have been very cyclical or regular, with three months in between each wave.” Based on this, he said that he expects another wave is likely around the end of April or beginning of May.

However, he said that this should not be looked on with fear “because even with a surge in high levels of infection we do have high levels of population immunity which we hope will continue, and we will have less severe outcomes of hospitalisation and death even with those high levels.”

Source: 702

Categories : Expert OpinionTags :

The Healthcare Threat of Chemical Warfare in Ukraine

On By ModernMedia
Photo by Pablo Stanic on Unsplash

Writing for MedPage Today, two experts examine the possibility of chemical weapon use in Ukraine. Gavin Harris, MD assistant professor of infectious diseases and critical care, and Joel Zivot, MD, an associate professor of anaesthesiology/critical care, both of Emory University School of Medicine, explained the consequences of such an attack, noting that Russia has used such weapons in the past.

Though it’s uncertain whether Russia would launch a chemical attack, A/Profs Harris and Zivot wrote: “one thing is clear: in a large-scale chemical attack within the current Russian-Ukrainian conflict, the prospect of any meaningful healthcare response is bleak.”

Chemical agents fall under a number of classifications, which include blistering/vesicants such as mustard gas, blood agents such as hydrogen cyanide, choking/pulmonary agents such as chlorine gas, incapacitating agents such as opioids, and nerve agents such as sarin or the Russian-made Novichok. Development of modern chemical weapon traces back to the 1930s with the development of various nerve agents: organophosphorus cholinesterase inhibitors, each with particular potency.

Russia has recently complained to the UN Security Council that Ukraine and the US were cooperating to produce chemical and biological weapons for use in the war. The US government has responded that Russia is laying this claim to prepare for its own use of such weapons in Ukraine.

The preparation of chemical and biological agents can be done in secret, and easily introduced into the air, water, or food supply.

Invisible and odourless, nerve agents include sarin, soman, tabun, and the American-produced VX. The V agents were at one time considered to be the most toxic agents ever produced and are ten times more toxic than sarin. VX, tonnes of which was produced by the US government, can kill a person rapidly after they have been exposed to an infinitesimal amount.

Exposure to such nerve agents can cause a “constellation of symptoms,” according to the authors. “Nerve agents block the action of acetylcholinesterase, and this leads to accumulation of the neurotransmitter acetylcholine,” they wrote. “High levels of acetylcholine in the synaptic cleft causes overstimulation of cholinergic receptors. Symptoms related to excess accumulation of acetylcholine are divided into three groups: muscarinic, nicotinic, and central. Overstimulation of muscarinic cholinergic receptors causes pupil constriction, glandular hypersecretion, urination, defecation, sweating, and vomiting. Nicotinic symptoms are weakness and ultimately paralysis. Central nervous system poisoning will manifest as irritability, delirium, fatigue, lethargy, seizures, coma, and death by respiratory depression.”

Chemical weapons would have a devastating impact on already strained healthcare systems, A/Profs Harris and Zivot concluded. “Such weapons can create a complex mass casualty event where the treating personnel and the healthcare facilities may themselves be within the zone of conflict,” they wrote. “Chemical and biologic attacks require intense and complex treatment, and in both types of attacks, treating personnel may themselves be at risk of becoming exposed and therefore decontamination may be required before the initiation of any supportive treatments. Emergency and medical providers would also need to have access to proper respiratory protection and hazardous material/chemically resistant suits, and in a widespread attack, in an ever-deteriorating war zone like Ukraine, such treatment capacity would be highly limited.”

The authors note that such an attack would not be the first for Russia, which has shown a willingness to use chemical agents on more than one occasion.

During a hostage crisis in 2002, where Chechen rebels took over a Moscow theatre and took 700 hostages, Russian authorities used a gas to incapacitate the rebels – as well as the hostages. The gas may have been a mixture of remifentanil/halothane or an aerosolised form of carfentanil, a synthetic opioid that is approximately 10 000 times more potent than morphine. Overdoses from carfentanil from substance abuse have been seen in recent years. In many cases of opioid overdose, death from respiratory failure is a consequence. After the raid, at least 33 Chechens and 129 hostages died, mostly from gas exposure and inadequate medical care. Russian authorities refused to release information on the gas used, hindering emergency response.

Russia has also apparently used Novichok, which may be up to eight times as potent as VX, in recent high-profile attempts to kill opponents of the Russian government. The most recent use of Novichok was an attempted assassination of Alexei Navalny, a prominent Russian dissident. Though whether Novichok was the agent, Navalny’s treatment was for nerve agent exposure, featuring large doses of atropine. Though he survived, his treatment was an intensive, organised effort. A large attack using Novichok or other chemical agent in Ukraine promises to be almost entirely lethal to civilians, military and first responders.

Source: MedPage Today

Categories : COVID Obstetrics & GynaecologyTags :

COVID Vaccination During Pregnancy Does not Cause Complications

On By ModernMedia
Source: Pixabay

COVID vaccination during pregnancy is not associated with a higher risk of pregnancy complications, according to a large scale Swedish and Norwegian study published in the journal JAMA.

The study, which comprised almost 160 000 pregnancies, found there to be no increase in the risk of preterm birth, growth retardation, low Apgar scores at birth or the need for neonatal care after vaccination against COVID during pregnancy.

“The results are reassuring and can hopefully make pregnant individuals more willing to get vaccinated,” said co-first author Anne Örtqvist Rosin, researcher at the Department of Medicine, Karolinska Institutet.

Studies have shown that, compared to non-pregnant peers, pregnant women are at risk of serious COVID requiring intensive care with a higher risk of death. Preterm births are also more likely in pregnant women with severe COVID. COVID vaccines have been available in Sweden and Norway since January 2021, and in May 2021 Sweden recommended all pregnant individuals to have a COVID jab, followed in August by Norway.

“We’re still seeing that vaccination rates are lower than in the rest of the population, so it’s likely that there’s some concern about how the vaccines affect the pregnant individual and the foetus,” explained Dr Örtqvist Rosin. “When the vaccines were produced, pregnant women were not included in the large clinical studies, and until now there have been no population-based data about any risk there might be to them.”

The researchers linked Sweden’s Pregnancy Register and Norway’s Medical Birth Register to each country’s vaccination register to obtain data on if and when pregnant individuals were vaccinated and with which vaccine. The study included a total of 157 521 individuals who gave birth between January 2021 and January 2022, of whom 18% had been vaccinated. It was found that vaccinated individuals were at no higher risk than unvaccinated of developing one of the studied complications.

The majority of the pregnant individuals included in the study were vaccinated after week 12 in accordance with current recommendations, and 95% received an mRNA vaccine. This should be factored in when interpreting the results, which were similar for the different mRNA vaccines regardless of whether one or two doses were given. Vaccination during the third trimester and vaccination with the Moderna vaccine was associated with a slightly lower risk of needing neonatal care.

A possible benefit of vaccination during pregnancy is that the antibodies generated pass through the placenta, conferring a certain degree of protection against COVID to the newborn baby.

“We’re now planning to study how long this protection lasts, and if SARS-CoV-2 infection or vaccination during pregnancy has any other lasting effects on the child’s health,” said joint last author Professor Olof Stephansson at the Karolinska Institutet .

Source: Karolinska Institutet

Categories : Metabolic DisordersTags :

Study Confirms Improved Chronic Kidney Disease Outcomes with MRAs

On By ModernMedia
Anatomic model of a kidney
Photo by Robina Weermeijer on Unsplash

In a study published in Hypertension, Osaka University researchers have demonstrated an association between the use of mineralocorticoid receptor antagonists (MRAs) and an improved renal prognosis in individuals with chronic kidney disease CKD in real-world settings.

As CKD progresses, the initiation of renal replacement therapy (RRT), which includes dialysis and kidney transplantation, may be necessary for life support in kidney failure. MRAs, which include spironolactone, eplerenone and potassium canrenoate, are commonly used to reduce swelling, blood pressure, and urine protein levels in people with CKD. However, the study was motivated by a lack of information on the link between MRA treatment and the initiation of RRT in a real-world population.

“We conducted a retrospective analysis of clinical data from over 3100 individuals with CKD,” explained lead author Tatsufumi Oka. “We evaluated MRA treatment in various populations of people with CKD, including those with diabetes, heart disease, and severely impaired renal function.”

The research team made use of a marginal structural model to analyse the association between MRA use and the initiation of RRT across multiple patient subgroups.

“Our analysis showed that MRA use was associated with a 28% lower rate of RRT initiation and a 24% lower rate of the combined outcomes of RRT initiation and death,” says senior author Jun-Ya Kaimori.

The researchers found a reduced risk for RRT initiation across various subgroups of people with CKD, including those with and without diabetes and those with severely impaired renal function. These findings highlight the association of MRA use and improved renal outcomes in a real-world population of CKD patients with varying health backgrounds. Overall, the study findings support the use of MRAs in treatment plans for various groups of people with CKD who are not undergoing dialysis.

Source: Osaka University

Categories : Diseases, Syndromes and ConditionsTags :

Why Some Infections Can Be so Persistent

On By ModernMedia
C. difficile bacteria. Source: CDC

University of Utah researchers have discovered a novel mechanism that infectious bacteria use to rapidly adapt to environmental stress, which could help explain why certain types of common infections such as sepsis can be so persistent.

The mechanism, described in the journal Nucleic Acids Research, alters the precision with which the bacteria make the proteins that carry out most of the work in cells. These changes may improve the bacteria’s chance for survival.

“Understanding how pathogens survive stressful situations can reveal new targets for development of anti-microbial drugs and vaccines,” said the study’s senior author, Professor Matthew Mulvey.

Adapt or die
Bacteria infecting a host are exposed to stresses such as acidity or antibiotics. If even one of the bacteria’s key pathways for survival is crippled, the entire population could die off.

However, bacteria can adapt, an ability that relies on a slight twist to basic principles of biology.

Traditionally, each gene is thought to carry instructions for making a single kind of protein. A molecule called transfer RNA (tRNA) then uses these instructions to oversee protein production in the cell. In times of stress, though, random changes to the tNRA-mediated process can be an especially quick way to alter a cell’s array of proteins. This can generate useful new proteins that help the organism to thrive.

“There is a growing appreciation that a little bit of noise in the system can be good,” Prof Mulvey said.

Shifting expectations
A graduate student in the lab happened to stumbled onto a bacterial enzyme, MiaA, which turned out to be both sensitive to environmental stress and key to regulating protein expression. In one experiment, he created a version of an especially pathogenic bacteria that lacked the gene that encodes MiaA.

“Every kind of stress we exposed the MiaA-deficient strain to seemed to cause problems,” said the study’s co-first author Matthew Blango, PhD, who is now a junior research group leader at the Leibniz Institute for Natural Product Research and Infection Biology in Jena, Germany. “So, we really thought that this protein might be playing an important role in gene regulation.”

Bacteria lacking MiaA did not thrive and did not cause urinary tract infections or sepsis in mice. This same effect also occurred with bacteria manipulated into expressing too much MiaA. “There appears to be a Goldilocks zone, where just the right amount of MiaA allows the optimal stress response,” Dr Blango said.

Seeing how badly things went when MiaA levels were out of balance, Brittany Fleming, PhD, the study’s co-first author, investigated further. She discovered that knocking out MiaA caused random ‘frameshifting’ – an error where tRNA delivers three-letter genetic codes to be translated into proteins that are off by one letter. For example, a genetic code of “CAT CAT GTA” might read as “ATC ATG TA…” when frameshifted. In the bacteria, the result of such a shift was impaired production of important proteins and production of unexpected proteins.

Another co-first author, graduate student Alexis Rousek, showed that changing levels of MiaA could alter the availability of key metabolites that feed into other important stress response pathways within the bacteria. These findings implicate MiaA as a key player within a web of pathways that can impact pathogen stress resistance

Prof Mulvey says his lab’s next step is learning how environmental stress alters MiaA levels within bacteria.

The implications for this research may extend beyond infection control. Humans express a version of MiaA that is linked to certain cancers and metabolic diseases. “What we learned about how MiaA works is likely to be relevant to research on cancer and other non-infectious human diseases,” Mulvey said.

Source: University of Utah