I am fortunate and glad that my previous article explaining basics regarding antibodies was well appreciated. The post was found to be detailed, yet simple enough such that any reader should be able to dispel all myths about antibodies.
However, I am aware that a lot of readers (sometimes I myself am guilty of the same) would just want answers to their questions without understanding the details. In fact, a few readers personally reached out to me requesting for another post in Q&A format, giving straight answers to commonly asked questions regarding antibodies.
Note: The answers are straight and brief. Hence explanations used here might be difficult to understand, since the idea is to keep answers short and straight to the point. If you face any challenge in understanding, please refer to the detailed explanations, which can accessed by clicking HERE
Table of Contents
Question 1: If I have low levels of antibodies against COVID-19, does it mean I am less protected?
Answer: Low levels or zero levels of antibodies DO NOT indicate that you are not protected
First thing to remember is that COVID-19 is a virus. A virus, to carry on its attack against us, has to go inside our cells. So long a virus is outside any cell, antibodies can fight against that virus. However, once the virus has penetrated a cell, antibodies against that virus are useless. To combat such viruses that have now taken shelter inside our cells, we have T cells. Antibody levels do not measure effectiveness of T cells.
Second thing to remember is that antibodies are not supposed to keep circulating in your blood life-long. The role of antibodies is to fight against pathogens like viruses or bacteria. So, antibodies are prepared only when you get infected, and these antibodies disappear soon after the infection is gone. However, the information to create these specific antibodies remain stored in special cells called “memory cells“. Hence, even after the antibodies disappear, our immune system “knows” how to prepare these specific antibodies quickly if attacked by the same pathogen.
Question 2: Do these memory cells, described in the answer to previous question, remain life- long?
Answer: It depends. But they remain long enough.
If infection happens repeatedly, they remain for a very long time. If an infection is serious, the consequential memory cells remain, again, for very long time. But, if it’s a mild infection that does not trouble us frequently, it’s efficient for the body to stop bothering about such infections. In such cases the memory cells don’t last life-long.
Immune memory stores information to produce specific antibodies against a particular signature. If the signature changes, then there is no guarantee that these specific memory cells will produce antibodies against new signature. Even if they produce antibodies, the same antibodies might or might not work, depending on how different the new signature is. An antibody works like a key to a lock. if some serrations inside a lock change, the key to that lock still might work- but there is no guarantee. And if there are significant changes to the lock, you will need an altogether a new key. This time the old key won’t work at all.
Question 3: Do vaccines prevent COVID-19 infection?
Answer: Vaccines may or may not prevent COVID-19 infection. If you recently had vaccination within 4-6 months, chances are you will remain protected- but there is no guarantee. There is very less possibility that your COVID-19 vaccine will protect you, if you get infected with a strain that is very different from what was used to design the vaccine.
A COVID-19 vaccine will train your body to prepare antibodies and T cells against that particular strain of COVID-19 virus. But after some time, only memory cells remain. The antibodies and the specific T cells disappear. (We discussed this part in Q2). This leaves the system vulnerable to infection by COVID-19 virus once again. But that hardly matters. Post vaccination, if the infection happens by the same strain of COVID-19 virus our immune system will rapidly prepare antibodies and specific T cells against that viral strain (thanks to the information stored in memory cells from the training by vaccine) leading to quick elimination of the virus.
But, we must remember that viruses like COVID-19 keep changing their structures, resulting in different strains. Each strain will have signature with some difference compared to signature of any other strain. Since antibodies work by recognizing these signatures, antibodies are strain specific. If the signature of the virus changes, the same antibodies might or might not work depending on how massive the change in signature is. Hence, antibodies against one strain of virus might or might not work against another strain of same virus.
So, vaccines manufactured in 2020 against alpha strain of COVID-19 virus may have very low efficacy against 2021 Omicron strain, if there are huge differences in the structures of these two strains. More the similarity between 2 strains, better will be the effect of the vaccine against the second strain although it was designed against the first strain. Hence, technically speaking, use of different types of vaccine for first and second dose might lead to better protection against COVID-19.
Question 4: Do vaccines prevent risk of death from COVID-19 infection?
Answer: Yes- definitely. Vaccines do reduce chances of hospitalization due to that infection significantly.
In infections like COVID-19, death is never because of virus- it’s always because of an immune system over- reacting while trying to eliminate the virus. An over- reaction can be imagined as army of a country dropping an atom bomb against a bunch of small-time criminals who can dealt simply by using pistols. The “atom-bomb” will of course kill these criminals but will also end up killing all the innocent citizens of that country.
Vaccination against a particular strain of virus trains the immune system to act in a mature way while facing the attack from the same viral strain. This “maturity” prevents immune system to “over-react”.
However, this protection against risk of death again is strain dependent. Vaccine produced against “Strain A” of COVID-19 will give very high protection if you are infected with “Strain A”. But if you are infected with “Strain B”, the same protection level won’t hold- it will be lower. More the difference between the two strains, lower will be the level protection.
Question 5: Can vaccination fail to save me in COVID-19?
Answer: Yes. There is no guarantee that vaccination will prevent COVID-19 infection or completely protect against complications of COVID-19. In fact, there is a very low likelihood that vaccination will prevent infection with COVID-19. However, there is an extremely high likelihood that COVID-19 vaccination will protect you from developing complications.
As explained in answers to Q3 and Q4 above, vaccine may NOT help prevent infection and DOES REDUCE risk of complications and death due to COVID-19.
However, despite full awareness that I am being repetitive, I will keep stressing that antibodies are strain specific. Antibodies against one strain of virus might or might not work against another strain of same virus. This is the main reason why we see COVID-19 infections even in those who are double vaccinated. Vaccines manufactured in 2020 against alpha strain of COVID-19 virus may have very low efficacy against the 2021 Omicron strain, if there are huge differences in the structures of these two strains of COVID-19 virus. More the similarity between 2 strains, better will be the effect of the vaccine against the second strain although it was designed against the first strain. Hence, technically speaking, use of different types of vaccines for first and second dose might lead to better protection against COVID-19.
Question 6: Without repeated booster shots of COVID-19, am I doomed?
Answer: Not really.
Vaccination trains our immune system in making antibodies against the particular strain of virus against which the vaccine has been developed. Antibodies are strain specific. Antibodies against one strain of virus might or might not work against another strain of same virus. More the similarity between 2 strains, better will be the effect of the vaccine against the second strain although it was designed against the first strain.
So, if you had vaccination in 2020 against COVID-19, the antibodies your body would develop due to that vaccine should work well against strains prevalent at that time (assuming these strains are similar). However, COVID-19 keeps changing its structure frequently. We call these changes as mutations. So, the 2022 COVID-19 virus may have a structure significantly different from the original 2020 strain. This is the main reason why we see COVID-19 infections even in those who are double vaccinated. This may mean that your 2020 vaccination might not fully protect you against 2022 strain. Similarly, the booster injections of the same vaccine might not also work, since they will prepare antibodies specific to 2020 strain and not 2022 strain. So, if at all you should take boosters, it is best to use of different type of vaccine for booster shot. I had taken 2 doses of DNA vaccine (COVISHIELD by Astra- Zeneca/Oxford) in 2021. If I am forced to take booster, I would prefer now to take mRNA vaccine instead of DNA vaccine. This will allow my body to make wider range of antibodies and hopefully few of these will still have effect on current strains of COVID-19. Of course, there is no guarantee. But chances of success with booster of a different vaccine, are higher.
Question 7: COVID-19 vaccines are dangerous in few patients and have caused deaths. Should I avoid vaccination?
Answer: There is always a rare risk of developing complications due to any COVID-19 vaccine.
Please remember that in case of actual COVID-19 infection, complications and deaths are never caused by the virus. In few unfortunate individuals, their immune system hyper-react. And this hyper reaction is the true cause of complications and deaths related to COVID-19. Our immune system generally reacts normally and uses appropriate amount of force to combat COVID-19 infection, such that the virus is killed without much damage to self. However, in some individuals, the same immune system hyper reacts and uses excessive force that ends up damaging vital organs leading to disastrous consequences.
A vaccine acts like a mini virus and is designed to train body to learn how to fight the actual virus without really getting infected. But this mini virus will be dealt with in the same way by our immune system as the real virus. So, here too, in few unfortunate individuals the immune system might over- react to the vaccine and cause catastrophic impact on vital organs. However, unlike virus, vaccine cannot multiply and the extent of such hyper- reaction to vaccines is generally limited. Hence, statistically, the chances of dying due to vaccination is very very low compared to chances of dying due to COVID-19 infection. But such outcomes cannot be accurately predicted.
One method of predicting what will happen upon vaccination is by measuring IRP. Read more on this- here.
Question 8: Can antibodies be used for diagnosis of COVID-19?
Answer: Yes. Definitely. But interpretations can be difficult and practical use is doubtful
For new infections, antibodies appear pretty late, and a person can be spreading infection even before he becomes positive for antibodies.
For repeat infections, antibodies will already be present, and it will be difficult to distinguish if these antibodies are from new infection, or from earlier infection or from vaccination!
So, let’s say you do antibody test for COVID-19 in a person who is at the airport. And you find antibodies. How will you interpret? Surely these antibodies may represent an active COVID-19 infection. If so, then you will quarantine this person. But these antibodies can be from previous infection from which this person has fully recovered. Then, it’s really unfair to issue orders for quarantine. And let’s say you find that this person was vaccinated recently. Then mostly these antibodies are due to the vaccine. So, how will you act if you test is positive for COVID-19 antibodies?
One way to try solve this confusion is to do “rising titres” as is done in case of typhoid. In this method, you measure antibodies twice- once now and once again after few days. If the antibody levels are going up, the person is currently infected. And this is quite a robust technique. But, it might not be practical. It takes too much of time to allow any meaningful action.
There is also a “theoretical” possibility of measuring IgM and IgG levels separately using single test and then comparing these levels, to give diagnosis. But it’s too complex and again can easily be inaccurate. I won’t discuss that theory here for a simple reason that I don’t think it can be used. So, forget this part and don’t get confused.
Question 9: Can we use antibodies from outside to cure COVID-19 infection?
Answer: Yes- but not always.
There are two types of “outside” antibodies- convalescent plasma and artificial antibodies.
Blood component collected from patients who have recently recovered is known as convalescent plasma They are rich in antibodies against the infection the patient recovered from. If another patient has been infected by same virus, convalescent plasma can be infused into such patient and the antibodies present will easily destroy the virus causing infection. Similarly, using genetic engineering techniques one can create such antibodies artificially in labs and can be injected directly to help a patient fight the infection.
The advantage of these “outside” antibodies is that patient doesn’t have to wait for his/her body to learn and prepare antibodies- it’s ready made here.
But this strategy doesn’t always work- especially in cases on viral infections such a COVID-19. Antibodies are highly specific. Antibodies against one strain might or might not work against another strain depending on how different the structures are. COVID-19 virus mutates rapidly and keeps changing its structure. So convalescent plasma from one patient might be ineffective in another patient. Same is the case with artificial antibodies such as Roche’s antibody cocktail (Casirivimab and Imdevimab).
Also, remember- in COVID-19 by Day 6 of symptoms there is actually no significant viral load that’s circulating. All the damage from that point is because of our own immune system. At this stage, it is illogical to target the virus. The target should be to calm the immune system.
I hope I was able to cover commonly asked questions regarding antibodies, especially in relation to COVID-19. I have already done a detailed post, which you can access here. But the current post was made honoring requests from many readers that they wanted a quick guide to their questions in the form of Q&A with one line answers.
Do let me know if I have missed any questions in your comments.