Antibody levels drop significantly over the weeks after COVID-19 vaccination – Innovita Research

Antibody levels drop significantly over the weeks after COVID-19 vaccination

COVID-19 pandemic is not over and it will not be over for quite some time. The only way we can bring the ending of it closer is by vaccinating. But for how long will these vaccines provide us the necessary protection? Scientists at UCL found that the total antibody levels appear to start declining from as early as six weeks after complete vaccination.

While vaccines can provide protection from COVID-19, it doesn't last forever. Image credit: Spencerbdavis via Wikimedia (CC.AS – 4.0)

Scientists analyzed data from over 600 people and found that two doses of the Pfizer or Astra Zeneca vaccine significantly increased the antibody count. In fact, vaccinated people have more antibodies than those who were sick with COVID-19 before. However, as predicted the antibody count decreases with time after the full vaccination. This doesn’t mean that people become unprotected – just that the most optimal protection against severe COVID-19 is achieved soon after vaccination.

For example, researchers found that in people vaccinated with Pfizer vaccines the antibody levels reduced from a median of 7506 U/mL at 21–41 days, to 3320 U/mL at 70 or more days. These numbers for Astra Zeneca were 1201 U/mL at first and 190 U/mL at 70 days or more. Scientists basically found that the level of antibodies can be reduced by more than 50% over 10 weeks. While at 10 weeks is still not a concern and vaccines remain effective, scientists are worried that over a longer period of time people will lose protection. This is especially important because of the new variants emerging and the sense of security that these vaccines provide.

Professor Andrew Hayward, one of the authors of the study, said: “When we are planning vaccination programmes around the world we need to take waning immunity and the likely need for booster doses into account – with limited global vaccine supply we need to balance protecting our most vulnerable through booster doses with ensuring we play a central role in supporting global vaccination efforts.“

Scientists note that the sample size of this study was not particularly big and further studies are absolutely necessary. However, it seems like better planning is also needed for vaccination programmes. It will be difficult to convince people to take vaccines if they find out that their effects are short-lived. While annual vaccination is expected, people are not going to vaccinate as enthusiastically if they need to do it several times per year. And this is a growing worry as new variants of the virus are emerging.

COVID-19 pandemic is not going to go anywhere. In many countries the number of new daily cases is growing regardless of the ongoing vaccination efforts. So now it is a race against the virus – if we vaccinate people quickly, maybe it will not have room to spread and will finally be away forever.


Source: UCL