A new study conducted by hospital workers in Stockholm found that antibody levels following COVID-19 vaccination decline faster than previously thought, Swedish Television reported on Tuesday.
The finding, according to the Swedish media SVT, would help to understand why Sweden and other countries in which a large part of the population has been fully immunized have registered more and more cases of COVID-19 among those who duly received their two shots.
The research, whose objective was to better understand the effect of vaccines and estimate the speed with which the immunity provided by them decreases, included more than 2,000 vaccinated people from the health field in that country.
People who had been vaccinated with the Pfizer vaccine and had not been exposed to the virus before vaccination had 85% fewer antibodies seven months after the second dose.
Researchers found an even higher drop in the number of cases among those who received the AstraZeneca vaccine.
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In those who received the AstraZeneca vaccine, the decline was even more pronounced. Just three months after vaccination, the people who received the drug had only a fifth of the antibody levels of those vaccinated with Pfizer.
Some study participants received Moderna’s vaccine, but that group was too small and had too short a follow-up time for the researchers to draw any conclusions.
“As expected, antibody levels fall over time, but I am surprised that they have dropped so significantly in such a relatively healthy and young group,” Charlotte Thalin, the head of the research, told the media.
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Low antibody levels could result in the spread of COVID-19 even in vaccinated groups, which can have consequences in particular for the elderly, Thalin warned.
“This is worrying and indicates that older and more fragile people should receive a third booster dose as soon as possible,” added the specialist.
Sweden has already fully vaccinated more than 64% of its population of 10 million against the coronavirus. Since the beginning of the pandemic, the European country has registered 1.15 million cases and almost 15,000 deaths.
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