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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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Common Respiratory Infections: Symptoms, Causes, and Prevention

Respiratory infections are one of the leading causes of illness across all age groups. They affect the respiratory tract, which includes the nose, throat, airways and lungs. While many respiratory infections are mild and self-limiting, some can become severe, especially in vulnerable populations.

Most respiratory infections are viral; antibiotics are not always required unless bacterial infection is confirmed.

In Common Cold vs Flu, add

Flu is usually more severe, with sudden fever, marked fatigue, and body aches.

Add COVID-19 mention briefly under respiratory infections list as an important viral infection

Understanding common respiratory infections, their causes and prevention strategies is essential for protecting lung health and preventing complications.

What Are Respiratory Infections?

Respiratory infections occur when viruses, bacteria or other pathogens infect the respiratory system. They are broadly classified into:

upper respiratory infections
lower respiratory infections

Upper respiratory infections affect the nose and throat, while lower respiratory infections involve the lungs and bronchi.

Common Types of Respiratory Infections

Common Cold

The most frequent respiratory infection, caused by viruses.

Symptoms include:

runny or blocked nose
sore throat
sneezing
mild cough

Influenza (Flu)

A viral infection that may cause more severe symptoms than the common cold.

Symptoms include:

high fever
body aches
fatigue
cough

Bronchitis

Inflammation of the bronchial tubes.

Symptoms include:

persistent cough
chest discomfort
mucus production

Pneumonia

A serious lung infection affecting air sacs.

Symptoms include:

fever
breathlessness
chest pain
productive cough

Sinus Infections

Infection of the sinus cavities.

Symptoms include:

facial pain
nasal congestion
headache

Causes of Respiratory Infections

Viral Causes

Viruses are the most common cause of respiratory infections and spread easily.

Bacterial Causes

Certain infections like pneumonia and sinusitis may be bacterial and require medical treatment.

Environmental Factors

Exposure to:

air pollution
smoke
allergens

can weaken respiratory defences.

Weakened Immunity

Low immunity increases susceptibility to infection.

How Respiratory Infections Spread

Respiratory infections commonly spread through:

coughing and sneezing
close personal contact
contaminated surfaces
crowded environments

Poor ventilation increases transmission risk.

Symptoms That Should Not Be Ignored

Seek medical advice if experiencing:

high or persistent fever
difficulty breathing
chest pain
bluish lips or nails
prolonged cough

Early care prevents complications.

Why Respiratory Infections Are Common in Certain Seasons

Seasonal factors such as:

cold weather
monsoon humidity
indoor crowding

increase infection spread.

Who Is Most at Risk?

High-risk groups include:

infants and children
elderly individuals
pregnant women
people with asthma, COPD or heart disease

Extra precautions are essential for these groups.

Prevention of Common Respiratory Infections

Maintain Good Hand Hygiene

Regular handwashing reduces transmission.

Follow Respiratory Etiquette

Cover mouth and nose while coughing or sneezing.

Improve Indoor Air Quality

Proper ventilation reduces airborne spread.

Stay Vaccinated

Vaccination protects against infections like influenza and pneumonia.

Strengthen Immunity

Balanced diet, adequate sleep and physical activity support immune health.

Avoid Smoking and Second-Hand Smoke

Smoke damages airway defence mechanisms.

Role of Nutrition in Respiratory Health

Adequate intake of:

vitamins
minerals
antioxidants

supports immune response and lung health.

Importance of Early Diagnosis

Early identification:

reduces disease severity
prevents complications
limits spread

Timely care improves recovery.

Long-Term Impact of Recurrent Respiratory Infections

Repeated infections may lead to:

chronic cough
reduced lung function
increased vulnerability to future illness

Prevention protects long-term respiratory health.

When to Consult a Doctor

Medical evaluation is recommended if:

symptoms worsen
recovery is delayed
breathing difficulty occurs

Prompt care reduces risk.

Conclusion

Common respiratory infections are widespread but largely preventable. Viruses, bacteria, environmental exposure and weakened immunity contribute to their development. Understanding symptoms, causes and prevention strategies helps individuals take early action and protect lung health. By practising good hygiene, staying vaccinated, improving immunity and seeking timely medical care, the risk of respiratory infections and their complications can be significantly reduced.

References

World Health Organization (WHO) – Respiratory Infections and Prevention Guidelines
Indian Council of Medical Research (ICMR) – Acute Respiratory Infection Reports
National Centre for Disease Control (NCDC) – Respiratory Disease Surveillance
Lancet Respiratory Medicine – Infection and Lung Health Studies
Ministry of Health and Family Welfare – Seasonal Respiratory Advisory
Statista – Global Respiratory Infection Trends

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