I have been vaccinated for Covid. Now what?

Do I have common cold or Corona Virus?

All of us have had viral infections sometimes in our lives. Common cold, the stomach virus and Influenza virus are some of the more common ones. The current worldwide epidemic named COVID-19 is a respiratory tract illness that is caused by a virus that belongs to the corona virus family. The official name of the virus is SARS-CoV-2.

The other well-known viruses in the corona virus family are SARS (Severe Acute Respiratory Syndrome) and MERS (Middle East Respiratory Syndrome) viruses.

The common way to diagnose infections is to culture the germs, e.g. for suspected strep throat, the doctor takes a swab from the throat and sends it to the lab for culture. The lab grows the bugs in the petri dish and report back to the doctor’s office in day or two.

Unfortunately, viruses cannot be grown in the petri dish. So how do we diagnose viral infections?  There are essentially two methods: One is to determine if the patient has the infection at the moment, and the other test is to see if the patient has had the infection in the past.

To diagnose if a patient has the corona virus at present, we need to perform a molecular test.  The test is done using RT-PCR (Reverse Transcription – Polymerase Chain Reaction) technology. To understand RT-PCR, we need to refresh our biology lessons.

The human DNA resides in the nucleus of the cell. DNA makes RNA which helps make proteins. Proteins that include enzymes and hormones, run our bodies. Whereas DNA remains locked up in the nucleus, its specific RNA copy is accessible in the blood and other tissues.

So the natural sequence is DNA → RNA  → Proteins.

Here is the problem:  Viruses do not have a nucleus. Viruses do not have a nucleus . In order to survive and propagate, viruses must insert their RNA or DNA into the nucleus of another cell to survive. Whereas we cannot access the viral DNA / RNA that is locked up in the nucleus of the cell, we do have access to the RNA made by that particular virus. So the trick is to identify the virus through its mRNA (messenger RNA) inside the cytoplasm of the cell. This is done by using the RT-PCR technology.

How it works is similar to the fingerprint technology one uses to detect a criminal.

Lets say Dan Whoever has committed a crime and has left his fingerprints on the weapon. The hidden camera has captured his photo. But we don’t know his name. We put his fingerprints and photo into our database, and Bingo! We have a match: Its Dan Whoever.

So how can we apply this concept to detect which virus is it? Corona virus? Influenza virus? Etc.

I just mentioned that we don’t have access to the corona virus’s RNA. What if we could detect the virus from its mRNA?

The answer is yes. We can do this by using the RT-PCR technology. The lab extracts the viral RNA from the nasal swab of the patient suspected of having corona virus infection and makes the corresponding copy by using the enzyme called Reverse Transcriptase. The number of the DNA / RNA molecules hence created are then increased in number by using the process called Polymerase Chain Reaction.  This molecule is the replica of the RNA that came from the nasal swab of the patient. 

This laboratory made DNA / RNA is the fingerprint of the culprit corona virus. The lab then uses computers to match this fingerprint with the known RNA (fingerprint) of the corona virus. If it matches, the diagnosis is confirmed. You can do the same to establish a diagnosis of Influenza virus, by using the Influenza virus's RNA as the fingerprint.

In the beginning only he CDC was performing the diagnostic test for the corona virus. But now the FDA has authorized certified commercial and hospital labs to do the testing. Hence the testing capability has increased significantly.

There is also a push to develop a vaccine. Once available, the vaccine will help prevent us from getting the COVID-19 infection in the future. But not during the current epidemic.

We hope that it will not be a recurring event. My family has booked on a cruise next February—on Princess Cruise. Hopefully an effective vaccine will be available by then. Stay Well.