Antibody Tests & COVID-19 Vaccines

By Suburban Diagnostics

The antibody test for the SARS-CoV-2 virus is a promising test that can aid in the endeavour of COVID-19 vaccination.

To paraphrase Queen Elizabeth II, the year 2020 was an “annus horribilis”. The COVID-19 pandemic reigned supreme through most of the year. At the time of writing, more than 1.7 million deaths have been attributed to COVID-19. But this year has also shown us how far we have come in our ability to fight such a virus. Yet, everything about this year was not misery and death. When historians look back at this year, they will see that we were able to identify the virus in less than a month. We sequenced the genome of the virus and devised tests in record time. They will note that there was an unprecedented global effort to develop a vaccine. The result of this is the fastest vaccine development project in the history of man. Not only did we manage to develop many different vaccines, but some of them have also taken less than a year.  To put this into perspective, it takes, on average, 10-15 years to develop a vaccine. The fastest development process before this was the Mumps vaccine which took 4 years.

Vaccination against COVID-19 has 2 desired endpoints, a clinical one and a serological one. The clinical endpoint for the vaccine would be to prevent infection, transmission of the disease or, at the very least, to prevent symptomatic infection. The serological endpoint, which forms the context of this article, is the successful production of neutralizing antibodies in an individual post-vaccination.

The logistical implications of vaccinating 7.7 billion people are staggering. The minimum requirement would be to vaccinate enough people to provide herd immunity. This would still put the figure at between 4.6 and 6 billion people. The antibody test for the SARS-CoV-2 virus is a good test that can aid in this endeavour, both logistically as well as in monitoring whether the desired serological goal has been met.

Targeted vaccination

As mentioned, the global vaccination program is a huge logistical challenge. The problem is especially apparent in a country like India with a population of 1.35 billion. Doses for the entire population will not be available immediately. We will receive it in phases. So, the logical thing to do is to vaccinate the high-risk population first. This is what the government proposes to do with the first batch of ~250 million doses in 2021. However, the virus is not going anywhere. It will continue to spread and kill whilst we are engaged in the mammoth task of vaccinating our population. Antibody testing would be a good recommendation to filter those who should be given priority. Once the antibody-negative individuals have been identified, they can be vaccinated first. The vaccination of antibody-positive patients can wait.

A study was done at Suburban Diagnostics, in which individuals who had contracted COVID-19 were followed up with serial antibody tests over a period of more than 6 months. What we found is that the antibodies continued to be detectable more than 6 months after the infection. Looking at the results of our study in conjunction with the fact that only a minuscule number of re-infection cases have been reported, we can be confident that these antibodies can protect against future infection. Thus, patients who are already antibody-positive due to having contracted the disease at some point can be considered to be at a much lower risk than those without antibodies.

By vaccinating the antibody-negative population first, we can achieve two things. We can optimize the usage of the limited doses of vaccine and reduce the incident mortality during the process.

Is the vaccine working?

There are many COVID-19 vaccines available at present, with many more on the way. Currently, none of the vaccines claim 100% efficacy. So, it is possible that a small percentage of the population may not attain the serological goal of vaccination i.e. developing protective antibodies against COVID-19. This is something the vaccinated person and their healthcare providers will need to know. The best way to find out is to check the patient's antibody levels post-vaccination. This information will be needed to identify those who have not responded to the vaccine and for whom other measures or vaccines may need to be tried.

An inextricable relationship

As mentioned, vaccine development trials have a serological endpoint viz the development of protective antibodies. One of the first steps of vaccine development is to identify if the proposed vaccine can produce a measurable immune response i.e. antibodies. So, from the very beginning, antibody testing is an invaluable part of vaccine development. Even after a vaccine has been approved and rolled out, the antibody test can help the judicious use of the vaccine and help determine its serological efficacy.

Optimistically, it will take at least 2-3 years for our vaccination programs to cover the required number of people. During that time, we should quickly identify and isolate all positive cases to prevent further outbreaks. Furthermore, I believe that we will need to keep up the scale and pace antibody testing if the vaccine is to be used in the best way possible.