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Published on: Jul 07, 2020
1 minute read
By: Dr Rajan Choudhary

Asymptomatic Carriers Of COVID

Why Asymptomatic carriers of COVID are as dangerous as symptomatic patients

Many countries have now begun enforcing masks for everyone to wear when out in public, in enclosed spaces, or on public transport. There is good evidence to support these measures, but unfortunately, some still show resistance to the idea. Whilst some reasons put forward are non-sensical (masks do not cause any noticeable or measurable decrease in oxygen delivery to the body), other people feel like they shouldn’t wear a mask because they do not have symptoms of COVID. And thus would not spread anything. Here we look at a recent publication in Nature, one of the most esteemed peer-reviewed scientific journals in the world, and what it shows us about the transmission of COVID in a population.

This study by Lavezzo et al looked at the suppression of the SARS-CoV-2 outbreak in the Italian municipality of Vo’. This municipality is 50 kilometers west of Venice with a population of just 3,416 people. It experienced its first casualty of COVID on the 21st of February, after which it underwent lockdown for 14 days. During this time data was collected on the clinical presentation and hospitalization of COVID patients, as well as other citizens through the contact tracing network.

In total 2,812 residents were tested in late February, with another 2,343 tests performed two weeks later at the end of lockdown. Nasal and throat swabs were taken to identify infected individuals. The study found only 2.6% of people were positive for COVID at the start of lockdown, which reduced to 1.2% two weeks later.

Out of this infected population, 42.5% were asymptomatic. They had no symptoms at the time of swab testing nor did they develop symptoms afterwards. When the viral load was measured between symptomatic and asymptomatic patients, there was little difference.

Evidence has pointed to a large asymptomatic population, and previous studies have shown it to be as high as 50% in some cases. Many would assume if a patient has no symptoms then they must have fought the infection before it became an issue, or had a very low viral load and therefore were not likely to spread it. This study shows it is simply not true. Asymptomatic carriers of COVID are likely to contribute to the transmission and spread of COVID amongst the population.

If you are asymptomatic you have as high a viral load as someone who is symptomatic. But there is no way to tell without a swab. You have as much of a potential to spread the infection to the vulnerable. Even in people who became symptomatic the height of transmission was found to be before the patient showed any symptoms.

So what does this mean? If you have COVID you are likely to spread it before you show any symptoms or any symptoms at all. We know masks are effective at significantly reducing the spread of COVID, by catching the water droplets that carry the SARS-CoV-2 Virus. Now that shops and public places are re-opening, the risk of spread is high.

Wear a mask. Stop the spread.

https://www.nature.com/articles/s41586-020-2488-1_reference.pdf suppression of a SARS article

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Shortness of Breath Causes: From Common Triggers to Serious Health Conditions

Shortness of breath, medically known as dyspnea, is a symptom that ranges from mild discomfort during exertion to a distressing sensation of not getting enough air. In India, increasing air pollution, lifestyle diseases and respiratory infections have made breathlessness a frequent complaint across age groups. Understanding shortness of breath causes is essential to identify when it is harmless and when it signals a medical emergency.

What Is Shortness of Breath?

Shortness of breath refers to difficulty breathing or a feeling of air hunger.

It may present as:

rapid breathing
shallow breathing
tightness in the chest
inability to take a deep breath

The sensation can develop suddenly or gradually.

Common and Benign Causes of Shortness of Breath

Physical Exertion

During exercise, the body demands more oxygen.

Temporary breathlessness during:

climbing stairs
running
heavy physical work

is normal and resolves with rest.

Anxiety and Panic Attacks

Stress and anxiety alter breathing patterns.

Symptoms include:

rapid breathing
chest tightness
dizziness

These episodes often resolve with calming techniques.

Respiratory Causes of Shortness of Breath

Asthma

Asthma causes airway narrowing and inflammation.

Symptoms include:

wheezing
chest tightness
breathlessness during exertion or at night

Asthma is a leading cause of chronic breathlessness.

Chronic Obstructive Pulmonary Disease

COPD includes chronic bronchitis and emphysema.

Risk factors include:

smoking
indoor air pollution
occupational exposure

WHO identifies COPD as a major cause of breathlessness in adults.

Respiratory Infections

Infections such as pneumonia and bronchitis reduce lung capacity.

Breathlessness may be accompanied by:

cough
fever
chest pain

Severe infections require urgent treatment.

Heart-Related Causes of Shortness of Breath

Heart Failure

The heart fails to pump blood efficiently.

This leads to:

fluid accumulation in lungs
breathlessness on exertion
breathlessness while lying flat

ICMR data shows heart disease as a major contributor to unexplained breathlessness.

Coronary Artery Disease

Reduced blood supply to the heart can cause:

breathlessness
chest discomfort
fatigue

This may occur even without chest pain in some individuals.

Blood and Metabolic Causes

Anemia

Low hemoglobin reduces oxygen delivery.

Common symptoms include:

fatigue
breathlessness on mild activity
pale skin

NFHS-5 highlights anemia as highly prevalent in India.

Thyroid Disorders

Hyperthyroidism increases metabolic demand, causing breathlessness.

Hypothyroidism may contribute indirectly through weight gain and reduced stamina.

Lung Circulation Disorders

Pulmonary Embolism

A blood clot in the lungs causes sudden, severe breathlessness.

This is a medical emergency and may be accompanied by:

chest pain
coughing blood
fainting

Immediate treatment is critical.

Lifestyle-Related Causes

Obesity

Excess body weight restricts lung expansion.

Breathlessness occurs due to:

increased oxygen demand
reduced lung volumes

Weight management improves breathing efficiency.

Sedentary Lifestyle

Poor physical conditioning reduces respiratory muscle strength.

Even mild exertion may cause breathlessness.

Environmental and Occupational Factors

Air Pollution

Pollutants irritate airways and reduce lung function.

Urban populations experience higher rates of breathlessness.

Workplace Exposure

Dust, chemicals and fumes increase respiratory risk.

Protective measures are essential in high-risk occupations.

When Shortness of Breath Is a Warning Sign

Seek urgent care if breathlessness:

starts suddenly
worsens rapidly
occurs at rest
is associated with chest pain, bluish lips or confusion

These may indicate life-threatening conditions.

How Shortness of Breath Is Diagnosed

Evaluation may include:

physical examination
chest imaging
blood tests
lung function tests
heart evaluation

Diagnosis focuses on identifying the root cause.

Preventive Measures and Lifestyle Care

Prevention includes:

regular physical activity
pollution protection
smoking cessation
weight control
managing chronic conditions

Preventive healthcare reduces long-term risk.

Importance of Early Medical Evaluation

Delayed diagnosis can worsen outcomes, especially in:

heart disease
lung infections
anemia

Early care improves treatment success.

Conclusion

Shortness of breath causes range from temporary exertion and anxiety to serious heart, lung and blood disorders. While occasional breathlessness may be harmless, persistent or sudden symptoms should never be ignored. Understanding the underlying causes and seeking timely medical evaluation can prevent complications and save lives. Paying attention to changes in breathing is an essential step toward protecting overall health and wellbeing.

References

Indian Council of Medical Research (ICMR) – Respiratory and Cardiac Health Reports
World Health Organization (WHO) – Breathlessness and Chronic Disease Guidelines
National Family Health Survey (NFHS-5) – Anemia and Respiratory Health Data
Lancet – Dyspnea Evaluation and Outcomes Research
NITI Aayog – Non-Communicable Disease Prevention Reports
Statista – Respiratory Disease and Air Pollution Trends

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