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Published on: Jul 09, 2020
2 minute read
By: Dr Rakesh Choudhary

COVID- 19 Tests – What Do You Need To Know?

COVID- 19 tests – What do you need to know?

Author: Dr. Rakesh Choudhary MBBS, MS, FRCS UK, FRCS Orth UK, MChOrth UK.

Dr. Choudhary is a practicing consultant surgeon in the UK.

So many of us think it is not their job to learn about COVID-19 tests and this should be left for the experts and governments to decide about these tests. But I strongly suggest the public must have a basic understanding of these tests which they may have to have themselves.

Basically there are two types of tests, one which can detect the virus in the body and the other one which tells if the person had the previous infection.

Virus test

The virus test detects an active infection. It detects the genetic material (RNA) of the virus during an active infection. It is also called a PCR (polymerase chain reaction) test or nucleic acid test and is sometimes inaccurately called an antigen test.

A swab is taken from deep in the back of your throat and deep in the nose. The swab should go deep up to 7-8 cm and is generally uncomfortable for the patient. Swabbing patients using the correct technique is paramount in ensuring an accurate result. By simply swabbing the inside of the nasal passage is not deep enough to verify that the virus is present.

What does virus testing tell you?

This test tells us if a patient is actively infected with the COVID-19 virus. Virus testing is used mainly for the diagnosis of COVID-19.

When should it be done?

The virus test works best during the first seven days of symptoms.

The coronavirus can be detected in swabs even before symptoms of illness first appear . This is why people can be infectious for a few days before the onset of symptoms, which usually appear about 5 days after the virus infects. Some people have no symptoms throughout their infection but are positive on the virus test and infectious to others. After a few days of illness, the concentration of the virus falls (as seen in swab samples) and the symptoms of the illness usually recede.

Accuracy of the test

In a person with COVID-19, the test is less likely to give a positive result late in the course of infection once the virus has been cleared by the immune system, or if an inadequate sample is taken from the nose or throat. There are concerns that the rate of ‘false negative’ test results could be as high as 30% and a significant number of people are wrongly being told they do not have the virus.

Antibody test

Antibody tests check your blood by looking for antibodies, which may tell you if you had a past infection with the virus that causes COVID-19. Antibodies are protein structures that are produced by the immune system in response to certain infections. The antibody can help fight off infections and can provide protection against getting that disease again (immunity). Antibodies are disease-specific. For example, measles antibodies will protect you from getting measles if you are exposed to it.

The antibody test detects the presence of antibodies as a marker of past infection. The antibody test (blood test) will only detect infections after the immune system has produced antibodies that recognize the virus. This happens approximately 7–10 days after symptoms develop.

Tests carried out a week after a patient develops symptoms will detect only 30% of people who had COVID-19 infection. Accuracy increases to 72% at two weeks and to 94% in the third week. Some people may take even longer to develop antibodies, and some people who are infected may not ever develop antibodies.

Interpretation of the antibody test is complex for non-medical people. Basically having antibodies to the virus that causes COVID-19 may provide protection from getting infected with the virus again. If it does, we do not know how much protection the antibodies may provide or how long this protection may last.

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Heat Exhaustion Warning Signs: Symptoms You Should Never Ignore

Heat-related illnesses are common during hot weather, particularly in tropical countries like India where summer temperatures can become extreme. Heat exhaustion is a serious condition that occurs when the body overheats due to prolonged exposure to high temperatures and inadequate hydration.

Recognizing heat exhaustion warning signs early can prevent life-threatening complications such as heatstroke.

What Is Heat Exhaustion?

Heat exhaustion is a heat-related illness caused by:

Excessive heat exposure
Dehydration
Loss of electrolytes through sweating

It often occurs during outdoor work, exercise or travel in hot environments.

If untreated, it may progress to heatstroke — a medical emergency.

Common Heat Exhaustion Warning Signs

1. Heavy Sweating

Excessive sweating is one of the earliest signs.

The body attempts to cool itself through perspiration, leading to fluid loss.

2. Dizziness or Lightheadedness

Low blood pressure due to dehydration may cause:

Feeling faint
Blurred vision
Weakness

3. Fatigue and Weakness

Muscle weakness and exhaustion occur as the body struggles to regulate temperature.

4. Nausea and Vomiting

Digestive discomfort is common in heat-related illnesses.

5. Headache

Dehydration and heat stress can trigger throbbing headaches.

6. Muscle Cramps

Electrolyte imbalance may cause painful muscle cramps, especially in legs.

7. Rapid Heartbeat

Increased heart rate helps circulate blood for cooling but may indicate strain.

8. Cool, Clammy Skin

Despite hot weather, skin may feel cool and moist due to heavy sweating.

Who Is at Higher Risk?

Certain groups are more vulnerable:

Outdoor laborers
Athletes
Elderly individuals
Children
People with chronic illnesses
Individuals on certain medications

Urban heat exposure increases risk during peak summer months in India.

Heat Exhaustion vs Heatstroke

Heat exhaustion is serious but manageable if treated promptly.

Heatstroke symptoms include:

High body temperature (above 40°C)
Confusion or disorientation
Dry, hot skin
Seizures
Loss of consciousness

Heatstroke requires immediate emergency medical attention.

Immediate Steps to Take

If heat exhaustion is suspected:

Move to a cool, shaded area
Loosen tight clothing
Drink water or oral rehydration solution
Apply cool cloths to body
Rest until symptoms improve

Seek medical care if symptoms persist beyond one hour.

Prevention Tips

Stay Hydrated

Drink water regularly, even if not thirsty.

Avoid Peak Sun Hours

Limit outdoor activity between 12 PM and 4 PM.

Wear Light Clothing

Choose loose, breathable fabrics.

Use Sun Protection

Wear hats and sunglasses when outdoors.

Take Frequent Breaks

Rest in shaded or air-conditioned areas.

Maintain Electrolyte Balance

Use oral rehydration solutions if sweating heavily.

Heat Illness in the Indian Context

India frequently experiences heatwaves, especially in northern and central regions. Public awareness about hydration and heat safety is essential to reduce hospitalizations and fatalities.

Community-level education can significantly improve prevention.

When to Seek Medical Help

Immediate medical attention is required if:

Symptoms worsen
Body temperature rises significantly
Confusion develops
Fainting occurs
Vomiting persists

Early treatment prevents severe complications.

Conclusion

Heat exhaustion is a preventable but potentially dangerous condition. Recognizing warning signs such as heavy sweating, dizziness, nausea and muscle cramps allows timely intervention.

With rising summer temperatures, especially in India, proactive hydration and heat safety measures are essential. Preventive care and awareness can protect vulnerable individuals and reduce health risks.

Staying cool and hydrated is the simplest way to safeguard your health during hot weather.

References

Indian Meteorological Department – Heatwave Reports
World Health Organization – Heat-Related Illness Guidelines
Indian Council of Medical Research – Public Health Advisory
National Disaster Management Authority (India) – Heatwave Action Plan
Lancet Planetary Health – Climate and Health Research

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