Herd immunity is when enough people are immune to a disease that it can no longer spread easily. This might be because they've had a vaccine to prevent it. Or, for some diseases, a person who gets sick and then recovers is immune for some amount of time after that.
DR CECIL ROSS MD
At the end of 2019, Wuhan, a city in China with a population of about 11 million, witnessed the outbreak of an unusual pneumonia. Now, the disease has spread to most parts of the world. SARS-CoV-2 (the virus that causes COVID-19) gets transmitted from one to another. When a person with infection coughs, sneezes, or talks he generates a lot of very small droplets. These Droplets typically do not travel more than six feet (about two meters). If it makes direct contact with the lining of the mouth, or nose, person-to-person spread occurs. This is similar to the spread of common cold. Infection can also occur if a person touches a contaminated surface and then touches his or her eyes, nose, or mouth.
Once the virus enters the lining of the mouth, nose or eyes, you can get symptoms within 5 days but can take as long as 2 weeks after the exposure. The symptoms are mild in approximately 80 percent of cases and often include fever, fatigue, and dry cough, loss of smell and taste. Sometimes you can get diarrhoea, headache, running nose, or sore throat. Difficulty in breathing occurs in approximately 20 to 30 percent of patients, typically arising five to eight days after symptom onset. They can worsen rapidly. Hence once you develop breathing difficulty, it is necessary to go to a hospital for evaluation and management.
Pneumonia is the most common manifestation of severe disease where there is a “cytokine storm”, in which you get fever, low BP and lack of oxygen to various parts of the body. This is the leading cause of death, followed by blood infection and heart complications.
What factors are associated with severe COVID-19?
Severe illness can occur in otherwise healthy individuals of any age, but it predominantly occurs in adults with older age group (more than 60 yrs) or underlying medical conditions like, cardiovascular disease, diabetes mellitus, hypertension, chronic lung disease, cancer, chronic kidney disease, obesity, and smoking.
What are the major cardiac complications?
Cardiac manifestations are common in hospitalized patients and occur most frequently in critically ill patients. The most common complications are,
Injury to the heart: This occurs in approximately 10 to 30 percent of hospitalized patients. It can be seen in laboratory tests like troponin, and ECG which can show irregularity in heartbeat, and heart failure.
Clotting of blood can occur in lungs, heart or blood vessels. This is called Thrombosis. It leads to venous thromboembolism (VTE; including deep vein thrombosis and pulmonary embolism) and arterial thrombosis, including stroke, myocardial infarction, and possibly gangrene of the hands and legs. The risk is highest in individuals in the intensive care unit (ICU), often despite preventive measures with blood thinners.
The greatest challenge is to distinguish COVID-19 clinically from other respiratory illnesses, particularly influenza. The clinical features of COVID-19 overlap substantially with influenza and other respiratory viral illnesses. There is no way to distinguish among them without testing.
When should patients be advised to stay at home? Go to the hospital?
Home management is appropriate for most patients with mild symptoms (e.g., fever, cough, and/or body aches without breathing difficulty), provided they can be adequately isolated, monitored, and supported at home. Patients being managed at home should be educated about the potential for worsening disease and advised to closely monitor for symptoms of more serious disease, including breathing difficulty or persistent chest pain. Once these symptoms develop, you should get hospitalised.
What are the different types of tests for COVID-19?
There are two major types of tests for COVID-19:
- Reverse transcription polymerase chain reaction [RT-PCR]) (takes 24 hrs for result)
- Rapid Antigen Test. (takes 2 hours for results)
Both these tests are done in throat swabs.
When is the best time to test for COVID-19 following an exposure?
Usually five to seven days following exposure is recommended based on the average incubation period.
Home care
For most patients with COVID-19 who are managed at home, we advise:
- supportive care with Paracetamol like Crocin/ Dolo 650
- Plenty of water for hydration
- Close contact with the doctor
- Monitoring for clinical worsening, particularly the development of new or worsening breathing difficulty, which should prompt admission into hospital
- Separation from other household members, including pets (e.g., staying in a separate room when possible and wearing a mask when in the same room)
- Frequent hand washing for all family members
- Frequent disinfection of commonly touched surfaces
What is herd immunity?
"Herd immunity" is when enough people are immune to a disease, that it can no longer spread easily. "Immune" means a person can't get the disease. This might be because they've had a vaccine to prevent it. Or, for some diseases, a person who gets sick and then recovers is immune for some amount of time after that. Eventually, when there is a vaccine for COVID-19, many people will become immune that way. Then they will be less likely to get and spread the infection. This will help protect people who cannot get the vaccine for some reason.
Have any medications been shown to prevent COVID-19?
No agent is known to be effective for preventing COVID-19. COVID-19 is a life-threatening living challenge for all of us. No specific drug exists for COVID-19. However, patients can be given a variety of medicines and supplements that improve immune responses and healthy life style.
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Dr Cecil Ross MD is a researcher, professor of medicine, and head of Hematology at St John’s Medical College Hospital, Bangalore.
