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What to know about coronaviruses



Typically, coronaviruses affect birds and mammals’ respiratory tracts, including humans. Physicians identify them with the common cold, bronchitis, pneumonia, severe acute respiratory syndrome (SARS), and coronavirus disease 2019 (COVID-19) (COVID-19). The gut may also be infected by these viruses.

The common cold is typically caused by coronaviruses, but they may be responsible for more severe diseases.

Over the past 80 years, scientists have found that mice, rats, dogs, cats, turkeys, horses, pigs, and cattle may be infected by these viruses. These animals also transfer viruses to humans.

Most recently, authorities detected a coronavirus outbreak in China at the end of 2019 that went on to hit other nations. The virus is called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and it causes the illness COVID-19.

We explain the various forms of human coronavirus in this article, the symptoms of the health problems they cause, and how they are transmitted from person to person.

We concentrate on 3 particularly deadly diseases caused by coronaviruses: COVID-19, SARS, and Middle East respiratory syndrome (MERS) (MERS).

What is a coronavirus?

In 1937, researchers first identified a coronavirus, isolating one that was responsible for a form of bronchitis in birds that could devastate stocks of poultry.

In the 1960s, in the noses of people with the common cold, scientists discovered signs of human coronaviruses.

Human coronaviruses include 229E, NL63, OC43, and HKU1, which are especially prevalent.

The word “coronavirus” originates from the crown-like projections on the surfaces of the virus. “Corona” means “halo” in Latin or “crown.”

In humans, in the winter and early spring, coronavirus infections most frequently occur.


The Centers for Disease Control and Prevention (CDC) began tracking the outbreak of SARS-CoV-2, a new coronavirus that causes COVID-19, in 2019. They first detected the virus in Wuhan, China.

The virus has spread to almost every nation since then, prompting the World Health Organization (WHO) to announce a pandemic.

Tens of millions of infections worldwide have been caused by the current coronavirus, causing over a million deaths. Of these infections and deaths, the United States has seen the largest number.

The first individuals with COVID-19 had links to a market for live animals and seafood. This indicates that the virus was originally transmitted to humans by animals. Then, individuals with no links to the market developed the disease, verifying that the virus can pass from person to person.

The majority of individuals who experience COVID-19 have a relatively mild type of the illness. Around 80 percent of people who get COVID-19 recover without having to be admitted to a hospital, according to the WHO.

The remaining 20% get seriously ill and have trouble breathing.

Some individuals, including older adults and people with chronic medical conditions, including high blood pressure, heart and lung disorders, diabetes and cancer, have a greater risk of serious disease and death.

The rate of mortality differs from country to country. The death rate is around 2.8 percent in the U.S. .

Most kids with COVID-19 have slight symptoms or none at all according to the CDC. Fewer children have developed COVID-19 than adults. That said, there may be an increased risk of serious illness and death from COVID-19 among infants and children with certain medical conditions.

Also the current evidence indicates that pregnant women may have a higher risk of severe illness from COVID-19. Although it is unknown if this is due to the virus itself, they may also have an increased risk of issues such as preterm birth.

Symptoms of COVID-19

Individuals can begin to experience COVID-19 symptoms 2–14 days after SARS-CoV-2 exposure, according to the CDC. Symptoms may include:

  • a fever
  • chills
  • a cough
  • shortness of breath or difficulty breathing
  • a sore throat
  • congestion or a runny nose
  • fatigue
  • a headache
  • muscle pain
  • a new loss of taste or smell
  • nausea, vomiting, or both
  • diarrhea

There is currently no vaccine available for COVID-19, although there are many in progress. Even if a person is not having symptoms, tests will detect the infection early on.

According to the CDC, the following groups have a greater chance of developing extreme COVID-19 disease:

  • older adults
  • people of any age with underlying health conditions, including heart disease, stroke, diabetes, cancer, high blood pressure, and obesity
  • pregnant people

Systemic healthcare disparities have placed many people from marginalized racial and ethnic groups at a higher risk of COVID-19 sickness and death.

General symptoms of coronavirus infections

Coronaviruses appear to cause symptoms that are cold or flu-like. The symptoms are usually mild, but they differ from person to person.

Symptoms of coronavirus infections may include:

  • a runny nose
  • a headache
  • a cough
  • a fever
  • a sore throat
  • generally feeling unwell

If it results from a coronavirus infection, there is actually no cure for the common cold. Treatments include self-care and over-the-counter medications.

Taking the following steps may help:

  • resting and avoiding overexertion
  • drinking plenty of water
  • avoiding smoking and smoky areas
  • taking acetaminophen (Tylenol) to reduce any pain and a fever
  • using a clean humidifier or cool mist vaporizer

In a sample of fluid from the body of an individual, such as a sample of blood or mucus from the nose, the virus responsible for infection may also be detected by a doctor.


In the Coronaviridae family, coronaviruses belong to the subfamily Coronavirinae.

Various forms of coronavirus cause diseases of varying severity. Others spread more easily than others as well.

Seven kinds of coronavirus which can infect humans are currently recognized by physicians. Four common types are:

  • 229E (alpha coronavirus) (alpha coronavirus)
  • NL63 (alpha coronavirus) (alpha coronavirus)
  • OC43 (beta coronavirus) (beta coronavirus)
  • HKU1 (beta coronavirus) (beta coronavirus)

MERS-CoV, which causes the disease MERS, and SARS-CoV, the virus responsible for SARS, are rarer strains that cause more serious diseases.

A new strain, named SARS-CoV-2, began circulating and causing the disease COVID-19 in 2019.


In public places where physical distance is difficult to maintain, the CDC suggests that individuals wear fabric face masks. This would help delay the spread of the virus through persons, particularly those who are asymptomatic, who do not know that they have contracted it. When continuing to practice physical distancing, individuals should wear cloth face masks. Instructions are available here for making masks at home. Note: It is important that surgical masks are reserved for healthcare staff and N95 respirators.

Researchers assume that viruses, such as mucus, are transmitted through fluids in the respiratory system.

For instance, a coronavirus can spread when a person:

  • coughs or sneezes without covering their mouth, dispersing droplets into the air
  • has physical contact with someone who has the infection
  • touches a surface that contains the virus, then touches their nose, eyes, or mouth

It is still uncertain if human coronaviruses may spread in the same way, although some animal coronaviruses can spread to humans through contact with feces.

At some stage, coronaviruses infect most individuals.

People with symptoms should remain at home, relax, and avoid coming into close contact with others in order to prevent transmission.

Covering the mouth and nose when coughing or sneezing with a tissue or handkerchief can also help avoid transmission. Disposing of used tissues right away and maintaining high levels of hygiene, particularly around the home is important.


SARS is an infectious disease that is caused by the SARS-CoV coronavirus infection. It leads to a life-threatening type of pneumonia in many cases.

In February 2003, the first mentions of SARS came from Asia. Then the virus spread to over two dozen nations.

Experts don’t consider SARS a risk anymore. The last confirmed human cases of SARS were reported in a laboratory-related outbreak in China in 2004.

Both the upper and lower respiratory tract are affected by SARS-CoV.

SARS symptoms progress over a period of 1 week and begin with a fever. People experience flu-like symptoms early on, like:

  • a dry cough
  • chills
  • diarrhea
  • breathlessness
  • aches

Usually, pneumonia, a serious lung infection, occurs. SARS causes failure of the lungs, heart, or liver at its most advanced level.

The CDC estimates that during the epidemic, 8,098 people contracted SARS. 774 of them died of the illness. SARS was finally regulated by the authorities in July 2003.

Among older adults, complications were more prevalent. Over half of those who died from the disease were over the age of 65, according to one source.


MERS is caused by the coronavirus MERS-CoV. After reports arose in Saudi Arabia, scientists first identified this extreme respiratory disorder in 2012. It has spread to other countries since then.

The virus reached the U.S. in 2014. Two individuals in the country tested positive for MERS-CoV. The CDC reports that there is a very low risk of developing MERS within the region.

Symptoms of MERS include:

  • a fever
  • breathlessness
  • coughing

Through close contact with individuals that have the infection, the disease spreads.

A 2019 research into MERS discovered that the disease is fatal in 35.2% of people who develop it.


Is alcohol antiviral? Things to know



Some viruses can be killed by alcohol, but not all. The virus’s efficiency is determined by the concentration and type of alcohol used, as well as the virus’s species.

The Centers for Disease Control and Prevention (CDC) recommend washing hands with soap and water, but this method is not always available. When it isn’t, alcohol-based hand sanitizers can help prevent viral illnesses like SARS-CoV-2, the virus that causes COVID-19, from spreading.

In addition to hand sanitizers, people can disinfect commonly touched devices in the home, such as phones and computer keyboards, with rubbing alcohol.

This page explains how alcohol kills viruses, how it works, and what concentrations to look for while using it. It also explains how to properly use hand sanitizers and rubbing alcohol.

Is alcohol antiviral?

alcohol and virus

A 2020 study found that both isopropyl and ethyl alcohol can kill viruses. Rubbing alcohol contains isopropyl alcohol, while alcoholic beverages include ethyl alcohol.

The efficacy of these alcohols varies with concentration and viral type. Nonenveloped viruses lack a lipid membrane, whereas enveloped viruses do. Encapsulated viruses are more susceptible to disinfectants.

Isopropyl alcohol kills enveloped viruses but not nonenveloped. Ethyl alcohol kills enveloped and non-enveloped viruses. They both have significant antiviral properties against:

These alcohols have little antiviral activity against viruses like polio and hepatitis A.

How does it work?

Few researches on alcohol’s antiviral effects Scientists believe alcohol damages the virus’s cell membrane by altering its protein structure. An essay from 2021 calls this “denaturing and coagulation.” The virus cannot multiply or infect without a functioning membrane.

Adding water to alcohol denaturizes proteins more effectively. Because alcohol evaporates quickly. It takes longer for viruses to digest alcohol in water.

Alcohol and SARS-CoV-2

The virus that caused the COVID-19 pandemic is SARS-CoV-2. Alcohol is beneficial against SARS-CoV-2 because the outermost membrane includes lipids.

According to a study published in 2020, ethyl or isopropyl alcohol at particular doses rendered the virus inactive after 30 seconds. When soap and water are not available, the CDC recommends using alcohol-based hand sanitizers to prevent SARS-CoV-2 transmission.

How strong does the alcohol need to be?

According to a study published in 2021, the recommended alcohol content in sanitizers is either 80 percent ethyl alcohol or 75 percent isopropyl alcohol. According to the CDC, sanitizers containing at least 60% alcohol are also effective.

The influence of hand sanitizer formulations on SARS-CoV-2 was studied in 2020, and it was discovered that concentrations more than or equal to 30% resulted in full viral inactivation.

What is the best way to use alcohol at home?

To clean small things and high-touch surfaces like phones and door handles, people can use alcohol-based sanitizers or rubbing alcohol around the house. To clean these objects, first do the following:

  • Make sure the room is well ventilated.
  • Using a cotton pad, apply rubbing alcohol.
  • To avoid inhaling, replace the cap.
  • Wipe the surface using the pad.
  • Safely dispose of the cotton pad.

Rubbing alcohol, according to the National Capital Poison Center, poses a number of risks. If a person inhales the fumes or drinks any amount of it, even little amounts are dangerous. To lessen the risk, one should:

  • rub alcohol should be kept out of the reach of children
  • It should only be used in well-ventilated areas
  • Keep a safe distance from open flames
  • don’t ever swallow rubbing alcohol

What is the best way to use alcohol on the skin?

Alcohol can be applied to the skin in two ways to kill viruses. The first is to use a hand sanitizer gel that is alcohol-based. Applying some gel to the palms and massaging it all over the hands, including between the fingers, is how people can use it. Then wait for it to dry.

Doctors no longer advocate using rubbing alcohol to clean wounds since it can cause more tissue damage. Instead, a person can clean the area under running tap water for 5–10 minutes before gently dabbing or wiping the skin with a gauze pad soaked in saline solution or tap water. They can also use an alcohol-free wipe instead.

Are there any risks associated with using alcohol to eliminate viruses?

Alcohol gels other sterilising treatments are excellent in killing a variety of potentially hazardous microorganisms, but they have some drawbacks.

Inferior to washing with soap and water

When feasible, the CDC recommends washing hands with soap and water. Soap and water, unlike hand sanitizers, can eradicate all types of bacteria from the hands. Bacteria, viruses, and other chemicals, such as pesticides, are all included.

Handwashing with soap and water is required in various conditions for optimal hygiene. These are some of them:

  • before, during, and after food preparation
  • after using the toilet
  • after touching garbage
  • when the hands are visibly greasy or dirty
  • before and after caring for a person who is sick
  • before and after visiting someone with a weakened immune system

If soap and water aren’t available, use a sanitizer with at least 60% alcohol content.

Inferior to other surface cleaners

When it comes to cleaning surfaces or equipment, alcohol is less effective than other disinfectants. In hospitals, for example, instead of using alcohol to clean surfaces like floors, workers often use hydrogen peroxide or other disinfectants.

These compounds can destroy a wider range of germs than alcohol, and because they don’t evaporate as rapidly, they stay in contact with the microbes for longer. They do, however, have their own set of advantages and disadvantages, and they have not completely replaced alcohol.

Alcohol’s rapid evaporation might be beneficial when sanitising noninvasive equipment like thermometers. Alcohol, unlike hydrogen peroxide, does not stain or damage clothing or materials.

Antibiotic resistance

In addition to their antiviral characteristics, alcohol-based sanitizers include antibacterial capabilities. Bacteria, on the other hand, can change over time to the point where compounds no longer damage them. Antibiotic resistance is the term for this.

According to some academics, hand sanitizers may lead to antibiotic resistance. However, according to a study published in 2021, alcohol has not been proved to cause bacterial resistance.

To limit the risk of residual bacteria gaining resistance, some experts recommend using a hand sanitizer for a full 20–30 seconds and then letting it to dry.


Both isopropyl and ethyl alcohol have the ability to destroy viruses with lipid-high cell membranes. SARS-CoV-2, as well as HIV, hepatitis B, and herpes viruses, fall within this category. Alcohol inhibits viral function by altering the structure of the viral membrane.

Using soap and water to wash your hands is preferable to using alcohol-based sanitizers. People can use hand gels containing 60–90 percent Trusted Source alcohol if this alternative is not accessible. 80 percent ethanol or 75 percent isopropyl alcohol are the best amounts.

Rubing alcohol can also be used to clean tiny items around the house, but it is important to use caution when handling it.



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What lies ahead for SARS-CoV-2 variants?



The majority of mutations in the coronavirus that causes severe acute respiratory syndrome (SARS-CoV-2) produce only minor harm. A modest number of alterations, on the other hand, can increase viral pathogenicity and strengthen host-virus interactions, both of which are necessary for viral entrance and infection. Because the spike protein promotes viral attachment to host cell surface receptors, changes in the SARS-CoV-2 spike protein can have a profound impact on viral behavior.

To avoid the formation of new SARS-CoV-2 variations that are resistant to currently existing vaccinations and treatments, it is critical to monitor and limit virus circulation. Despite the efforts of several governments throughout the world, mass vaccination campaigns have not attained the population coverage essential to prevent SARS-CoV-2 transmission,

SARS-CoV-2 variants
Image Credit: Naeblys /

SARS-CoV-2 variant classification

It is critical to examine the emergence and spread of variations, as well as their effects on disease transmission and human health, in order to effectively control the pandemic. SARS-CoV-2 variations with a potential public health risk have been divided into three groups by the World Health Organization (WHO): variants under monitoring (VUMs), variants of interest (VOIs), and variants of concern (VOCs).

VUMs are viral variations having genetic alterations that change viral properties, but their phenotypic or epidemiological significance is unknown. Mutations in VOIs can influence infectivity, disease progression, and diagnostic or therapeutic escape, potentially resulting in community transmission and a global public health issue. VOCs have been linked to higher transmissibility, virulence, or disease severity, as well as the ability to reduce the efficacy of interventions, diagnostics, therapies, and vaccinations.

Because the virus is constantly evolving, these varieties may need to be categorized in the future. Quantifying the number of variations that could constitute a public health risk is essential for future planning in the battle against viral outbreaks.

About the study

Researchers used a function that solely rely on the global number of infected cases since the start of the pandemic to fit data on the most important SARS-CoV-2 variants according to the WHO in a new study published on the preprint platform medRxiv*. Their match allows for a fairly accurate estimate of the number of SARS-CoV-2 variants that could emerge for a given number of infected people around the world. In every epidemiological circumstance, our novel technique can also anticipate the amount of new relevant variations per 10 million instances.

The researchers gathered data on SARS-CoV-2 variants, including WHO-reported variant characteristics, PANGO (Phylogenetic Assignment of Named Global Outbreak) classification, current relevance (VOC, VOI, or VUM), date and country of first detection, total number of global cases at the end of the month of detection, and a cumulative number of variants. PANGO is a nomenclature method for recognizing and tracking SARS-CoV-2 genomic lineages. The WHO data was numerically fit using the function v(N) = k x Nlog N, where k is the numerical fit constant and is equal to 3.35 x 10−6.

“Our method depends critically on the WHO efficiency in tracking the most relevant SARS-CoV-2 variants.”

Study findings

According to the study’s findings, there were almost 44 SARS-CoV-2 subtypes that were relevant until November 2021. In November 2021, the number of new relevant variants per ten million cases was 1.64, decreasing 28.4 percent from 2.29 in March 2020.

Cumulative number of relevant SARS-CoV-2 variants
Cumulative number of relevant SARS-CoV-2 variants versus the cumulative number of cases in the world. The dots from 1 to 10 indicate the data reported by WHO [12] from March 2020 to May 2021; the solid line represents the numerical fit υ = k · N/log N obtained with Wolfram Mathematica

Until November 2021, there were around 252 million COVID-19 instances worldwide, which corresponded to 43.7 relevant variants. This is nearly 19 variations more than what the WHO published in May 2021.


The number of new significant variations per ten million instances fell relatively slowly as the total number of cases increased, according to the findings of this study. As a result, new SARS-CoV-2 variations will continue to evolve as long as the virus is in circulation.

Using the cumulative global number of infected cases, the scientists developed a mathematical model to calculate the number of relevant SARS-CoV-2 variants. This model simply looked at the relationship between the number of virus replications and the appearance of important variants, ignoring all other parameters that affect the spread of new variants.

The capacity to anticipate the frequency of new relevant SARS-CoV-2 variations will be critical in the future for effective vaccination campaign planning, as novel variants can change viral properties and have a significant impact on global pandemic management.

*Important notice

Preliminary scientific papers published on medRxiv are not peer-reviewed and should not be regarded as conclusive, should not be used to influence clinical practice or health-related behavior, and should not be recognized as established information.

Journal reference:

Littera, R., & Melis, M. (2021). How many relevant SARS-CoV-2 variants might we expect in the future? medRixv.

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COVID-19 boosters to prevent SARS-CoV-2 infections in adults



Since it was initially announced on March 11, 2020, the unusual coronavirus disease 2019 (COVID-19) pandemic produced by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has posed a threat to world health. Since then, the BNT162b2/Pfizer and mRNA-1273/Moderna messenger ribonucleic acid (mRNA) vaccines against SARS-CoV-2 have been rolled out in two-dose regimens in the United States, with a December 2020 deadline. Both of these vaccines provide at least six months of protection against COVID-19-related hospitalization and mortality.

COVID-19 booster vaccine

Because of the weakened immunity, the transmission of the SARS-CoV-2 B.1.617.2 (Delta) variant increased, resulting in a larger number of COVID-19 cases in the summer of 2021. Booster vaccines for higher-risk persons were approved by the US Food and Drug Administration in response to the abrupt surge in illnesses.

Serological studies have since showed that the antibody response increases significantly from the first to the second dosage of the mRNA vaccines. However, after six months of full vaccination, the duration and amount of antibody response to booster doses are uncertain.

Understanding COVID-19 booster antibody responses

Researchers measured anti-receptor-binding domain (RBD) immunoglobulin G (IgG) and surrogate virus neutralization of the interaction between the SARS-CoV-2 spike protein and the human angiotensin-converting enzyme (ACE2) receptor before and after vaccination with boosters in 33 healthy adults in a recent study published on the medRxiv* preprint server. Participants were requested to fill out an e-consent form and complete online surveys about their COVID-19 vaccination status and history.

Before receiving the booster dose, the subjects supplied finger stick dried blood spot samples, which were collected 6-10 days later. The study’s findings were compared to data from a previous community-based study that followed the identical protocols.

The antibody responses were assessed in a prior community-based trial after SARS-CoV-2 infection or after receiving the second dose of the mRNA vaccine. The presence of anti-RBD IgG before vaccination was used to classify the participants as seropositive or seronegative.

Findings of the research

The study’s findings revealed that antibody responses after 6-10 days of receiving the booster dose are higher than natural SARS-CoV-2 infection, after two doses of the mRNA vaccine, and after both natural infection and immunization. Notably, females’ post-booster IgG levels were greater than men’ and were adversely associated to age.

In addition, the SARS-CoV-2 Delta variant displayed strong surrogate neutralization, but this response was still lower than that shown after exposure to the wild-type SARS-CoV-2 strain. There were no differences in SARS-CoV-2 Delta variant neutralization between males and females, although the inhibitory concentration of 50% (IC50) was adversely related to age.

COVID-19 boosters to prevent SARS-CoV-2 infections in adults
A) Response to COVID-19 mRNA vaccine and booster was measured as anti-RBD IgG antibodies from dried blood spots. Median IgG concentration (black dashed line) increased from 4.4µg/ml pre-booster to 101.6µg/ml post-booster (*p<0.001). Grey dotted lines represents paired samples. n=33. B) There was a median 25-fold change post-booster. C) Median anti-RBD IgG concentration (black dashed line) are shown. Individuals with outpatient COVID-19 had a median of 1.92 µg/ml (n=76) 14-42 days after infection, while individuals with a history of COVID-19 followed by vaccination were higher (60.61µg/ml, n=73, 5-42 days after 2nd dose). Individuals without a known history of COVID-19 who were either seropositive or seronegative and then 2-dose vaccinated had median IgG of 34.15µg/ml (n=181) and 33.09µg/ml (n=687), respectively. Pre-booster levels mean 237.9 days after 2-doses of vaccine were 4.4 µg/ml (n=33) compared to post-booster vaccination level of 101.6 µg/ml (n=33). Dotted lines represent the 25th and 75th percentiles. (*p<0.001).


The findings suggested that giving BNT162b2/Pfizer or mRNA-1273/Moderna boosters to healthy adults could prevent infections from progressing due to the production of significant antibody responses. Furthermore, when compared to antibody-mediated immunity created after the second vaccine dosage, antibody-mediated immunity may be sustained for a longer period of time.

The study has several drawbacks, including a short timeframe, a small sample size, and the lack of cellular immunity tests. Future research can look into the impact of boosters on cell-mediated immunity.

“These data support the use of boosters to prevent breakthrough infections and suggest that antibody-mediated immunity may last longer than after the second vaccine dose.”

*Important notice

Preliminary scientific papers published on medRxiv are not peer-reviewed and should not be regarded as conclusive, should not be used to influence clinical practice or health-related behavior, and should not be recognized as established information.

Journal reference:

  • Demonbreun, A. R., Sancilio, A., Vaught, L. A., et al. (2021). Antibody titers before and after booster doses of SARS-CoV-2 mRNA vaccines in healthy adults. medRxiv.

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