Current Affair 1:

Aerosols Are a Bigger Coronavirus threat than WHO Guidelines Suggest

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When someone coughs, talks or even breathes, they send tiny respiratory droplets into the surrounding air. The smallest of these droplets can float for hours, and there is strong evidence that they can carry live coronavirus if the person is infected.

What was an issue?

Until this week, however, the risk from these aerosols wasn’t incorporated into the World Health Organization’s formal guidance for nations. The WHO instead suggested that the coronavirus was primarily transmitted by coughing or sneezing large droplets into someone’s face, rather than being a longer-term threat that can float in the air.

More than 200 scientists published an open letter to the WHO on July 6 warning about airborne transmission of COVID-19 via aerosols and urging the organization to recognize the risks. The WHO responded with an update in which it acknowledged the growing evidence of airborne spread of the disease, but it did so with hesitation.

What is an aerosol and how does it spread?

Aerosols are particles that are suspended in the air. When humans breathe, talk, sing, cough or sneeze, the emitted respiratory droplets mix in the surrounding air and form an aerosol. Because larger droplets quickly fall to the ground, respiratory aerosols are often described as being made up of smaller droplets that are less than 5 microns, or about one tenth the width of a human hair.

Droplets that are smaller than 5 microns can remain suspended in the air for many minutes to hours because the effect of air drag relative to gravity is large. In addition, the water content of virus-carrying droplets evaporates while they are airborne, decreasing their size. Even if most of the fluid evaporates from a virus-laden droplet, the droplet does not disappear; it just becomes smaller, and the smaller the droplet, the longer it will stay suspended in the air. Because smaller diameter droplets are more efficient at penetrating deep into the pulmonary system, they also pose a much greater infection risk.

Do masks protect from aerosol transmission? Just for your information and safety.

Face coverings and masks are absolutely necessary for protection against aerosol transmission. They serve a twofold purpose.

1. First, they filter the air expelled by an individual, capturing respiratory droplets and thereby reducing the exposure risk for others.
2. This is particularly important as they are most effective at capturing larger droplets that are more likely to have larger quantities of viruses encapsulated within them. This prevents the larger droplets from directly affecting someone or evaporating down to a smaller size and circulating in the air.
3. They also reduce the speed of the puff of air that is produced when sneezing, coughing or talking. Decreasing the velocity of the expelled air reduces the distance that droplets are initially transported into the person’s surroundings.

We will learn bit more on Aerosols,

Aerosols and Incoming Sunlight (Direct Effects)

The Sun provides the energy that drives Earth’s climate, but not all of the energy that reaches the top of the atmosphere finds its way to the surface. That’s because aerosols—and clouds seeded by them—reflect about a quarter of the Sun’s energy back to space. Although most aerosols reflect sunlight, some also absorb it. An aerosol’s effect on light depends primarily on the composition and color of the particles. Broadly speaking, bright-colored or translucent particles tend to reflect radiation in all directions and back towards space. Darker aerosols can absorb significant amounts of light. See how different Aerosols reflect to light:

Pure sulfates and nitrates reflect nearly all radiation they encounter, cooling the atmosphere. Black carbon, in contrast, absorbs radiation readily, warming the atmosphere but also shading the surface. Organic carbon, sometimes called brown carbon or organic matter, has a warming influence on the atmosphere depending on the brightness of the underlying ground. Dust impacts radiation to varying degrees, depending on the composition of the minerals that comprise the dust grains, and whether they are coated with black or brown carbon. Salt particles tend to reflect all the sunlight they encounter. Windblown dust, sea salts, volcanic ash, smoke from wildfires, and pollution from factories are all examples of aerosols.

Aerosols can have a major impact on climate

Aerosols influence climate in two primary ways: by changing the amount of heat that gets in or out of the atmosphere, or by affecting the way clouds form.

When the sun’s rays beam down on them, they bounce the rays back out of the atmosphere, preventing that heat from ever reaching Earth’s surface. For example,

Aerosols also influence how clouds form and grow. Water droplets coalesce readily around particles, so a particle-rich atmosphere promotes cloud formation. White clouds reflect incoming sun, preventing it from getting to the surface and warming land or water—but they also absorb the heat that the planet is constantly emitting back outward, trapping it in the lower atmosphere. Depending on the cloud type and location, they can either warm their surroundings or cool them.

Aerosols increase drought severity over the Indian subcontinent

A team of atmospheric scientists from India, USA and Canada have found that aerosols in the atmosphere can increase the severity of droughts over the Indian subcontinent by as much as 17 per cent during El Niño years. The El Niño phenomenon, which occurs when there is abnormal warming over the Pacific Ocean, is already considered as a deterrent for the Indian monsoon on the grounds that it blocks the flow of moisture bearing winds from the oceans to the Indian landmass.

The new study has found that it further weakens the monsoon by transporting aerosols from the lower altitudes in East Asian region up and into the higher altitudes (12-18 km) forming an aerosol layer called Asian Tropopause Aerosol Layer (ATAL) over South Asian region.

It remains hanging over there during monsoon. The thickening of this aerosol layer results in reduction in the amount of solar energy reaching the earth thus weakening the monsoon circulation and increasing the severity of drought conditions.

Aerosols affect albedo

In addition to scattering or absorbing radiation, aerosols can alter the reflectivity, or albedo, of the planet. Bright surfaces reflect radiation and cool the climate, whereas darker surfaces absorb radiation and produce a warming effect. White sheets of sea ice, for example, reflect a great deal of radiation, whereas darker surfaces, such as the ocean, tend to absorb solar radiation and have a net warming effect.

Aerosols, particularly black carbon, can alter reflectivity by depositing a layer of dark residue on ice and other bright surfaces. In the Arctic especially, aerosols from wildfires and industrial pollution are likely hastening the melting of ice.

Now you have got the fair idea about Aerosols, you can attempt now Prelims as well as Mains question.

Now, if they ask in Prelims:

1. Does Aerosols affect albedo?
2. Does Aerosols bring drought to regions on earth?
3. Does Aerosols influence clouds?
4. Does Aerosols influence climate?

Everything can be answered.

Current Affair 2:

How Different Vaccines Work?

Lot of vaccines in process of development for COVID-19. You should have a basic idea how it works.

What makes designing a potential vaccine for COVID-19 challenging? To answer this question, it is important to understand how a vaccine elicits an appropriate immune response in the body.

Active and passive immunisation

The immune response towards any infection can be passive or active. Passive immunisation is when antibodies are directly transferred from one individual to another. Such passively transferred antibodies accord immediate protection – but it wanes gradually, and the individual eventually becomes susceptible to the disease again. It could be natural or artificial. Few examples of Passive immunity:

Placental transfer of antibodies from the mother to the foetus gives natural passive immunity. Convalescent plasma therapy, involving the transfer of plasma containing specific antibodies from recovered individuals to susceptible individuals, provides passive immunity as well.

Vaccines provide active immunisation: they deliberately introduce a foreign substance, called an antigen, into the body to induce the body to mount an immune response. Though the protection is not conferred immediately, the immunity lasts for a considerably longer period once established. Repeated doses of the same antigen could boost immunity further.

How does a vaccine work?

1. A vaccine works like a virus and initiates an immune response – but without causing major illness.
2. The immune response is brought on by different types of cells. However, a specialized group of white blood cells, called the B and T lymphocytes, are important to sustain the immune response in the long run.
3. When an antigen enters the body, cells called dendritic cells get attracted to it, and then carry the antigen to T lymphocytes. The T lymphocytes identify these antigens and bind to them.
4. Meanwhile, B lymphocytes also pick up the antigens, process them and present them to the T lymphocytes.
5. After this interaction, T lymphocytes release signaling molecules called cytokines, which stimulate the B lymphocytes. In response, the B lymphocytes rapidly turn into plasma and ‘memory’ B cells. One B lymphocyte can produce thousands of such daughter cells in a few days.
6. The plasma cells are responsible for secreting antibodies that will tackle the antigen and eliminate the infection. And once the infection has been removed from the body, the plasma cells die while ‘memory’ B cells rest in the bone marrow and keep secreting low levels of antibodies.

When the body is exposed to the same antigen again, the circulating antibodies bind to the antigen. This is what they mean when they say the immune system becomes familiar with the antigen, and the immune response the second time is even more effective. This memory is known as immunological memory, and it forms the basis of vaccination.

Also, learn Live attenuated and inactivated killed vaccines

Ideally, a vaccine should trigger an adequate immune response without harming the body. There are different types of vaccines to achieve this outcome. Conventional vaccines fall into two broad categories: live attenuated vaccines and inactivated killed vaccines.

1. Live attenuated vaccines contain whole virus particles. Inducing the virus to replicate under unnatural conditions reduces its virulence. For example, researchers could have injected the virus into an ‘unnatural’ host, causing the virus to eventually lose its adaptation towards the actual host, and transform to a less virulent form. That is, it can no longer cause disease as well as it could before. This process is called attenuation.
2. The level of attenuation is critical to a vaccine’s success. Over-attenuation could render the vaccine ineffective, while under-attenuation could cause the vaccine itself to produce disease. The chickenpox, measles, mumps and rubella vaccines are all live vaccines.
3. Inactivated vaccines contain a part of the virus instead of the whole. During preparation, researchers remove those parts of the virus required for viral replication, making these vaccines safer than the live attenuated type.
4. On the flip side, inactivated vaccines in general don’t accord long-lasting protection, like live vaccines. Sometimes, a substance called an adjuvant is added to inactivated vaccines to boost the immune response and make them last considerably longer. However, including an adjuvant increases their overall cost.

The COVAXIN vaccine against COVID-19, developed by Hyderabad-based Bharat Biotech, is an inactivated vaccine with alum as adjuvant.

DNA vaccines

Apart from conventional vaccines, in the last few years, researchers have tried a new generation of vaccines. One of them is a DNA vaccine. The ZyCoV-D vaccine being developed by Zydus Cadila is of this type.

1. Cells have DNA in their chromosomes – and also outside the chromosomes in a form called plasmids. First, researchers obtain plasmids from a bacterium. Then, they separate some genetic material from the virus and insert it into the plasmid and inject this plasmid into the body.
2. The viral genes then integrate themselves into cells in the body and begin to express foreign proteins. This triggers an immune response.

Questions can be asked in any form. So, read it properly. After March, most of the Current Affairs is full of vaccines only. So, please be careful. Too much reading today, no problem. Look at the image given below.

Current Affair 3:

Assam’s Dehing Patkai Wildlife Sanctuary to get national park status

The Assam government has decided to upgrade the Dehing Patkai Wildlife Sanctuary to national park status. The decision was taken at a meeting chaired by Chief Minister on July 6. Who gave right to State Government to declare National Park?

National Park and Wildlife Sanctuaries are declared under Wildlife Protection Act, 1972.

Other Important Provisions:

About Dehing Patkai Wildlife Sanctuary:

The Dehing Patkai Wildlife Sanctuary, also known as the Jeypore Rainforest is a part of Dehing Patkai Elephant Reserve. It is located in the districts of Dibrugarh and Tinsukia. Dehing Patkai is a deciduous rainforest interspersed with semi-evergreen and lush green flora, the only patch of virgin rainforest in Assam.

Current Affair 4:

1.2 million Indians died of snake bites in last 20 years

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Just have a look at statistics. Not to learn anything.

An estimated 1.2 million people have died from snake bites in India in the past 20 years, a new study has found. The study, published in the open access journal eLife, was conducted by leading Indian and international experts. It's based on data collected from India's ambitious Million Death Study.

The study also found that between 2001 and 2014, some 70% of the snake bite deaths occurred in eight states - Bihar, Jharkhand, Madhya Pradesh, Odisha, Uttar Pradesh, Andhra Pradesh (including Telangana, a new state) Rajasthan and Gujarat. Spatial distribution of snakebite mortality risk in India for 2004-13:

Half of the victims were between 30 and 69 years of age while a quarter were children. Half of the deaths happened in the summer monsoon between June and September and most of the victims were bit on the legs. The snake species most responsible were Russell’s vipers, kraits and cobras.

In 2018, WHO passed a resolution in which it declared Snake bites are now a "global health priority.

Current Affair 5:

Ophiocordyceps sinensis (yarchagumba)

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Also known as Himalayan Viagra, it is the world’s costliest fungus. It has entered the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species.

IUCN has placed the fungus, known for its aphrodisiac and rejuvenation properties, in the ‘vulnerable’ category. The fungus, also known as keeda jadi in Uttarakhand because of its caterpillar-like appearance, is endemic to the Himalayan and Tibetan plateau and is found in China, Bhutan, Nepal and India.

Current Affair 6:

Itolizumab: Emergency Covid-19 Drug

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The Drug Controller General of India (DGCI) has given “restricted emergency use” approval to Itolizumab, a drug used to cure skin ailment psoriasis, for treating Covid-19 patients with moderate-to-severe acute respiratory distress.

1. Itolizumab is a ‘humanised monoclonal antibody’ developed by the Bangalore-based biopharmaceutical company, Biocon, in collaboration with the Centre for Molecular Immunology (CIM) in Cuba.
2. Monoclonal antibodies are antibodies produced by immune cells that are cloned from one parent immune cell. These antibodies are designed to bind to a specific type of proteins.
3. In the case of Itolizumab, it selectively targets CD6, a protein found in the outer membrane of T-cell. T-cell is a type of white blood cell that plays a central role in the body’s immune response.
4. Protein CD6 is important for the continued activity of T-Cells when the body encounters a foreign pathogen.
5. However, in case of the Covid-19 infection, sometimes the immune system goes into an overdrive — a process known as cytokines storm — causing inflammation and organ damage.
6. Itolizumab, by binding to CD6, down regulates T-cell activation, and causes reduction in synthesis of pro-inflammatory cytokines.

The drug has previously been shown to be effective for treating psoriasis, an autoimmune disease in which skin cells build up and form scales and itchy, dry patches.

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