The Science Behind Antibodies to Coronavirus

Students, employees, and workers are getting cabin fever during the prolonged lock down and are eager to return to normalcy or the new normal. The authorities are torn between safeguarding the public health vs. allowing resumption of routine social and business activities.

So when will it be safe to return to work or school? There is no one answer because each situation and circumstance will be different.

One general answer is: When we will have herd immunity. To achieve that goal, we will need to test a lot of people, millions of people. That is easy said, but difficult to do.

A key component of herd immunity is to know how many have developed antibodies to the virus and therefore have some level of protection against being re-infected.

If we think of the virus as a “body” or a foreign entity that attacks us, then the “antibody” is the substance that is produced to repel and prevent the infection from taking hold.

The “antibodies” produced by our immune system are special proteins called “immunoglobulins”. Each antibody is specific and has only one target. So even if we may have antibodies to influenza caused by another coronavirus, these antibodies cannot attack and kill the virus that causes COVID-19.

A question that is frequently asked is: If I have antibodies to the novel coronavirus, can I return to work, and will I be safe for the rest of my life?

The answer: It depends on many factors.

When exposed to the virus, not everyone will make adequate quantity of the antibodies. The immune response (antibody production) will depend on the amount and the frequency of the exposure to the virus, the health of the individual’s immune system and underlying health issues. An individual whose immune system is depressed (due to illness, medications, age or genetics) may not produce the same quantity of immune globulins (antibodies) as another individual having had a similar exposure.

In general, the immune proteins (antibodies) appear in the blood within a week or so after exposure to the virus. The initial batch of such proteins are temporary in nature and disappear in a month or two. They belong to the IgM class of immune proteins. The more long-lasting antibodies (IgG class of immune globulins) appear as the level of IgM type of proteins are falling off. The IgG class of antibodies stay in the blood for a long time. A class of immune cells called the memory cells, maintain the ability to manufacture IgG type of antibodies as and when the foreign entity (such as coronavirus) tries to re-enter the body in the future.

As of now, we do not have the enough data from the COVID-19 patients as to the blood antibody levels and the minimal amount (called titer) of these proteins that is necessary to be considered an effective shield. The data has started to come in as the focus is now shifting from testing for the virus, to antibody testing.

The accuracy of the antibody tests is another big issue. As many laboratories are pushing to develop these tests, biology, technology, quality control, and other manufacturing problems are surfacing. Till the dust settles, it is recommended that one should only get tested at a reputable and certified laboratory that uses FDA approved processes and reagents. Home testing kits (like the pregnancy test kits) will become available in due course but are not reliable as of this writing.

Once a vaccine has been developed, it will greatly increase the number of people who will have robust number of antibodies and will be immune. A big worry is the possibility that over time, the virus may mutate to a degree that the vaccine may not be effective.

The general rule of “herd immunity” is to have a minimum of 40% of people in a community to be protected against an epidemic. The ideal number however is 80%. If 80% or more people in a community have antibodies to the novel coronavirus, the virus will no longer be able to cause an epidemic. Of course, those who have not been vaccinated or do not have adequate number of antibodies, could get sick but the virus will not be able to cause widespread epidemic.

Hopefully, the herd immunity will reach 80% or higher and we will be able to resume our lives in a (new) normal way. God Willing.