Coronavirus: What does an antibody test tell you post-vaccination? Should you get one done?

While there's been a rise in the COVID vaccinations, a number of studies and the fast-spreading coronavirus variants have confirmed our fears- vaccine driven immunity might not be as long-lasting as we had initially pegged it to be.

ALSO READ: What you should know about COVID antibody tests

Even though vaccines have been clinically tested and proven to reduce disease transmission and severity, the immune defence generated by the vaccines can start to wane, and make a person prone to risks yet again. This has given a rise to antibody testing, with many who have been fully vaccinated opting for the tests to ascertain their risks. But when should one go for it? If so, how accurate are the readings be?

Antibody tests or serology tests determine the IgG and IgM proteins created by the immune system. In a way, they also determine the level of protective immunity an individual may have and hence, a means by which many check how protected they are, and see if the vaccine is actually doing its job well.

While vaccines aren't a complete cure in themselves, they work very well to reduce the odds of infection, the severity of illness and transmission for a considerable while- as long as the immune protection last. With all the given benefits, the vaccines we have do not really protect us for a lifetime.

As per several findings and available clinical evidence, vaccine generated immunity, which is substantially different from natural immunity can start to dip 90-120 days after full vaccination, implying that a person who has developed peak immunity starts to record waning antibody counts months after vaccination. The dip can also be aggravated with variants like the Delta variant, which can easily surpass antibodies and render them ineffective. While the dip may not be significant in the beginning, it can steadily wane in the weeks following and cause concern.

Waning immunity can also be an issue with some vaccines more than others. As evident, some vaccines are more capable of generating a higher, stronger or lasting antibody response than others, so, the dip in immunity could be more drastically seen with some vaccines.

While there are strong indications of an upcoming third wave, getting an antibody test right now, especially weeks (or months) following full vaccination can be a really good approach if you find yourself to be at a heightened risk.

Even though without the public availability of booster shots, there's not much a fully vaccinated person could do at this point (apart from taking added precautions), finding out results from an antibody test could help identity who may be at a higher risk than others, or may be in need of more protection, despite having received both shots of the vaccine. The tests could identify and provide a fair idea of the added preventive measures which may be needed.

There may also be people who might benefit from getting an antibody test done weeks following vaccination. Immunocompromised people, or those battling severe comorbidities, as research has shown, may not be able to efficiently mount required antibodies post-vaccination, or record a faster decline in their immunity levels, post-immunization. Getting an antibody test, thus at the right time, could help measure if the vaccine is working well and providing neccessary protection needed against coronavirus and its variants.

Therefore, even though getting an antibody test may not be an absolute necessity for everyone, some groups, such as those immunocompromised, frail immunity, heavily exposed COVID warriors, or those with preconditions may benefit from getting a test done at some point post-vaccination and know about their risks beforehand.

Do remember that precision and timing are key factors with serological tests, and indiscriminate use after vaccination can sometimes lead to discrepancies and hence, should be used carefully and only when required (case by case).

One of the biggest shortcomings of these tests could be the inaccuracy of the results. Depending on the time you get the test done, for example, can indicate different, or miscalculated results. Getting the test done before time may show a wrong result, despite the body actively doing its work. Secondly, antibody tests may not also be an accurate tool to detect vaccine-generated antibodies since the time immunity peaks, or the time it may last can differ from individual to individual, and depend on a lot of factors. Therefore, with a lot of factors at play, while it may not be an absolute wise idea to rely on them completely, antibody tests may be helpful to ascertain some risks or know whether or not you are in need of more prioritized measures than before, or when the time comes, be prioritized for booster vaccinations.

Now, experts also do note that there's a certain thing to remember, even if you do get a concerning result with antibody tests- even with rapidly declining antibody count after vaccination, the body is still, very well doing its job and thus, immunity with vaccination isn't completely derivative of antibodies alone.

While immunity in itself is a broad concept, post-vaccination, doctors have suggested that the body has different systems in place to 'maintain' some level of immunity against any pathogen, or in this case, the SARS-COV-2 virus. The memory-B cells and T-cell immunity help remember traces of the infection and dole some level of immunity which plays its role in protecting the body. While this immunity may not be as protective or strong as the initial one garnered by the vaccine (we do not have conclusive evidence of the same as well), the body actively works to keep itself protected. Added measures and individual factors, such as mask-wearing, risk exposure etc. play parts in safeguarding a person from risk. Therefore, even though there may be a while before we see booster shots being made available and waning immunity a big concern, the immune system is doing its job well to protect you, and following COVID appropriate behaviour is the only way to double up safety.