Coronavirus vaccine: Are you still protected if you are fully vaccinated but have no antibodies?

COVID-19 vaccination is not just helpful to minimize infection risks but also benefits greatly in lowering severity and mortality rates associated with COVID-19. However, not only has the emergence of newer mutants made vaccines less effective, there are concerning reports that suggest that they may also lower antibody defence.

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A recent study done by the Indian Council of Medical Research (ICMR), for example, has currently shown that Covishield, one of the premier COVID-19 vaccines being used in the country is not only less effective against the Delta variant of the virus, but mounts a lower than expected antibody response. As many as 16% of fully vaccinated people, who got Covishield, had zero antibodies against COVID-19.

Vaccine-driven antibodies are a key marker in potentially evading the risk of infection, and showcasing how effective a vaccine could be. But, if a vaccine mounts no antibodies, despite proper administration, what risks does it exactly entail. More so, will you be still protected if you are fully vaccinated but have no antibodies?

A recent ICMR study, which focussed on the effectiveness of the Covishield (Oxford-Astrazeneca) vaccine, found that there were no neutralising antibodies found against the Delta variant in over 16.1% of people who had received both doses of the COVID-19 vaccine, which is also being widely-used globally.

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Not only has the study led to startling findings, but many experts also believe that the lack of neutralizing antibodies could also be one of the primary factors responsible for the emergence of breakthrough cases, or COVID-19 infections in those who have been fully vaccinated.

Additionally, contrasting the observation, the study has also found that the antibodies were highest amongst those who had a prior infection history and had been vaccinated. The levels of neutralizing antibody titlers were much higher than what was expected.

In the past, similar studies were also observed on the workability of Covaxin, which pegged that the vaccine prompted fewer or no antibodies upon vaccination.

Vaccine-generated antibodies help the immune system recognize the spike protein and remember the infection if a person happens to be infected in the future.

While most vaccines work well-effectively against the Alpha variant (SARS-COV-2 original strain), mutations allow the virus to easily surpass these antibodies, and in a way, reduce their strength and effectiveness. Lesser, or lesser potent antibodies would also mean that it is easier for a person to fall prey to the infection, or in this case, get reinfected.

To date, we do not know how lasting vaccine-driven immunity is. While there’s some evidence that suggests mRNA vaccines may mount lasting antibodies and promise immune protection in comparison to waning immunity with traditional vaccines like Covishield, there’s no proven link between the same.

Having said that, while experts continue to look into concrete evidence supportive of the same, immunity and antibody defence with vaccines could also be dependent on certain factors.

The effectiveness and ability of a COVID-19 vaccine to protect us could also be lowered down by a few factors- including a person's age, health condition and the natural ability of the immune system to fight pathogens.

A study, which was carried out on 2309 fully-vaccinated individuals by a professor from Banaras Hindu University (BHU) found that many elders did not develop any antibodies after getting both doses.

Not only does our immune system become 'weaker' as we age, and prone to mounting fewer defensive antibodies, several studies and research have established that the vaccines may be less effective or mount a poor immune response in someone who has diminished immunity, or suffers from comorbidities that impair immunity. Thus, the antibody defence could be surprisingly weaker in people who suffer from problems like these or have immuno-diminishing conditions.

Poor antibody response or nil at that could be genuinely concerning since we have newer mutations of COVID-19 posing a threat. Some also worry that even if cellular-level immunity remains, it may not be evident enough to be remembered or offer adequate protection.

So, to speak, a poor vaccine-driven antibody response or developing zero antibodies could imply that a person is still very much at risk. Having said that, it should be remembered that we have scanty data with us right now, and poor immunity with vaccines may not happen with everyone.

We are also looking at a reality where booster, additional shots may become a necessity, especially to protect people at risk. A team of researchers based out of Oxford University has currently showcased interim results proving lasting immunity and success rates with a potential, spaced-out third dose. If these circumstances are indeed true, additional doses may be required.

Do remember that even with the given factors, vaccines still offer some level of protection, albeit temporary, against the infection. While the ones at risk still need to put in preventable measures to safeguard themselves, the benefits of getting vaccinated definitely outweigh the cons.

There's been an exponential rise in the demands for antibody (quantitative IgG ) testing post vaccination. Factors like these could also prompt an individual to get tested and evaluate the risks they may face. However, experts still advise people to not do so.

For one, not only can faulty or improperly taken tests (done at the wrong time) give a wrong result, the diagnostic serology tests we have may not be accurately measuring vaccine-antibodies, or cellular level immunity that determines how protected one is. Therefore, it isn't any more reliable, or may not show effective results.

While antibody tests may not be a complete necessity, the best practices to ensure the vaccines are working well would be to strengthen the immune system naturally, minimize your risks from infection as much as you can and follow COVID-appropriate behaviour.