Study: Vaccination Is Not Enough by Itself to Stop the Spread of Variants

Maggie Fox wrote . . . . . . . . .

Vaccination alone won’t stop the rise of new variants and in fact could push the evolution of strains that evade their protection, researchers warned Friday.

They said people need to wear masks and take other steps to prevent spread until almost everyone in a population has been vaccinated.

Their findings, published in Nature Scientific Reports, support an unpopular decision by the US Centers for Disease Control and Prevention to advise even fully vaccinated people to start wearing masks again in areas of sustained or high transmission.

“We found that a fast rate of vaccination decreases the probability of emergence of a resistant strain,” the team wrote.

“Counterintuitively, when a relaxation of non-pharmaceutical interventions happened at a time when most individuals of the population have already been vaccinated, the probability of emergence of a resistant strain was greatly increased,” they added.

“Our results suggest that policymakers and individuals should consider maintaining non-pharmaceutical interventions and transmission-reducing behaviors throughout the entire vaccination period.”

“When most people are vaccinated, the vaccine-resistant strain has an advantage over the original strain,” Simon Rella of the Institute of Science and Technology Austria, who worked on the study, told reporters.

“This means the vaccine resistant strain spreads through the population faster at a time when most people are vaccinated.”
But if so-called non pharmaceutical interventions are maintained — such as mask use and social distancing — the virus is less likely to spread and change. “There is a chance to remove the vaccine resistant mutations from the population,” Rella said.

The team used a mathematical model to predict these changes, but their findings follow what is known about the epidemiology of viruses and what’s known as selective pressure — the force that drives any organism to evolve.

The findings suggest that policymakers should resist the temptation to lift restrictions to celebrate or reward vaccination efforts.

This is likely to be especially true with a more transmissible variant such as the Delta variant, said Fyodor Kondrashov, also of the Institute of Science and Technology Austria.

“Generally, the more people are infected, the more the chances for vaccine resistance to emerge. So the more Delta is infectious, the more reason for concern,” Kondrashov told reporters.

“By having a situation where you vaccinate everybody, a vaccine-resistant mutant actually gains a selective advantage.”

On Tuesday, the US CDC altered its guidance on mask use. The CDC said earlier this year that fully vaccinated people are very safe from infection and can take off their masks in most situations.

Now, it says even fully vaccinated people can sometimes catch the virus and if they catch the Delta variant, they are just as likely to infect someone else as an unvaccinated person would be. It advised everyone in areas of high or sustained virus transmission to wear masks when around others.

Many GOP politicians have derided the new advice. On Thursday, Mississippi Gov. Tate Reeves called it “foolish.”

While the CDC was not thinking about the evolution of variants, Kondrashov said people skeptical of maintaining vigilance should be.

“The individual who already vaccinated and putting on a mask should not think this is pointless but should think that there is a vaccine resistant strain running around,” he said.

“By preventing spread of vaccine resistant strains, you are preventing evolution of this virus,” he added.

“We have two tools in our toolbox to do this. One is non pharmaceutical interventions such as mask wearing and the whole shebang, and the second is vaccines. From an evolutionary perspective, what is necessary to reduce this (spread) is to vaccinate as many people as possible as fast as possible and across the globe.”


Source : CNN

In Pictures: Food of Restaurant Petrus (珀翠) in Admiralty, Hong Kong

Contemporary French Cuisine

The Michelin 1-star Restaurant

Cleaning Up the Air Could Help Prevent Alzheimer’s

Dennis Thompson wrote . . . . . . . . .

Air pollution causes you to gasp and wheeze. Smog puts strain on your hearts and inflames your lungs.

Could dirty air also be costing you your brain health?

A trio of new studies finds that air quality appears linked to a risk of thinking declines and dementia, and bad air might even promote toxic brain proteins that are a hallmark of Alzheimer’s disease.

“This is extremely exciting, because it indicates the potential that improving air quality levels could have on mortality levels, other areas of health, and also perhaps risk of dementia,” said Claire Sexton, director of scientific programs and outreach for the Alzheimer’s Association.

In the first study, researchers found that reduction of fine particulate pollution and smog over a decade was tied to reductions in dementia risk among women.

The study followed more than 2,200 women between the ages of 74 and 92 without dementia who’d enrolled in a long-term study of brain health. Researchers tracked their thinking, reasoning and memory skills as they aged, and compared the results to the air quality of their various communities.

The women’s risk of dementia decreased by up to 26% for every 10% improvement in air quality in their neighborhoods, the researchers concluded. Women in areas with cleaner air had dementia risk similar to that seen in women two to three years younger.

Cleaner air also seems to slow overall decline in cognitive function and memory, similar to women one to two years younger, results showed.

These benefits occurred regardless of age, education or neighborhood, said lead researcher Xinhui Wang, an assistant professor of research neurology at the University of Southern California.

“Air pollution is a modifiable risk factor,” Wang said. “The impact will be great because everybody is exposed to some level of air pollution. If we reduce air pollution, everybody will benefit.”

A second study from researchers led by Noemie Letellier, a postdoctoral scholar at University of California, San Diego, found that reductions in fine particle pollution between 1990 and 2000 caused dementia and Alzheimer’s risk to fall among a group of more than 7,000 people in France.

Dementia risk fell by 15% and Alzheimer’s risk by 17% for every microgram reduction in air pollution per cubic meter of air, researchers found. Again, the changes benefited everyone, regardless of their income or where they lived in a community.

The third study, led by Christina Park, a doctoral student in the University of Washington’s Department of Epidemiology, provided a potential explanation for why air pollution might affect brain health.

Researchers found that people with longer exposure to particle pollution and smog had higher levels of beta amyloid, a sticky protein that can clump in the brain. Amyloid plaques are one of the hallmarks of Alzheimer’s disease.

Air pollution also might increase dementia risk by causing inflammation in the body and by damaging heart and lung health, Wang and Sexton said.

So battling air pollution might not be just a way to stop climate change and protect heart health, but a way to actually reduce dementia among aging folks, experts concluded.

“There’s been improvements in air quality over a number of years and decades, but there’s still so much further to go,” Sexton said. “Globally, more than 90% of people breathe air that fails to meet World Health Organization standards.”

All three studies will be presented Monday at the Alzheimer’s Association annual meeting, held both in Denver and online. Findings presented at medical meetings are considered preliminary until published in a peer-reviewed journal.

Source: HealthDay

Braised Ham with Madeira Sauce

Ingredients

4 tbsp unsalted butter
4 shallots, finely chopped
2 tbsp plain flour
2 cups beef stock
1 tbsp tomato puree
6 tbsp Madeira
4 ham steaks (about 6-7 oz each)
black pepper
watercress, to garnish
creamed potatoes, to serve

Method

  1. Melt half the butter in a heavy medium-size saucepan, over a medium-high heat, then add the shallots and cook for 2-3 minutes until just softened, stirring frequently.
  2. A Sprinkle over the flour and cook for 3-4 minutes until well browned, stirring constantly.
  3. Whisk in the stock and tomato puree and season with pepper. Simmer over a low heat until the sauce is reduced by about half, stirring occasionally.
  4. Taste the sauce and adjust the seasoning, then stir in the Madeira and cook for 2-3 minutes.
  5. Strain into a small serving bowl or gravy boat and keep warm. (The sauce can be made up to three days in advance and chilled. Reheat to serve.)
  6. Snip the edges of the ham steaks to prevent them curling.
  7. Melt the remaining butter in a large heavy frying pan over a medium-high heat, then add the ham steaks and cook for 4-5 minutes, turning once, until the meat feels firm to the touch.
  8. Arrange the ham steaks on warmed plates and pour a little sauce over each.
  9. Garnish with watercress and serve the steaks with a little more of the sauce accompanied by creamed potatoes.

Cook’s Tip

To make the sauce a deeper, richer colour, add a few drops of gravy browning liquid to the stock.

Makes 4 servings.

Source: Taste of France


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