POST COVID COMPLICATIONS

Corona is a pandemic that we are going through this situation. The pandemic has affected the worldwide so adversely that not having much protection poses a great risk for all. The vaccine has been developed and been used widely to provide immunizations. Almost 95% of immunization is provided by these vaccines. But unfortunately, the nation is now facing a 2^nd wave which happens to be a mutant species of the SARS CoV- 2.

The real question is whether we are still in danger after the infection? And sadly, the answer is yes, we are still in danger. This is the basis of the topic “post covid complications.” The coronavirus almost affects all the organs in our body from the brain to the skin due to which the risk of facing a lot of post covid complications rises.

The pathophysiology of corona virus involves the target receptor ACE2. Upon entering the healthy human body via the infected air droplets released from a sick patient, the corona virus penetrates the cell after fusion with the ACE2 receptor. The corona virus consists of spike glycoproteins on its cell surface, which helps in the penetration. There are two subunits S1 and S2. The S1 subunit gets cleaved by the TMPRSS2 and the S2 subunit fuses with the fusion protein on the ACE2 receptor. This helps the genetic material of the virus to be transferred into the cell membrane of the human host. The genetic material of the virus is recognized as its own by the human cell. The process is proceeded by the formation of new viral RNA and its package to form new viruses. It then gets released out to the cell and infects other cells and organs, thus resulting in the proven signs and symptoms and leading to a variety of complications.

Let’s begin with Neurologic complications: The coronavirus affects the brain by two hypothesized mechanisms.:

1.  Via the olfactory nerve: the olfactory nerve is the only cranial nerve which is exposed into the environment, which makes it the perfect route through which the virus gains entry to the brain. Upon entering the brain, the virus interacts with the ACE2 receptor and causes inflammation.

2.    Via blood brain barrier: the endothelial cells consist of ACE2 receptor and hence after interacting with the receptor, the virus gets transported into the brain, crossing the BBB.

After entering the brain, the virus goes on to infect the brain cells causing brain encephalitis, stroke, hallucinations, delirium, Seizures, brain fog, anosmia, ageusia, and in rare cases gullian barre syndrome and bell’s palsy.

Next, we have Respiratory complications: acute respiratory distress syndrome and post covid fibrosis.

The SARS- CoV2 affects the lungs by interacting with the ACE2 receptor and causing inflammation of the lungs. This leads to the decreased production of oxygen, because of which the infected person has to breath frequently to cope with the lack of oxygen, which results in symptoms like breathlessness. Increased inflammation leads to scarring of the lungs which causes fibrosis and accumulation of fluid in the air sacs of the lungs leading to ARDS.

Cardiopulmonary Complications

The corona virus is known to cause a lot of cardiological complications ranging from heart attack to myocardial infarction. The mechanism by which the SARS- CoV 2 causes these complications is due to its interaction with the ACE 2 receptors present in the heart cells. The virus causes inflammation in the heart muscle, decreasing its capacity to pump the blood efficiently, disruption in the heart signalling, interfering with the conduction of abnormal heart rhythms, leading to arrythmia or worsening of the pre-existing condition. When the lungs get inflamed due to the infection, which decreases the amount of oxygen for respiration. This leads to increased burden for the lungs which pumps more rapidly to cope up with the decreased oxygen. This results in the inflammation of the heart cells. Also, the upon interacting with the endothelial cells, there occurs the formation of blood clots which goes on to clog the blood vessels leading to myocardial infarction.

Renal Complications

The corona virus infection leads to acute kidney injury. This is due to the interaction of the virus with the ACE 2 receptors in the tubular epithelial cells, podocytes, and endothelial cells which gets inflamed and lead to acute tubular necrosis (ATN), collapsing focal segmental glomerulonephritis (FSGS) and endotheliitis of the glomerular capillaries respectively. All these eventually lead to acute kidney injury.

Hepatobiliary Complications

Although its known that the covid usually affects the lungs, it can also lead to liver inflammation. The virus affects the liver since there are ACE 2 receptors present in the liver. The liver inflammation in signified by the elevation in the liver enzymes such as ALT and AST.

Musculoskeletal Complications

Although not much has been studied about the musculoskeletal complications, but it has been hypothesised that due to the pulmonary inflammation it can lead to systemic inflammation and release of chemokines and cytokines like CXCL 10, IFN gamma, IFN 1 beta, IL 6, IL 8, IL 17, TNF alpha …etc. This can lead to skeletal muscle and bone and muscle complications like myalgias, atrophy, weakness, fatigue, bone mineral loss, osteonecrosis and chondrolysis. It has also been reported that rhabdomyolysis may occur as a result of acute kidney injury.

Dermatologic Complications

Most reported complication is the incidence of covid toes post infection. It is a chilblain like skin infection which not only occur in the toes but also other extremities like the finger. Covid toes begin with a red coloration on the fingers and toes which then gradually turns purple in colour.it can also form blisters, itch or pain. Some people develop painful raised bumps or areas of rough skin. Sometimes there can be pus under the skin.

Ms. ANJALI AMBROSE, Vth PHARM-D