In a new study from Tel Aviv University, researchers found people who’ve been fully vaccinated against COVID-19 have a much stronger immune system response against the new coronavirus than those who’ve previously been infected.
They found vaccinated individuals had the highest antibody levels, nearly three times higher than that of convalescent individuals recovering from symptomatic COVID-19.
They also found while 99.4% of vaccinated people tested positive for COVID-fighting antibodies in blood samples just six days after their second dose of vaccine, less than 76% of people recovering from a COVID-19 infection were positive in an antibody test.
These findings might encourage people who believe they’re already well-protected because of a prior encounter with SARS-CoV-2 to go ahead and get vaccinated.
In the study, the team assessed COVID-19 antibody levels in more than 26,000 blood samples from vaccinated and unvaccinated people, along with people who’d recovered from their COVID-19 infections.
They also found that men and women have different antibody levels after either vaccination or infection.
Among those older than 51, antibody levels were found to be higher in women than in men.
This may be related to the change in levels of the female hormone estrogen, which occurs around this age and affect the immune system.
In men, a rise in antibody levels was seen starting around 35, possibly linked to changes in levels of the male sex hormone testosterone and its effect on the immune system.
In addition, young adults had a higher level of antibodies that lasted longer compared to older vaccinated adults.
In young adults, a high concentration of antibodies is usually due to a strong immune response, while in older people it usually indicates overreaction of the immune system linked to severe illness.
The team says further research is needed to obtain an in-depth understanding of the immune system’s response to COVID-19, to recovery from the disease, and to the vaccine.
The study is published in medRxiv. One author of the study is Noam Shomron.
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